Sediment-Associated Contaminants 

Caddo Lake, East Texas, 1940–2002

Water-Resources Investigations Report 03–4253

U.S. Department of the Interior

U.S. Geological Survey
Cover:

Left, Carter Lake; right, collecting box core at Carter Lake.
U.S. Department of the Interior

U.S. Geological Survey

Occurrence of and Trends in Selected

Sediment-Associated Contaminants in

Caddo Lake, East Texas, 1940–2002

By Jennifer T. Wilson

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03–4253

In cooperation with the U.S. Environmental Protection Agency, 

Region 6, Superfund Division

Austin, Texas

2003
ii

U.S. DEPARTMENT OF THE INTERIOR

Gale A. Norton, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Any use of trade, product, industry, or firm names is for descriptive or location 

purposes only and does not imply endorsement by the U.S. Government nor 

impute responsibility for any present or potential effects on the natural resources.

For additional information write to

District Chief

U.S. Geological Survey

8027 Exchange Dr.

Austin, TX 78754–4733

E-mail: dc_tx@usgs.gov

Copies of this report can be purchased from

U.S. Geological Survey

Information Services

Box 25286

Denver, CO 80225–0286

E-mail: infoservices@usgs.gov
CONTENTS iii

CONTENTS

Abstract ................................................................................................................................................................................ 1

Introduction .......................................................................................................................................................................... 2

Purpose and Scope .................................................................................................................................................... 2

Background ............................................................................................................................................................... 2

Study Design ............................................................................................................................................................ 5

Review of Existing Information ............................................................................................................................... 5

Acknowledgments .................................................................................................................................................... 9

Methods of Sediment Collection and Analysis .................................................................................................................... 9

Sediment-Core Collection Method ........................................................................................................................... 9

Sediment-Core Analytical Methods ......................................................................................................................... 10

Sediment-Core Age Dating ...................................................................................................................................... 13

Assessing Contaminant Levels ................................................................................................................................. 15

Trend Testing ............................................................................................................................................................ 17

Sediment-Core Burden and Focusing Factor ............................................................................................................ 17

Quality Assurance of Chemical Data ................................................................................................................................... 18

Occurrence and Trends ......................................................................................................................................................... 19

Goose Prairie Creek .................................................................................................................................................. 19

Age Dating and Sedimentation Rates ........................................................................................................... 19

Contaminant Occurrence and Trends ............................................................................................................ 21

Harrison Bayou ......................................................................................................................................................... 28

Age Dating and Sedimentation Rates ........................................................................................................... 28

Contaminant Occurrence and Trends ............................................................................................................ 28

Mid-Lake .................................................................................................................................................................. 33

Age Dating and Sedimentation Rates ........................................................................................................... 33

Contaminant Occurrence and Trends ............................................................................................................ 33

Carter Lake ............................................................................................................................................................... 33

Age Dating and Sedimentation Rates ........................................................................................................... 33

Contaminant Occurrence and Trends ............................................................................................................ 35

Sediment-Core Burdens, Focusing Factors, and General Sources of Mercury ........................................................ 36

Comparison of Findings to Those of Other Texas Lakes ......................................................................................... 39

Implications of Findings Relative to Drainage Area Sources of Contaminants ....................................................... 39

Summary .............................................................................................................................................................................. 42

References ............................................................................................................................................................................ 43

Appendixes

1. Descriptions of Sediment Push Cores .................................................................................................................. 47

1.1. Description of Sediment Push Cores Collected at Caddo Lake, Texas, May 2002 ................................... 48

2. Analytical and Trend Testing Results ................................................................................................................... 49

2.1. Analytical Results for Radionuclides ........................................................................................................ 50

2.2. Analytical Results for Organochlorine Compounds .................................................................................. 51

2.3. Analytical Results for Polycyclic Aromatic Hydrocarbons ....................................................................... 53

2.4. Analytical Results for Forms of Carbon and Major and Trace Elements .................................................. 58

2.5. Analytical Results for Petroleum Biomarkers ........................................................................................... 61

3. Quality-Assurance Data ........................................................................................................................................ 63

3.1. Quality-Control Samples for Radionuclides .............................................................................................. 64

3.2. Quality-Control Samples for Organochlorine Compounds ....................................................................... 65

3.3. Quality-Control Samples for Polycyclic Aromatic Hydrocarbons ............................................................ 68

3.4. Quality-Control Samples for Forms of Carbon and Major and Trace Elements ....................................... 76

3.5. Quality-Control Samples for Petroleum Biomarkers ................................................................................ 88
iv 

FIGURES

1–3. Maps showing: 

1. Locations of Longhorn Army Ammunition Plant (LHAAP) and bottom-sediment coring sites 

sampled in Caddo Lake, Texas, May 2002 ................................................................................................ 3

2 Drainage areas of creeks and contaminated or potentially contaminated areas on Longhorn Army 

Ammunition Plant (LHAAP), Texas, identified by U.S. Army during a public health assessment 

of the plant in July 1999 ............................................................................................................................. 4

3. Drainage areas of interest defined using digital elevation models and possible sources of 

contamination (PSOCs) identified by U.S. Geological Survey Source Water Assessment Program 

in the Caddo Lake, Texas, area .................................................................................................................. 8

4–15. Graphs showing: 

4. Relation between logarithm of unsupported lead-210 and cumulative dry mass in cores from 

(a) mid-lake and (b) Carter Lake, Caddo Lake, Texas, May 2002 ............................................................. 14

5. Mean annual precipitation at National Weather Service station in Karnack, Texas, 1943–97; 

monthly mean discharge in Big Cypress Creek near Jefferson, Texas, 1930–2000; and daily lake

altitude at Caddo Lake dam, Louisiana, 1932–2000 .................................................................................. 16

6. Concentrations of selected constituents used to compute sediment deposition dates in cores 

collected at (a) Goose Prairie Creek, (b) Harrison Bayou, (c) mid-lake, and (d) Carter Lake sites, 

Caddo Lake, Texas, May 2002 ................................................................................................................... 20

7. Organochlorine pesticide (DDE and DDD) and polychlorinated biphenyl (PCB) concentrations in 

cores collected from Caddo Lake, Texas, May 2002 ................................................................................. 22

8. Selected polycyclic aromatic hydrocarbon (PAH) concentrations and trends in core collected near 

Goose Prairie Creek, Caddo Lake, Texas, May 2002 ................................................................................ 23

9. Selected trace element concentrations and trends in core collected near Goose Prairie Creek, 

Caddo Lake, Texas, May 2002 ................................................................................................................... 29

10. Selected polycyclic aromatic hydrocarbon (PAH) concentrations in core collected near Harrison 

Bayou, Caddo Lake, Texas, May 2002 ...................................................................................................... 30

11. Selected trace element concentrations and trends in core collected near Harrison Bayou, Caddo 

Lake, Texas, May 2002 .............................................................................................................................. 32

12. Selected polycyclic aromatic hydrocarbon (PAH) concentrations in core collected in mid-lake of 

Caddo Lake, Texas, May 2002 ................................................................................................................... 34

13. Selected trace element concentrations and trends in core collected in mid-lake of Caddo Lake, 

Texas, May 2002 ........................................................................................................................................ 35

14. Selected polycyclic aromatic hydrocarbon (PAH) concentrations and trends in core collected 

from Carter Lake, Caddo Lake, Texas, May 2002 ..................................................................................... 37

15. Selected trace element concentrations and trends in core collected from Carter Lake, Caddo 

Lake, Texas, May 2002 .............................................................................................................................. 38

TABLES

1. Description of sediment box cores collected from Caddo Lake, Texas, May 2002 ............................................. 9

2. Constituents and laboratory reporting levels for samples collected from Caddo Lake, Texas, May 2002 ........... 11

3. Selected consensus-based sediment-quality guidelines used to assess contaminant concentrations in 

cores collected from Caddo Lake, Texas, May 2002 ............................................................................................ 15

4. Summary of trend testing results for organochlorine compounds detected in sediment cores from Caddo 

Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date ................................. 24

5. Summary of trend testing results for polycyclic aromatic hydrocarbon compounds detected in sediment 

cores from Caddo Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition 

date ........................................................................................................................................................................ 25

6. Summary of trend testing results for major and trace elements detected in sediment cores from Caddo 

Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date ................................. 27

7. Summary of results of analysis for selected trace elements in sediment cores from Caddo Lake, Texas, 

May 2002 .............................................................................................................................................................. 31
CONTENTS v

8. Sediment focusing data and core burdens for mercury, Caddo Lake, Texas, May 2002 ...................................... 36

9. Summary of trace element and selected PAH concentrations and ratio of 2- and 3-ringed to 4- and 5-ringed 

PAH assemblages in sediment cores from Caddo Lake, Texas, May 2002, from Lake Meredith, Texas, May 

1999, and from Cottonwood Bay in Mountain Creek Lake, Texas, May–July 1996 ........................................... 40

VERTICAL DATUM

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). 
Abstract 1

Occurrence of and Trends in Selected 

Sediment-Associated Contaminants in 

Caddo Lake, East Texas, 1940–2002

By Jennifer T. Wilson

Abstract

Bottom-sediment cores were collected from 

four sites in Caddo Lake in East Texas during 

May 2002 for analyses of radionuclides (for age 

dating), organochlorine pesticides, polychlorinated 

biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and major and trace elements, and 

to describe the occurrence and trends of these 

sediment-associated contaminants. The Goose 

Prairie Creek and Harrison Bayou sites receive 

drainage from an area that includes parts of the 

now-closed Longhorn Army Ammunitions Plant. 

The mid-lake site is relatively close to dense oil and 

gas operations in the lake. The Carter Lake site 

receives minimal discharge from developed areas.

Sediment age (deposition) dates represented 

in the cores ranged from 1940 to 2002. The only 

organochlorine compounds detected in all core 

samples were the DDT degradation products DDE 

or DDD, and PCB Aroclors 1242, 1254, and 1260 

were detected only at the Goose Prairie Creek site. 

One or more of the DDE concentrations at all sites 

exceeded a consensus-based threshold effect concentration (on benthic biota), but none exceeded a 

consensus-based probable effect concentration. 

The Goose Prairie Creek site had significant downward trends in concentrations of organochlorine 

compounds, except for no trend in DDE concentrations. The Ammunitions Plant is a possible historical source of the few organochlorine compounds 

detected at the Goose Prairie Creek and Harrison 

Bayou sites.

PAH concentrations at all sites were below 

respective threshold effect concentrations. Highest 

PAH concentrations at all four sites were of C2-

alkylated naphthalenes. Nearly all statistically significant PAH trends in the cores were downward. 

On the basis of PAH source-indicator ratios, the 

majority of PAH compounds appear to have originated from uncombusted sources such as leaks or 

spills from oil and gas operations or vehicles (automobiles, boats, aircraft) in the Caddo Lake area.

Concentrations of several of the eight trace 

elements with threshold effect concentrations and 

probable effect concentrations (among 26 analyzed) were above the respective threshold effect 

concentrations, but all, except one lead concentration at the Goose Prairie Creek site (deposited 

about 1961), were below respective probable effect 

concentrations. Among trace element concentrations at the four sites, lead and mercury were consistently relatively high at the Goose Prairie Creek 

site. Again the Ammunitions Plant, because of its 

proximity and history of industrial activities, is the 

suspected primary source. Statistically significant 

trends in trace element concentrations were mixed, 

but more were downward than upward.

Computations to indicate the dominant 

source (atmospheric fallout or drainage area) of 

mercury to the Caddo Lake sediment core sites 

(except Carter Lake) indicate that about one-third 

of the mercury at the Goose Prairie Creek site 

might result from drainage area sources. No drainage area sources were indicated for the Harrison 

Bayou and mid-lake sites. Arsenic, cadmium, and 

zinc concentrations were highest at the Carter Lake 

site. No relation between the relatively higher trace 

element concentrations and any potential source of 

contamination in the Carter Lake drainage area (for 

example, oil and gas operations, a road, a boat 

ramp) is indicated.
2 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

INTRODUCTION

Caddo Lake in East Texas (and Louisiana) (fig. 1) 

is designated a Wetlands of International Importance by 

the Ramsar Convention on Wetlands (an intergovernmental treaty to promote the wise use of wetlands) and 

is home to numerous and unique species of fish, birds, 

and plants (Ramsar Sites Database, 2003). Caddo Lake 

serves as the primary source of drinking water for several surrounding communities (for example, Uncertain 

and Karnack) and provides recreational opportunities 

and lakeshore residential areas. It is the only natural 

lake in Texas—that is, it was not impounded by humans. 

The most widely accepted hypothesis regarding the origin of the lake is that the water was pooled in the early 

1800s by a logjam. About 1914 the logjam was replaced 

with a constructed dam on the Louisiana end of the lake 

to stabilize water levels. The lake was re-dammed in 

1971, which increased the surface area of the lake to its 

current (2003) 103 square kilometers (km2). The Caddo 

Lake drainage area is estimated from digital elevation 

models to be 7,230 km2

 (Toby Welborn, U.S. Geological Survey, written commun., 2002). 

The Longhorn Army Ammunitions Plant 

(LHAAP) operated on the southwestern shore of Caddo 

Lake for 55 years as a munitions loading and assembly 

facility. The LHAAP has several areas of known 

contamination, and surface runoff from the plant 

drains toward Caddo Lake (fig. 2). Several sedimentassociated contaminants are of concern to waterresource managers because of their common occurrence 

and toxicity. For example, the Agency for Toxic Substances and Disease Registry (ATSDR) releases a priority list of substances as required by the Comprehensive 

Environmental Response, Compensation, and Liability 

Act (CERCLA). This list describes, in order of priority, 

275 substances that are most commonly detected at 

facilities on the (Superfund) National Priorities List 

(NPL) and that have been determined to pose the most 

substantial potential threat to human health because of 

their known or suspected toxicity and potential for 

human exposure at NPL sites (Agency for Toxic Substances and Disease Registry, 2001). The LHAAP was 

placed on the NPL in August 1990. The analyses of the 

sediment samples from Caddo Lake yielded 54 of the 

275 substances on the ATSDR CERCLA priority list 

including eight of the top 10 substances. 

The U.S. Army Corps of Engineers (USACE) 

and the Texas Commission on Environmental Quality 

(TCEQ) (formerly the Texas Natural Resource Conservation Commission) have sampled Caddo Lake bottom 

sediments in Texas extensively (Texas Natural Resource 

Conservation Commission, 2002a, 2002b; Cliff Murray, 

U.S. Army Corps of Engineers, unpub. data, 2002). 

However, both agencies described only the occurrence 

of contaminants and did not describe contaminant 

trends over time. The bottom sediments in Caddo Lake 

(Texas part only) were sampled in May 2002 by the 

U.S. Geological Survey (USGS), in cooperation with 

the U.S. Environmental Protection Agency, Region 6, 

Superfund Division. The evaluation of contaminant 

trends over time can be used to improve knowledge 

of possible contaminant sources, the extent of contamination in the sediments, and the potential effects on 

aquatic biota, and can be used to determine whether 

conditions are getting better or worse. 

Purpose and Scope

The purpose of this report is to describe the occurrence of and trends in selected sediment-associated 

contaminants in age-dated sediment cores from four 

sites in the Texas part of Caddo Lake. Radionuclides 

were used to age date the sediment layers in the cores, 

which makes possible evaluation of changes in contaminant concentrations over time. The report explains the 

age-dating process and associates dates of deposition 

with successive intervals in each core. Concentrations 

of selected organochlorine compounds, polycyclic aromatic hydrocarbons (PAHs), and trace elements are 

compared to sediment-quality guidelines that reflect 

relative sediment toxicity to aquatic biota. Trends based 

on contaminant concentrations in intervals of core 

sediment were tested for statistical significance. Potential sources of contaminants, particularly mercury, are 

discussed.

Background

Caddo Lake can be described as a wetland with 

bottomland hardwoods and bald cypress swamps. The 

habitats of the lake support some of the largest populations of wood ducks and mallards in Texas, in addition 

to migratory birds, restricted wetland species (American alligator and river otter), and other wildlife such as 

the barred owl, gray squirrel, beaver, and green heron 

(Cloud and Short, 1993). The lake supports Texas’ most 

diverse fish fauna—one study collected 69 species 

(Gray, 1955)—and is described by the Texas Parks and 

Wildlife Department as “the epitome of fish habitat, 

supporting large populations of largemouth bass, black 
INTRODUCTION 3

TEXAS

LOUISIANA

Kitchen 

James Bayou

Harold

Creek

Mill Creek

James Bayou

BIG

CYPRESS

CREEK

Haggerty Creek

Watson

Bayou

Creek

Hunts Creek

onterey M

Lake

CADDO LAKE

CLINTON LAKE

CARTER LAKE

P

AA

H

L

AA

H

L AA H

P

EXPLANATION

Longhorn ArmyAmmunitionPlant (LHAAP)Caddo Lake StatePark boundaryUSGS sediment coring site

and core identifier CDO.MD

94o

32o45'

32o37'30"

94o07'30"

0 5 10 KILOMETERS

Study

area

TEXAS

LongwoodOil Field

Rodessa Oil Field

Vivian Oil Field

Vivian Oil Field

Oil Field

Pine Island

Oil Branch

PotterOilField

Base from U.S. Geological SurveyDigital data: 1:100,000Universal Transverse Mercator projectionZone 15

CDO.MD

CDO.HB

CDO.GP

CDO.CR

Mooringsport

Vivian

Potters Point

Karnack

Uncertain

OilCity

HorseIsland

LittleGreenBrake

Figure 1. Locations of Longhorn Army Ammunition Plant (LHAAP) and bottom-sediment coring sites sampled in Caddo Lake, Texas, May 2002. 
4 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

CADDO LAKE

CYPRESS

CREEK

Karnack

Uncertain

Caddo Lake 

State Park

Drainage area

 

Goose Prairie Creek

Central Creek

Harrison Bayou

Saunders Branch

Boundary of LHAAP

A

B 

C

D

E 

Contaminated or potentially contaminated area

Burning ground no. 3 and

unlined evaporation pond

Old landfill

Former TNT production area

Ground signal test area

South test area

USGS sediment coring

site and core identifier

EXPLANATION

CDO.GP

CDO.HB

CDO.GP

Saunders

Harrison Branch

Bayou

Central Creek

Goose

Prairie

Creek

B A

C

D

E

32o

37'30"

94o

07'30"

32o

41'15"

94o

11'15"

0 1 2 3 4 5 KILOMETERS Base from U.S. Geological Survey

Digital data: 1:100,000

Universal Transverse Mercator projection

Zone 15

Figure 2. Drainage areas of creeks and contaminated or potentially contaminated areas on Longhorn Army 

Ammunition Plant (LHAAP), Texas, identified by U.S. Army during a public health assessment of the plant in July 

1999 (Texas Department of Health, 1999). 
INTRODUCTION 5

and white crappie, channel catfish, and bluegill” (Toole 

and Ryan, 1981, in Cloud and Short, 1993, p. 5). Several 

other fish species also are supported by Caddo Lake, for 

example, bowfin, paddlefish, American eel, southern 

brook lamprey, and chain pickerel. Caddo Lake and its 

forested wetlands of mature bald cypress and bottomland hardwoods are considered a unique, fragile, and 

irreplaceable high-quality habitat for fish and wildlife 

(Cloud and Short, 1993). 

Caddo Lake overlies the Caddo oil and gas field. 

Oil production in Caddo Lake and its drainage area 

began in the early 1900s. Gulf Oil Corporation leased 

the bottom of Caddo Lake for oil development and built 

the first over-water drilling platform in 1911. Most of 

the current (2003) producing wells in the lake are in 

Louisiana. 

The LHAAP operated from 1942 to 1997 on the 

southwestern shore of Caddo Lake near the towns of 

Karnack and Uncertain (fig. 1). The plant manufactured 

trinitrotoluene (TNT) and rocket motors; loaded, 

assembled, and packed pyrotechnic and signal ammunition; and performed rocket demilitarization (U.S. Environmental Protection Agency, 2002). Five areas on the 

LHAAP (A–E, fig. 2) have active releases of contaminants to surface water: (active) burning ground no. 3, 

old landfill, former TNT production area, ground signal 

test area, and south test area. In addition, 15 other areas 

are contaminated or possibly contaminated and have the 

potential for contaminant migration off the LHAAP 

(U.S. Environmental Protection Agency, 2002). The 

LHAAP site was designated as the Caddo Lake 

National Wildlife Refuge in October 2000 and will be 

transferred to the U.S. Department of the Interior, U.S. 

Fish and Wildlife Service, as areas are designated 

appropriate for use as a wildlife refuge (U.S. Environmental Protection Agency, 2002). 

Study Design

The study was designed to sample and analyze the 

bottom sediments in Caddo Lake to indicate whether 

contaminants associated with historical activities at the 

now-closed LHAAP are being transported into Caddo 

Lake and if the amount of contaminants associated with 

activities at the LHAAP or other potential sources has 

changed over time. Four natural drainage areas direct 

runoff and stormwater from the LHAAP into Caddo 

Lake: Goose Prairie Creek, Central Creek, Harrison 

Bayou, and Saunders Branch (fig. 2). The estimated percentages of surface water draining from the LHAAP 

through the four creeks are 30 percent in Goose Prairie 

Creek, 29 percent in Central Creek, 30 percent in Harrison Bayou, and 11 percent in Saunders Branch (Texas 

Department of Health, 1999). 

Two sediment cores were collected near the 

shores of the LHAAP, one near the mouth of Goose 

Prairie Creek (core CDO.GP) and one near the mouths 

of Central Creek, Harrison Bayou, and Saunders Branch 

(core CDO.HB) (figs. 1, 2). These two sites were 

selected to assess the occurrence and trends of contaminants that might enter the lake from the LHAAP and to 

determine if sediment-bound contaminants presumably 

from the Goose Prairie Creek drainage area differed 

from those presumably from the three other drainage 

areas. Another core was collected from the middle of 

the main body of the lake (core CDO.MD) (fig. 1). This 

third site was selected to indicate whether contaminants 

are being transported into the main body of the lake and 

whether oil and gas production or industrial activity in 

Caddo Lake and its drainage area have released contaminants to the lake sediments, such as through improper 

drilling-mud disposals or oil spills. The CDO.MD core 

was collected near an abandoned oil pipeline. The 

fourth core was collected from upper Caddo Lake in an 

area called Carter Lake (core CDO.CR) (fig. 1). This 

site was selected to indicate background concentrations 

of contaminants because the location does not receive 

runoff from the LHAAP and is far from the area of the 

lake with dense oil and gas operations. No residential, 

commercial, or industrial development is near the 

CDO.CR core site. Industrial activity could be a source 

of contaminants, however, through atmospheric transport and deposition. 

Review of Existing Information

There have been numerous studies of Caddo Lake 

and its drainage areas because it is such a unique and 

biologically important area. The topics of studies 

include local history, habitat, possible contaminant 

sources (such as on-site studies of the LHAAP), and 

contaminant concentrations in various media in and 

around Caddo Lake (for example, Gray, 1955; Cloud 

and Short, 1993; Crowe, 1996; U.S. Environmental Protection Agency, 2002). This section describes existing 

information that is readily available. 

The ATSDR classifies the LHAAP as a hazardous 

waste site and has a site contaminants list showing the 

presence of 233 chemicals in various media on the site 

(Agency for Toxic Substances and Disease Registry, 
6 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

2003). Of relevance to this report is the documented 

presence of arsenic, barium, beryllium, cadmium, 

chromium, copper, lead, manganese, nickel, strontium, 

zinc, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-

DDE), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane 

(p,p'-DDT), dieldrin, and aldrin in the soils or the sediment of the LHAAP, or both. Only three contaminant 

concentrations for the soils and sediments sampled 

on-site were reported: 1,290 milligrams per kilogram 

(mg/kg) of lead and 25.4 mg/kg of dieldrin in the soil 

and 20,500 mg/kg of barium in the sediment. Mercury 

was not listed as a contaminant in soil or sediment samples from the LHAAP; however, it does not appear that 

soil or sediment samples were analyzed for mercury. 

Mercury was reported at 3.3 micrograms per liter (μg/L) 

in ground-water samples collected during a health 

assessment at the plant. 

The Texas Department of Health (TDH) released 

a public health assessment of the LHAAP in July 1999 

that stated the site posed no apparent public health hazard (Texas Department of Health, 1999). The public 

health assessment cites releases of arsenic, barium, 

chromium, and lead on the LHAAP and their presence 

in ground water. Production wastes were washed into 

ponds or buried in landfills until about 1984. Areas 

identified by the Army as contaminated or potentially 

contaminated during the Installation Restoration Program by the Department of Defense included burning 

ground no. 3 where flammable wastes were burned 

beginning in the early 1950s; the unlined evaporation 

pond, which received about 61 cubic meters per day 

(16,000 gallons per day) of waste containing arsenic, 

barium, chromium, lead, and zinc during 1972–84; the 

old landfill where TNT wastes were disposed during 

1942–44; the former TNT production area; and the 

ground signal and south test areas where rocket motors 

and ammunition were tested (fig. 2). 

The USACE sampled sediment in Caddo Lake 

three times. The first round of sampling was in August 

2000 and included samples from Caddo Lake near the 

inlets of Goose Prairie Creek, Harrison Bayou, Central 

Creek, and Saunders Branch. Samples were analyzed 

for major and trace elements, organochlorine pesticides, 

organophosphorus pesticides, herbicides, polychlorinated biphenyls (PCBs), explosives, volatile organic 

compounds (VOCs), semivolatile organic compounds 

(SVOCs) that included several PAHs, and dioxins and 

furans. The second round of sampling was in May 2001 

in Clinton Lake (northwestern part of Caddo Lake; 

fig. 1) to determine background concentrations. The 

samples were analyzed for major and trace elements 

and dioxins and furans. The final round of sampling was 

in March 2002 and focused on sediments near the inlets 

of Goose Prairie Creek and Harrison Bayou, and in 

Clinton Lake. Samples were analyzed for eight trace 

elements (arsenic, cadmium, chromium, copper, lead, 

nickel, silver, and zinc), PCBs, perchlorate, and dioxins 

and furans. During all sampling events the bottom-sediment samples were collected to a depth of 0.46 meter 

(m), and three 0.15-m sediment intervals were analyzed. 

The USACE compared sample concentrations to 

the sediment-quality guidelines (SQGs) of Long and 

others (1995) to determine which constituents were at 

levels of concern in regard to adverse biological effects 

(Cliff Murray, U.S. Army Corps of Engineers, written 

commun., 2002). The two SQGs recommended by Long 

and others (1995) were based on data obtained from 89 

reports that contained chemical data and simultaneous 

measures of biological effects: (1) the effects range-low 

(ER–L) and (2) the effects range-median (ER–M) concentrations. Sediment concentrations below the ER–L 

were “rarely” associated with adverse biological effects. 

Concentrations above the ER–L but below the ER–M 

were “occasionally” associated with adverse biological 

effects; those above the ER–M were “frequently” associated with adverse biological effects. Several trace elements had concentrations that exceeded the SQGs—that 

is, concentrations that were above threshold concentrations associated with “occasional” or “frequent” 

adverse biological effects. Lead, mercury, and silver 

concentrations exceeded the ER–Ms in the upper two 

sampled depth intervals (0 to 0.15 and 0.15 to 0.3 m) 

from the near Goose Prairie Creek inlet site. The samples from Harrison Bayou had one concentration of 

mercury and one concentration of nickel that exceeded 

the ER–Ls, both in the 0.15- to 0.3-m interval in two different cores. The top interval from one core collected 

near Central Creek had concentrations of mercury and 

nickel that exceeded the ER–Ls. Arsenic, nickel, and 

mercury concentrations exceeded the ER–Ls in the 

upper two intervals of the samples from Clinton Lake. 

The cores collected near Saunders Branch had no trace 

element concentrations that exceeded the SQGs of Long 

and others (1995). 

There were a few detections of VOCs and SVOCs 

in the cores from near Goose Prairie Creek. Commonly 

detected compounds were acetone, carbon disulfide, 

and phenol. The cores from near Goose Prairie Creek 

had several PAHs at concentrations of 1,000 to 3,000 

micrograms per kilogram (μg/kg). Acetone and carbon 
INTRODUCTION 7

disulfide also were detected in the cores from near Harrison Bayou, Central Creek, and Saunders Branch. 

VOCs were not analyzed in the Clinton Lake cores 

(U.S. Army Corps of Engineers, written commun., 

2002). SQGs are not included for VOCs and SVOCs 

(Long and others, 1995). 

A fish consumption advisory was issued by the 

TDH in November 1995 that included Caddo Lake and 

Big Cypress Creek (fig. 1), discouraging the consumption of largemouth bass and freshwater drum because of 

elevated mercury concentrations (Texas Department of 

Health, 1995). Caddo Lake is one of five East Texas 

lakes for which fish consumption advisories have been 

issued because of elevated mercury concentrations in 

largemouth bass and freshwater drum. The TDH and 

TCEQ have sampled several species of fish from Caddo 

Lake for mercury and have detected concentrations 

ranging from 0.14 to 1.63 parts per million (ppm) 

(Crowe, 1996). The mercury is thought to be from 

atmospheric deposition of nonpoint-source emissions 

(Texas Department of Health, 1999). Possible sources 

of emissions of mercury in the Big Cypress Creek Basin 

include a lignite-fired power plant, a coal-fired power 

plant, a chicken-processing plant, and a steel company, 

but emissions distant from the basin could be sources of 

mercury as well. Mercury was not used at the LHAAP 

and has not been detected in its permitted discharge 

(Crowe, 1996). Caddo Lake has favorable conditions for 

mercury methylation and subsequent uptake into the 

aquatic food chain, such as low pH, low alkalinity, low 

dissolved calcium, high dissolved organic carbon, high 

sulfate, and seasonally flooded wetlands (Lange and 

others, 1993; Wiener, 1995; Crowe, 1996; Krabbenhoft 

and others, 2002). 

The TCEQ currently (2003) samples Caddo 

Lake as part of its Surface Water Quality Monitoring 

Program. A draft version of the 2002 Water Quality 

Inventory (Texas Natural Resource Conservation Commission, 2002a, p. 11) listed sediment contaminants of 

concern at two sites (mid-lake and Carter Lake) and 

their possible sources. Two TCEQ sampling sites were 

near two of the coring sites of the study documented in 

this report (CDO.MD and CDO.CR). TCEQ data from 

March 1996 through February 2001 listed lead, manganese, mercury, and zinc as metals of concern in the 

samples collected from the mid-lake site. Barium, manganese, mercury, selenium, and zinc were listed as contaminants of concern at the Carter Lake site. At least 

two possible sources were identified by the TCEQ: 

industrial activity for lead, manganese, mercury, and 

zinc at the mid-lake site and for manganese, mercury, 

selenium, and zinc at the Carter Lake site; oil and gas 

drilling for barium at the Carter Lake site (because barium is used in drilling mud to increase specific gravity) 

(Texas Natural Resource Conservation Commission, 

2002b). 

Crowe (1996) summarized the mercury concentrations in water, sediment, soil, and fish samples 

collected from the Big Cypress Creek Basin during 

May–October 1994. Sediment samples were collected 

from two sites in Caddo Lake using an Eckman dredge. 

The sites were identical to the TCEQ sampling locations, one in mid-lake and the other in Carter Lake. 

Mercury concentrations in the sediment samples collected from the mid-lake site ranged from less than 

0.01 to 1.57 ppm, and those from the Carter Lake site 

did not exceed the reporting level of 0.01 ppm. 

Possible sources of contamination (PSOCs) were 

identified by various State agencies and compiled by the 

USGS as part of the Source Water Assessment Program 

(SWAP) of the TCEQ. SWAP was developed to comply 

with 1996 amendments to the Safe Drinking Water Act 

that require States to develop and implement programs 

to analyze existing and potential threats to the quality of 

public drinking water in each State (U.S. Environmental 

Protection Agency, 2003). The PSOC database included 

the location of the PSOC, the source of the data, a list of 

regulated contaminants associated with the PSOC, and 

the method of introduction of the contaminant into the 

environment. The majority of PSOCs in the Caddo Lake 

area are oil and gas wells, but other PSOCs in the area 

include private and industrial wastewater outfalls, 

mined land, abandoned municipal solid-waste sites, an 

airport, roads, a marina, and boat ramps (fig. 3). About 

50 aircraft per year use two oiled-dirt runways of the 

private airport (AirNav.com, 2003). Boating is popular 

in the lake; however, dense vegetation and numerous 

obstructions such as trees and oil wells in the lake 

require careful navigation of the waters. Thus, most 

probably follow the channels or “boat roads” that are 

dredged throughout the lake to provide a pathway clear 

of the thick aquatic vegetation. 

The National Atmospheric Deposition Program 

collected weekly precipitation samples from a site at 

Longview, Tex. (site TX21), in cooperation with the 

TCEQ (National Atmospheric Deposition Program, 

2003). The Longview site is part of the Mercury Deposition Network, which has been providing precipitation 

samples for total mercury analysis since 1995. Longview is about 72 kilometers southwest of Caddo Lake. 
8 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

1

2

3

4

5

6

6

5

4

3

2

1

EXPLANATION

Drainage area

Saunders Branch

Harrison Bayou

Central Creek 

Goose Prairie Creek 

Carter Lake coring site

Kitchen Creek 

Possible source of

contamination

Producing oil or gas well

Plugged oil or gas well

Cemetery

Injection well

Petroleum storage

Livestock or animal pens

Septic system

Railroad

Airport

Marina

Boat ramp

Wastewater

Private wastewater outfall

Industrial wastewater outfall

Mined land (active or 

abandoned)

Abandoned municipal 

solid waste

Industrial hazardous 

waste site

Superfund site

Corrective action site

Perchlorate site

Base from U.S. Geological Survey

Digital data: 1:100,000

Universal Transverse Mercator projection

Zone 15

0 1 2 3 4 5 6 7 KILOMETERS

32o

45'

32o

37'30"

32o

30'

94 94 o o

94 07'30" o

15'

Horse

Island

Little

Green

Brake

CADDO

 LAKE

CLINTON

 LAKE

CARTER

 LAKE

Figure 3. Drainage areas of interest defined using digital elevation models and possible sources of contamination 

(PSOCs) identified by U.S. Geological Survey Source Water Assessment Program (R.L. Ulery, U.S. Geological 

Survey, written commun., 2002) in the Caddo Lake, Texas, area.
METHODS OF SEDIMENT COLLECTION AND ANALYSIS 9

Complete mercury data were available for 1996–2001. 

The annual deposition of mercury at the Longview site 

increased from 9,000 nanograms per square meter 

(ng/m2

) in 1996 to 15,000 ng/m2 in 2001 (National 

Atmospheric Deposition Program, 2003). Sulfate concentrations, a constituent important for mercury methylation (Krabbenhoft and others, 2002), were available 

for precipitation samples collected during 1983–2001. 

The average annual sulfate deposition was 17.6 kilograms per hectare (kg/ha) (1.76 grams per square meter 

[g/m2]), with peak sulfate deposition occurring in 1991 

at 23.7 kg/ha (2.37 g/m2

) (National Atmospheric Deposition Program, 2003).

Acknowledgments

The author thanks Dr. Roy Darville of East Texas 

Baptist University for taking the USGS sampling team 

on his boat during lake reconnaissance and sediment 

coring. Thanks to Dwight Shellman, president of the 

Caddo Lake Institute, for the use of his dock during 

USGS sampling activities. Thanks also to Cliff Murray, 

USACE, for assistance during reconnaissance of the 

LHAAP and sediment-core collection. 

METHODS OF SEDIMENT COLLECTION 

AND ANALYSIS

This section describes the methods used in the 

sediment study at Caddo Lake. The methods descriptions will be in the order in which they were used—first, 

a description of how the sediment cores were collected 

from Caddo Lake and subsampled for analyses; second, 

the analytical methods used by the several laboratories 

to analyze the sediment samples; third, an overview of 

the methods used to compute and estimate deposition 

dates for each sample interval; fourth, the criteria used 

to assess the degree of sediment contamination; then, 

the trend test used to assess temporal trends is briefly 

discussed; and finally, sediment-core burdens and 

focusing factors.

Sediment-Core Collection Method

Sediment box cores were collected by the USGS 

in May 2002 for chemical analyses of radionuclides (for 

age dating), organochlorine pesticides, PCBs, PAHs, 

petroleum biomarkers, forms of carbons, and major and 

trace elements. Cores were collected from Caddo Lake 

near the inlet of Goose Prairie Creek (CDO.GP), near 

the inlet of Harrison Bayou (CDO.HB), in the main 

stem of the lake (mid-lake) near Little Green Brake 

(CDO.MD), and in Carter Lake near Horse Island 

(CDO.CR) (fig. 1; table 1). The samples were collected 

using a custom-built 14- by 14- by 30-centimeter (cm) 

aluminum Wildco box corer. An extension rod was 

attached to the top of the box corer and used to lower the 

corer onto the bottom and gently press it through the 

sediment until 20 to 30 cm of sediment was penetrated 

or the corer could not be pushed deeper because consolidated material was encountered. After a box core was 

obtained at a sampling site, the core was transported 

back to shore and subsampled to minimize sediment 

disturbance. 

The box cores were subsampled by placing the 

box core liner containing the sample onto a piston and 

pushing the sample up through the core liner. Small 

intervals of the sediment were sliced off the top of the 

Table 1. Description of sediment box cores collected from Caddo Lake, Texas, May 2002 

[m, meters; cm, centimeters] 

Site name

Core 

identifier

(fig. 1)

Latitude and

longitude

of site

USGS

site ID

Water

depth

(m)

Box core

length

(cm)

Caddo Lake near Goose Prairie 

Creek inlet

CDO.GP N 32°42'08.0"

W 94°07'34.6"

324208094073500 0.86 30

Caddo Lake near Harrison Bayou 

inlet

CDO.HB N 32°41'13.2"

W 94°06'18.7"

324113094061900 1.2 20

Caddo Lake mid-lake (main stem 

near Little Green Brake)

CDO.MD N 32°41'02.2"

W 94°04'13.6"

324102094041400 2.4 13

Carter Lake near Horse Island CDO.CR N 32°44'24.5"

W 94°09'45.7"

324424094094600 1.95 25
10 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

core and placed into sample containers for analysis. The 

Goose Prairie Creek and Harrison Bayou cores were 

subsampled at 1-cm intervals throughout their lengths. 

The mid-lake box core was subsampled at 0.5-cm intervals from 0 to 10 cm and at 1-cm intervals below 10 cm. 

The Carter Lake core was subsampled at 0.5-cm intervals from 0 to 5 cm and at 1-cm intervals below 5 cm. 

Samples for organic analysis were placed into prebaked glass jars, and samples for inorganic analysis 

were placed in polypropylene jars. All samples were 

immediately stored on ice and frozen upon arrival at the 

USGS Austin office. Sample identifiers include the site 

and depth interval; for example, CDO.GP 1–2 is the 

1- to 2-cm depth interval of the Goose Prairie Creek box 

core.

Push cores also were collected at each sampling 

site for description. A push core was collected by pushing a hollow cylinder (6-cm diameter) through the sediment until it could not be pushed farther. The push cores 

were capped and stored in the upright position until the 

following day when they were extruded, and their color 

and texture were described (appendix 1). No further 

analyses were done on the push core samples. 

Sediment-Core Analytical Methods

Box core samples from the four coring sites were 

analyzed for radionuclides (table 2) by Severn Trent 

Laboratories, Inc., Richland, Wash. (STL Richland), 

under contract with the USGS National Water Quality 

Laboratory (NWQL), Denver, Colo. Samples were 

freeze-dried and ground to a fine powder. Cesium-137 

(

137Cs) was analyzed by gamma spectroscopy using a 

high-purity germanium (HPGe) photon detector. 

Lead-210 (210Pb) and radium-226 (226Ra) were analyzed using a low-energy photon spectrometer (LPES) 

(Jackie Waddell, Severn Trent Laboratories, Inc., oral 

commun., 2002). 

Box core samples from the four coring sites were 

analyzed for organochlorine pesticides, PCBs, and 

PAHs (table 2) by the NWQL. Additionally, selected 

samples from the mid-lake site were analyzed by the 

NWQL for petroleum biomarkers (appendix 2.5). A 

laboratory reporting level (LRL) for each constituent 

was established by the NWQL for a 25-gram (g) dry 

sediment weight sample (table 2). The LRL is increased 

when less than 25 g is submitted to the lab for analysis. 

Several surficial samples had low dry sediment weights, 

which resulted in high LRLs. The sample mass available was insufficient for analysis of organochlorine 

compounds and PAHs in surficial sample CDO.CR 

0–0.5.

Samples for analysis of organochlorine pesticides, PCBs, PAHs, and petroleum biomarkers were 

extracted, isolated, and analyzed using a variation of the 

procedures of Foreman and others (1995) and Furlong 

and others (1996). Briefly, sediment was extracted overnight with dichloromethane in a Soxhlet apparatus. Two 

aliquots of the sample extract were injected into a polystyrene-divinylbenzene gel permeation column (GPC) 

and eluted with dichloromethane to remove sulfur and 

partially isolate the target analytes from co-extracted 

high-molecular-weight interferences such as humic 

substances. The first aliquot was analyzed for PAHs, 

alkyl-PAHs, and petroleum biomarkers by capillarycolumn gas chromatography (GC) with detection by 

mass spectrometry (MS). The second aliquot was further split into two fractions by combined alumna/silica 

adsorption chromatography prior to analysis of the 

organochlorine pesticides and PCBs by dual capillarycolumn gas chromatography with electron capture 

detection (GC–ECD). 

Variations on the procedures of Furlong and 

others (1996) for the analysis of PAHs and petroleum 

biomarkers include the addition of a silica column 

cleanup step following the GPC step and the use of 

selected ion monitoring (SIM) MS to reduce chemical 

interferences and improve detection limits. Eighteen 

parent PAHs, 10 specific alkyl-PAHs, and the homologues series of alkyl-PAHs were identified for this 

report (table 2). Concentrations of n-alkanes, three individual biomarkers, and three biomarker classes were 

reported by the NWQL. The petroleum biomarker 

results are provided in appendix 2.5; however, the 

results are not discussed in this report. Comparison of 

the petroleum biomarker concentrations in the mid-lake 

core to those of a local crude oil sample was planned, 

but a crude oil sample was not collected, which made 

the biomarker results less useful. 

Box core samples were analyzed for forms of carbon and major and trace elements (table 2) by the USGS 

Geologic Discipline laboratory in Denver, Colo. Samples were freeze-dried and ground to a fine powder. 

Total carbon was analyzed by combustion with an automatic carbon analyzer, inorganic carbon was determined as carbon dioxide by coulometric titration, and 

organic carbon was computed by difference (Arbogast, 

1996). Samples for major and trace elements were 
METHODS OF SEDIMENT COLLECTION AND ANALYSIS 11

Table 2. Constituents and laboratory reporting levels for samples collected from Caddo Lake, Texas, May 2002—

Continued

Constituent

(units)

Laboratory

reporting

level

Constituent

(units)

Laboratory

reporting

level

Radionuclides (STL Richland) Polycyclic aromatic hydrocarbons (NWQL)—Cont.

Cesium-137 (pCi/g) 0.20 Parent compounds:—Cont.

Lead-210 (pCi/g) .10 Fluoranthene (μg/kg) 5

Radium-226 (pCi/g) .40 Pyrene (μg/kg) 5

Organochlorine compounds (NWQL) Benz(a)anthracene (μg/kg) 5

Lindane (μg/kg) .5 Chrysene (μg/kg) 5

Heptachlor (μg/kg) .5 Benzo(b)fluoranthene (μg/kg) 5

Aldrin (μg/kg) .5 Benzo(k)fluoranthene (μg/kg) 5

Heptachlor epoxide (μg/kg) .5 Benzo(e)pyrene (μg/kg) 5

Technical chlordane (μg/kg) 5.0 Benzo(a)pyrene (μg/kg) 5

Endosulfan I (μg/kg) .5 Benzo(g,h,i)perylene (μg/kg) 5

Dieldrin (μg/kg) .5 Indeno(1,2,3-c,d)pyrene (μg/kg) 5

Endrin (μg/kg) .5 Dibenzo(a,h)anthracene (μg/kg) 5

p,p'-DDE (μg/kg) .5 Coronene (μg/kg) 5

p,p'-DDD (μg/kg) .5 Alkylated compounds:

p,p'-DDT (μg/kg) .5 2-Ethylnaphthalene (μg/kg) 5

p,p'-Methoxychlor (μg/kg) 2.0 2,6-Dimethylnaphthalene (μg/kg) 5

Mirex (μg/kg) .5 1,6-Dimethylnaphthalene (μg/kg) 5

Toxaphene (μg/kg) 50 1,2-Dimethylnaphthalene (μg/kg) 5

PCB Aroclor 1242 (μg/kg) 5.0 2,3,6-Trimethylnaphthalene (μg/kg) 5

PCB Aroclor 1254 (μg/kg) 5.0 1-methyl-9H-Fluorene (μg/kg) 5

PCB Aroclor 1260 (μg/kg) 5.0 2-Methylanthracene (μg/kg) 5

Polycyclic aromatic hydrocarbons (NWQL) 4,5-Methylenephenanthrene (μg/kg) 5

Parent compounds: 1-Methylphenanthrene (μg/kg) 5

Naphthalene (μg/kg) 5 1-Methylpyrene (μg/kg) 5

Acenaphthylene (μg/kg) 5 C1-128 isomers (μg/kg) 5

Acenaphthene (μg/kg) 5 C2-128 isomers (μg/kg) 5

9H-Fluorene (μg/kg) 5 C3-128 isomers (μg/kg) 5

Phenanthrene (μg/kg) 5 C4-128 isomers (μg/kg) 5

Anthracene (μg/kg) 5 C5-128 isomers (μg/kg) 5

Table 2. Constituents and laboratory reporting levels for samples collected from Caddo Lake, Texas, May 2002

[STL Richland, Severn Trent Laboratories, Inc.; pCi/g, picocuries per gram; NWQL, USGS National Water Quality 

Laboratory; μg/kg, micrograms per kilogram; GD, USGS Geologic Discipline laboratory; μg/g, micrograms per gram] 
12 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

Polycyclic aromatic hydrocarbons (NWQL)—Cont. Major elements (GD)—Cont.

Alkylated compounds:—Cont. Potassium (μg/g) 20

C1-178 isomers (μg/kg) 5 Sodium (μg/g) 6

C2-178 isomers (μg/kg) 5 Titanium (μg/g) 40

C3-178 isomers (μg/kg) 5 Trace elements (GD)

C4-178 isomers (μg/kg) 5 Antimony (μg/g) .02

C5-178 isomers (μg/kg) 5 Arsenic (μg/g) .1

C1-202 isomers (μg/kg) 5 Barium (μg/g) .5

C2-202 isomers (μg/kg) 5 Beryllium (μg/g) .001

C3-202 isomers (μg/kg) 5 Cadmium (μg/g) .003

C4-202 isomers (μg/kg) 5 Cerium (μg/g) .5

C5-202 isomers (μg/kg) 5 Chromium (μg/g) .2

C1-228 isomers (μg/kg) 5 Cobalt (μg/g) .1

C2-228 isomers (μg/kg) 5 Copper (μg/g) .5

C3-228 isomers (μg/kg) 5 Gallium (μg/g) .006

C4-228 isomers (μg/kg) 5 Lanthanum (μg/g) .3

C5-228 isomers (μg/kg) 5 Lead (μg/g) .2

C1-252 isomers (μg/kg) 5 Lithium (μg/g) .2

C2-252 isomers (μg/kg) 5 Manganese (μg/g) .2

C3-252 isomers (μg/kg) 5 Mercury (μg/g) .02

C4-252 isomers (μg/kg) 5 Molybdenum (μg/g) .1

C5-252 isomers (μg/kg) 5 Nickel (μg/g) 1

Forms of carbon (GD) Niobium (μg/g) 2

Carbon, carbonate (inorganic) (percent) .01 Scandium (μg/g) .3

Carbon, organic (percent) .01 Selenium (μg/g) .2

Carbon, total (percent) .01 Silver (μg/g) 3

Major elements (GD) Strontium (μg/g) .05

Aluminum (μg/g) 8 Thorium (μg/g) .03

Calcium (μg/g) 20 Uranium (μg/g) .02

Iron (μg/g) 50 Vanadium (μg/g) .4

Magnesium (μg/g) .3 Zinc (μg/g) 5

Phosphorus (μg/g) 8

Table 2. Constituents and laboratory reporting levels for samples collected from Caddo Lake, Texas, May 2002—

Continued

Constituent

(units)

Laboratory

reporting

level

Constituent

(units)

Laboratory

reporting

level
METHODS OF SEDIMENT COLLECTION AND ANALYSIS 13

completely digested using a mixture of hydrochloricnitric-perchloric-hydrofluoric acids and analyzed for 

32 elements by inductively coupled plasma/mass spectrometry (ICP/MS) (Briggs and Meier, 1999). Mercury 

was analyzed separately by cold vapor atomic absorption spectrometry (Arbogast, 1996). 

Sediment-Core Age Dating 

Sediment-core deposition dates were based primarily on radionuclide concentrations with supporting 

evidence for the deposition dates provided by the concentrations of DDD, DDE, and elemental lead. Selected 

samples from the Goose Prairie Creek and Harrison 

Bayou sites were analyzed for 137Cs, and those from the 

mid-lake and Carter Lake sites were analyzed for 137Cs, 

210Pb, and 226Ra for age dating purposes. The samples 

from the Goose Prairie Creek and Harrison Bayou cores 

were analyzed for only 137Cs because the cores were 

expected to consist of young sediment deposits (post1950). The sites were located adjacent to creek inlets 

where thick sediment deposits tend to accumulate rapidly. Conversely, the samples from the mid-lake and 

Carter Lake cores were not located adjacent to the 

mouths of incoming creeks where sediment deposits 

accumulate rapidly; so the cores were expected to 

consist of both old (pre-1950) and young (post-1950) 

sediment deposits, which limited the effectiveness of 

137Cs alone for age dating purposes. These samples 

therefore were analyzed for 210Pb (in addition to 137Cs), 

which, as will be explained later in this section, can be 

used to compute the date at which the 210Pb was at the 

sediment surface. 137Cs (half-life of 30.8 years) was 

released to the atmosphere through nuclear weapons 

testing beginning about 1952, and atmospheric concentrations peaked during 1963–64. Wet atmospheric 

fallout and strong and rapid sorption of 137Cs to soil 

particles make it useful for studying sediment accumulation rates in lakes and reservoirs (Bolt and others, 

1976; Ritchie and McHenry, 1990). 

Peak 137Cs activities in the cores were assigned a 

date of 1964.0, the time at which atmospheric concentrations were highest. The top of each core also was 

used as a date marker matching the date of sample collection (2002.4). An average mass accumulation rate 

(MAR) in grams per square centimeter per year was 

computed using the two depth-date markers, and the 

porosity and density of each sample were computed 

using the wet and dry sediment weights. The computation of an average MAR assumed a constant sedimentation rate for the core. The average MAR of the core was 

used to compute deposition dates for samples between 

the date markers. 

The deposition dates computed for the samples 

were compared to concentrations of lead and total DDT 

in the cores for corroboration. The concentration of lead 

typically peaks in lake sediments deposited during the 

mid-1970s (Callender and Van Metre, 1997) when the 

Clean Air Act prompted the phasing out of leaded gasoline. In this report, total DDT is defined as the sum of 

the para, para (p,p') isomers of DDT and its degradates, 

p,p'-DDD and p,p'-DDE. The ortho, para (o,p') isomers 

of the compounds were not analyzed by the laboratory. 

Total DDT concentrations in lake sediments generally 

peaked during the mid-1960s (Van Metre and others, 

1997), coincident with peak DDT use in the United 

States (Smith and others, 1988).

The mid-lake and Carter Lake cores were analyzed for 210Pb and 226Ra in addition to 137Cs. 210Pb is 

a naturally occurring radionuclide in the uranium-238 

(

238U) decay series: 

, (1)

(simplified decay sequence from Appleby and Oldfield 

[1992]). The daughter product of 226Ra, radon-222 

(

222Rn), is a gas that moves from the soil into the atmosphere where it quickly decays to produce 210Pb. The 

residence time of 210Pb in the atmosphere is less than 1 

month, after which it is removed from the atmosphere 

through precipitation or dry deposition and adsorbed 

onto surficial soils. The amount of atmospheric fallout 

of 210Pb is nearly equal to the amount of 222Ra moving 

into the atmosphere, and the atmospheric fallout of 

210Pb is considered reasonably constant at any given 

locality (Appleby and Oldfield, 1992; Durrance, 1992). 

The amount of atmospherically derived 210Pb is called 

excess or unsupported 210Pb and is the amount of 210Pb 

present in the soil excluding that contributed by the inplace decay of 226Ra. The unsupported 210Pb in any 

given layer of a sediment deposit reduces exponentially 

over time following the radioactive decay law and thus 

can be used to compute the date at which it was first 

adsorbed onto the surface of the deposit. The unsupported 210Pb was computed by subtracting the concentration of 226Ra from the concentration of 210Pb. 

238U 226Ra 222Rn 210Pb

4.51 X 109 yr 1602 yr 3.82 d

 206Pb 22.26 yr
14 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

The unsupported 210Pb and cumulative dry sediment mass1

 were used in the constant accumulation rate 

model (which assumes that there is a constant rate of 

accumulation of unsupported 210Pb and that each layer 

of the sediment deposited has the same initial unsupported 210Pb) to compute the age of each sample 

collected from the mid-lake and Carter Lake sites, following the method of Appleby and Oldfield (1992). 

They define the unsupported 210Pb concentration (activity) in sediments of age t as 

, (2)

where 

C = concentration in sediments of age t, in picocuries per gram; 

C0 = current (2002) surficial concentration, in picocuries per gram; 

λ210 = 210Pb radioactive decay constant (about 

0.03114 per year); 

t = cum (grams per centimeter square)/MAR 

(grams per centimeter square per year), in 

years; and 

cum = cumulative dry sediment mass, in grams per 

square centimeter. 

Using this first-order decay equation, the natural log of 

unsupported 210Pb was graphed as a function of the 

cumulative dry mass, and a least-squares line was fit to 

the data from each of the two sites (fig. 4). The slope of 

the least-squares line on the graph equals -λ210/MAR; 

thus the MAR was obtained by dividing -λ210 by the 

computed slope from the graph (actually from the 

least-squares equation [fig. 4]). The age was then computed as the cumulative mass divided by the MAR. A 

poor fit to the line can be caused by variable sedimentation rates, variable initial unsupported 210Pb in the layers, or post-depositional sediment mixing (Appleby 

and Oldfield, 1992).

Caution is needed regarding age dating of the 

Caddo Lake cores. A thick clay was encountered at the 

bottom of the cores collected from Goose Prairie Creek, 

Harrison Bayou, and mid-lake (appendix 1), and age 

dating indicated that the Goose Prairie Creek and 

Harrison Bayou cores did not penetrate lacustrine 

sediment deposited before 1948. Historical records of 

local precipitation, stream discharge, and lake altitude 

were investigated for evidence of extremely dry conditions associated with low lake levels around 1948 

that could have resulted in the lacustrine sediments of 

Caddo Lake being exposed, dried, and compacted to 

form the thick clay layer encountered by the three cores. 

A record of annual precipitation during 1943–97 for 

the National Weather Service station in Karnack, Tex. 

1 Computed by multiplying effective density times thickness 

of sample interval and summing results for each sample interval 

over the length of the core.

C C0e

λ210 – t =

CUMULATIVE DRY MASS, IN GRAMS

PER SQUARE CENTIMETER

CUMULATIVE DRY MASS, IN GRAMS

PER SQUARE CENTIMETER

012345 0123

LN (UNSUPPORTED LEAD-210)

LN (UNSUPPORTED LEAD-210)

0

0.5

1

1.5

2

0

1

2

3 (a) (b)

ln y=-0.3134 x+2.4365

R2

=.8059

ln y=-0.1979 x+1.5082

R2

=.4117

Figure 4. Relation between logarithm of unsupported lead-210 and cumulative dry mass in cores from (a) midlake and (b) Carter Lake, Caddo Lake, Texas, May 2002.
METHODS OF SEDIMENT COLLECTION AND ANALYSIS 15

(fig. 1) showed a drought in the early 1950s (fig. 5). 

The lowest annual precipitation on record at the weather 

station was 60.4 cm in 1951. The average annual precipitation over the period of record was 120.7 cm. The 

monthly mean discharge in Big Cypress Creek near 

Jefferson, Tex. (USGS station 07346000) was low (near 

zero) several times around 1950; however, comparably 

low stream discharge occurred regularly throughout the 

years of record (fig. 5). Similarly, the lake water level 

was low a few times around 1950 and was comparably 

low in other years. Stream discharge and lake waterlevel records did not support the hypothesis of subaerial 

exposure of lacustrine sediments in Caddo Lake around 

1950; nonetheless, the coring tools could not penetrate 

the thick clay layer, and sediment deposited at the 

Goose Prairie Creek and Harrison Bayou sites before 

1948 was not collected. 

Assessing Contaminant Levels

Sediment concentrations can be compared to 

SQGs to indicate the degree of contamination of sediments. SQGs are based on numerous field studies and 

toxicity tests and have been shown to be reasonable 

predictors of toxicity or other adverse effects on biota 

from contaminants in sediments (MacDonald and others, 2000). SQGs are derived through a variety of laboratory, field, and theoretical methods and are not 

definitive for determining sediment toxicity to benthic 

biota; only sediment toxicity tests can determine this 

(Long and others, 1995; MacDonald and others, 2000). 

In addition, SQGs cannot be extrapolated to determine 

the possibility that the sediments might be harmful to 

fish, aquatic plants, or humans. 

Two consensus-based SQGs are used in this 

report: the threshold effect concentration (TEC) and 

the probable effect concentration (PEC). The TEC 

represents the concentration below which adverse 

effects to benthic biota rarely occur, and the PEC represents the concentration above which adverse effects are 

expected to occur frequently (MacDonald and others, 

2000). TECs and PECs for a number of substances 

analyzed for in this report are listed in table 3. The 

consensus-based SQGs were developed using a number 

of published SQGs. Some of the SQGs used to develop 

the consensus-based SQGs were normalized with 

organic carbon (for example, Swartz, 1999). These 

organic carbon normalized SQGs were converted to 

Table 3. Selected consensus-based sediment-quality guidelines used to assess contaminant concentrations in 

cores collected from Caddo Lake, Texas, May 2002 

[TEC, threshold effect concentration (MacDonald and others, 2000); PEC, probable effect concentration (MacDonald and 

others, 2000); μg/kg, micrograms per kilogram; μg/g, micrograms per gram]

1 Sum of 13 PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz(a)-

anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene [Swartz, 1999]).

Constituent TEC PEC Constituent TEC PEC

Organochlorine compounds (μg/kg) Polycyclic aromatic hydrocarbons (μg/kg)—Cont.

DDE 3.16 31.3 Pyrene 195 1,520 

DDD 4.88 28.0 Total SQG PAH1 1,610 22,800

Total PCBs 59.8 676 Trace elements (μg/g)

Polycyclic aromatic hydrocarbons (μg/kg) Arsenic 9.79 33.0

Anthracene 57.2 845 Cadmium .99 4.98

Fluorene 77.4 536 Chromium 43.4 111

Naphthalene 176 561 Copper 31.6 149

Phenanthrene 204 1,170 Lead 35.8 128

Benz(a)anthracene 108 1,050 Mercury .18 1.06

Benzo(a)pyrene 150 1,450 Nickel 22.7 48.6

Chrysene 166 1,290 Zinc 121 459

Fluoranthene 423 2,230
16 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 1930 1940 1950 1960 1970 1980 1990 2000 YEAR

0

50

250200150100

MONTHLY MEAN DISCHARGE,

IN CUBIC METERS PER SECOND

0

8040

200160120

MEAN ANNUAL 

PRECIPITATION,

IN CENTIMETERS

56555453525150

DAILY LAKE ALTITUDE

ABOVE NGVD 29, IN METERS

Figure 5. Mean annual precipitation at National Weather Service station in Karnack, Texas, 1943–97 (National Climatic Data Center, 1999); 

monthly mean discharge in Big Cypress Creek near Jefferson, Texas, 1930–2000 (U.S. Geological Survey, 2003); and daily lake altitude at Caddo Lake dam, Louisiana, 1932–2000 (U.S. Army Corps of Engineers, 1932–98; 1999–2000 data, U.S. Army Corps of Engineers, unpub. data, 2002).
METHODS OF SEDIMENT COLLECTION AND ANALYSIS 17

dry-weight normalized values at 1-percent organic carbon (MacDonald and others, 2000). Previous studies 

have shown that dry-weight normalized SQGs predict 

sediment toxicity as well or better than organic carbon 

normalized SQGs in field-collected sediment samples 

(Barrick and others, 1988; Long and others, 1995; 

Ingersoll and others, 1996; U.S. Environmental Protection Agency, 1996; MacDonald, 1997). 

Trend Testing

Time series of concentrations of selected compounds (those with three or more detections) were 

tested for statistically significant trends using Kendall’s 

tau (Helsel and Hirsch, 1992). Positive or negative 

trends were considered significant at the 95-percent 

confidence level (p-value <.05). Kendall’s tau is a nonparametric (normal distribution of data not required) 

test based on ranks. Thus the outcome of a trend test is 

based on the rank order of concentrations rather than 

actual concentrations. 

The NWQL qualifies some organic compound 

concentrations with an “E” (for estimated), which signifies that although the compounds are qualitatively identified as present, their reported concentrations have 

greater uncertainty than those reported without qualification (G.L. Cottrell, U.S. Geological Survey, written 

commun., 2001). In some cases, estimated concentrations of organic compounds reported by the NWQL 

were less than the LRL. (See Childress and others 

[1999] for an explanation of conditions under which 

estimated concentrations can be less than LRLs.) However, the NWQL reports nondetections as “less than the 

LRL” (Childress and others, 1999). Nondetections were 

included in trend testing of organic compounds. Nondetections commonly are set equal to LRLs in such tests; 

but to avoid situations in which nondetections (concentration = LRL) ranked higher than some estimated concentrations (concentration < LRL), nondetections were 

set equal to values just below the lowest estimated concentration for each compound tested, rather than leaving 

them at the LRL as reported by the NWQL. 

No concentrations of major and trace elements 

reported by the Geologic Discipline laboratory were 

less than respective LRLs. Thus, for trend testing, nondetections reported as less than the LRL were set equal 

to the LRL.

Sediment-Core Burden and Focusing Factor

“Burden” is a term for the amount per unit area of 

a contaminant in a sediment core. Burdens of 137Cs and 

mercury were computed as an interim step in estimating 

what the atmospheric fallout rate of mercury would 

have to have been to account for the accumulated mercury in a core and thus provide information on whether 

the predominant source of mercury in a core is atmospheric fallout or point and nonpoint sources in the 

Caddo Lake drainage area. The 137Cs burden for each 

sample interval, in picocuries per square centimeter, 

was computed by multiplying the 137Cs concentration, 

in picocuries per gram, by the dry mass of sediment, in 

grams per square centimeter. The interval burdens were 

summed over the length of the core to yield the 137Cs 

burden for the core (φc), in a manner comparable to that 

of Van Metre and others (1997). 

Similarly, the mercury burden for each sample 

interval in a core, in micrograms per square centimeter, 

was computed by multiplying the mercury concentration of the interval by the dry mass of sediment and 

summing the interval burdens over the length of the core 

to yield the mercury burden for the core (φhg).

“Focusing factor” (FF) is the ratio of the φc to the 

model-predicted (from the fallout prediction model of 

Sarmiento and Gwinn [1986]) atmospheric fallout of 

137Cs for the coring site. FF provides an estimate of the 

degree of focusing of particle-associated contaminants 

from the drainage area and other parts of a lake to the 

coring site (Van Metre and others, 1997). An FF near 

unity implies that the site is influenced only by atmospheric fallout. The 137Cs atmospheric fallout flux 

(mass per unit area) was computed for the Caddo Lake 

area using the fallout prediction model of Sarmiento and 

Gwinn (1986). Precipitation data from the National 

Weather Service station at Karnack was used in the 

model. Monthly 137Cs fallout was decay-corrected 

using the core collection date of the Caddo Lake sampling and summed over the period 1954–74 (the period 

upon which the prediction model is based) to yield the 

cumulative 137Cs fallout deposition (φf

). FF for each 

core was then computed by dividing φc by φf

. 

To estimate what the atmospheric fallout rate of 

mercury would have to have been to account for the 

accumulated mercury in a core, φhg is normalized 

(divided) by FF. 137Cs is supplied to lakes only by 

atmospheric fallout on the lake and its drainage area—

therefore normalized burdens represent the estimated 

cumulative atmospheric loading of mercury over the 
18 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

drainage area that would be necessary to supply the 

measured core burdens, assuming no point and nonpoint 

sources in the drainage area (Van Metre and others, 

1997). 

QUALITY ASSURANCE OF CHEMICAL 

DATA

Quality-control (QC) samples are included with 

each group of environmental samples analyzed to assure 

the quality of the analytical results. Analytical results 

from two types of duplicate samples are included in this 

report—environmental duplicates and laboratory duplicates. An environmental duplicate is a sample that was 

split into two jars at the time of collection, and both jars 

were submitted to the laboratory for analysis. A laboratory duplicate is a single sample that was split at the laboratory during preparation and analyzed in duplicate. 

Three QC samples were included with each group 

of environmental samples analyzed for radionuclides: a 

laboratory duplicate, a blank, and a laboratory control 

sample (LCS). A blank is a sample of reagent (deionized) water. An LCS is a reference material used by the 

laboratory to assess the recovery of radionuclides by the 

analytical instruments. The USGS and STL Richland 

have established contractually required detection limits 

for the environmental and QC samples; however, the 

contractually required detection limits were not met for 

the environmental samples because the sediment available was insufficient for analysis. STL Richland reports 

overall method uncertainty estimates with their analytical results, which are listed with sample concentrations 

in appendix 2.1 (Jackie Waddell, Severn Trent Laboratories, Inc., written commun., 2002).

The analytical results for each group of samples 

analyzed for radionuclides included blank concentration, percent recovery of the LCS, and relative percent 

difference (RPD) of the duplicate (appendix 3.1). The 

RPD is a measure of the variability in the concentrations 

produced by the analytical method. The RPD was computed for each pair of duplicate samples using the 

equation 

, (3)

where sample 1 and sample 2 are the concentrations of 

individual compounds in duplicate samples. 

The overall median RPD of duplicate analyses for 

137Cs is 8.7 percent. There were two duplicate analyses 

for 226Ra (RPD = 16.10 and 5.65 percent), but 210Pb 

was not analyzed in duplicate. 

Four QC samples were included with each group 

of environmental samples analyzed for organic compounds: a laboratory duplicate, a blank, a spiked reagent 

sample, and a certified reference material (CRM). The 

overall median RPD of duplicate analyses for organochlorine compounds is 15.4 percent and for PAHs, 

10.0 percent (appendixes 3.2, 3.3). 

There were no detections in the organochlorine 

blank samples, spike recoveries for four of the five 

groups analyzed were within acceptable limits, and the 

CRM concentrations for three of the five groups were 

within an acceptable range (appendix 3.2). Group number 200221106 had low spike recoveries for mirex and 

PCB Aroclor 1254 because of a problem in the preparation of the spike at the NWQL. Mirex and PCB Aroclor 

1254 were not detected in any of the environmental 

samples analyzed in group number 200221106. Mirex 

rarely has been detected in lake-bottom sediments 

collected as part of the USGS National Water-Quality 

Assessment Program, but PCB Aroclor 1254 frequently 

has been detected (P.C. Van Metre, U.S. Geological 

Survey, unpub. data, 2003). The LRL for PCB Aroclor 

1254 in group number 200221106 ranged from 5.0 

to 150 μg/kg. Despite the low spike recoveries for 

this group, the nondetections of PCB Aroclor 1254 

were believed to be credible because most samples 

had low LRLs (5.0 to 15 μg/kg), and the two samples 

with the highest LRLs (70 and 150 μg/kg for samples 

CDO.GP 0–1 and CDO.CR 4.5–5, respectively) were 

not expected to have detectable concentrations of PCB 

Aroclor 1254. PCB Aroclor 1254 was not expected in 

CDO.CR 4.5–5 because no other samples from that 

core had detections of PCBs. The CRM concentrations 

were below the acceptable limits in group number 

200220603 (CDO.HB; CDO.GP) for heptachlor, aldrin, 

heptachlor epoxide, endosulfan, dieldrin, DDE, and 

endrin; and in group number 200222605 (CDO.MD) for 

heptachlor epoxide, endosulfan, and dieldrin. The CRM 

concentrations were low because of problems in preparation of the sample at the NWQL; however, environmental sample results are not affected by the CRM 

recoveries. 

PAH concentrations were low (estimated [E] 

values less than LRL) in some blank samples for all 

groups, PAH spike recoveries were considered normal 

(the NWQL has not established acceptable recovery 

ranges), and one compound concentration was below 

the acceptable CRM limits. Group number 8022R02177 

RPD 100 sample1 sample2 –

sample1 sample2 +

2 --------------------------------------------------    

= × -------------------------------------------------------
OCCURRENCE AND TRENDS 19

(CDO.HB) had the most detections in its blank sample 

with low concentrations of naphthalene (E0.15 μg/kg), 

2,6-dimethylnaphthalene (E0.44 μg/kg), acenaphthene 

(E0.18 μg/kg), phenanthrene (E0.24 μg/kg), anthracene 

(E0.54 μg/kg), fluoranthene (E0.61 μg/kg), pyrene 

(E0.62 μg/kg), and chrysene (E0.28 μg/kg). The blanks 

in group number 8022R02171 (CDO.MD) had one 

detection of naphthalene (E0.23 μg/kg), and group 

number 8022R02169 (CDO.GP; CDO.HB) had one 

detection of 2,6-dimethylnaphthalene (E0.46 μg/kg). 

The LRL for the blank is 5.0 μg/kg, so these detections 

were considered insignificant. The spike recoveries 

ranged from 41.4 to 98.7 percent with a median 

recovery of 70.5 percent. Spike recoveries typically 

were lowest for coronene and highest for dibenzo(a,h)-

anthracene. The NWQL used CRM 362 for groups 

8022R02169, 8022R02171, and 8022R02177; and 

CRM 354 for group number 8022R02165. The CRM is 

a commercially available organic soil from Environmental Resource Associates Arvada, Colo. The percent 

recovered of pyrene was 110.2 in group number 

8022R02165 (CDO.CR), above the acceptable range of 

32 to 90 percent.

QC samples included with samples analyzed for 

major and trace elements were duplicate and triplicate 

samples, several blanks, and standard reference materials (SRMs). The blanks were not analyzed for forms of 

carbon or mercury but were analyzed for major and 

other trace elements. The SRMs used by the laboratory 

were the National Research Council Canada Marine 

Estuarine Sediment (MESS–1), National Institute of 

Standards and Technology Buffalo River Sediment 

(NIST 2704), USGS Cody Shale (SCO–1), USGS 

Marine Sediment (MAG–1), and Chinese Quangxi 

Province Stream Sediment (GSD–8). 

The environmental samples were analyzed in two 

groups, and two duplicates and one triplicate were 

included with each group (appendix 3.4). The RPD was 

computed for a triplicate sample by comparing triplicate 

sample 1 to triplicate sample 2, triplicate sample 1 to 

triplicate sample 3, and triplicate sample 2 to triplicate 

sample 3. The overall median RPD for all duplicate and 

triplicate samples analyzed for forms of carbon and 

major and trace elements was 2.4 percent. Four blanks 

were analyzed in group number 3959: two of the blanks 

had arsenic concentrations of 0.1 and 0.2 microgram per 

gram (μg/g), respectively; the LRL for arsenic is 0.1 

μg/g. Three of the blanks had beryllium concentrations 

of 0.003, 0.006, and 0.007 μg/g, respectively; the LRL 

for beryllium is 0.001 μg/g. The range of arsenic and 

beryllium concentrations in the environmental samples 

included in group 3959 was 12 to 15 μg/g and 2.9 to 3.5 

μg/g, respectively (appendix 2.4). Group number 3958 

included three blank samples, which yielded two detections of beryllium, 0.008 and 0.01 μg/g. The concentration of beryllium in the environmental samples in group 

3958 ranged from 1.3 to 2.6 μg/g. The detections of 

arsenic and beryllium in the blank samples were considered negligible relative to concentrations in environmental samples. SRMs were analyzed with both groups, 

but MESS–1 was not used in group number 3958. The 

concentrations obtained by laboratory analysis of the 

SRMs were compared to the published SRM values 

(Xuejing and Mingcai, 1985; Potts and others, 1992), 

and the RPD was computed. The median RPD of the 

SRMs analyzed in group 3959 was 5.3 percent, and the 

RPD for group 3958 was 4.7 percent. 

OCCURRENCE AND TRENDS 

The findings on occurrence and trends are 

grouped by coring location. Sources of mercury based 

on burden and FF computations, a comparison of findings to those of other lakes, and implications of the findings relative to drainage area sources are discussed in 

this section. 

Goose Prairie Creek

Age Dating and Sedimentation Rates

The Goose Prairie Creek core was analyzed for 

137Cs for age dating. The core has a clearly defined 

137Cs peak at 20.5 cm that was used as the 1964.0 datedepth marker (fig. 6a). The 137Cs peak was used to compute a constant average MAR of 0.15 gram per square 

centimeter per year (g/cm2-yr) for the core and deposition dates for the remaining samples. Sediment deposition dates were computed back to about 1948 for the 

Goose Prairie Creek core. DDE concentrations were 

variable throughout the core, and a clear peak is not well 

defined. The highest DDE concentration was dated as 

1969, which was slightly later than the time of peak historical use of the pesticide but reasonable in the context 

of possible transport through the drainage area and error 

associated with age-dating techniques. The lead profile 

had a pronounced peak, which was dated as 1961 on the 

basis of the MAR computed from the 137Cs peak. The 

lead peak in the Goose Prairie Creek core was dated 

much earlier than lead peaks in the 1970s in most urban 

lakes (Callender and Van Metre, 1997); however, lead 
20 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

EXPLANATION

Cesium-137 concentration—

error of uncertainty is 2 standard

deviations

DDE (a) or total DDT (b,c,d) concentration

Lead concentration

(d) DEPOSITION DATE

1965

1970

1975

1980

1985

1990

1995

2000

2005

LEAD CONCENTRATION,

IN MICROGRAMS PER GRAM

TOTAL DDT CONCENTRATION,

IN MICROGRAMS PER KILOGRAM

CESIUM-137 CONCENTRATION,

IN PICOCURIES PER GRAM

0123 02468

20 30 40 50

LEAD CONCENTRATION,

IN MICROGRAMS PER GRAM

TOTAL DDT CONCENTRATION,

IN MICROGRAMS PER KILOGRAM

CESIUM-137 CONCENTRATION,

IN PICOCURIES PER GRAM

0 0.5 1 1.5 2 01234

20 22 24 26 28 30

1940

1950

1960

1970

1980

1990

2000

9.75 cm

DEPOSITION DATE

(c)

15.5 cm

DEPOSITION DATE

1940

1950

1960

1970

1980

1990

2000

LEAD CONCENTRATION,

IN MICROGRAMS PER GRAM

TOTAL DDT CONCENTRATION,

IN MICROGRAMS PER KILOGRAM

CESIUM-137 CONCENTRATION,

IN PICOCURIES PER GRAM

0 2 4 6 8 10

20 25 30 35 40

0 123

(b)

20.5 cm

DEPOSITION DATE

1940

1950

1960

1970

1980

1990

2000

LEAD CONCENTRATION,

IN MICROGRAMS PER GRAM

DDE CONCENTRATION,

IN MICROGRAMS PER KILOGRAM

CESIUM-137 CONCENTRATION,

IN PICOCURIES PER GRAM

0 2 4 6 8 10

40 80 120 160 200

0 0.5 1 1.5 2

(a)

Figure 6. Concentrations of selected constituents used to compute sediment deposition dates in cores collected at 

(a) Goose Prairie Creek, (b) Harrison Bayou, (c) mid-lake, and (d) Carter Lake sites, Caddo Lake, Texas, May 

2002.
OCCURRENCE AND TRENDS 21

concentrations at this site could reflect historical industrial releases and not urban use of leaded gasoline. 

Neither DDE nor lead was good corroborating 

evidence for the 137Cs-based age dates; however the 

137Cs profile shows a clear peak and was considered 

more reliable than the DDE and lead-concentration profiles. It is unlikely that the sediment accumulation rate 

at the Goose Prairie Creek site was constant over the 

period of deposition represented in the core, but no 

additional date-depth markers were in the core (such as 

a pre-reservoir surface) to use for the computation of 

more than one MAR; therefore, an uncertainty of ±5 

years was estimated for the age dates of the samples in 

the Goose Prairie Creek core. 

Contaminant Occurrence and Trends

The only organochlorine compounds detected in 

the Goose Prairie Creek core were DDE and PCB Aroclors 1242, 1254, and 1260 (fig. 7; appendix 2.2). DDE 

and PCB Aroclor 1260 were detected in all samples 

analyzed for organochlorines. PCB Aroclor 1242 was 

detected in samples deposited between 1961 and 1975, 

and PCB Aroclor 1254 was detected in samples deposited between 1961 and 1987. Fifty-six percent of the 

sample concentrations of DDE in the Goose Prairie 

Creek core exceeded the consensus-based SQG TEC for 

DDE, but they were well below the PEC (table 3; appendix 2.4). An SQG was available for total PCB, which 

was computed as the sum of PCB Aroclors 1242, 1254, 

and 1260. Estimated concentrations were included in 

the summation. Only one sample concentration, deposited about 1969 before restrictions on the use of PCBs, 

exceeded the TEC for total PCB (table 3; appendix 2.2). 

The organic compounds discussed in this report 

have been shown to preferentially sorb to the organic 

matter in sediment (Elzerman and Coates, 1987; 

Schwarzenbach and others, 1993); therefore, a trend in 

organic carbon could affect the trends of organic compounds. For this reason, the concentrations of organic 

compounds that were to be trend tested were normalized 

with (divided by) the concentrations of organic carbon 

if organic carbon had a statistically significant trend. 

Organic carbon had a significant upward trend in the 

Goose Prairie Creek core (Kendall’s τ = 1, p = 0); therefore, the organochlorine compounds with sufficient 

numbers of detections for trend testing were normalized 

with organic carbon before trend testing. Organic carbon normalized PCB Aroclors 1242 and 1254 had significant downward trends (Kendall’s τ = -.83 and -.67, 

p-value = .01 and .01, respectively). No other organic 

carbon normalized organochlorines had significant 

trends (table 4).

Numerous PAHs were detected, although their 

concentrations were low (appendix 2.3), comparable to 

concentrations in lakes in remote areas (P.C. Van Metre, 

U.S. Geological Survey, unpub. data, 2003) and to 

those in a core from a forested area of Lake Houston 

(Van Metre and Sneck-Fahrer, 2002). The naphthalene 

homologues with two alkyl groups (C2-alkylated 

naphthalenes), particularly 2,6-dimethylnaphthalene, 

and fluoranthene had the highest concentrations (fig. 8). 

No consensus-based SQG has been established for 2,6-

dimethylnaphthalene. None of the samples analyzed 

from the Goose Prairie Creek core had concentrations of 

individual PAH compounds higher than the respective 

TEC. Thirty-six of the 53 PAH compounds analyzed 

(includes parent compounds and alkylated homologues) 

were detected in the Goose Prairie Creek samples analyzed. Nineteen individual organic carbon normalized 

PAHs had statistically significant trends—all downward 

(table 5). 

A consensus-based SQG, or TEC, was available 

for the sum of 13 PAHs (naphthalene, acenaphthylene, 

acenaphthene, fluorene, phenanthrene, anthracene, 

fluoranthene, pyrene, benz(a)anthracene, chrysene, 

benzo(b)fluoranthene, benzo(k)fluoranthene, and 

benzo(a)pyrene [Swartz, 1999]), which is referred to as 

“total SQG PAH” in this report. The most recently 

deposited sample in the Goose Prairie Creek core had 

the highest total SQG PAH concentration, which was 

about one-sixth of the TEC. A significant downward 

trend was indicated for organic carbon normalized total 

SQG PAH concentrations in the Goose Prairie Creek 

core (Kendall’s τ = -.67, p = .01). 

Another commonly studied group of PAHs, 

called “combustion PAH,” is the sum of ten 4- and 

5-ringed parent compounds (fluoranthene, pyrene, 

benz(a)anthracene, chrysene, benzo(b)fluoranthene, 

benzo(k)fluoranthene, benzo(e)pyrene, benzo(a)-

pyrene, indeno(1,2,3-c,d)pyrene, and benzo(g,h,i)-

perylene) that are produced by high-temperature 

burning of fuels and are independent of fuel type (Prahl 

and Carpenter, 1983). The combustion PAH in the 

Goose Prairie Creek core did not exceed 260 μg/kg, 

and the organic carbon normalized combustion PAH 

had a significant downward trend (Kendall’s τ = -.61, 

p = .02). As an indicator of general PAH source, the 

ratio of concentrations of 2- and 3-ringed compounds 

plus homologues to the 4- and 5-ringed combustion 
22 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

Harrison Bayou Mid-lake Carter Lake

Goose Prairie

Creek

Goose Prairie

Creek

Goose Prairie

Creek

DDE

TEC

DDE

TEC

DDE

TEC

DDE

DDE/OC

DDD

DDE

DDE/OC

DDD

DDE

DDD

DDE

DDE/OC

PCB 1242

PCB 1242/OC

PCB 1254

PCB 1254/OC

PCB 1260

PCB 1260/OC

OC, organic carbon

TEC, threshold effect concentration (MacDonald and others, 2000)

EXPLANATION

012345

0 0.01 0.02 0.03 0.04 0.05

02468

0 0.04 0.08 0.12

0 4 8 12 16 20 24

0 2 4 6 8 10 01234

0 0.04 0.08 0.12

0 10 20 30 40 50

0 0.2 0.4 0.6 0.8

ORGANIC COMPOUND CONCENTRATION, IN MICROGRAMS PER KILOGRAM

ORGANIC COMPOUND CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION (MICROGRAMS OF

ORGANIC COMPOUND PER GRAM OF ORGANIC CARBON)

ORGANIC COMPOUND CONCENTRATION, IN MICROGRAMS PER KILOGRAM

ORGANIC COMPOUND CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION (MICROGRAMS OF

ORGANIC COMPOUND PER GRAM OF ORGANIC CARBON)

0 0.1 0.2 0.3 0.4

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

DEPOSITION DATE DEPOSITION DATE

Figure 7. Organochlorine pesticide (DDE and DDD) and polychlorinated biphenyl (PCB) concentrations in cores 

collected from Caddo Lake, Texas, May 2002.
OCCURRENCE AND TRENDS 23

PAH

TEC = 1,610

PAH

TEC = 423

PAH

PAH/OC

OC, organic carbon

TEC, threshold effect concentration

(MacDonald and others, 2000)

SQG, sediment-quality guideline

EXPLANATION

C2-alkylated

Naphthalenes Fluoranthene Benzo(b)-

fluoranthene

Indeno-

(1,2,3-c,d)-

pyrene

Total

SQG

PAH

Combustion

PAH

0 200 400 600 800 0 25 50 75 100 0 10 20 30 40 50 0 10 20 30 40 50

02468 02468

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM

012345 0123 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 0.3

0 100 200 300 400 500 0 100 200 300 01234

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM 2- AND 3-RINGED PAH /

COMBUSTION PAH

PAH CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION

(MICROGRAMS OF PAH PER GRAM OF ORGANIC CARBON)

PAH CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION

(MICROGRAMS OF PAH PER GRAM OF ORGANIC CARBON)

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

DEPOSITION DATE DEPOSITION DATE

Figure 8. Selected polycyclic aromatic hydrocarbon (PAH) concentrations and trends in core collected near 

Goose Prairie Creek, Caddo Lake, Texas, May 2002.

PAH was computed for each sample analyzed. The 2- 

and 3-ringed and alkylated homologue compounds are 

not typically produced by combustion and are more 

commonly from uncombusted PAH sources such as 

crude oil, vehicular fuels, crankcase oil, and organic 

matter. If the ratio of uncombusted to combusted PAH 

concentrations is greater than 1, the PAH mixture in the 

sediments is primarily from uncombusted sources; if the 

ratio is less than 1, the mixture is primarily from combusted sources. The ratio was about 1 throughout the 
24 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

core, until about 1995 when the ratio increased (fig. 8), 

indicating predominance of uncombusted sources in 

recent years.

The Goose Prairie Creek core was analyzed for 

eight major elements and 26 trace elements (appendix 

2.4). Several major elements compose the bulk of geologic materials, although some also are derived from 

human activities. For example, phosphorus is a nutrient 

essential to plant growth and is used in fertilizers. Calcium is a secondary essential plant nutrient and also is 

used in fertilizers (Hem, 1985; James, 1993). 

Several major elements had significant trends in 

the sediment cores (table 6): potassium (τ = -.89, p = 0), 

sodium (τ = -.78, p = 0), and titanium (τ = -1, p = 0) had 

downward trends, and calcium (τ = 1, p = 0) and phosphorus (τ = .89, p = 0) had upward trends. 

Aluminum, iron, and titanium are stable elements; significant trends in stable elements often are 

associated with changes in sedimentation rates. In the 

Goose Prairie Creek core, no trend was indicated for 

aluminum or iron concentrations, although titanium 

concentrations had a significant downward trend. The 

Table 4. Summary of trend testing results for organochlorine compounds detected in sediment cores from Caddo 

Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date 

[Significant trends at 95-percent confidence level shown in bold; --, not tested] 

Organochlorine

compound

Goose Prairie Creek inlet Harrison Bayou inlet

Non-normalized

concentrations

Organic carbon

normalized

concentrations

Non-normalized

concentrations

Kendall’s

tau p-value Kendall’s

tau p-value Kendall’s

tau p-value

Organic carbon 1 0 -- -- .11 .71

DDE 0 1 -.44 .10 -.71 .01

DDD -- -- -- -- -- --

Total DDT 0 1 -.44 .10 -.71 .01

PCB Aroclor 1242 -.47 .08 -.83 .01 -- --

PCB Aroclor 1254 -.30 .25 -.67 .01 -- --

PCB Aroclor 1260 .29 .28 -.28 .30 -- --

Total PCB -.11 .67 -.28 .30 -- --

Organochlorine

compound

Mid-lake (main stem near Little Green Brake) Carter Lake near Horse Island

Non-normalized

concentrations

Organic carbon

normalized

concentrations

Non-normalized

concentrations

Organic carbon

normalized

concentrations

Kendall’s

tau p-value Kendall’s

tau p-value Kendall’s

tau p-value Kendall’s

tau p-value

Organic carbon .86 0 -- -- .73 0 -- --

DDE -.50 .08 -.57 .048 -.85 .003 -0.86 .003

DDD -- -- -- -- -- -- -- --

Total DDT -.50 .08 -.79 .01 -.85 .003 -.86 .003

PCB Aroclor 1242 -- -- -- -- -- -- -- --

PCB Aroclor 1254 -- -- -- -- -- -- -- --

PCB Aroclor 1260 -- -- -- -- -- -- -- --

Total PCB -- -- -- -- -- -- -- --
OCCURRENCE AND TRENDS 25

Table 5. Summary of trend testing results for polycyclic aromatic hydrocarbon compounds detected in sediment 

cores from Caddo Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date 

[Significant trends at 95-percent confidence level (p-value <.05) shown in bold; --, not tested]

Polycyclic

aromatic

hydrocarbon

Goose Prairie Creek inlet Harrison Bayou inlet

Non-normalized

concentrations

Organic carbonnormalized

concentrations

Non-normalized

concentrations

Kendall’s

tau p-value Kendall’stau p-value Kendall’stau p-value

Organic carbon 1 0 -- -- .11 .71

Naphthalene .48 .07 -.44 .10 -.04 .90

2,6-Dimethylnaphthalene .78 0 .22 .40 .21 .46

1,6-Dimethylnaphthalene .78 0 .11 .68 .14 .62

C2-128 isomers .72 .01 .06 .83 .29 .32

Acenaphthylene .65 .02 -.33 .21 -.18 .54

1,2-Dimethylnaphthalene .83 0 .17 .53 .25 .38

Acenaphthene .72 .01 -.17 .53 -.04 .90

C3-128 isomers -.37 .17 -.72 .01 .49 .09

2,3,6-Trimethylnaphthalene .03 .92 -.78 0 .29 .32

9H-Fluorene -.17 .53 -.67 .007 .64 .03

1-methyl-9H-Fluorene .39 .14 -.50 .06 -.64 .03

Phenanthrene .44 .10 -.50 .06 .21 .46

Anthracene .54 .04 -.50 .06 .29 .32

2-Methylanthracene -.26 .33 -.83 0 -- --

4,5-Methylenephenanthrene -.17 .53 -.78 .004 -.55 .06

C1-178 isomers -.44 .10 -.89 0 -- --

1-Methylphenanthrene 0 1 -.67 .01 0 1

C2-178 isomers -.67 .01 -.94 0 -.53 .06

Fluoranthene -.39 .14 -.78 .004 .14 .62

Pyrene -.33 .21 -.78 .004 0 1

C3-178 isomers -.61 .02 -.83 0 -- --

1-Methylpyrene .20 .46 -.61 .02 -.48 .09

C1-202 isomers -.65 .02 -.83 0 -- --

C2-202 isomers .40 .13 -.33 .21 -- --

Benz(a)anthracene .44 .10 -.50 .06 .40 .17

Chrysene .20 .46 -.67 .01 .14 .62

C1-228 isomers -.18 .49 -.89 0 -- --

Benzo(b)fluoranthene .61 .02 -.44 .10 .14 .62

Benzo(k)fluoranthene .44 .10 -.44 .10 .07 .80

Benzo(e)pyrene .48 .07 -.39 .14 .14 .62

Benzo(a)pyrene .61 .02 -.39 .14 -.07 .80

C1-252 isomers -- -- -- -- -- --

Benzo(g,h,i)perylene 0 1 -.72 .01 -.14 .62

Indeno(1,2,3-c,d)pyrene .72 .01 -.17 .53 .07 .80

Dibenzo(a,h)anthracene -.03 .91 -.61 .02 -.53 .06

Coronene -.20 .45 -.83 0 .18 .53

Total SQG PAH .17 .53 -.67 .01 .14 .62

Combustion PAH .22 .40 -.61 .02 .14 .62
26 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

Table 5. Summary of trend testing results for polycyclic aromatic hydrocarbon compounds detected in sediment 

cores from Caddo Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date—

Continued 

Polycyclic

aromatic

hydrocarbon

Mid-lake (main stem near Little Green Brake) Carter Lake near Horse Island

Non-normalized

concentrations

Organic carbonnormalized

concentrations

Non-normalized

concentrations

Organic carbonnormalized

concentrations

Kendall’s

tau p-value Kendall’stau p-value Kendall’stau p-value Kendall’stau p-value

Organic carbon .86 0 -- -- .73 0 -- --

Naphthalene -.11 .71 -.29 .32 .32 .26 .07 .80

2,6-Dimethylnaphthalene .36 .22 .21 .46 .64 .06 .50 .08

1,6-Dimethylnaphthalene .57 .05 .36 .22 .50 .08 .50 .08

C2-128 isomers .36 .22 .21 .46 .64 .03 .50 .08

Acenaphthylene .64 .03 .50 .08 -- -- -- --

1,2-Dimethylnaphthalene -- -- -- -- -.09 .76 -.43 .14

Acenaphthene .37 .20 .07 .80 -- -- -- --

C3-128 isomers -- -- -- -- -- -- -- --

2,3,6-Trimethylnaphthalene -- -- -- -- -- -- -- --

9H-Fluorene -.23 .42 -.36 .22 -.53 .06 -.71 .01

1-methyl-9H-Fluorene -- -- -- -- -.53 .06 -.71 .01

Phenanthrene .36 .22 .14 .62 .43 .14 .36 .22

Anthracene .62 .03 .21 .46 -.11 .71 -.07 .80

2-Methylanthracene -- -- -- -- -- -- -- --

4,5-Methylenephenanthrene .19 .51 -.07 .80 -.73 .01 -.79 .01

C1-178 isomers -.48 .09 -.71 .01 -- -- -- --

1-Methylphenanthrene -- -- -- -- .29 .32 .21 .46

C2-178 isomers -.64 .03 -.79 .01 -- -- -- --

Fluoranthene .40 .17 .21 .46 .21 .46 .14 .62

Pyrene .07 .80 -.36 .22 .57 .05 .43 .14

C3-178 isomers -- -- -- -- -- -- -- --

1-Methylpyrene -- -- -- -- -- -- -- --

C1-202 isomers -- -- -- -- -- -- -- --

C2-202 isomers -- -- -- -- -- -- -- --

Benz(a)anthracene -.08 .78 -.36 .22 -- -- -- --

Chrysene .40 .17 -.21 .46 .57 .05 .50 .08

C1-228 isomers -- -- -- -- -- -- -- --

Benzo(b)fluoranthene .29 .32 0 1 .43 .14 .36 .22

Benzo(k)fluoranthene 0 1 -.29 .32 .50 .08 .43 .14

Benzo(e)pyrene .33 .26 -.07 .80 .50 .08 .43 .14

Benzo(a)pyrene .47 .10 .07 .80 .50 .08 .43 .14

C1-252 isomers -.76 .01 -.86 0 -.49 .09 -.50 .08

Benzo(g,h,i)perylene .64 .03 .14 .62 -.73 .01 -.79 .01

Indeno(1,2,3-c,d)pyrene .43 .14 0 1 .21 .46 .21 .46

Dibenzo(a,h)anthracene .34 .24 -.07 .80 -.64 .03 -.79 .01

Coronene -.47 .10 -.71 .01 0 1 -.29 .32

Total SQG PAH .43 .14 -.07 .81 .79 .006 .71 .01

Combustion PAH .43 .14 -.14 .62 .64 .03 .64 .03
OCCURRENCE AND TRENDS 27

Table 6. Summary of trend testing results for major and trace elements detected in sediment cores from Caddo 

Lake, Texas, May 2002—Kendall’s tau correlation of concentration with deposition date 

[Significant trends at 95-percent confidence level (p-value <.05) shown in bold; nd, not detected] 

Constituent

Goose Prairie

Creek inlet

Harrison Bayou

inlet

Mid-lake (main stem

near Green Brake)

Carter Lake near

Horse Island

Kendall’s

tau p-value Kendall’s

tau p-value Kendall’s

tau p-value Kendall’s

tau p-value

Organic carbon 1 0 .11 .71 .86 0 .73 0

Total carbon 1 0 .22 .44 .86 0 .71 0

Aluminum -.25 .34 -.71 .01 0 1 -.69 0

Calcium 1 0 .07 .80 .11 .71 .60 0

Iron .08 .75 .86 0 1 0 -.85 0

Magnesium .89 .34 -.79 .07 -.14 .62 -.49 .01

Phosphorus .89 0 .93 0 1 0 -.32 .11

Potassium -.89 0 -.07 .80 -.93 0 -.63 0

Sodium -.78 0 0 1 -.86 0 .03 .87

Titanium -1 0 -.43 .14 -.79 .01 -.61 0

Antimony -.39 .14 -.93 0 -.62 .03 -.67 0

Arsenic -.44 .10 -.21 .46 .57 .05 -.60 0

Barium -.87 0 .36 .22 .47 .10 -.38 .06

Beryllium .17 .53 -.36 .22 -.25 .38 -.82 0

Cadmium .28 .30 .47 .10 .18 .53 -.54 .01

Cerium -.61 .02 .07 .80 -.57 .05 -.26 .20

Chromium -.61 .02 -.62 .03 -.21 .46 -.76 0

Cobalt .42 .11 .50 .08 -.50 .08 -.08 .70

Copper -.22 .40 -.64 .03 -.50 .08 .32 .11

Gallium -.37 .17 -.69 .02 -.26 .36 -.75 0

Lanthanum -.61 .02 .07 .80 -.55 .06 -.27 .19

Lead -.89 0 -.71 .01 -.14 .62 -.86 0

Lithium -.76 0 -.71 .01 -.64 .03 -.88 0

Manganese 1 0 .93 0 1 0 .02 .91

Mercury -.56 .04 .89 0 .78 .01 -.62 0

Molybdenum .54 .04 -.43 .14 .36 .22 .36 .08

Nickel .22 .40 -.50 .08 -.50 .08 -.80 0

Niobium -.67 .01 -.36 .22 -.71 .01 -.57 0

Scandium -.54 .04 -.69 .02 -.43 .14 -.70 0

Selenium .99 0 0 1 .18 .53 .05 .82

Silver -.44 .10 nd nd nd nd nd nd

Strontium .28 .30 -.40 .17 -.40 .17 -.07 .74

Thorium -.89 0 -.43 .14 -.71 .01 -.61 0

Uranium -.83 0 -.64 .03 -.79 .01 -.64 0

Vanadium -.50 .06 -.64 .03 -.36 .22 -.83 0

Zinc .44 .10 -.14 .62 .04 .90 -.73 0
28 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

significant downward trend in titanium concentrations 

was not considered strong enough evidence to support a 

change in the sedimentation rate. Decreasing concentrations of phosphorus with depth have been reported 

as an effect of early diagenesis (for example, Sundby 

and others, 1992) and might not be related to changes 

in fertilizer usage. A significant downward trend in iron 

was not indicated in the Goose Prairie Creek core. 

The eight trace elements with consensus-based 

SQGs (MacDonald and others, 2000) are arsenic, cadmium, chromium, copper, lead, mercury, nickel, and 

zinc (table 3). All samples analyzed for trace elements 

in the Goose Prairie Creek core exceeded the TEC for 

chromium, lead, mercury, and nickel; and 78 percent 

of samples were at or higher than the TEC for copper 

and zinc (fig. 9; table 7). One sample, deposited about 

1961, exceeded the PEC for lead with a concentration 

of 181 μg/g. The highest concentration of cadmium 

(not graphed in fig. 9) was 55 percent of the TEC. The 

concentrations of chromium, lead, and mercury have 

had significant downward trends since about 1961. In 

sediments deposited after 1980, nickel and zinc had 

significantly increasing concentrations (τ = 1 and 

p = .014 for both). Seventy percent of the trace elements 

without SQGs but with significant trends had decreasing concentrations over time in the Goose Prairie Creek 

core. 

Goose Prairie Creek was the only coring site 

where silver was detected (LRL is 3 μg/g). Silver 

was detected in all samples in the core except the oldest 

sample interval analyzed, which had an estimated deposition date of 1948 (fig. 9). The concentration increased 

to a maximum of 23.8 μg/g in the sample deposited 

about 1969. Although no consensus-based SQGs exist, 

Long and others (1995) published recommended SQGs 

(which included silver). For silver, the ER–L is 1.0 

μg/g, and the ER–M is 3.7 μg/g. The concentration of 

silver (fig. 9) was higher than the ER–M in all samples 

deposited after 1960. The concentrations did not have a 

statistically significant trend when all samples were 

included in the trend test; however, the concentrations 

decreased significantly over time from the sample 

deposited in 1969 to the most recently deposited sample 

(τ = -0.86, p = .003).

Harrison Bayou

Age Dating and Sedimentation Rates

A clearly defined 137Cs peak at 15.5 cm was used 

as the 1964.0 date-depth marker (fig. 6b), resulting in an 

average MAR of 0.063 g/cm2

-yr for the core. Sediment 

deposition dates were computed back to about 1950 for 

the Harrison Bayou core. The highest total DDT concentration had a deposition date of 1961, which was 

compatible with historical DDT use. The highest lead 

concentration was dated as 1950; however a small 

“hump” in the lead profile occurred in sediments deposited around the mid- to late-1970s, which was compatible with historical environmental lead concentrations. 

The 137Cs peak was considered the most reliable agedate marker in the core. The sediment accumulation rate 

in Harrison Bayou probably was not constant over the 

period of deposition represented in the core, but no 

additional date-depth markers were in the core to use for 

the computation of more than one MAR; therefore, an 

uncertainty of ±2 years was estimated for the age dates 

of the samples in the Harrison Bayou core. 

Contaminant Occurrence and Trends

DDE was detected in all samples from the Harrison Bayou core that were analyzed for organochlorine 

compounds. Five of the six samples deposited before 

1995 had DDE concentrations higher than the TEC but 

much lower than the PEC. DDD was detected in the 

oldest sample only, which was deposited about 1950 

(fig. 7). Most organic carbon concentrations were 

between 9.86 and 11.6 percent and did not indicate 

a significant trend for the core (Kendall’s τ = .11, 

p = .71); therefore, organic compound concentrations 

were not normalized with organic carbon before trend 

testing. DDE concentrations in sediment at the site had 

a significant downward trend. PCB Aroclors 1242, 

1254, and 1260 were not detected in the core. 

The PAH mixture was dominated by high 

concentrations of C2- and C3-alkylated naphthalenes. 

Concentrations in three of the eight samples exceeded 

2,000 and 300 μg/kg for the C2- and C3-alkylated 

naphthalenes, respectively. Concentrations of all other 

compounds were less than 50 μg/kg (appendix 2.3). 

Concentrations of most individual PAH compounds 

were highest in the most recently deposited sample, 

but most PAH time series did not show significant 

upward trends (fig. 10). Individual PAHs and total 

SQG PAHs were well below the respective TECs. 
OCCURRENCE AND TRENDS 29

The ratio of 2- and 3-ringed compounds to combustion PAH was greater than 1 in all samples and substantially greater than 1 in three of four post-1983 

samples (fig. 10). Only two of the PAH compounds, 

9H-fluorene and 1-methyl-9H-fluorene had significant 

trends—upward and downward, respectively (table 5). 

Total SQG PAH and combustion PAH had no trend 

(fig. 10).

0 50 100 150 200 250

0 50 100 150 200

0 0.25 0.5 0.75 1 0 10 20 30 40

TRACE ELEMENT CONCENTRATION, IN MICROGRAMS PER GRAM

0 2 4 6 8 10 0 25 50 75 100 0 10 20 30 40

0 5 10 15 20 25

1945

1955

1965

1975

1985

1995

2005

1945

1955

1965

1975

1985

1995

2005

DEPOSITION DATE DEPOSITION DATE

Arsenic Copper

Zinc

Lead

Mercury Nickel

Chromium

Silver

ER-L

ER-M

nondetection

PEC

TEC

TEC

TEC

TEC

TEC

TEC

TEC

TEC, threshold effect concentration

PEC, probable effect concentration

ER-L, effects range-low

ER-M, effects range-median

EXPLANATION

(MacDonald and others, 2000)

(Long and others, 1995)

Figure 9. Selected trace element concentrations and trends in core collected near Goose Prairie Creek, Caddo 

Lake, Texas, May 2002.
30 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

Concentrations of the major elements were 

tested for significant trends in the Harrison Bayou core 

(table 6). Aluminum concentrations had a significant 

downward trend (Kendall’s τ = -.71, p = .01), iron concentrations had a significant upward trend (τ = 0.86, 

p = 0), and titanium concentrations had no significant 

trend (τ = -.43, p = .14). As with the Goose Prairie 

Creek data, the lack of similarity among the trends of 

aluminum, iron, and titanium concentrations provides 

some evidence that the sedimentation rate over time has 

not been constant. 

Three of the trace elements with SQGs (chromium, nickel, and zinc) had concentrations higher than 

the respective TECs, although none exceeded the PECs 

0 500 1,000 1,500 2,000 2,500 0 25 50 0 25 50 0 25 50

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM

0 100 200 300 400 500 0 100 200 300 400 0 4 8 12

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM 2- AND 3-RINGED PAH /

COMBUSTION PAH

1945

1955

1965

1975

1985

1995

2005

1945

1955

1965

1975

1985

1995

2005

DEPOSITION DATE DEPOSITION DATE

C2-alkylated 

Naphthalenes

Fluoranthene Benzo(b)-

fluoranthene

Indeno-

(1,2,3-c,d)-

pyrene

Total

SQG

PAH

Combustion

PAH

TEC = 423

TEC = 1,610

SQG, sediment-quality guideline

TEC, threshold effect concentration (MacDonald and others, 2000)

EXPLANATION

Figure 10. Selected polycyclic aromatic hydrocarbon (PAH) concentrations in core collected near Harrison Bayou, 

Caddo Lake, Texas, May 2002.
OCCURRENCE AND TRENDS 31

Table 7. Summary of results of analysis for selected trace elements in sediment cores from Caddo Lake, Texas, 

May 2002 

[TEC, threshold effect concentration (MacDonald and others, 2000); PEC, probable effect concentration (MacDonald and 

others, 2000); --, not applicable] 

1 Percent samples greater than ER–L (effects range-low) and ER–M (effects range-median) (Long and others, 1995).

Coring

site

Trace

element

Concentrations

greater than TEC

(percent)

Concentrations

greater than PEC

(percent)

Statistically

significant

trend

If trend, percent change

from highest or lowest

concentration to present

concentration

Goose Prairie Creek

(9 samples)

Arsenic 0 0 No trend --

Cadmium 0 0 No trend --

Chromium 100 0 Downward 43

Copper 78 0 No trend --

Lead 100 11 Downward 72

Mercury 100 0 Downward 57

Nickel 100 0 No trend --

Zinc 78 0 No trend --

Silver 189 1

89 No trend --

Harrison Bayou

(8 samples)

Arsenic 0 0 No trend --

Cadmium 0 0 No trend --

Chromium 100 0 Downward 18

Copper 0 0 Downward 7.5

Lead 0 0 Downward 32

Mercury 0 0 Upward 33

Nickel 100 0 No trend --

Zinc 100 0 No trend --

Mid-lake

(8 samples)

Arsenic 25 0 Upward 93

Cadmium 0 0 No trend --

Chromium 100 0 No trend --

Copper 0 0 No trend --

Lead 0 0 No trend --

Mercury 0 0 Upward 50

Nickel 87.5 0 No trend --

Zinc 62.5 0 No trend --

Carter Lake

(14 samples)

Arsenic 100 0 Downward 20

Cadmium 0 0 Downward 12

Chromium 100 0 Downward 21

Copper 7 0 No trend --

Lead 29 0 Downward 33

Mercury 93 0 Downward 9.5

Nickel 100 0 Downward 16

Zinc 100 0 Downward 28
32 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

0 10 20 30 40 0 0.04 0.08 0.12 0.16 0.2 0 10 20 30 40 50 0 40 80 120 160

TRACE ELEMENT CONCENTRATION, IN MICROGRAMS PER GRAM

0 2 4 6 8 10 0 0.2 0.4 0.6 0 25 50 75 0 10 20 30 40

1945

1955

1965

1975

1985

1995

2005

1945

1955

1965

1975

1985

1995

2005

DEPOSITION DATE DEPOSITION DATE

Arsenic Cadmium Chromium Copper

Lead Mercury Nickel Zinc

TEC

TEC

TEC

TEC

TEC

TEC

TEC = 0.99

TEC

PEC

TEC, threshold effect concentration

PEC, probable effect concentration

EXPLANATION

(MacDonald and others, 2000)

Figure 11. Selected trace element concentrations and trends in core collected near Harrison Bayou, Caddo Lake, 

Texas, May 2002.

(fig. 11; table 7). The concentrations of nickel were 

close to, but still lower than, the PEC. Cadmium concentrations were lower than the TEC, and concentrations of arsenic, copper, lead, and mercury were lower 

than the respective TECs. Chromium, copper, and lead 

concentrations had significant downward trends, and 

mercury concentrations had a significant upward trend 

(fig. 11; table 6). For trace elements without SQGs but 

with significant trends, 86 percent of the trends were 

upward. 
OCCURRENCE AND TRENDS 33

Mid-Lake

Age Dating and Sedimentation Rates

The mid-lake core was analyzed for 137Cs, 210Pb, 

and 226Ra. A plot of unsupported 210Pb as a function 

of cumulative dry mass was scattered and did not follow 

a linear decrease (when plotted on a logarithmic scale) 

(R2 = .4117; fig. 4a). It was decided not to use the 210Pb 

concentrations for age dating the core. The 137Cs concentrations were used instead because they showed a 

clear peak at 9.75 cm. An average MAR of 0.074 

g/cm2

-yr and sediment deposition dates back to about 

1940 were computed for the core, which resulted in age 

dates of 1976.0 for the highest total DDT concentration 

and 1982.9 for the highest lead concentration. These 

dates were later than their known historical peak concentrations in cores from other lakes (Callendar and 

Van Metre, 1997; Van Metre and others, 1997); however, the peak total DDT and lead concentrations in the 

core might have been missed by the wide sample analysis interval used at the bottom of the core. Only two 

samples were analyzed for organochlorine compounds 

and trace elements near the bottom of the core. The estimated deposition dates for those samples were 1950 and 

1967. It is unlikely that the sediment accumulation rate 

in the mid-lake was constant over the period of deposition represented in the core, but no additional date-depth 

markers were in the core to use for the computation of 

more than one MAR; therefore, an uncertainty of ±5 

years is estimated for the age dates of the samples in the 

mid-lake core.

Contaminant Occurrence and Trends

DDE was detected in all samples from the midlake site analyzed for organochlorine compounds, and 

DDD was detected in the two oldest samples only, 

deposited in 1950 and 1967 (fig. 7). Only in the sample 

deposited in 1976 was a DDE concentration higher than 

the TEC. Because organic carbon concentrations had a 

significant upward trend (Kendall’s τ = .86, p = 0), 

organic compound concentrations were normalized 

with organic carbon concentrations before trend testing. 

DDE had a statistically significant downward trend in 

the mid-lake core (Kendall’s τ = -.57, p = .048). PCB 

Aroclors 1242, 1254, and 1260 were not detected in the 

core. 

PAH concentrations in the mid-lake core were 

low. The PAH mixture in the mid-lake core was dominated by C2-alkylated naphthalenes, with 2,6-dimethylnaphthalene contributing about one-half to threefourths of the total C2-alkylated naphthalene concentration. Most individual PAH concentrations were below 

20 μg/kg and well below their TECs (fig. 12). Total 

SQG PAHs did not exceed 120 μg/kg, an order of magnitude lower than the TEC. The ratio of 2- and 3-ringed 

compounds to combustion PAH was about 1 or greater 

than 1 in all but the surficial sample. Organic carbon 

normalized concentrations of C1-178 isomers, C2-178 

isomers, C1-252 isomers, and coronene had significant 

downward trends (table 5). No trends were indicated by 

concentrations of total SQG PAH and combustion PAH 

(fig. 12). 

Concentrations of the major elements were tested 

for significant trends in the mid-lake core (table 6). 

Aluminum concentrations had no trend (Kendall’s τ = 0, 

p = 1), iron concentrations had a significant upward 

trend (τ = 1, p = 0), and titanium concentrations had 

a significant downward trend (τ = -.79, p = .01). As 

with the other core data described, the lack of similarity 

among the trends of aluminum, iron, and titanium 

concentrations indicates the possibility of a changing 

sedimentation rate over time. The organic carbon concentrations in the mid-lake core were noticeably lower 

than those in the other three cores collected from the 

lake (appendix 2.4). 

Variation in trace element concentrations in the 

mid-lake core was more subtle than in the other cores—

arsenic, manganese, and mercury concentrations had 

significant upward trends (fig. 13; table 6). Decreasing 

concentrations of manganese with depth in sediment 

have been reported as an effect of diagenesis (for example, Gobeil and others, 1997). All chromium concentrations in the core exceeded the TEC (table 7); seven of 

eight nickel concentrations exceeded the TEC; the five 

samples deposited between 1976 and 1998 had zinc 

concentrations that exceeded the TEC; and the two most 

recently deposited samples had arsenic concentrations 

that exceeded the TEC. All concentrations of cadmium, 

copper, lead, and mercury were below the TEC. No 

trace element concentration exceeded the PEC. 

Carter Lake

Age Dating and Sedimentation Rates

The Carter Lake core was analyzed for 137Cs, 

210Pb, and 226Ra for age dating. Unsupported 210Pb 

graphed on a logarithmic scale as a function of cumulative dry mass was almost linear (R2

 = .8059; fig. 4b), 
34 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

and a clearly defined 137Cs peak for a 1964.0 date-depth 

marker was not available; thus the slope of the line fit to 

the points was used to compute age dates back to about 

1965 for the samples in the core. A MAR of 0.099 

g/cm2-yr was computed for the core. The highest total 

DDT and lead concentrations had a deposition date of 

1975.8 (fig. 6d). This sample interval was the deepest 

analyzed for organochlorine compounds, so the total 

DDT peak might have occurred in sediments deeper 

than those analyzed at this site. The age dates were 

0 50 100 150 0 50 100 150 0123

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM 2- AND 3-RINGED PAH /

COMBUSTION PAH

0 50 100 150 200

0246

0 5 10 15 20 25

0 0.2 0.4 0.6 0.8 1

0 5 10 15 20

0 0.2 0.4 0.6 0.8

0 5 10 15 20

0 0.2 0.4 0.6 0.8

012345 012345

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM

PAH CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION

(MICROGRAMS OF PAH PER GRAM OF ORGANIC CARBON)

PAH CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION

(MICROGRAMS OF PAH PER GRAM OF ORGANIC CARBON)

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

DEPOSITION DATE DEPOSITION DATE

C2-alkylated

Naphthalenes

Pyrene Benzo(b)-

fluoranthene

Indeno-

(1,2,3-c,d)-

pyrene

Combustion

PAH

Total

SQG

PAH PAH

PAH/OC

OC, organic carbon

TEC, threshold effect concentration

(MacDonald and others, 2000)

SQG, sediment-quality guideline

EXPLANATION

PAH

TEC = 1,610

PAH

TEC = 195

Figure 12. Selected polycyclic aromatic hydrocarbon (PAH) concentrations in core collected in mid-lake of Caddo 

Lake, Texas, May 2002.
OCCURRENCE AND TRENDS 35

consistent with historical lead concentrations in cores. 

137Cs concentrations increased with depth in the 

core back to 1975, which is consistent with the 210Pb 

deposition dates (fig. 6d). It was unlikely that the sediment accumulation rate in Carter Lake was constant 

over the period of deposition collected in the core, but 

as with the other cores, no additional date-depth markers were in the Carter Lake core to use for the computation of more than one MAR; therefore, an uncertainty of 

±2 years was estimated for the age dates of the samples 

in the Carter Lake core.

Contaminant Occurrence and Trends

DDE was detected in samples deposited between 

1975 and 1994, and DDD was detected in the oldest 

sample only, deposited about 1975 (fig. 7). Only the 

0 4 8 12 0 0.1 0.2 0.3 0 20 40 60 80 0 5 10 15 20

0 10 20 30 0 10 20 30 0 40 80 120 160

TRACE ELEMENT CONCENTRATION, IN MICROGRAMS PER GRAM

0 0.05 0.10 0.15

1945

1955

1965

1975

1985

1995

2005

1945

1955

1965

1975

1985

1995

2005

DEPOSITION DATE DEPOSITION DATE

Arsenic Cadmium Chromium Copper

Lead Nickel Mercury Zinc

TEC

TEC

TEC

TEC

TEC = 35.8 TEC = 0.18

TEC = 0.99 TEC = 31.6

TEC, threshold effect concentration, (MacDonald and others, 2000)

EXPLANATION

Figure 13. Selected trace element concentrations and trends in core collected in mid-lake of Caddo Lake, Texas, 

May 2002.
36 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

oldest sample had a DDE concentration above the TEC. 

PCB Aroclors 1242, 1254, and 1260 were not detected 

in the Carter Lake core. Organic carbon concentrations 

ranged from 8.06 to 11.2 percent and had a significant 

upward trend (Kendall’s τ = .73, p = 0); therefore, 

organic compound concentrations were normalized 

with organic carbon concentrations before trend testing. 

Organic carbon normalized DDE concentrations had 

a significant downward trend (Kendall’s τ = -.86, 

p = .003). 

PAH concentrations in the Carter Lake core were 

less than the TECs (fig. 14). The C2-alkylated naphthalenes had the highest concentrations, particularly 2,6-

dimethylnaphthalene. The concentrations of other compounds were about an order of magnitude lower than 

the C2-alkylated naphthalenes and of similar magnitude 

to one another. The organic carbon normalized concentrations of 9H-Fluorene, 1-methyl-9H-Fluorene, 

4,5-methylenephenanthrene, benzo(g,h,i)perylene, and 

dibenzo(a,h)anthracene had significant downward 

trends (table 5), but total SQG PAH and combustion 

PAH had significant upward trends. The ratio of 2- and 

3-ringed PAH to combustion PAH was greater than 1 for 

all but one sample deposited in 1989, which indicates a 

predominance of uncombusted PAH sources.

Concentrations of the major elements in the 

Carter Lake core were trend tested (table 6). Aluminum, 

iron, and titanium concentrations had significant downward trends (Kendall’s τ = -.69, p = 0; τ = -.85, p = 0; 

and τ = -.61, p = 0, respectively). The downward trends 

of these three stable elements indicate a decreasing sedimentation rate over time in the Carter Lake core.

Concentrations of several trace elements in the 

samples from the Carter Lake core exceeded the respective TECs (fig. 15; table 7), but none exceeded the 

PECs. All sample concentrations of arsenic, chromium, 

nickel, and zinc exceeded the TECs; all but one mercury 

concentration exceeded the TEC. Lead concentrations 

in samples deposited before 1985 were higher than the 

TEC, but concentrations in samples deposited after 

1985 were lower. The copper concentration in one sample, with a deposition date of 1997, exceeded the TEC 

for copper. The concentrations of seven of the eight 

trace elements with SQGs had significant downward 

trends—all except copper. The trends in concentrations 

of trace elements without SQGs were all downward. 

Sediment-Core Burdens, Focusing Factors, 

and General Sources of Mercury

The burdens of 137Cs (φc) and mercury (φhg) for 

the Goose Prairie Creek core, Harrison Bayou core, and 

mid-lake core, and the FFs for the three coring sites 

were computed as described in the “Sediment-Core 

Burden and Focusing Factor” section. The φhg for each 

core was normalized with the respective FF to compute 

the amount of cumulative atmospheric mercury fallout 

necessary over the Caddo Lake region to produce the 

measured φhg. Similar data for the Carter Lake core 

were not computed because the oldest Carter Lake sediment analyzed for 137Cs (20- to 21-cm interval) was 

age dated to 1973.9, essentially at the end of the period 

1954–74 upon which the prediction model used to 

obtain cumulative atmospheric fallout deposition of 

137Cs (φf

) for the Caddo Lake region is based. Thus, 

because φc and φf

 could not be obtained for a common 

period, a meaningful focusing factor (FF = φc /φf

) for the 

Carter Lake site could not be computed. 

The φc ranged from 2.45 pCi/cm2 for the midlake core to 6.82 pCi/cm2 for the Goose Prairie core 

(table 8). The φf

 for the Caddo Lake region was computed to be 4.65 pCi/cm2

. Comparison of the modelpredicted φf

 to decay-corrected fallout measured by the 

U.S. Energy Research and Development Administration, Health and Safety Laboratory (1977), indicated 

Table 8. Sediment focusing data and core burdens for mercury, Caddo Lake, Texas, May 2002 

[pCi/cm2

, picocuries per square centimeter; μg/cm2, micrograms per square centimeter] 

Sediment core

137Cs burden

(φc)

(pCi/cm2)

Mercury

burden (φhg)

(μg/cm2)

Cumulative 137Cs

fallout deposition,

1954–74 (φf)

(pCi/cm2)

Focusing

factor (FF)

(φc /φf

)

Mercury burden

normalized with

focusing factor

(μg/cm2)

Goose Prairie Creek 6.82 5.17 4.65 1.47 3.53

Harrison Bayou 4.36 .49 4.65 .94 .52

Mid-lake 2.45 .52 4.65 .53 1.00
OCCURRENCE AND TRENDS 37

uncertainty of about 20 percent in the model-predicted 

φf and subsequent focusing computations. 

The sediment FF was about 1.5 for the Goose 

Prairie Creek site, about 1.0 for the Harrison Bayou site, 

and about 0.5 for the mid-lake site (table 8). Comparable FFs have been reported for the Great Lakes 

(Eadie and Robbins, 1987; Eisenreich and others, 

1989), and larger FFs have been reported for reservoirs 

0 100 200 300 400 500 0 100 200 300 400 500 02468

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM 2- AND 3-RINGED PAH /

COMBUSTION PAH

0 1,000 2,000 3,000 0 40 80 120 160 200 0 25 50 75 100 125 150 0 25 50 75 100

1234 01234

PAH CONCENTRATION, IN MICROGRAMS PER KILOGRAM

0 5 10 15 20 25 0 0.4 0.8 1.2 1.6 2 0 0.4 0.8 1.2 1.6 0 0.2 0.4 0.6 0.8

1975

1980

1985

1990

1995

2000

2005

1975

1980

1985

1990

1995

2000

2005

DEPOSITION DATE DEPOSITION DATE

C2-alkylated

Naphthalenes

Pyrene Chrysene Indeno(1,2,3-c,d)-

pyrene

Total

SQG

PAH

Combustion

PAH

PAH

PAH/OC

OC, organic carbon

TEC, threshold effect concentration

(MacDonald and others, 2000)

SQG, sediment-quality guideline

EXPLANATION

PAH CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION

(MICROGRAMS OF PAH PER GRAM OF ORGANIC CARBON)

PAH CONCENTRATION NORMALIZED WITH 

ORGANIC CARBON CONCENTRATION

(MICROGRAMS OF PAH PER GRAM OF ORGANIC CARBON)

PAH TEC = 1,610

PAH TEC = 195 PAH TEC = 166

Figure 14. Selected polycyclic aromatic hydrocarbon (PAH) concentrations and trends in core collected from 

Carter Lake, Caddo Lake, Texas, May 2002.
38 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

across the country (for example, Van Metre and 

others, 1997). The Goose Prairie Creek FF indicates 

that about one-third of the mercury at the Goose Prairie 

Creek site might result from drainage area sources. 

After normalizing for sediment focusing, the Goose 

Prairie Creek mercury burden is about 3.5 and 7 times 

larger than the burdens for the Harrison Bayou and 

mid-lake sites, respectively. No drainage area sources 

are indicated by the FFs for the Harrison Bayou 

and mid-lake sites. In a recent statewide inventory 

of water-quality concerns, the TCEQ (Texas Natural 

Resource Conservation Commission, 2002b, p. 8–10) 

reported that the source of mercury to sites near 

the mid-lake and Carter Lake sites of this report 

is both industrial point sources and atmospheric 

deposition. 

0 4 8 12 16 0 0.2 0.4 0.6 0.8 1 0 25 50 75 100 0 10 20 30 40

0 10 20 30 40 50 0 0.05 0.1 0.15 0.2 0.25 0 10 20 30 40 50 0 100 200 300 400

TRACE ELEMENT CONCENTRATION, IN MICROGRAMS PER GRAM

1965

1970

1975

1980

1985

1990

1995

2000

2005

1965

1970

1975

1980

1985

1990

1995

2000

2005

DEPOSITION DATE DEPOSITION DATE

Arsenic Cadmium Chromium Copper

Lead Nickel Mercury Zinc

PEC

TEC

TEC

TEC

TEC

TEC

TEC

TEC

TEC

TEC, threshold effect concentration

PEC, probable effect concentration

EXPLANATION

(MacDonald and others, 2000)

Figure 15. Selected trace element concentrations and trends in core collected from Carter Lake, Caddo Lake, 

Texas, May 2002.
OCCURRENCE AND TRENDS 39

Comparisons of Findings to Those of Other 

Texas Lakes 

The USGS cored Lake Meredith in the Texas Panhandle to investigate the effects of oil and gas production in the area on the sediments in that reservoir 

(Mahler and Van Metre, 2001). More than 250 wells are 

in the Lake Meredith area, and oil and gas exploration 

has been ongoing since about 1930. Lake Meredith is in 

a dry, desert-like environment and has high sedimentation rates (MAR 1.1 to 1.7 g/cm2

-yr), whereas Caddo 

Lake is in a much more humid, swamp-like environment with low sedimentation rates. 

Although drainage area characteristics are different, oil and gas production is common to both drainage 

areas. Concentrations of the trace elements and PAHs 

were compared for Lake Meredith and Caddo Lake 

(table 9). Arsenic and cadmium concentrations in the 

Goose Prairie Creek, Harrison Bayou, and mid-lake 

cores from Caddo Lake were similar to concentrations 

in the Lake Meredith cores; concentrations in the Carter 

Lake core were somewhat higher. Barium concentrations were similar for the four Caddo Lake cores but 

higher in the Lake Meredith cores. Chromium, copper, 

and nickel concentrations were similar in sediments 

from the two water bodies. Lead concentrations were 

similar, except for the Goose Prairie Creek core in 

which concentrations were at least three times higher. 

Mercury concentrations in the Lake Meredith cores 

did not exceed 0.04 μg/g, considerably less than those 

in the Caddo Lake cores, which ranged from 0.08 to 

0.86 μg/g. Zinc concentrations in the Goose Prairie 

Creek, Harrison Bayou, and mid-lake cores were about 

1.2 to 1.4 times higher than those in the Lake Meredith 

cores, and concentrations in the Carter Lake core were 

about 2.5 times higher. 

The concentrations of PAHs were of the same 

order of magnitude in cores from both lakes. Similar to 

Caddo Lake sediments, Lake Meredith sediments generally contained more 2- and 3-ringed PAHs (uncombusted sources) than 4- and 5-ringed PAHs (combusted 

sources). 

The USGS did another sediment coring study in 

Mountain Creek Lake in the cities of Dallas and Grand 

Prairie (Jones and others, 1997). The reservoir is on 

Mountain Creek, a tributary of the Trinity River, and 

was constructed to provide cooling water for a utilities 

power plant. Land use in the Mountain Creek Lake 

drainage area is a mixture of commercial, residential, 

and military facilities. The sedimentation rates (MAR 

0.53 to 0.96 g/cm2-yr) in the reservoir are about double 

the rates computed for Caddo Lake. The Naval Weapons 

Industrial Reserve Plant was built adjacent to the northeastern part of the reservoir in 1941, with a primary mission of military aircraft manufacturing, and is still in 

operation today (2003). Box cores collected in Cottonwood Bay (a part of Mountain Creek Lake) near the 

Naval Weapons Industrial Reserve Plant had mostly 

higher concentrations of arsenic, chromium, copper, 

and nickel than the cores from Caddo Lake (table 9). 

Barium concentrations in the Caddo Lake cores were 

about two times higher than those in the Mountain 

Creek Lake cores. The Goose Prairie Creek core had 

higher concentrations of lead and mercury than those in 

Mountain Creek Lake cores, but lead concentrations in 

the three other cores from Caddo Lake were similar to 

those in Mountain Creek Lake cores. Zinc concentrations in the Carter Lake core were slightly lower than 

those in Mountain Creek Lake cores, and concentrations 

in the other Caddo Lake cores were much lower. 

The PAH assemblages are different in sediments 

of the two lakes. Combustion-derived compounds predominate in Mountain Creek Lake sediments, whereas 

the PAH compounds in Caddo Lake sediments generally are from uncombusted sources. 

Among the three lakes, oil and gas production is 

in the drainage areas of Caddo Lake and Lake Meredith 

but not Mountain Creek Lake. Barium concentrations in 

Caddo Lake and Lake Meredith sediments about twice 

those in Mountain Creek Lake sediments thus could be 

associated with oil and gas production. Association of 

other contaminants with drainage-area characteristics, 

for example weapons production facilities common to 

the drainage areas of Caddo and Mountain Creek Lakes 

but not that of Lake Meredith, is less clear. 

Implications of Findings Relative to Drainage 

Area Sources of Contaminants

The organochlorine pesticides DDE and DDD, 

degradation products of DDT, were detected in all four 

cores and three of four cores, respectively, collected 

from Caddo Lake. DDT probably was used by the 

LHAAP, businesses, and households in the Caddo Lake 

area during the period of DDT production. The peak 

concentrations of DDE at the Goose Prairie Creek and 

Harrison Bayou sites, the two sites closest to points of 

entry of runoff from the LHAAP, were about twice the 

peak concentrations at the mid-lake and Carter Lake 

sites. The Carter Lake core had the fewest detections of 
40 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 Table 9. Summary of trace element and selected PAH concentrations and ratio of 2- and 3-ringed to 4- and 5-ringed PAH assemblages in sediment cores from Caddo Lake, Texas, May 2002, from Lake Meredith, Texas, May 1999, and from Cottonwood Bay in Mountain Creek Lake, Texas, May–July 1996 

[μg/g; micrograms per gram; 

μg/kg; micrograms per kilogram; na, not analyzed] 

1 Unpublished data summarized in Mahler and Van Metre, 2001.2 From Jones and others, 1997.

Constituent

(units)

Caddo Lake - Goose Prairie Creek Caddo Lake - Harrison Bayou Caddo Lake - Mid-lake

Minimum

concentration

Maximum

concentration

Median

concentration

Minimum

concentration

Maximum

concentration

Median

concentration

Minimum

concentration

Maximum

concentration

Median

concentration

Arsenic (

μg/g) 3.8 9.2 7.8 6.6 8.8 7.9 5.7 11 7.2

Barium (

μg/g) 373 530 435 462 570 508 484 516 492

Cadmium (

μg/g) .18 .54 .32 .42 .51 .49 .20 .28 .24

Chromium (

μg/g) 51.6 90.6 67.1 53.9 72.3 60.2 50.3 63.4 52.1

Copper (

μg/g) 20.8 35.9 32.9 24.1 26.6 25.5 13.6 16.6 14.3

Lead (

μg/g) 50.4 181 96.8 23.0 35.1 27.1 23.0 27.6 25.1

Mercury (

μg/g) .34 .86 .52 .12 .16 .15 .08 .12 .12

Nickel (

μg/g) 23.2 38.4 30.8 37.1 44.2 41.6 22.6 27.0 23.9

Zinc (

μg/g) 82.0 222 138 131 155 146 109 144 124

Total SQG PAH (

μg/kg) 90.5 280 198 145 311 230 52 115 78.3

C2-alkylated Naphthalenes (

μg/kg) 13.9 762 39.8 73.5 2,380 664 31.0 198 76.1

Ratio of 2- and 3-ringed PAH to 4- 

and 5-ringed PAH

.74 3.5 .95 1.0 11.7 2.8 .61 2.2 1.2

Constituent

(units)

Caddo Lake - Carter Lake Lake Meredith1 Mountain Creek Lake2

Minimum

concentration

Maximum

concentration

Median

concentration

Minimum

concentration

Maximum

concentration

Median

concentration

Minimum

concentration

Maximum

concentration

Median

concentration

Arsenic (

μg/g) 12 15 14 3.70 13.7 9.96 7.8 20.7 16.0

Barium (

μg/g) 432 507 447 534 845 593 96 334 224

Cadmium (

μg/g) .70 .86 .75 .17 .50 .31 na na na

Chromium (

μg/g) 56.8 74.6 61.8 27.3 83.1 70.2 117 574 322

Copper (

μg/g) 22.4 32.4 23.8 12.9 29.4 27.0 15.2 88.3 63.8

Lead (

μg/g) 27.1 41.8 32.3 13.6 26.8 23.1 32.8 93.4 60.0

Mercury (

μg/g) .18 .21 .20 .02 .04 .03 .052 .28 .16

Nickel (

μg/g) 39.8 47.2 43.8 13.0 35.8 32.8 31 109 53.2

Zinc (

μg/g) 235 328 264 35.4 118 106 127 448 340

Total SQG PAH (

μg/kg) 104 399 202 2.2 74.3 14.3 2,037 173,043 14,443

C2-alkylated Naphthalenes (

μg/kg) 178 2,230 920 2.4 77.5 26.5 89.9 756 238

Ratio of 2- and 3-ringed PAH to 4- 

and 5-ringed PAH

1.0 7.5 3.4 .68 4.3 2.1 0.13 1.2 .18
OCCURRENCE AND TRENDS 41

DDE, perhaps because adjacent development was 

sparse and thus DDT use minimal. A public health 

assessment of the LHAAP found DDD, DDE, aldrin, 

and dieldrin in soil samples (Agency for Toxic Substances and Disease Registry, 2003). Recently deposited 

sediments in the four cores had low DDE concentrations 

(below the TEC) and no detections of DDD, aldrin, or 

dieldrin. These findings indicate that the LHAAP is a 

possible source of the detected organochlorines in sediments, although not from recent transport.

The Goose Prairie Creek core was the only core in 

which PCBs were detected. The former TNT production 

area of the LHAAP and the town of Uncertain are in the 

Goose Prairie Creek drainage area (fig. 2). Because 

PCBs were not detected in the cores from other sites in 

Caddo Lake and could have been used in industrial 

activities at the LHAAP, the LHAAP is a potential 

source of the PCBs to the sediments at the Goose Prairie 

Creek site. Uncertain would seem an unlikely source of 

PCBs to the environment. 

All PAHs were detected at concentrations below 

SQGs in the Caddo Lake sediment cores. PAHs in the 

sediment samples often are from uncombusted sources, 

as indicated by the dominance of the alkylated naphthalenes in the PAH mixtures and PAH ratio computations. 

Uncombusted sources are common in the Caddo Lake 

area, with several oil and gas fields near the lake (fig. 1), 

oil and gas wells in the lake, and an airport, roads, 

marina, and numerous boat ramps on or near the shores 

(fig. 3). Spills or leaks from oil or gas wells, automobiles, aircraft, or boats in or near the lake could contribute PAHs to the sediments in the drainage area and lake. 

The composition of oil is highly variable depending 

upon the type of oil, weathering, refinery, and length of 

use (such as with a lubricant) (for example, Short and 

others, 1999; Pruell and Quinn, 1988). Likewise, the 

composition of gasoline is highly variable depending 

upon the type of gasoline (such as unleaded gasoline for 

automobiles, aviation gasoline, various grades, octane 

ratings, and additives) (Irwin and others, 1998). Regardless of their composition, uncombusted sources such as 

oil and gasoline are characterized by low molecular 

weight and alkylated PAHs (Eganhouse and Gossett, 

1991). However, differentiation among uncombusted 

sources using the PAH assemblage in the Caddo Lake 

sediment core samples was not possible. 

The only exceedance of a PEC was one lead concentration in a sample from the Goose Prairie Creek 

site. Lead concentrations at the Goose Prairie Creek site 

were substantially higher than at the other three sites, 

although the trend has been steadily downward from a 

peak about 1961 (fig. 9). As previously described 

(Review of Existing Information), lead has been 

detected in soil and sediment samples collected from the 

LHAAP. Based on this evidence and the sampling site’s 

proximity to the LHAAP, the LHAAP could have been 

a principal source of the lead detected at the Goose Prairie Creek site. If the 1961–2002 decreasing trend at the 

Goose Prairie Creek site continues, lead concentrations 

there should be comparable to concentrations at the 

other three sites in a few years.

Like lead concentrations, mercury concentrations 

at the Goose Prairie Creek site were substantially higher 

than at the other three sites and have been trending 

downward from a peak about 1961 (fig. 9). Although no 

reports of mercury use or discharge at the LHAAP have 

been found, the FF for the Goose Prairie Creek site, 

unlike FFs for the Harrison Bayou and mid-lake sites 

(no FF for Carter Lake site), indicates that a substantial 

part of the mercury at the Goose Prairie Creek site might 

have come from drainage area sources in addition to 

atmospheric deposition. The LHAAP remains a possible source of mercury to the site, although no direct link 

is evident. If the 1961–2002 downward trend at the 

Goose Prairie Creek site continues, mercury concentrations there should be comparable to concentrations at 

the other three sites in 10 to 15 years.

Arsenic, cadmium, and zinc concentrations were 

highest at the Carter Lake site, the site that was selected 

to represent background conditions because that location does not receive runoff from the LHAAP, is far 

from the area of the lake with dense oil and gas operations (fig. 3), and has little development within its drainage basin. However, some producing oil and gas wells 

are in the waters to the north of the Carter Lake site, at 

least one abandoned (plugged) oil or gas well is in the 

small Carter Lake drainage area, and a road and boat 

ramp are near the coring site. No relation between the 

relatively higher trace element concentrations and any 

potential source is indicated. The same potential sources 

of contamination in the Carter Lake drainage area also 

are in the drainage areas of the three other coring sites 

in Caddo Lake. 

None of the trace element concentrations was 

salient at the Harrison Bayou or mid-lake sites, despite 

numerous producing and abandoned oil and gas wells in 

the Harrison Bayou drainage area and the proximity of 

dense oil and gas operations in the lake to the east of the 

mid-lake site. No specific sources of trace elements 

detected at those sites are indicated by available data. 
42 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, East Texas, 1940–2002 

SUMMARY 

Bottom-sediment cores collected from four sites 

in Caddo Lake, Texas, in May 2002 were analyzed for 

radionuclides (for age dating), organochlorine pesticides, PCBs, PAHs, and major and trace elements to 

describe the occurrence and trends of these sedimentassociated contaminants. The sediment cores were 

obtained from sites near the mouth of Goose Prairie 

Creek; near the mouths of Harrison Bayou, Central 

Creek, and Saunders Branch; in the main body of the 

lake (mid-lake); and in a western part of the lake called 

Carter Lake. The Goose Prairie Creek and Harrison 

Bayou sites receive drainage from an area that includes 

parts of the now-closed Longhorn Army Ammunitions 

Plant (LHAAP). The mid-lake site is the closest to 

dense oil and gas operations in the lake. The Carter Lake 

site receives minimal discharge from developed areas. 

Sediment deposition dates represented in the cores were 

computed back to about 1948 for the Goose Prairie 

Creek site, 1950 for the Harrison Bayou site, 1940 for 

the mid-lake site, and about 1965 for the Carter Lake 

site on the basis of the concentrations of 137Cs, 210Pb, 

or both. Contaminant concentrations were compared to 

sediment-quality guidelines (SQGs)—threshold effect 

concentrations (TECs) and probable effect concentrations (PECs)—that indicate the degree of potential harm 

to benthic biota. Samples were tested for statistically 

significant temporal trends using Kendall’s tau. 

The only organochlorine compounds detected in 

the Goose Prairie Creek core were DDE and PCB Aroclors 1242, 1254, and 1260. Fifty-six percent of the 

sample concentrations of DDE in the Goose Prairie 

Creek core exceeded the consensus-based TEC for 

DDE but were well below the PEC. Only one sample 

concentration, deposited about 1969 before restrictions 

on the use of PCBs, exceeded the TEC for total PCB. 

PCB Aroclors 1242 and 1254 had significant downward 

trends; no other organochlorines had significant trends. 

Numerous PAHs were detected in the Goose 

Prairie Creek core, although concentrations were low, 

all below the respective TECs. The naphthalene homologues with two alkyl groups (C2-alkylated naphthalenes) had the highest concentrations. Nineteen PAHs 

had statistically significant trends—all downward. 

Since about 1995, PAHs appear to have come primarily 

from uncombusted sources such as petroleum-based 

fuels, as opposed to combusted sources associated with 

the high-temperature burning of fuels.

The Goose Prairie Creek core (and other cores) 

was analyzed for eight major elements and 26 trace elements, eight of which have SQGs. All samples analyzed 

for trace elements in the Goose Prairie Creek core 

exceeded the TEC for chromium, lead, mercury, and 

nickel, and 78 percent of samples were at or above the 

TEC for copper and zinc. One sample, deposited about 

1961, exceeded the PEC for lead. The concentrations of 

chromium, lead, and mercury had significant downward 

trends since about 1961. In sediments deposited after 

1980, nickel and zinc had significantly increasing concentrations. Seventy percent of the trace elements without SQGs but with significant trends had decreasing 

concentrations over time in the core. 

In the Harrison Bayou core, DDE was detected in 

all samples analyzed for organochlorine compounds. 

Five of the six samples deposited before 1995 had DDE 

concentrations higher than the TEC but much lower 

than the PEC. DDE concentrations at the site had a significant downward trend. DDD was detected in the oldest sample only, deposited about 1950. PCB Aroclors 

1242, 1254, and 1260 were not detected in the core. 

The PAH mixture was dominated by high concentrations of C2- and C3-alkylated naphthalenes, some 

greater than 2,000 μg/kg. Concentrations of all other 

compounds were less than 50 μg/kg. Concentrations of 

most individual PAH compounds were highest in the 

most recently deposited sample, but most PAH concentrations did not show significant upward trends. All 

PAHs were below the respective TECs. Uncombusted 

PAH sources dominated.

Among trace element concentrations in the Harrison Bayou core, chromium, nickel, and zinc concentrations were higher than the respective TECs, but none 

exceeded the PECs. Chromium, copper, and lead concentrations had significant downward trends, and mercury concentrations had a significant upward trend.

DDE occurred in all samples from the mid-lake 

site analyzed for organochlorine compounds. Only in 

the sample deposited in 1976 was a DDE concentration 

higher than the TEC. DDD was detected in the two oldest samples only, deposited in 1950 and 1967. DDE 

concentrations had a statistically significant downward 

trend. PCB Aroclors 1242, 1254, and 1260 were not 

detected in the core. 

PAH concentrations in the mid-lake core were 

low. As in the previously mentioned cores, the PAH 

mixture in the mid-lake core was dominated by C2-

alkylated naphthalenes. Most individual PAH concentrations were below 20 μg/kg and well below their 
REFERENCES 43

TECs. The few significant trends in PAHs were all 

downward. Uncombusted sources dominated.

Variation in trace element concentrations in the 

mid-lake core was more subtle than in the other cores—

arsenic, manganese, and mercury concentrations had 

significant upward trends. One or more sample concentrations of arsenic, chromium, nickel, and zinc exceeded 

the respective TEC; no trace element concentration 

exceeded the PEC.

Similar to organochlorine analyses from the other 

three cores, DDE was the most commonly detected 

compound in Carter Lake samples. Only the oldest sample had a DDE concentration above the TEC, and there 

was a significant downward trend in DDE concentrations. DDD was detected only in the oldest sample, 

deposited about 1975. No PCBs were detected.

PAH concentrations in the Carter Lake core 

were less than the TECs. As in the other cores, the 

C2-alkylated naphthalenes had the highest concentrations, some greater than 2,000 μg/kg and comparable 

to those at the Harrison Bayou site. The concentrations 

of other compounds were about an order of magnitude 

lower than the C2-alkylated naphthalenes. Among the 

few PAHs with significant trends, almost all were downward. As in the other cores, uncombusted sources 

dominated.

Concentrations of several trace elements in the 

samples from the Carter Lake core exceeded the respective TECs, but none exceeded the PECs. The concentrations of seven of the eight trace elements with SQGs had 

significant downward trends—all except copper.

Burdens (amount per unit area of a contaminant 

in a sediment core) of 137Cs and mercury and sediment 

focusing factors (FF) (quantitative measure of the extent 

to which contaminants from drainage area sources 

occur at a site) were computed to provide information 

on the dominant source (atmospheric fallout or drainage 

area) of mercury to the Caddo Lake sediment core sites 

(except Carter Lake). Results indicate that about onethird of the mercury at the Goose Prairie Creek site 

might result from drainage area sources. No drainage 

area sources were indicated for the Harrison Bayou and 

mid-lake sites.

Specific drainage area sources of contaminants 

detected in the lake sediments are difficult to determine 

with certainty. The fact that peak concentrations of the 

DDT degradation products at the Goose Prairie Creek 

and Harrison Bayou sites, the two sites closest to points 

of entry of runoff from the LHAAP, were about twice 

the peak concentrations at the mid-lake and Carter Lake 

sites, and the fact that DDD, DDE, aldrin, and dieldrin 

have been detected in soil samples from the LHAAP 

indicate that the LHAAP is a possible historical source 

of the detected organochlorines. As PCBs were detected 

only at the Goose Prairie Creek site, the LHAAP is a 

possible source for those as well.

The majority of PAH compounds appear to have 

originated from uncombusted fuel sources. Uncombusted fuel sources are common in the Caddo Lake area, 

with several oil and gas fields near the lake and oil and 

gas wells in the lake. Oil and gas production in Caddo 

Lake and its drainage area is a possible source of PAHs 

in Caddo Lake sediments. 

Among trace element concentrations at the four 

sites, lead and mercury were consistently relatively high 

at the Goose Prairie Creek site. Again the LHAAP, 

because of its proximity and history of industrial activities, is a suspected source. Lead has been detected in 

soil and sediment samples collected from the LHAAP; 

mercury has not, although burden and FF computations 

possibly indicate drainage area sources for part of the 

mercury in sediment at the site.

Arsenic, cadmium, and zinc concentrations were 

highest at the Carter Lake site. No direct link between 

these relatively higher trace element concentrations and 

oil and gas operations is indicated, but the proximity 

between the site and oil or gas wells and the absence of 

other potential sources makes oil and gas operations a 

possible source. 

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Appendix 1.1 47

Occurrence of and Trends in Selected SedimentAssociated Contaminants in Caddo Lake, Texas, 

1940–2002

Appendix 1.1

APPENDIX 1—

Description of Sediment Push Cores
48 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 

Appendix 1.1. Description of sediment push cores collected at Caddo Lake, Texas, May 2002 

[cm, centimeters] 

Depth interval

(cm) Color Comments

Goose Prairie Creek Inlet

0–5 Olive-gray Very watery and soft

5–20 Olive-gray with some darker gray 

areas

More aquatic vegetation than overlying and underlying intervals; 

lots of roots; one large white root at 15 cm; similar to box core

20–35 Light gray Much stiffer clay than the overlying material with a lot of root hairs 

and wood chunks

Harrison Bayou Inlet

0–9 Medium olive-gray Very wet, loose combination of sediment and algae

9–22 Medium olive-gray Still fairly wet; a lot of stringy organics; leaf veins and pine needles; 

especially dense vegetation at 15 cm

22–30 Light olive-gray Thick mass of stringy organics that look like roots

30–40 Light greenish-gray Wet, clayey, more cohesive sediment

40–55 Light greenish-gray A lot stiffer and dryer than the overlying interval; big black spot at 

50 cm that looks like ash; big wood chunk at 53–55 cm; a few 

root hairs

Mid-lake (main stem near Little Green Brake)

0–7 Mostly dark olive-gray with some 

light olive-gray and rusty 

brown spots

Very soft with a small amount of sand

7–31 Light gray Dry, stiff clay; pine needles and charred wood bits speckled 

throughout

Carter Lake near Horse Island

0–19 Dark olive-gray Wet at top, becoming more firm and gelatinous with depth

19–35 Light olive-gray Gelatinous sediment

35–42 Light olive-gray Large chunks of wood in the sediment

42–45 Light olive-gray Gelatinous sediment

45–50 Dark olive-gray Mat of roots and vegetation

50–75 Medium olive-gray Stiff, sticky clay; especially hard below 62 cm
Appendix 2 49

Occurrence of and Trends in Selected SedimentAssociated Contaminants in Caddo Lake, Texas, 

1940–2002

Appendix 2

APPENDIX 2—

Analytical and Trend Testing Results
50 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 

Appendix 2.1 Appendix 2.1. Analytical results for radionuclides

[In picocuries per gram; uncertainty, two standard deviations; ID, identifier; --, not applicable] 

USGS station ID Sample ID Cs-137 Cs-137 uncertainty Pb-210 Ra-226 Ra-226 uncertainty

Goose Prairie Creek core:

324208094073500 CDO.GP 1–2 0.693 0.25 -- -- --

324208094073500 CDO.GP 3–4 .86 .27 -- -- --

324208094073500 CDO.GP 5–6 .921 .231 -- -- --

324208094073500 CDO.GP 8–9 .848 .263 -- -- --

324208094073500 CDO.GP 11–12 .922 .252 -- -- --

324208094073500 CDO.GP 14–15 .964 .204 -- -- --

324208094073500 CDO.GP 17–18 1.1 .19 -- -- --

324208094073500 CDO.GP 20–21 1.3 .211 -- -- --

324208094073500 CDO.GP 22–23 .754 .125 -- -- --

324208094073500 CDO.GP 24–25 .133 .0515 -- -- --

Harrison Bayou core:

324113094061900 CDO.HB 1–2 .77 .27 -- -- --

324113094061900 CDO.HB 3–4 .652 .231 -- -- --

324113094061900 CDO.HB 5–6 1.13 .263 -- -- --

324113094061900 CDO.HB 7–8 1.25 .252 -- -- --

324113094061900 CDO.HB 9–10 1.47 .204 -- -- --

324113094061900 CDO.HB 11–12 1.62 .19 -- -- --

324113094061900 CDO.HB 13–14 1.63 .211 -- -- --

324113094061900 CDO.HB 15–16 2.36 .125 -- -- --

324113094061900 CDO.HB 17–18 2.03 .0515 -- -- --

324113094061900 CDO.HB 19–20 1.19 .27 -- -- --

Mid-lake core:

324102094041400 CDO.MD 0–1 .399 .27 6.29 1.66 0.37

324102094041400 CDO.MD 1–1.5 .531 .231 6.04 2.03 1.1

324102094041400 CDO.MD 2.5–3 .442 .263 2.84 -.65 1.16

324102094041400 CDO.MD 4–4.5 .503 .252 3.93 1.07 1.04

324102094041400 CDO.MD 5–5.5 .582 .204 5.94 2.08 .589

324102094041400 CDO.MD 6.5–7 .886 .19 5.57 1.66 .598

324102094041400 CDO.MD 8–8.5 .896 .211 4.35 1.98 .883

324102094041400 CDO.MD 9.5–10 1.3 .125 6.35 .824 1.1

324102094041400 CDO.MD 12–13 .2 .0515 3.21 2.08 .473

Carter Lake core:

324424094094600 CDO.CR 0.5–1 .339 .27 16.6 3.22 1.13

324424094094600 CDO.CR 2–2.5 .875 .231 10.7 1.2 .832

324424094094600 CDO.CR 3.5–4 .648 .263 13 .416 1.55

324424094094600 CDO.CR 5–6 .632 .252 8.23 .904 .622

324424094094600 CDO.CR 8–9 .84 .204 10 1.7 .54

324424094094600 CDO.CR 11–12 .952 .19 8.29 1.73 .444

324424094094600 CDO.CR 14–15 1.46 .211 8.52 1.65 .389

324424094094600 CDO.CR 17–18 1.45 .125 7.83 1.82 .447

324424094094600 CDO.CR 20–21 2.36 .0515 5.65 1.08 .429
Appendix 2.2 51

Appendix 2.2

Occurrence of and Trends in Selected SedimentAssociated Contaminants in Caddo Lake, Texas, 1940–2002

Appendix 2.2. Analytical results for organochlorine compounds [In micrograms per kilogram dry sediment; ID, identifier; <, less than; E, estimated] 

USGS

site ID Sample ID Group number Deposition date Lindane Heptachlor Aldrin Heptachlor epoxide Technical chlordane Endo- sulfan I Dieldrin

Goose Prairie Creek core:

324208094073500 CDO.GP 0–1 200221106 2001.8 <7.0 <7.0 <7.0 <7.0 <70 <7.0 <7.0324208094073500 CDO.GP 3–4 200220603 1997.5 <3.5 <3.5 <3.5 <3.5 <35 <3.5 <3.5324208094073500 CDO.GP 6–7 200220603 1992.9 <1.5 <1.5 <1.5 <1.5 <15 <1.5 <1.5324208094073500 CDO.GP 9–10 200220603 1987.8 <3.0 <3.0 <3.0 <3.0 <30 <3.0 <3.0324208094073500 CDO.GP 12–13 200220603 1981.9 <2.5 <2.5 <2.5 <2.5 <25 <2.5 <2.5324208094073500 CDO.GP 15–16 200220603 1975.7 <1.0 <1.0 <1.0 <1.0 <10 <1.0 <1.0324208094073500 CDO.GP 18–19 200220603 1969.1 <2.0 <2.0 <2.0 <2.0 <20 <2.0 <2.0324208094073500 CDO.GP 21–22 200220603 1961.1 <1.0 <1.0 <1.0 <1.0 <10 <1.0 <1.0324208094073500 CDO.GP 24–25 200220603 1948.5 <.5 <.5 <.5 <.5 <5.0 <.5 <.5

Harrison Bayou core:

324113094061900 CDO.HB 0–1 200221211 2001.5 <8.5 <8.5 <8.5 <8.5 <85 <8.5 <8.5324113094061900 CDO.HB 2–3 200220603 1996.9 <4.0 <4.0 <4.0 <4.0 <40 <4.0 <4.0324113094061900 CDO.HB 4–5 200221211 1991.7 <6.0 <6.0 <6.0 <6.0 <60 <6.0 <6.0324113094061900 CDO.HB 7–8 200221211 1984.9 <2.5 <2.5 <2.5 <2.5 <25 <2.5 <2.5324113094061900 CDO.HB 10–11 200220603 1977.4 <3.5 <3.5 <3.5 <3.5 <35 <3.5 <3.5324113094061900 CDO.HB 13–14 200220603 1969.4 <4.0 <4.0 <4.0 <4.0 <40 <4.0 <4.0324113094061900 CDO.HB 16–17 200221211 1961.3 <3.5 <3.5 <3.5 <3.5 <35 <3.5 <3.5324113094061900 CDO.HB 19–20 200221211 1950.4 <2.5 <2.5 <2.5 <2.5 <25 <2.5 <2.5

Mid-lake core:

324102094041400 CDO.MD 0–1 200222605 2001.5 <3.0 <3.0 <3.0 <3.0 <30 <3.0 <3.0324102094041400 CDO.MD 1.5–2 200221106 1998.4 <1.5 <1.5 <1.5 <1.5 <15 <1.5 <1.5324102094041400 CDO.MD 3–3.5 200221106 1993.9 <1.0 <1.0 <1.0 <1.0 <10 <1.0 <1.0324102094041400 CDO.MD 4.5–5 200221106 1988.9 <1.0 <1.0 <1.0 <1.0 <10 <1.0 <1.0324102094041400 CDO.MD 6–6.5 200221106 1982.9 <1.0 <1.0 <1.0 <1.0 <10 <1.0 <1.0324102094041400 CDO.MD 7.5–8 200221106 1976.0 <1.0 <1.0 <1.0 <1.0 <10 <1.0 <1.0324102094041400 CDO.MD 9–9.5 200221106 1967.2 <.5 <.5 <.5 <.5 <5.0 <.5 <.5324102094041400 CDO.MD 11–12 200221106 1950.8 <.5 <.5 <.5 <.5 <5.0 <.5 <.5

Carter Lake core:

324424094094600 CDO.CR 1.5–2 200219708 2001.3 <6.5 <6.5 <6.5 <6.5 <65 <6.5 <6.5324424094094600 CDO.CR 3–3.5 200219708 1999.4 <26 <26 <26 <26 <260 <26 <26324424094094600 CDO.CR 4.5–5 200221106 1997.6 <15 <15 <15 <15 <150 <15 <15324424094094600 CDO.CR 7–8 200219708 1993.8 <7.0 <7.0 <7.0 <7.0 <70 <7.0 <7.0324424094094600 CDO.CR 10–11 200219708 1989.5 <2.0 <2.0 <2.0 <2.0 <20 <2.0 <2.0324424094094600 CDO.CR 13–14 200219708 1985.2 <5.5 <5.5 <5.5 <5.5 <55 <5.5 <5.5324424094094600 CDO.CR 16–17 200219708 1980.7 <3.0 <3.0 <3.0 <3.0 <30 <3.0 <3.0324424094094600 CDO.CR 19–20 200219708 1975.8 <2.5 <2.5 <2.5 <2.5 <25 <2.5 <2.5
52 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 2.2. Analytical results for organochlorine compounds—Continued Sample ID p,p'- DDE Endrin p,p'- DDD p,p'- DDT Methoxy- chlor Mirex Toxa- phene PCB Aroclor 1242 PCB Aroclor 1254 PCB Aroclor 1260 Calculated values Total PCB Total DDT Goose Prairie Creek core: CDO.GP 0–1 2.0 <7.0 <7.0 <7.0 <28 <7.0 <700 <70 <70 E23 E23 E2.0 CDO.GP 3–4 4.1 <3.5 <3.5 <3.5 <14 <3.5 <350 <35 <35 E23 E23 E4.1 CDO.GP 6–7 E1.4 <1.5 <1.5 <1.5 <6.0 <1.5 <150 <15 <15 E11 E11 E1.4 CDO.GP 9–10 5.7 <3.0 <3.0 <3.0 <12 <3.0 <300 <30 E18 E36 E54 E5.7 CDO.GP 12–13 E3.8 <2.5 <2.5 <2.5 <10 <2.5 <250 <25 E13 E22 E35 E3.8 CDO.GP 15–16 2.9 <1.0 <1.0 <1.0 <4.0 <1.0 <100 E3.8 E8.1 16 E28 E2.9 CDO.GP 18–19 7.8 <2.0 <2.0 <2.0 <8.0 <2.0 <200 E8.7 E23 46 E78 E7.8 CDO.GP 21–22 4.0 <1.0 <1.0 <1.0 <4.0 <1.0 <100 E5.2 E14 E16 E35 E4.0 CDO.GP 24–25 .77 <.5 <.5 <5.0 <2.0 <.5 <50 <5.0 <5.0 E2.6 E2.6 E.77 Harrison Bayou core: CDO.HB 0–1 E2.7 <8.5 <8.5 <8.5 <34 <8.5 <850 <85 <85 <85 <255 E2.7 CDO.HB 2–3 E1.4 <4.0 <4.0 <4.0 <16 <4.0 <400 <40 <40 <40 <120 E1.4 CDO.HB 4–5 E3.2 <6.0 <6.0 <6.0 <24 <6.0 <600 <60 <60 <60 <180 E3.2 CDO.HB 7–8 5.1 <2.5 <2.5 <2.5 <10 <2.5 <250 <25 <25 <25 <75 E5.1 CDO.HB 10–11 E3.1 <3.5 <3.5 <3.5 <14 <3.5 <350 <35 <35 <35 <105 E3.1 CDO.HB 13–14 5.2 <4.0 <4.0 <4.0 <16 <4.0 <400 <40 <40 <40 <120 E5.2 CDO.HB 16–17 9.4 <3.5 <3.5 <3.5 <14 <3.5 <350 <35 <35 <35 <105 E9.4 CDO.HB 19–20 7.5 <2.5 E.83 <2.5 <10 <2.5 <250 <25 <25 <25 <75 E8.3 Mid-lake core: CDO.MD 0–1 E1.6 <3.0 <3.0 <3.0 <12 <3.0 <300 <30 <30 <30 <90 E1.6 CDO.MD 1.5–2 E1.3 <1.5 <1.5 <1.5 <6.0 <1.5 <150 <15 <15 <15 <45 E1.3 CDO.MD 3–3.5 1.2 <1.0 <1.0 <1.0 <4.0 <1.0 <100 <10 <10 <10 <30 E1.2 CDO.MD 4.5–5 1.4 <1.0 <1.0 <1.0 <4.0 <1.0 <100 <10 <10 <10 <30 E1.4 CDO.MD 6–6.5 1.7 <1.0 <1.0 <1.0 <4.0 <1.0 <100 <10 <10 <10 <30 E1.7 CDO.MD 7.5–8 3.5 <1.0 <1.0 <1.0 <4.0 <1.0 <100 <10 <10 <10 <30 E3.5 CDO.MD 9–9.5 2.8 <.5 E.36 <.5 <2.0 <.5 <50 <5.0 <5.0 <5.0 <15 E3.2 CDO.MD 11–12 2.3 <.5 .74 <.5 <2.0 <.5 <50 <5.0 <5.0 <5.0 <15 E3.0 Carter Lake core: CDO.CR 1.5–2 <6.5 <6.5 <6.5 <6.5 <26 <6.5 <650 <65 <65 <65 <195 <19.5 CDO.CR 3–3.5 <26 <26 <26 <26 <104 <26 <2,600 <260 <260 <260 <780 <78 CDO.CR 4.5–5 <15 <15 <15 <15 <62 <15 <1,500 <150 <150 <150 <450 <45

CDO.CR 7–8 E2.4 <7.0 <7.0 <7.0 <28 <7.0 <700 <70 <70 <70 <210 E2.4CDO.CR 10–11 E.68 <2.0 <2.0 <2.0 <8.0 <2.0 <200 <20 <20 <20 <60 E.68CDO.CR 13–14 E2.4 <5.5 <5.5 <5.5 <22 <5.5 <550 <55 <55 <55 <165 E2.4CDO.CR 16–17 E2.5 <3.0 <3.0 <3.0 <12 <3.0 <300 <30 <30 <30 <90 E2.5CDO.CR 19–20 4.1 <2.5 E2.2 <2.5 <10 <2.5 <250 <25 <25 <25 <75 E6.3
Appendix 2.3 53

Appendix 2.3 Appendix 2.3. Analytical results for polycyclic aromatic hydrocarbons 

[In micrograms per kilogram dry sediment; ID, identifier; E, estimated; <, less than] 

USGS

site ID Sample ID Group number Depo- sition date Naph- thalene

C1-128

isomers,

methylated

Naphthalenes

2-Ethylnaphthalene 2,6-Di- methyl- naph- thalene 1,6- Dimethyl- naph thalene 

C2-128

isomers,

C2-

alkylated

Naphthalenes

Acenaphthylene 1,2-Di- methyl- naph- thalene

Goose Prairie core:

324208094073500 CDO.GP 0–1 8022R02169 2001.8 E8.9 <550 <75 604 102 762 E13.3 E62.1324208094073500 CDO.GP 3–4 8022R02169 1997.5 E6.3 <315 <35 110 E26.5 212 E6.0 E27.8324208094073500 CDO.GP 6–7 8022R02169 1992.9 E2.6 <80 <20 22.6 E6.8 39.8 E2.9 E7.9324208094073500 CDO.GP 9–10 8022R02169 1987.8 E5.7 <100 <30 E22.1 E10.6 45.4 E5.6 E15.0324208094073500 CDO.GP 12–13 8022R02169 1981.9 E4.9 <80 <25 E16.1 E9.0 42.5 E4.2 E6.6324208094073500 CDO.GP 15–16 8022R02169 1975.7 E2.6 <40 E.87 E7.0 E4.0 13.9 E2.0 E3.4324208094073500 CDO.GP 18–19 8022R02169 1969.1 E6.5 <60 <20 E10.0 E5.8 37.4 E4.0 E6.3324208094073500 CDO.GP 21–22 8022R02169 1961.1 E3.0 <40 <10 E8.9 E5.7 20.7 E3.0 E5.0324208094073500 CDO.GP 24–25 8022R02169 1948.5 E2.0 <25 <5 9.9 E2.8 20.5 E2.0 E2.8

Harrison Bayou core:

324113094061900 CDO.HB 0–1 8022R02177 2001.5 <90 <540 <90 1,340 268 2,250 <90 E40.0324113094061900 CDO.HB 2–3 8022R02169 1996.9 E5.3 <100 <40 108 E17.1 190 E5.7 E12.4324113094061900 CDO.HB 4–5 8022R02177 1991.7 E18.6 <690 <65 2,100 348 2,380 <65 <65324113094061900 CDO.HB 7–8 8022R02177 1984.9 <30 <600 <30 1,590 281 2,050 <30 E24.0324113094061900 CDO.HB 10–11 8022R02169 1977.4 E4.2 E6.4 E2.3 E30.6 E10.1 73.5 E4.4 E5.4324113094061900 CDO.HB 13–14 8022R02169 1969.4 E7.4 E12.6 <45 47.9 E17.6 86.8 <45 <45324113094061900 CDO.HB 16–17 8022R02177 1961.3 E6.4 <380 <35 462 112 736 <35 E15.3324113094061900 CDO.HB 19–20 8022R02177 1950.4 <30 <220 <30 438 75.1 591 E6.1 E11.8

Mid-lake core:

324102094041400 CDO.MD 0–1 8022R02171 2001.5 E4.4 <100 <30 E25.3 E9.9 50.4 E4.7 <30324102094041400 CDO.MD 1.5–2 8022R02171 1998.4 E2.7 <160 <20 106 E16.0 198 E3.3 <20324102094041400 CDO.MD 3–3.5 8022R02171 1993.9 E2.0 <100 <10 77.4 E8.2 108 E2.2 <10324102094041400 CDO.MD 4.5–5 8022R02171 1988.9 E2.3 <20 <10 95.1 10.5 130 <10 <10324102094041400 CDO.MD 6–6.5 8022R02171 1982.9 E2.0 <70 <10 48.4 E6.5 71.5 E2.1 <10324102094041400 CDO.MD 7.5–8 8022R02171 1976.0 E2.6 <60 <10 44.2 E7.2 61.6 E2.3 <10324102094041400 CDO.MD 9–9.5 8022R02171 1967.2 E2.9 <90 <10 59.0 E7.8 80.6 <10 <10324102094041400 CDO.MD 11–12 8022R02171 1950.8 E3.0 <20 <10 21.8 E3.1 31.0 <10 <10

Carter Lake core:

324424094094600 CDO.CR 1.5–2 8022R02165 2001.3 <60 <300 <60 1,200 174 1,660 <60 <60324424094094600 CDO.CR 3–3.5 8022R02165 1999.4 E22.9 <500 <270 1,600 E248 2,230 <270 E62.3324424094094600 CDO.CR 4.5–5 8022R02165 1997.6 E12.8 <400 <125 1,520 250 2,160 <125 <125324424094094600 CDO.CR 7–8 8022R02165 1993.8 <60 <300 <60 1,150 189 1,430 <60 <60324424094094600 CDO.CR 10–11 8022R02165 1989.5 E2.9 <30 <25 134 E17.8 178 E3.6 <25324424094094600 CDO.CR 13–14 8022R02165 1985.2 E8.5 <60 <60 292 E58.0 409 E7.8 E11.4324424094094600 CDO.CR 16–17 8022R02165 1980.7 <30 <50 <30 235 40.0 315 <30 <30324424094094600 CDO.CR 19–20 8022R02165 1975.8 <30 <50 <30 205 E28.3 294 <30 E6.6
54 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 2.3. Analytical results for polycyclic aromatic hydrocarbons—Continued Sample ID Ace- naph- thene C3-128 isomers, C3- alkylated Naphtha- lenes 2,3,6- Tri- methyl- naph- tha- lene 9H- Fluor- ene C4-128 isomers, C4- alkylated Naphtha- lenes 1- methyl- 9H- Fluor- ene Phe- nan- threne Anthra- cene C5-128 isomers, C5- alkylated Naphtha- lenes 2- Methyl- anthra- cene 4,5- Methyl- ene- phenan- threne C1-178 isomers, methylated Phenan- threne/ anthra- cenes Goose Prairie core: CDO.GP 0–1 E10.9 <140 <75 E11.8 <75 E22.5 E25.5 E22.8 <75 <75 E15.0 <300 CDO.GP 3–4 E4.4 <70 E4.0 E9.0 <70 E10.8 E18.8 E13.2 <35 <35 E11.0 <130 CDO.GP 6–7 E1.8 <20 <20 E4.4 <20 <20 E8.7 E5.8 <20 <20 E5.2 <20 CDO.GP 9–10 E3.2 E25.7 E3.7 E9.4 <30 E9.0 E23.2 E12.4 <30 E6.8 E13.9 35.3 CDO.GP 12–13 E2.6 E16.6 E3.0 E9.2 <25 E7.1 E20.2 E9.7 <25 E5.0 E14.2 27.0 CDO.GP 15–16 E1.3 <15 E1.6 E5.4 <10 E4.2 10.1 E5.3 <10 E2.7 10.0 16.8 CDO.GP 18–19 E2.4 35.1 E3.5 E14.4 <20 E9.3 E19.6 E11.9 <20 E5.2 25.8 36.1 CDO.GP 21–22 E1.5 23.7 E2.6 11.5 <15 E7.0 11.7 E8.8 <10 E3.5 21.5 30.3 CDO.GP 24–25 E1.2 10.7 E1.7 11.4 <10 E4.5 5.9 5.8 <5 E2.4 13.8 20.2 Harrison Bayou core: CDO.HB 0–1 <90 448 E14.5 E11.8 <90 <90 E26.0 E25.5 <90 <90 <90 <400 CDO.HB 2–3 E4.0 <60 <40 E7.0 <40 E9.8 E13.2 E10.7 <40 <40 E11.6 <230 CDO.HB 4–5 <65 514 E13.5 E10.7 <65 <65 E20.7 E22.1 <65 <65 <65 <400 CDO.HB 7–8 E5.1 332 E8.3 E5.9 <75 <30 E19.3 E20.4 <30 <30 E15.2 <360 CDO.HB 10–11 E2.2 E31.9 E3.6 E4.4 <40 E6.8 E10.4 E7.6 <40 E6.8 E9.7 <50 CDO.HB 13–14 E3.5 45.0 E4.9 E6.2 <45 E10.5 E19.1 E12.2 <45 <45 E16.6 <70 CDO.HB 16–17 <35 <160 E5.8 E5.6 <35 E15.2 E23.5 E18.0 <35 <35 E18.8 <100 CDO.HB 19–20 E3.3 <100 E4.4 E4.6 <30 E10.9 E16.1 E12.4 <30 <30 E13.2 <65 Mid-lake core: CDO.MD 0–1 <30 <30 <30 <30 <30 <30 E6.4 E6.7 <30 <30 E4.9 <30 CDO.MD 1.5–2 E1.3 <90 <20 <20 <20 <20 E5.0 E5.3 <20 <20 <20 <20 CDO.MD 3–3.5 E1.1 <50 <10 E2.1 <10 <10 E4.9 E4.1 <10 <10 E2.9 <10 CDO.MD 4.5–5 <10 <60 <10 E1.5 <10 <10 E3.2 E3.7 <10 <10 <10 10.9 CDO.MD 6–6.5 E1.1 <40 <10 E1.6 <10 <10 E3.4 E3.5 <10 <10 E2.1 <10 CDO.MD 7.5–8 E.98 <30 <10 E1.6 <10 <10 E3.8 E3.7 <10 <10 <10 E8.2 CDO.MD 9–9.5 <10 <30 <10 E2.0 <10 <10 E6.8 E5.1 <10 <10 E2.8 13.4 CDO.MD 11–12 <10 <50 <10 <10 <10 E2.5 E2.3 E2.3 <10 <10 E1.8 E7.3 Carter Lake core: CDO.CR 1.5–2 <60 <340 <60 <60 <60 <60 E13.4 <60 <60 <60 <60 <120 CDO.CR 3–3.5 <270 <550 <270 <270 <270 <270 E34.8 <270 <270 <270 <270 <270

CDO.CR 4.5–5 <125 <500 <125 <125 <125 <125 E24.6 E28.7 <125 <125 <125 <130CDO.CR 7–8 <60 <300 <60 <60 <60 <60 E17.6 E19.3 <60 <60 <60 <70CDO.CR 10–11 <25 <60 <25 E3.2 <25 E5.7 E5.5 E5.7 <25 <25 E5.9 <25CDO.CR 13–14 <60 <140 <60 E7.6 <60 E13.2 E15.4 E12.4 <60 <60 E16.1 <60CDO.CR 16–17 <30 <100 <30 <30 <30 <30 E8.9 E5.5 <30 <30 E9.6 <40CDO.CR 19–20 E2.5 <100 <30 E4.7 <30 E8.0 E11.2 E8.4 <30 E6.9 E11.6 <30
Appendix 2.3 55

Appendix 2.3. Analytical results for polycyclic aromatic hydrocarbons—Continued 

Sample ID

1-

Methylphenanthrene

C2-178

isomers,

C2-alkylated

Phenanthrene/

anthracenes

Fluoranthene Py- rene 

C3-178

isomers,

C3-alkylated

Phenanthrene/

anthracenes

C4-178

isomers,

C4-alkylated

Phenanthrene/

anthracenes

1-

Methylpyrene

C1-202

isomers,

methylated

Fluoranthene/

pyrenes

C2-202

isomers,

C2-alkylated 

Fluoranthene/

pyrenes

C5-178

isomers,

C5-alkylated

Phenanthrene/

anthracenes

Benz-

(a)-

anthracene

Goose Prairie core:

CDO.GP 0–1 <75 <75 E34.8 E28.0 <150 <700 E10.4 <1,800 <250 <75 E25.5CDO.GP 3–4 E7.8 <35 E31.4 E24.9 <35 <400 <35 <730 150 <35 E13.7CDO.GP 6–7 E4.1 <20 E16.0 E12.0 <20 <20 <20 E7.9 37.8 <20 E6.6CDO.GP 9–10 E9.4 E19.4 46.4 30.2 E15.3 <30 E5.3 E26.7 <50 <30 E14.3CDO.GP 12–13 E6.9 E16.1 46.0 29.5 E11.3 <25 E4.1 32.1 54.5 <25 E12.8CDO.GP 15–16 E4.3 14.2 30.2 19.2 <25 <10 E2.2 10.3 <20 <10 E6.2CDO.GP 18–19 E8.8 25.0 75.3 44.5 E14.5 <20 E4.0 39.8 <60 <20 E12.9CDO.GP 21–22 E5.7 27.0 70.9 37.4 14.7 <10 E2.8 66.4 <30 <10 10.5CDO.GP 24–25 E3.3 19.7 53.4 30.0 17.0 <10 E1.9 23.5 <20 <5 7.2

Harrison Bayou core:

CDO.HB 0–1 <90 <90 E49.6 E43.8 <90 <90 <90 <90 <90 <90 E24.3CDO.HB 2–3 E7.6 <40 E36.3 E34.9 <40 <40 <40 E37.3 81.3 <40 E16.2CDO.HB 4–5 E54.2 <65 E41.4 E36.8 <65 <65 <65 <65 <150 <65 E18.9CDO.HB 7–8 53.0 <75 36.5 30.8 <30 <30 E6.4 <30 <100 <30 E16.6CDO.HB 10–11 E8.1 E13.7 E22.4 E25.2 E9.9 <40 E5.4 E21.3 52.2 <40 E13.8CDO.HB 13–14 E13.1 E26.0 E43.4 45.8 E19.4 <45 <45 <45 <60 <45 E16.6CDO.HB 16–17 E11.7 35.8 44.7 46.4 <35 <35 E7.7 <35 <35 <35 E18.7CDO.HB 19–20 E6.7 <30 31.2 31.8 <30 <30 E5.5 <40 <30 <30 E13.3

Mid-lake core:

CDO.MD 0–1 <30 <30 15.0 17.2 <30 <30 <30 <30 <30 <30 <30CDO.MD 1.5–2 <20 <20 E12.3 E14.0 <20 <20 <20 <20 <20 <20 E7.2CDO.MD 3–3.5 <10 <10 13.7 14.6 <10 <10 <10 <10 <10 <10 E7.0CDO.MD 4.5–5 E1.9 E9.7 E9.5 12.0 <10 <10 <10 E5.3 <10 <10 <10CDO.MD 6–6.5 <10 E8.1 E8.0 11.4 E8.3 E5.8 <10 <10 <10 <10 <10CDO.MD 7.5–8 <10 10.4 E9.5 14.9 <10 <10 <10 <10 <10 <10 <10CDO.MD 9–9.5 <10 13.6 17.0 21.7 <10 13.4 <10 <10 <10 <10 10.1CDO.MD 11–12 E1.6 E8.2 E6.1 12.6 E7.1 <10 <10 <10 <10 <10 E3.2

Carter Lake core:

CDO.CR 1.5–2 E21.0 <60 E12.8 159 <60 <1,200 E22.8 <60 <60 <60 78.6CDO.CR 3–3.5 <270 <270 E60.7 E57.4 <270 <270 <270 <270 <270 <270 <270CDO.CR 4.5–5 E33.0 <125 E43.0 E41.5 <125 <400 <125 <125 <125 <125 <125CDO.CR 7–8 E15.7 <60 E28.1 E32.6 <60 <60 <60 <60 <60 <60 <60CDO.CR 10–11 E5.6 <25 E11.7 E14.1 <25 <25 <25 <25 <25 <25 <25CDO.CR 13–14 E12.9 <60 E30.3 E41.0 <60 <60 <60 <60 <60 <60 <60CDO.CR 16–17 E7.0 <30 E16.8 E26.0 <30 <30 <30 <30 <30 <30 <30CDO.CR 19–20 E6.9 <30 E20.9 33.6 <30 <30 <30 <30 <30 <30 <30
56 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 2.3. Analytical results for polycyclic aromatic hydrocarbons—Continued Sample ID Chry- sene C3-202 isomers, C3- alkylated Fluoran- thene/ pyrenes C1-228 isomers, methylated Benzo(a)- anthracene/ chrysenes C4-202 isomers, C4- alkylated Fluoran- thene/ pyrenes C5-202 isomers, C5- alkylated Fluoran- thene/ pyrenes C2-228 isomers, C2- alkylated Benzo(a)- anthracene/ chrysenes Benzo(b)- fluoran- thene Benzo(k)- fluoran- thene Benzo(e)- pyrene Benzo(a)- pyrene C1-252 isomers, C1- methylated Benzo- pyrene/ perylenes Goose Prairie core: CDO.GP 0–1 E23.2 <325 <90 <75 <75 <75 E35.2 E20.0 E20.8 E20.2 <75 CDO.GP 3–4 E17.4 <260 <35 <35 <35 <35 E24.8 E15.9 E13.2 E12.6 <35 CDO.GP 6–7 E7.8 <20 <20 <20 <20 <20 E11.0 E5.6 E5.6 E5.3 <20 CDO.GP 9–10 E18.4 <30 E18.4 <30 <30 <30 E23.7 E15.8 E13.1 E11.1 <30 CDO.GP 12–13 E15.2 <75 <25 <25 <25 <25 E17.0 E10.0 E9.3 E8.3 <25 CDO.GP 15–16 10.2 <10 <10 <10 <10 <10 10.0 E6.1 E5.6 E4.2 <10 CDO.GP 18–19 22.1 <40 E15.2 <20 <20 <20 E19.3 E12.4 E12.0 E8.8 <20 CDO.GP 21–22 17.4 <10 11.8 <20 <10 <10 13.4 E8.2 E7.9 E5.5 <10 CDO.GP 24–25 10.9 <20 <10 <5 <5 <5 9.5 6.3 5.7 E3.0 <5 Harrison Bayou core: CDO.HB 0–1 E36.6 <90 <90 <90 <90 <90 E41.6 E26.5 E21.4 E24.8 <90 CDO.HB 2–3 E15.3 <100 <40 <40 <40 <40 E22.3 E13.2 E11.9 E13.0 <40 CDO.HB 4–5 E21.6 <65 <65 <65 <65 <65 E38.5 E18.0 E18.3 E20.1 <65 CDO.HB 7–8 E20.0 <50 <30 <30 <30 <30 35.0 E17.7 E16.5 E16.3 <30 CDO.HB 10–11 E10.8 <40 <40 <40 <40 <40 E18.4 E10.4 E8.6 E10.3 <40 CDO.HB 13–14 E20.4 <70 <45 <45 <45 <45 E26.6 E19.6 E14.2 E16.4 <45 CDO.HB 16–17 E25.2 <35 <35 <35 <35 <35 40.0 E24.3 E19.2 E21.0 <35 CDO.HB 19–20 E18.8 <30 <30 <30 <30 <30 32.0 E16.5 E16.3 E15.2 <30 Mid-lake core: CDO.MD 0–1 E9.7 <30 <30 <30 <30 <30 E17.8 E7.5 E9.6 E10.4 E22.8 CDO.MD 1.5–2 E7.8 <20 E4.8 <20 <20 <20 13.3 E6.5 E8.4 E7.5 25.2 CDO.MD 3–3.5 E7.5 <10 <10 <10 <10 <10 13.4 E4.8 E7.3 E7.0 25.2 CDO.MD 4.5–5 E6.6 <10 <10 <10 <10 <10 E9.9 E5.7 E6.2 E5.6 26.7 CDO.MD 6–6.5 E6.2 <10 <10 <10 <10 <10 10.9 E4.4 E6.2 E5.2 32.1 CDO.MD 7.5–8 E7.5 <10 <10 <10 <10 <10 12.8 E6.6 E7.9 E6.0 58.6 CDO.MD 9–9.5 11.9 <10 <10 <10 <10 <10 18.6 E8.5 10.5 10.4 54.4 CDO.MD 11–12 E5.3 <10 <10 <10 <10 <10 E7.2 E6.1 E4.9 E3.9 36.3 Carter Lake core: CDO.CR 1.5–2 73.9 <1,900 <60 <60 <60 <60 E28.5 E14.9 E14.8 E18.2 <60 CDO.CR 3–3.5 E31.9 <310 <270 <270 <270 <270 E72.7 E30.7 E33.8 E54.1 <270 CDO.CR 4.5–5 E27.3 <440 <125 <125 <125 <125 E48.0 E23.5 E22.2 E33.6 <125

CDO.CR 7–8 E14.2 <400 <60 <60 <60 <60 E33.8 E19.3 E16.3 E20.6 71.1CDO.CR 10–11 132 <150 <25 <25 <25 <25 E10.4 E5.8 E5.3 E6.9 E14.9CDO.CR 13–14 E17.5 <240 <60 <60 <60 <60 E29.8 E13.4 E13.6 E17.9 E40.8CDO.CR 16–17 E9.8 <130 <30 <30 <30 <30 E18.7 E7.5 E9.2 E10.8 32.8CDO.CR 19–20 E13.0 <130 <30 <30 <30 <30 E25.6 E10.0 E11.0 E12.0 32.9
Appendix 2.3 57

Appendix 2.3. Analytical results for polycyclic aromatic hydrocarbons—Continued 

Sample ID

C3-228

isomers, C3-

Benzo(a)-

anthracene/

chrysenes

C2-252

isomers, C2-

alkylated

Benzopyrene/

perylenes

C4-228

isomers, C4-

Benzo(a)-

anthracene/

chrysenes

Benzo-

(g,h,i)-

perylene

Indeno-

(1,2,3-c,d)-

pyrene

Dibenzo-

(a,h)-

anthracene

C3-252

isomers, C3-

alkylated

Benzopyrene/

perylenes

C4-252

isomers, C4-

alkylated

Benzopyrene/

perylenes

C5-228

isomers, C5-

Benzo(a)-

anthracene/

chrysenes

C5-252

isomers, C5-

alkylated

Benzopyrene/

perylenes

Coronene

Goose Prairie core:

CDO.GP 0–1 <75 <75 <75 <75 E45.9 <75 <75 <75 <75 <75 <75CDO.GP 3–4 <35 <35 <35 E12.7 E25.5 <35 <35 <35 <35 <35 <35CDO.GP 6–7 <20 <20 <20 E5.8 E10.7 E5.8 <20 <20 <20 <20 <20CDO.GP 9–10 <30 <30 <30 E13.4 E19.1 E10.2 <30 <30 <30 <30 E9.0CDO.GP 12–13 <25 <25 <25 E7.9 E11.8 E7.7 <25 <25 <25 <25 E5.3CDO.GP 15–16 <10 <10 <10 E4.8 E6.6 E3.6 <10 <10 <10 <10 E3.0CDO.GP 18–19 <20 <20 <20 E9.1 E11.6 E6.8 <20 <20 <20 <20 E5.1CDO.GP 21–22 <10 <10 <10 E7.5 E8.5 <10 <10 <10 <10 <10 E3.4CDO.GP 24–25 <5 <5 <5 6.0 6.2 E2.8 <5 <5 <10 <5 E2.5

Harrison Bayou core:

CDO.HB 0–1 <90 <90 <90 E27.4 E46.2 <90 <90 <90 <90 <90 E22.5CDO.HB 2–3 <40 <40 <40 E14.4 E20.5 <40 <40 <40 <40 <40 <40CDO.HB 4–5 <65 <65 <65 <65 E39.1 <65 <65 <65 <65 <65 E15.6CDO.HB 7–8 <30 <30 <30 35.4 E14.2 <30 <30 <30 <30 <30 E14.8CDO.HB 10–11 <40 <40 <40 E9.9 E14.6 E10.6 <40 <40 <40 <40 E7.0CDO.HB 13–14 <45 <45 <45 E15.9 E21.8 E14.0 <45 <45 <45 <45 <45CDO.HB 16–17 <35 <35 <35 E29.0 36.8 <35 <35 <35 <35 <35 E17.3CDO.HB 19–20 <30 <30 <30 E20.4 E28.2 E12.1 <30 <30 <30 <30 E14.1

Mid-lake core:

CDO.MD 0–1 <30 <30 <30 E14.5 E16.4 E10.8 <30 <30 <30 <30 <30CDO.MD 1.5–2 <20 <20 <20 E10.9 E13.4 <20 <20 <20 <20 <20 <20CDO.MD 3–3.5 <10 <10 <10 10.4 11.1 E4.7 <10 <10 <10 <10 <10CDO.MD 4.5–5 <10 E6.8 <10 E8.9 10.1 E3.9 <10 <10 <10 <10 <10CDO.MD 6–6.5 <10 <10 <10 E8.3 E8.9 <10 <10 <10 <10 <10 <10CDO.MD 7.5–8 <10 <10 <10 E13.6 E12.6 E4.2 <10 <10 <10 <10 E4.9CDO.MD 9–9.5 <10 <10 <10 <15 16.2 <10 <10 <10 <10 <10 <10CDO.MD 11–12 <10 <10 <10 E6.9 E7.9 E3.1 <10 <10 <10 <10 E3.3

Carter Lake core:

CDO.CR 1.5–2 <60 79.6 <60 <60 <60 <60 <60 <60 <60 <60 E12.7CDO.CR 3–3.5 <270 <270 <270 <270 E89.3 <270 <270 <270 <270 <270 <270CDO.CR 4.5–5 <125 <125 <125 <125 E56.6 <125 <125 <125 <125 <125 <125CDO.CR 7–8 <60 <60 <60 <60 E37.4 <60 <60 <60 <60 <60 <60CDO.CR 10–11 <25 <25 <25 E8.6 E10.4 E6.8 <25 <25 <25 <25 E6.5CDO.CR 13–14 <60 <60 <60 E20.3 E24.6 E16.9 <60 <60 <60 <60 <60CDO.CR 16–17 <30 <30 <30 E14.7 E17.5 E10.0 <30 <30 <30 <30 <30CDO.CR 19–20 <30 <30 <30 E16.4 E19.5 E9.3 <30 <30 <30 <30 E8.5
58 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 2.4 Appendix 2.4. Analytical results for forms of carbon and major and trace elements [In micrograms per gram dry sediment unless otherwise specified; ID, identifier; <, less than; na, not analyzed] USGS site ID Sample ID Group number Depo- sition date Inorganic car- bon, as CO3 (percent) Organic carbon (percent) Total carbon (percent) Alumi- num Cal- cium Iron Magne- sium Potas- sium Phos- phorus Sodi- um Goose Prairie Creek core: 324208094073500 CDO.GP 0–1 3958 2001.8 0.07 18.5 18.6 61,100 4,260 27,000 2,660 6,250 1,780 818 324208094073500 CDO.GP 3–4 3958 1997.5 .04 16.0 16.0 69,100 3,760 25,900 2,740 5,760 1,370 648 324208094073500 CDO.GP 6–7 3958 1992.9 .04 13.9 13.9 71,100 3,330 24,500 2,970 6,310 1,130 760 324208094073500 CDO.GP 9–10 3958 1987.8 .04 12.8 12.8 77,100 3,070 26,000 2,740 6,740 1,050 790 324208094073500 CDO.GP 12–13 3958 1981.9 .03 9.77 9.80 76,500 2,720 25,000 2,760 7,270 791 1,030 324208094073500 CDO.GP 15–16 3958 1975.7 .03 9.00 9.03 69,000 2,410 25,000 3,000 7,130 698 1,130 324208094073500 CDO.GP 18–19 3958 1969.1 .03 7.07 7.10 76,500 2,250 29,700 2,750 7,680 674 1,090 324208094073500 CDO.GP 21–22 3958 1961.1 .02 4.69 4.71 86,700 2,100 29,000 3,240 8,920 739 1,280 324208094073500 CDO.GP 24–25 3958 1948.5 <.01 2.28 2.29 66,900 1,490 20,400 2,450 8,960 372 1,510 Harrison Bayou core: 324113094061900 CDO.HB 0–1 3958 2001.5 .09 10.4 10.5 72,800 3,660 41,600 3,750 8,440 1,490 1,130 324113094061900 CDO.HB 2–3 3958 1996.9 .08 9.86 9.94 66,900 4,070 40,700 3,900 8,870 1,630 1,960 324113094061900 CDO.HB 4–5 3958 1991.7 .07 11.5 11.6 69,900 3,360 39,800 3,810 8,200 1,340 1,140 324113094061900 CDO.HB 7–8 3958 1984.9 .05 10.3 10.4 73,400 3,650 36,900 4,050 8,540 1,290 1,290 324113094061900 CDO.HB 10–11 3958 1977.4 .04 11.6 11.6 77,400 3,780 37,200 4,230 8,370 990 1,080 324113094061900 CDO.HB 13–14 3958 1969.4 .04 11.3 11.3 76,100 3,860 36,500 4,360 7,950 823 1,110 324113094061900 CDO.HB 16–17 3958 1961.3 .04 10.4 10.4 77,000 3,680 34,500 4,170 8,460 815 1,330 324113094061900 CDO.HB 19–20 3958 1950.4 .03 6.90 6.93 90,700 3,470 36,100 5,080 9,920 693 1,250 Mid-lake core: 324102094041400 CDO.MD 0–1 3958 2001.5 .05 3.73 3.78 61,800 2,910 56,600 2,410 8,250 1,050 1,160 324102094041400 CDO.MD 1.5–2 3958 1998.4 .05 3.95 4.00 64,000 2,360 56,300 2,380 8,430 1,040 1,180 324102094041400 CDO.MD 3–3.5 3958 1993.9 .04 3.51 3.55 61,600 2,060 52,000 2,310 8,300 796 1,170 324102094041400 CDO.MD 4.5–5 3958 1988.9 .03 3.63 3.66 61,000 2,040 49,500 2,280 8,500 712 1,200 324102094041400 CDO.MD 6–6.5 3958 1982.9 .03 3.36 3.39 65,500 2,190 49,300 2,450 9,000 624 1,260 324102094041400 CDO.MD 7.5–8 3958 1976.0 .03 3.13 3.16 60,200 2,220 42,000 3,000 9,140 549 1,550 324102094041400 CDO.MD 9–9.5 3958 1967.2 .01 2.53 2.54 61,100 2,060 32,600 2,270 9,250 388 1,380 324102094041400 CDO.MD 11–12 3958 1950.8 <.01 2.21 2.22 76,000 2,400 29,200 3,700 10,200 351 1,600 Carter Lake core: 324424094094600 CDO.CR 0–0.5 3959 2002.3 .09 10.5 10.6 67,900 3,180 46,000 2,960 6,260 1,600 892 324424094094600 CDO.CR 1–1.5 3959 2001.6 .08 10.4 10.5 68,200 3,480 49,000 2,700 6,050 1,700 728 324424094094600 CDO.CR 1.5–2 3959 2001.3 .08 10.9 11.0 71,400 2,970 49,000 2,650 6,190 1,600 697 324424094094600 CDO.CR 3–3.5 3959 1999.4 .08 11.2 11.3 68,100 2,900 48,000 2,700 6,210 1,600 749 324424094094600 CDO.CR 4–4.5 3959 1998.1 .08 10.5 10.6 66,600 2,730 47,000 2,670 5,920 1,500 705 324424094094600 CDO.CR 4.5–5 3959 1997.6 .08 10.2 10.3 72,400 2,880 50,000 2,690 6,390 1,600 746 324424094094600 CDO.CR 7–8 3959 1993.8 .08 9.56 9.64 77,900 2,750 51,000 2,700 6,640 1,700 695 324424094094600 CDO.CR 9–10 3959 1990.9 .09 9.73 9.82 77,300 2,760 52,000 2,770 6,520 1,800 682

324424094094600 CDO.CR 10–11 3959 1989.5 .10 9.55 9.65 73,800 2,660 52,000 2,680 6,170 2,000 671324424094094600 CDO.CR 13–14 3959 1985.2 .09 9.37 9.46 78,000 3,270 56,000 2,760 6,690 3,000 726324424094094600 CDO.CR 15–16 3959 1982.3 .08 9.92 10.0 77,800 2,760 56,000 2,780 6,610 1,900 723324424094094600 CDO.CR 16–17 3959 1980.7 .08 9.51 9.59 77,700 2,720 60,000 2,820 6,650 2,000 707324424094094600 CDO.CR 19–20 3959 1975.8 .09 8.44 8.53 83,800 2,570 66,000 3,030 7,230 1,600 764324424094094600 CDO.CR 22–23 3959 1969.1 .07 8.06 8.13 93,200 2,640 64,000 3,390 8,360 1,600 868
Appendix 2.4 59

Appendix 2.4. Analytical results for forms of carbon and major and trace elements—Continued 

Sample ID Tita- nium Anti- mony Arse- nic Bar- ium Beryll- ium Cad- mium Ceri- um Chro- mium Cobalt Cop- per Gal- lium Lan- thanum Lead Lith- ium

Goose Prairie Creek core:

CDO.GP 0–1 2,230 0.88 6.9 382 1.9 0.54 61.5 51.6 28.4 29.8 14 30.2 50.4 32.2CDO.GP 3–4 2,690 .93 7.1 373 1.8 .44 57.6 58.9 24.6 31.6 15 29.2 56.0 37.3CDO.GP 6–7 2,880 .95 7.2 393 1.6 .27 51.8 62.3 16.4 33.5 16 28.2 61.2 39.0CDO.GP 9–10 3,020 .98 7.8 416 1.4 .24 56.0 67.1 14.1 32.9 16 28.6 71.8 42.8CDO.GP 12–13 3,190 .92 7.9 435 1.3 .25 57.9 70.2 14.1 33.6 16 29.3 96.8 44.5CDO.GP 15–16 3,260 1.01 8.3 435 1.5 .32 64.1 69.5 15.0 35.9 15 32.7 111 42.8CDO.GP 18–19 3,410 1.02 9.2 445 1.7 .38 70.7 76.9 22.2 31.9 16 35.2 127 48.2CDO.GP 21–22 3,990 1.28 7.9 530 2.0 .41 80.8 90.6 18.4 34.2 19 40.3 181 54.0CDO.GP 24–25 4,240 .85 3.8 452 1.5 .18 76.7 59.7 9.59 20.8 14 37.8 117 43.1

Harrison Bayou core:

CDO.HB 0–1 2,920 .67 7.4 531 2.2 .51 71.4 59.4 26.1 24.6 16 38.9 23.9 40.5CDO.HB 2–3 2,610 .67 6.6 570 2.0 .45 64.6 53.9 25.1 24.1 15 35.2 23.0 37.1CDO.HB 4–5 2,810 .71 8.0 507 2.2 .50 69.9 57.6 27.0 24.9 16 38.6 24.6 38.9CDO.HB 7–8 2,930 .75 7.9 509 2.4 .49 74.3 60.2 27.8 26.3 17 39.8 26.2 41.1CDO.HB 10–11 3,000 .83 8.8 495 2.4 .51 69.8 62.5 25.5 25.1 18 38.3 30.0 43.0CDO.HB 13–14 2,960 .87 8.4 462 2.3 .50 65.0 61.3 21.8 25.8 17 36.2 29.9 41.5CDO.HB 16–17 2,690 .83 7.4 496 2.2 .44 62.7 60.2 19.7 26.6 17 34.5 28.0 41.9CDO.HB 19–20 3,320 1.06 7.9 519 2.4 .42 78.8 72.3 20.3 26.2 20 41.5 35.1 49.2

Mid-lake core:

CDO.MD 0–1 3,010 .58 11 516 2.2 .24 82.2 50.7 18.1 13.9 14 42.3 25.0 40.2CDO.MD 1.5–2 3,420 .64 10 504 2.3 .26 84.3 52.6 18.2 14.2 14 42.9 24.8 42.0CDO.MD 3–3.5 3,060 .62 7.5 488 2.2 .24 80.6 50.5 18.7 14.4 13 41.4 24.9 42.1CDO.MD 4.5–5 3,190 .63 6.6 492 2.1 .24 81.9 51.9 19.0 13.6 13 44.5 25.2 41.6CDO.MD 6–6.5 3,360 .69 6.4 498 2.3 .25 86.8 53.9 19.8 15.5 14 47.2 27.6 44.5CDO.MD 7.5–8 3,440 .73 6.9 484 2.6 .28 89.4 52.3 21.0 15.9 14 46.1 27.0 42.7CDO.MD 9–9.5 3,630 .65 5.7 492 2.1 .23 85.0 50.3 17.0 14.1 13 42.9 26.4 42.2CDO.MD 11–12 4,060 .69 7.4 491 2.6 .20 106 63.4 20.9 16.6 18 57.7 23.0 50.2

Carter Lake core:

CDO.CR 0–0.5 2,600 .86 12 432 3.1 .76 122 59.3 46.7 26.0 16 52.7 28.1 42.2CDO.CR 1–1.5 2,800 .80 13 448 2.9 .70 122 57.0 48.8 23.3 16 55.4 27.3 41.4CDO.CR 1.5–2 2,600 .84 13 432 2.9 .74 122 60.6 52.7 23.8 16 52.0 27.3 42.3CDO.CR 3–3.5 2,600 .84 13 446 3.0 .71 119 57.5 50.5 23.5 16 51.0 27.1 41.4CDO.CR 4–4.5 2,500 .85 13 451 3.0 .73 120 56.8 48.2 23.9 15 51.7 28.8 42.5CDO.CR 4.5–5 2,600 .82 13 447 3.1 .71 123 59.9 48.6 32.4 16 52.8 29.2 43.3CDO.CR 7–8 3,200 .84 14 440 3.2 .73 130 62.6 49.4 25.0 17 56.0 32.2 45.5CDO.CR 9–10 2,800 .89 14 436 3.3 .75 132 63.0 50.4 23.7 17 56.4 32.4 45.8CDO.CR 10–11 3,000 .87 14 449 3.2 .75 128 61.0 51.0 23.9 17 55.3 32.8 44.7CDO.CR 13–14 3,200 .91 15 481 3.2 .83 134 64.5 53.0 24.1 17 56.9 35.0 46.8CDO.CR 15–16 2,900 .88 15 439 3.4 .84 125 63.8 51.9 22.8 17 53.8 37.8 46.9CDO.CR 16–17 3,000 .94 15 443 3.4 .86 122 65.1 51.7 23.1 17 54.0 39.8 47.2CDO.CR 19–20 3,200 .92 14 458 3.5 .79 125 67.5 44.2 22.4 18 54.5 41.8 51.1CDO.CR 22–23 3,900 .98 13 507 3.5 .78 122 74.6 37.8 23.3 20 54.0 40.0 57.1
60 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 2.4. Analytical results for forms of carbon and major and trace elements—Continued Sample ID Man- ganese Mer- cury Molyb- denum Nickel Nio- bium Scand- ium Sele- nium Silver Stron- tium Thor- ium Ura- nium Vana- dium Zinc Goose Prairie Creek core: CDO.GP 0–1 1,200 0.37 1.6 35.2 9 9.0 2.0 5.12 62.2 7.7 2.2 80.1 222 CDO.GP 3–4 773 .42 2.0 33.9 11 10.0 1.8 7.79 61.0 8.4 2.4 86.2 189 CDO.GP 6–7 585 .47 2.1 30.8 14 10.7 1.8 9.64 60.9 9.0 2.5 89.6 138 CDO.GP 9–10 479 .52 2.1 29.9 14 11.0 1.6 12.2 61.5 9.2 2.6 93.9 122 CDO.GP 12–13 386 .75 1.7 29.1 13 10.8 1.5 16.6 61.6 9.6 2.7 94.0 107 CDO.GP 15–16 314 .76 1.7 30.6 23 10.8 1.4 14.2 57.9 10.2 3.0 89.0 127 CDO.GP 18–19 309 .85 1.5 35.1 16 11.2 1.3 23.8 58.4 10.1 3.2 96.7 153 CDO.GP 21–22 305 .86 1.4 38.4 19 12.9 1.2 21.4 65.3 11.1 3.3 110 151 CDO.GP 24–25 234 .34 .79 23.2 20 10.1 .67 <3 55.7 11.0 3.0 87.0 82.0 Harrison Bayou core: CDO.HB 0–1 1,550 .16 1.1 39.4 13 10.7 1.7 <3 83.9 8.8 2.4 91.1 146 CDO.HB 2–3 1,740 .15 1.3 37.1 13 9.7 1.5 <3 99.2 8.0 2.3 83.7 131 CDO.HB 4–5 1,410 .15 1.6 41.2 15 10.7 1.7 <3 81.4 8.8 2.5 89.4 145 CDO.HB 7–8 1,240 .15 1.8 42.1 13 10.8 1.8 <3 86.6 9.0 2.5 93.8 150 CDO.HB 10–11 966 .15 3.3 44.2 14 11.4 1.8 <3 86.8 9.0 2.7 100 155 CDO.HB 13–14 781 .14 3.1 43.2 14 11.1 1.8 <3 86.8 8.9 2.6 98.8 149 CDO.HB 16–17 573 .13 2.6 40.8 13 11.0 1.7 <3 96.6 8.6 2.5 97.4 143 CDO.HB 19–20 467 .12 1.5 44.1 17 13.2 1.6 <3 93.2 10.2 2.8 117 147 Mid-lake core: CDO.MD 0–1 2,200 .12 1.6 22.6 13 8.6 1.3 <3 75.5 9.2 2.6 80.8 120 CDO.MD 1.5–2 1,500 .12 1.3 24.0 15 8.9 1.1 <3 68.0 9.5 2.7 83.3 127 CDO.MD 3–3.5 1,160 .12 1.1 23.7 13 8.6 1.3 <3 63.8 9.2 2.6 80.4 124 CDO.MD 4.5–5 1,020 .12 1.0 23.8 14 8.7 1.2 <3 65.5 9.5 2.7 81.5 124 CDO.MD 6–6.5 954 .12 1.2 26.2 15 9.1 1.1 <3 69.1 9.8 2.8 86.4 131 CDO.MD 7.5–8 788 .11 1.2 26.9 17 9.1 1.5 <3 70.6 10.2 2.9 83.9 144 CDO.MD 9–9.5 608 .11 .92 22.8 15 8.6 1.0 <3 70.6 9.8 2.8 80.5 109 CDO.MD 11–12 561 .08 1.2 27.0 24 11.4 1.3 <3 80.2 11.9 3.5 101 117 Carter Lake core: CDO.CR 0–0.5 1,350 .19 3.0 39.8 14 10.1 2.0 na 56.6 9.2 2.5 95.0 235 CDO.CR 1–1.5 1,790 .18 3.1 40.3 13 9.8 2.2 na 58.4 8.6 2.4 93.8 236 CDO.CR 1.5–2 1,440 .20 3.0 42.2 12 10.2 2.2 na 56.3 8.5 2.5 98.5 254 CDO.CR 3–3.5 2,090 .19 2.9 40.8 12 10.0 2.3 na 56.3 8.5 2.5 95.5 244 CDO.CR 4–4.5 1,570 .20 3.0 40.9 13 9.6 2.5 na 61.1 8.8 2.6 94.3 240 CDO.CR 4.5–5 1,660 .20 2.9 41.3 12 10.3 2.3 na 57.8 8.7 2.5 98.7 250 CDO.CR 7–8 1,390 .20 3.0 43.6 14 11.0 2.1 na 56.1 9.1 2.6 105 266 CDO.CR 9–10 1,570 .20 3.1 43.9 13 10.8 2.4 na 55.2 9.1 2.6 105 264 CDO.CR 10–11 2,220 .21 3.3 44.6 13 10.2 2.5 na 55.8 9.2 2.7 102 264

CDO.CR 13–14 1,900 .21 3.2 45.0 14 11.1 2.4 na 61.4 9.5 2.7 106 293CDO.CR 15–16 1,390 .20 2.8 45.8 14 10.9 2.2 na 56.5 9.0 2.5 106 313CDO.CR 16–17 1,440 .21 2.5 47.2 14 11.1 2.3 na 56.3 9.2 2.6 107 328CDO.CR 19–20 1,400 .21 1.8 46.1 15 11.4 1.8 na 57.0 10.1 2.7 110 299CDO.CR 22–23 1,570 .20 1.7 44.2 18 12.4 1.8 na 61.9 10.5 2.7 117 272
Appendix 2.5 61

Appendix 2.5

Appendix 2.5. Analytical results for petroleum biomarkers[In micrograms per kilogram dry sediment; ID, identifier; E, estimated; <, less than] 

USGS

site ID Sample ID Nonane (C9) Decane (C10) Unde- cane (C11) Dode- cane (C12) Tride- cane (C13) Tetrade- cane (C14) Pentade- cane (C15) Hexade- cane (C16) Heptace- cane (C17) Pris- tane

Mid-lake core:

324102094041400 CDO.MD 0–1 E17.1 E46.2 E101 E17.3 E15.4 E31.8 E55 139 E864 11.6324102094041400 CDO.MD 1.5–2 E3.2 E19.4 E44.8 E18.8 E8.0 E16.3 E38.7 88.9 1,880 15.5324102094041400 CDO.MD 3–3.5 <40 E14.2 E30.7 E11.4 E5.8 E11.6 E33.3 49.5 1,310 14.2324102094041400 CDO.MD 4.5–5 E6.1 E11.7 E29.0 E7.6 E6.0 E10.6 E16.9 41.5 632 9.3324102094041400 CDO.MD 6–6.5 E5.3 E9.0 E22.8 E5.8 E5.0 E11.0 E14.8 E32.4 292 6.2324102094041400 CDO.MD 7.5–8 <40 E9.1 E24.0 E8.1 E4.8 E7.2 E10.2 48.1 190 5.9324102094041400 CDO.MD 9–9.5 <40 E11.1 E26.7 E8.5 E5.7 E9.0 E14.8 53.9 402 8.8324102094041400 CDO.MD 11–12 E3.4 E9.5 E24.5 E3.7 E3.3 E7.1 E7.2 E23.2 73.6 3.2

Sample ID

Octadecane

(C18)

Phytane Nona- decane (C19) Eico- sane (C20) Henei- cosane (C21) Doco- sane (C22) Trico- sane (C23) Tetrac- osane (C24) Penta- cosane (C25) 5B(H) Cholane Hexa- cosane (C26) n-Hepta- cosane (C27)

Mid-lake core—Continued

CDO.MD 0–1 E64 115 188 172 320 E206 E744 E309 E752 <135 E318 E1,140CDO.MD 1.5–2 E70.0 139 190 140 295 E150 E810 E205 E957 <80 E198 E1,220CDO.MD 3–3.5 49.8 133 198 133 226 E107 E522 E128 E570 <40 E147 E717CDO.MD 4.5–5 E38.8 100 208 130 203 E92.3 E474 E144 E474 <40 E133 E541CDO.MD 6–6.5 E26.4 53.5 206 119 187 E91.4 E472 E162 E578 <40 E132 E781CDO.MD 7.5–8 E24.0 40.8 166 120 152 E103 E400 E320 E541 <40 E139 E734CDO.MD 9–9.5 E31.6 60.7 258 133 233 E112 E548 E137 E674 <40 E150 E895CDO.MD 11–12 E12.8 14.8 97.1 58.6 99.6 E65.1 E278 E87.8 E459 <40 E116 E713
62 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 2.5. Analytical results for petroleum biomarkers—Continued Sample ID Choles- tane series Octaco- sane (C28) Cholestane

+

Coprostane

4A-Methylsterane

series

n-Nonacosane

(C29)

Hopane

triterpanoid

series

17A(H)

22,29,30

Trisnorhopane

4A-C28

Methylsterane

n-Triacontane

(C30)

n-Hentriacontane

(C31)

17B(H)

21A(H) 30

Norhopane

Mid-lake core—Continued

CDO.MD 0–1 E110 E344 E6.8 2,990 E1,380 4,210 E29.7 <135 E262 E1,180 <135CDO.MD 1.5–2 144 E246 E5.4 2,670 E1,320 4,150 E28.7 <80 E164 E1,060 <80CDO.MD 3–3.5 137 E137 E3.2 2,310 E619 3,110 E17.9 <40 E70.1 E476 <40CDO.MD 4.5–5 73.6 E129 E2.5 1,880 E604 2,450 E18.9 <40 E76.7 E430 <40CDO.MD 6–6.5 66.0 E163 <40 1,400 E740 1,860 E23.5 <40 E100 E562 <40CDO.MD 7.5–8 85.0 E141 E5.0 1,720 E666 3,040 E26.5 <40 E99.9 E473 <45CDO.MD 9–9.5 101 E174 E7.9 2,120 E816 3,200 E34.8 <40 E100 E582 <55CDO.MD 11–12 E36.7 E127 E2.1 1,260 E609 2,000 <40 <40 E104 E523 <40

Sample ID

4A-C30

Methylsterane

17A(H)

21B

Hopane

n-Dotriacontane

(C32)

17B(H)

21A

Hopane

n-Tritriacontane

(C33)

17B(H)21B(H)

Hopane

n-Tetratriacontane

(C34)

n-Pentatriacontane

(C35)

n-Hexatriacontane

(C36)

n-Octatriacontane

(C38)

Nonatriacontane

(C39)

n-Tetracontane

(C40)

Mid-lake core—Continued

CDO.MD 0–1 <330 E60.7 E191 <135 E887 E92.4 E111 E528 E95.0 <150 E254 <140CDO.MD 1.5–2 <160 E57.6 E113 <100 E721 84.1 E45.7 E518 E62.8 <140 E152 E149CDO.MD 3–3.5 <100 43.7 <40 <80 E89.7 72.2 <40 E256 E33.2 <60 E102 E71.8CDO.MD 4.5–5 <55 E43.0 E68.4 <80 E270 45.6 <40 E146 E31.7 E39.6 E46.7 E57.2CDO.MD 6–6.5 <40 47.3 E53.3 <75 E327 64.8 E25.4 E187 E48.0 <75 E103 E87.9CDO.MD 7.5–8 <50 62.0 E50.6 <80 E233 67.0 E24.4 E141 E32.4 <70 <80 <70CDO.MD 9–9.5 <55 70.8 E57.7 <90 E404 82.6 E35.5 E220 E35.9 <90 E126 E98.7CDO.MD 11–12 <40 E27.7 E58.4 <40 E260 E26.9 E32.0 E101 E37.6 <100 E84.8 E56.9
Appendix 3 63

Occurrence of and Trends in Selected SedimentAssociated Contaminants in Caddo Lake, Texas, 

1940–2002

Appendix 3

APPENDIX 3—

Quality-Assurance Data
64 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 

Appendix 3.1

Appendix 3.1. Quality-control samples for radionuclides

[In picocuries per gram unless otherwise specified; ID, identifier; STL, Severn Trent Laboratories, Inc.; na, not analyzed; lab

dup, laboratory duplicate; RPD, relative percent difference; env dup, environmental duplicate; LCS, laboratory control sample]

Sample ID STL lot number Cesium-137 Radium-226 Lead-210

CDO.MD 12–13 J2G090162 0.200 2.08 na

CDO.MD 12–13 lab dup J2G090162 .336 1.77 na

RPD of radionuclide: 50.75 16.10

CDO.HB 7–8 J2G090162 1.25 na na

CDO.HB 7–8 lab dup J2G090162 1.29 na na

RPD of radionuclide: 3.15

CDO.CR 17–18 J2F260205 1.45 1.82 na

CDO.CR 17–18 lab dup J2F260205 1.78 1.72 na

RPD of radionuclide: 20.43 5.65

CDO.GP 3–4 J2F260205 .860 na na

CDO.GP 3–4 lab dup J2F260205 .788 na na

RPD of radionuclide: 8.74

CDO.HB 15–16 env dup J2G110278 3.04 na na

CDO.HB 15–16 env dup, lab dup J2G110278 2.83 na na

RPD of radionuclide: 7.16

CDO.GP 14–15 J2F260205 .964 na na

CDO.GP 14–15 env dup J2F260205 .994 na na

RPD of radionuclide: 3.06

CDO.HB 15–16 J2G110278 2.36 na na

CDO.HB 15–16 env dup J2G110278 3.04 na na

RPD of radionuclide: 25.19

Blank J2G090162 -.0239 na na

Percent recovered of LCS J2G090162 98.40 na na

Blank J2G090162 -.0131 .149 -.00460

Percent recovered of LCS J2G090162 100.47 na 102.77

Blank J2F260205 -.0107 na na

Percent recovered of LCS J2F260205 103.36 na na

Blank J2F260205 -.0253 .0832 -.00443

Percent recovered of LCS J2F260205 109.10 na 107.48

Blank J2G110278 -.0118 na na

Percent recovered of LCS J2G110278 98.41 na na
Appendix 3.2 65

Appendix 3.2

Occurrence of and Trends in Selected SedimentAssociated Contaminants in Caddo Lake, Texas, 1940–2002

Appendix 3.2. Quality-control samples for organochlorine compounds[In micrograms per kilogram except as noted; ID, identifier; <, less than; env dup, environmental duplicate; RPD, relative percent difference; lab dup, laboratory 

duplicate; CRM, certified reference material] 

Sample ID Group number Lindane Heptachlor Aldrin Heptachlor epoxide Technical chlordane

CDO.CR 7–8 200219708 <7.0 <7.0 <7.0 <7.0 <70CDO.CR 7–8 env dup 200219708 <6.0 <6.0 <6.0 <6.0 <60Median RPD of sample = 23.3CDO.HB 4–5 200221211 <6.0 <6.0 <6.0 <6.0 <60CDO.HB 4–5 env dup 200221211 <6.0 <6.0 <6.0 <6.0 <60Median RPD of sample = 3.2CDO.HB 19–20 200221211 <2.5 <2.5 <2.5 <2.5 <25CDO.HB 19–20 lab dup 200221211 <2.5 <2.5 <2.5 <2.5 <25Median RPD of sample = 10.0Lk Austin Site DC 200222605 <1.0 <1.0 <1.0 <1.0 <10Lk Austin Site DC lab dup 200222605 <1.0 <1.0 <1.0 <1.0 <10Median RPD of sample = 23.0CDO.MD 11–12 200221106 <.5 <.5 <.5 <.5 <5CDO.MD 11–12 lab dup 200221106 <.5 <.5 <.5 <.5 <5Median RPD of sample = 20.2CDO.GP 21–22 200220603 <1.0 <1.0 <1.0 <1.0 <10CDO.GP 21–22 lab dup 200220603 <1.0 <1.0 <1.0 <1.0 <10Median RPD of sample = 10.1Lab blank 200219708 <.5 <.5 <.5 <.5 <5.0Lab spike, percent recovered (control limits) 200219708 53 (15–112) 63 (25–109) 57 (15–133) 72 (15–155) <5.0 (not spiked)CRM 362 (acceptable range, true value) 200219708 78 (50–217, 143) 87 (56–196, 134) 119 (87–253, 186) 92 (78–185, 146) <5.0 (not spiked)Lab blank 200221211 <.5 <.5 <.5 <.5 <5.0Lab spike, percent recovered (control limits) 200221211 65 (15–112) 59 (25–109) 51 (15–133) 65 (15–155) <5.0 (not spiked)CRM 362 (acceptable range, true value) 200221211 79 (50–217, 143) 85 (56–196, 134) 131 (87–253, 186) 94 (78–185, 146) <5.0 (not spiked)Lab blank 200222605 <.5 <.5 <.5 <.5 <5.0Lab spike, percent recovered (control limits) 200222605 62 (15–112) 72 (25–109) 76 (15–133) 72 (15–155) <5.0 (not spiked)CRM 362 (acceptable range, true value) 200222605 58 (50–217, 143) 62 (56–196, 134) 87 (87–253, 186) 62 (78–185, 146) <5.0 (not spiked)Lab blank 200221106 <.5 <.5 <.5 <.5 <5.0Lab spike, percent recovered (control limits) 200221106 22 (15–112) 30 (25–109) 30 (15–133) 30 (15–155) <5.0 (not spiked)CRM 362 (acceptable range, true value) 200221106 83 (50–217, 143) 78 (56–196, 134) 121 (87–253, 186) 102 (78–185, 146) <5.0 (not spiked)Lab blank 200220603 <.5 <.5 <.5 <.5 <5.0Lab spike, percent recovered (control limits) 200220603 57 (15–112) 68 (25–109) 69 (15–133) 63 (15–155) <5.0 (not spiked)CRM 362 (acceptable range, true value) 200220603 54 (50–217, 143) 49 (56–196, 134) 66 (87–253, 186) 56 (78–185, 146) <5.0 (not spiked)
66 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.2. Quality-control samples for organochlorine compounds—Continued Sample ID Endosulfan I Dieldrin p,p'- DDE Endrin p,p'- DDD p,p'- DDT CDO.CR 7–8 <7.0 <7.0 E2.4 <7.0 <7.0 <7.0 CDO.CR 7–8 env dup <6.0 <6.0 E1.9 <6.0 <6.0 <6.0 Median RPD of sample = 23.3 RPD = 23.3 CDO.HB 4–5 <6.0 <6.0 E3.2 <6.0 <6.0 <6.0 CDO.HB 4–5 env dup <6.0 <6.0 E3.1 <6.0 <6.0 <6.0 Median RPD of sample = 3.2 RPD = 3.2 CDO.HB 19–20 <2.5 <2.5 7.5 <2.5 E.83 <2.5 CDO.HB 19–20 lab dup <2.5 <2.5 7.6 <2.5 E1.0 <2.5 Median RPD of sample = 10.0 RPD = 1.3 RPD = 18.6 Lk Austin Site DC <1.0 <1.0 E.27 <1.0 <1.0 <1.0 Lk Austin Site DC lab dup <1.0 <1.0 E.34 <1.0 <1.0 <1.0 Median RPD of sample = 23.0 RPD = 23.0 CDO.MD 11–12 <.5 <.5 2.3 <.5 .7 <.5 CDO.MD 11–12 lab dup <.5 <.5 2.1 <.5 .5 <.5 Median RPD of sample = 20.2 RPD = 9.1 RPD = 31.3 CDO.GP 21–22 <1.0 <1.0 4.0 <1.0 <1.0 <1.0 CDO.GP 21–22 lab dup <1.0 <1.0 4.2 <1.0 <1.0 <1.0 Median RPD of sample = 10.1 RPD = 4.9 Lab blank <.5 <.5 <.5 <.5 <.5 <.5 Lab spike, percent recovered (control limits) 65 (25–94) 84 (15–150) 78 (34–140) 98 (33–133) 74 (22–158) 57 (15–150) CRM 362 (acceptable range, true value) 102 (71–229, 188) 142 (93–265, 191) 104 (74–194, 146) 113 (93–219, 151) 178 (120–401, 271) 160 (94–261, 212) Lab blank <.5 <.5 <.5 <.5 <.5 <.5 Lab spike, percent recovered (control limits) 58 (25–94) 62 (15–150) 82 (34–140) 72 (33–133) 67 (22–158) 60 (15–150) CRM 362 (acceptable range, true value) 91 (71–229, 188) 135 (93–265, 191) 112 (74–194, 146) 118 (93–219, 151) 183 (120–401, 271) 141 (94–261, 212) Lab blank <.5 <.5 <.5 <.5 <.5 <.5 Lab spike, percent recovered (control limits) 63 (25–94) 71 (15–150) 89 (34–140) 82 (33–133) 71 (22–158) 70 (15–150) CRM 362 (acceptable range, true value) 62 (71–229, 188) 84 (93–265, 191) 77 (74–194, 146) 84 (93–219, 151) 124 (120–401, 271) 95 (94–261, 212) Lab blank <.5 <.5 <.5 <.5 <.5 <.5

Lab spike, percent recovered (control limits) 28 (25–94) 32 (15–150) 34 (34–140) 36 (33–133) 31 (22–158) 32 (15–150)CRM 362 (acceptable range, true value) 98 (71–229, 188) 141 (93–265, 191) 99 (74–194, 146) 124 (93–219, 151) 183 (120–401, 271) 153 (94–261, 212)Lab blank <.5 <.5 <.5 <.5 <.5 <.5

Lab spike, percent recovered (control limits) 53 (25–94) 70 (15–150) 132 (34–140) 83 (33–133) 85 (22–158) 68 (15–150)

CRM 362 (acceptable range, true value) 53 (71–229, 188) 84 (93–265, 191) 63 (74–194, 146) 90 (93–219, 151) 132 (120–401, 271) 101 (94–261, 212)
Appendix 3.2 67

Appendix 3.2. Quality-control samples for organochlorine compounds—Continued 

Sample ID Methoxy- chlor Mirex Toxaphene PCB Aroclor 1242 PCB Aroclor 1254 PCB Aroclor 1260

CDO.CR 7–8 <28 <7.0 <700 <70 <70 <70CDO.CR 7–8 env dup <24 <6.0 <600 <60 <60 <60Median RPD of sample = 23.3CDO.HB 4–5 <24 <6.0 <600 <60 <60 <60CDO.HB 4–5 env dup <24 <6.0 <600 <60 <60 <60Median RPD of sample = 3.2CDO.HB 19–20 <10 <2.5 <250 <25 <25 <25CDO.HB 19–20 lab dup <10 <2.5 <250 <25 <25 <25Median RPD of sample = 10.0Lk Austin Site DC <4.0 <1.0 <100 <10 <10 <10Lk Austin Site DC lab dup <4.0 <1.0 <100 <10 <10 <10Median RPD of sample = 23.0CDO.MD 11–12 <2.0 <.5 <50 <5.0 <5.0 <5.0CDO.MD 11–12 lab dup <2.0 <.5 <50 <5.0 <5.0 <5.0Median RPD of sample = 20.2CDO.GP 21–22 <4.0 <1.0 <100 E5.2 E14 E16CDO.GP 21–22 lab dup <4.0 <1.0 <100 E5.2 E12 20.0Median RPD of sample = 10.1 RPD = 0.0 RPD = 15.4 RPD = 22.2Lab blank <2.0 <.5 <50 <5.0 <5.0 <5.0Lab spike, percent recovered (control limits) 66 (15–150) 72 (32–120) <50 (not spiked) 60 (17–145) 80 (53–150) 80 (33–150)CRM 362 (acceptable range, true value) 168 (144–622, 426) <.5 (not spiked) <50 (not spiked) <5.0 (not spiked) <5.0 (not spiked) <5.0 (not spiked)Lab blank <2.0 <.5 <50 <5.0 <5.0 <5.0Lab spike, percent recovered (control limits) 84 (15–150) 64 (32–120) <50 (not spiked) 70 (17–145) 82 (53–150) 85 (33–150)CRM 362 (acceptable range, true value) 289 (144–622, 426) <.5 (not spiked) <50 (not spiked) <5.0 (not spiked) <5.0 (not spiked) <5.0 (not spiked)Lab blank <2.0 <.5 <50 <5.0 <5.0 <5.0Lab spike, percent recovered (control limits) 90 (15–150) 74 (32–120) <50 (not spiked) 90 (17–145) 116 (53–150) 118 (33–150)CRM 362 (acceptable range, true value) 216 (144–622, 426) <.5 (not spiked) <50 (not spiked) <5.0 (not spiked) <5.0 (not spiked) <5.0 (not spiked)Lab blank <2.0 <.5 <50 <5.0 <5.0 <5.0Lab spike, percent recovered (control limits) 39 (15–150) E31 (32–120) <50 (not spiked) 32 (17–145) E42 (53–150) E40 (33–150)CRM 362 (acceptable range, true value) 259 (144–622, 426) <.5 (not spiked) <50 (not spiked) <5.0 (not spiked) <5.0 (not spiked) <5.0 (not spiked)Lab blank <2.0 <.5 <50 <5.0 <5.0 <5.0Lab spike, percent recovered (control limits) 46 (15–150) 64 (32–120) <50 (not spiked) 33 (17–145) 62 (53–150) 65 (33–150)CRM 362 (acceptable range, true value) 222 (144–622, 426) <.5 (not spiked) <50 (not spiked) <5.0 (not spiked) <5.0 (not spiked) <5.0 (not spiked)
68 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.3 Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons [In micrograms per kilogram, except as noted; ID, identifier; E, estimated; <, less than; env dup, environmental duplicate; RPD, relative percent difference; lab dup, laboratory duplicate; CRM, certified reference material] Sample ID Group number Naphthalene C1-128 isomers, methylated Naphthalenes 2-ethyl- Naphthalene 2,6- Dimethyl- naphthalene 1,6- Dimethyl- naphthalene CDO.HB 4–5 8022R02177 E18.6 <690 <65 2,100 348 CDO.HB 4–5 env dup 8022R02177 <65 <750 <65 1,740 310 Median RPD of sample = 6.7 RPD of compound = 18.8 11.6 CDO.HB 19–20 8022R02177 <30 <220 <30 438 75.1 CDO.HB 19–20 lab dup 8022R02177 E6.4 <160 <30 334 65.2 Median RPD of sample = 4.2 RPD of compound = 26.9 14.1 CDO.MD 11–12 8022R02171 E3.0 <20 <10 21.8 E3.1 CDO.MD 11–12 lab dup 8022R02171 E1.2 <30 <10 16.3 E4.3 Median RPD of sample = 9.1 RPD of compound = 85.7 28.9 32.4 CDO.CR 7–8 8022R02165 <60 <300 <60 1,150 189 CDO.CR 7–8 env dup 8022R02165 <60 <200 <60 1,010 148 Median RPD of sample = 18.8 RPD of compound = 13.0 24.3 Lab blank 8022R02165 <5 <5 <5 <5 <5 Lab spike, percent recovered 8022R02165 62.02 61.94 60.94 63.03 CRM 354, percent recovered (acceptable range) 8022R02165 3.85 (15–95) Lab blank 8022R02169 <5 <5 <5 E.46 <5 Lab spike, percent recovered 8022R02169 66.69 67.61 66.10 65.22 CRM 362, percent recovered (acceptable range) 8022R02169 38.58 (0–117) Lab blank 8022R02171 E.23 <5 <5 <5 <5 Lab spike, percent recovered 8022R02171 E41.42 56.02 57.80 56.02

CRM 362, percent recovered (acceptable range) 8022R02171 32.10 (0–117)Lab blank 8022R02177 E.15 <5 <5 E.44 <5Lab spike, percent recovered 8022R02177 65.46 65.09 66.06 67.48CRM 362, percent recovered (acceptable range) 8022R02177 44.67 (0–117)
Appendix 3.3 69

Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued 

Sample ID

C2-128

isomers,

C2-alkylated

Naphthalenes

Acenaphthylene

1,2-

Dimethylnaphthalene Acenaph- thene

C3-128

isomers,

C3-alkylated

Naphthalenes

2,3,6-

Trimethylnaphthalene 9H- Fluor- ene

C4-128

isomers,

C4-alkylated

Naphthalenes

CDO.HB 4–5 2,380 <65 <65 <65 514 E13.5 E10.7 <65CDO.HB 4–5 env dup 2,190 <65 <65 <65 461 <65 E9.9 <65Median RPD of sample = 6.7 8.3 10.9 7.8CDO.HB 19–20 591 E6.1 E11.8 E3.3 <100 E4.4 E4.6 <30CDO.HB 19–20 lab dup 516 E6.4 E11.8 E2.9 <125 E4.5 E4.6 <30Median RPD of sample = 4.2 13.6 4.8 0 12.9 2.2 0CDO.MD 11–12 31.0 <10 <10 <10 <50 <10 <10 <10CDO.MD 11–12 lab dup 25.8 E1.6 <10 E.76 <15 <10 E.97 <10Median RPD of sample = 9.1 18.3CDO.CR 7–8 1,430 <60 <60 <60 <300 <60 <60 <60CDO.CR 7–8 env dup 1,310 <60 <60 E5.6 <70 <60 E7.8 <60Median RPD of sample = 18.8 8.8Lab blank <5 <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 59.00 62.07 62.97 60.44 62.46CRM 354, percent recovered (acceptable range)Lab blank <5 <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 65.86 68.05 68.41 70.37 71.93CRM 362, percent recovered (acceptable range) 29.32 (28–105) 50.48 (36–113)Lab blank <5 <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 53.77 58.63 58.65 64.72 65.84CRM 362, percent recovered (acceptable range) 33.43 (28–105) 55.87 (36–113)Lab blank <5 <5 <5 E.18 <5 <5 <5 <5Lab spike, percent recovered 63.11 65.24 66.83 66.80 67.77CRM 362, percent recovered (acceptable range) 41.99 (28–105) 70.59 (36–113)
70 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued Sample ID 1-methyl- 9H- Fluorene Phenan- threne Anthra- cene C5-128 isomers, C5-alkylated Naphthalenes 2-Methyl- anthra- cene 4,5- Methylene- phenan- threne C1-178 isomers, methylated Phenanthrene/ anthracenes CDO.HB 4–5 <65 E20.7 E22.1 <65 <65 <65 <400 CDO.HB 4–5 env dup <65 E17.8 E21.3 <65 <65 E17.1 <375 Median RPD of sample = 6.7 15.1 3.7 CDO.HB 19–20 E10.9 E16.1 E12.4 <30 <30 E13.2 <65 CDO.HB 19–20 lab dup E10.6 E15.9 E13.0 <30 <30 E12.9 <65 Median RPD of sample = 4.2 2.8 1.3 4.7 2.3 CDO.MD 11–12 E2.5 E2.3 E2.3 <10 <10 E1.8 E7.3 CDO.MD 11–12 lab dup E2.3 E2.1 E2.2 <10 E1.9 E1.8 E5.3 Median RPD of sample = 9.1 8.3 9.1 4.4 0 31.7 CDO.CR 7–8 <60 E17.6 E19.3 <60 <60 <60 <70 CDO.CR 7–8 env dup <60 E13.9 E12.7 <60 <60 <60 <100 Median RPD of sample = 18.8 23.5 41.3 Lab blank <5 <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 64.23 67.17 63.00 63.95 67.09 CRM 354, percent recovered (acceptable range) 75.89 (39–94) 91.51 (18–95) Lab blank <5 <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 73.47 70.98 68.97 69.43 71.46 CRM 362, percent recovered (acceptable range) 59.21 (44–124) 45.99 (38–105) Lab blank <5 <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 73.29 72.67 70.38 72.44 76.33 CRM 362, percent recovered (acceptable range) 80.52 (44–124) 59.86 (38–105)

Lab blank <5 E.24 E.54 <5 <5 <5 <5Lab spike, percent recovered 69.73 70.58 67.94 67.69 69.52CRM 362, percent recovered (acceptable range) 83.90 (44–124) 65.01 (38–105)
Appendix 3.3 71

Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued 

Sample ID

1-Methylphenanthrene

C2-178

isomers,

C2-alkylated

Phenanthrene/

anthracenes

Fluoranthene Pyrene

C3-178

isomers,

C3-alkylated

Phenanthrene/

anthracenes

C4-178

isomers,

C4-alkylated

Phenanthrene/

anthracenes

1-Methylpyrene

CDO.HB 4–5 E54.2 <65 E41.4 E36.8 <65 <65 <65CDO.HB 4–5 env dup E47.7 <75 E38.8 E34.4 <65 <65 <65Median RPD of sample = 6.7 12.8 6.5 6.7CDO.HB 19–20 E6.7 <30 31.2 31.8 <30 <30 E5.5CDO.HB 19–20 lab dup E8.0 <30 31.2 32.1 E16.4 <30 E5.5Median RPD of sample = 4.2 17.7 0 0.9 0CDO.MD 11–12 E1.6 E8.2 E6.1 12.6 E7.1 <10 <10CDO.MD 11–12 lab dup <10 E8.1 E6.0 11.8 <10 <10 <10Median RPD of sample = 9.1 1.2 1.7 6.6CDO.CR 7–8 E15.7 <60 E28.1 E32.6 <60 <60 <60CDO.CR 7–8 env dup E12.9 <60 E25.5 E29.0 <60 <60 <60Median RPD of sample = 18.8 19.6 9.7 11.7Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 70.26 74.28 74.30 76.71CRM 354, percent recovered (acceptable range) 51.69 (33–90) 110.20 (32–90)Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 72.05 76.23 76.51 80.19CRM 362, percent recovered (acceptable range) 67.17 (43–125) 65.57 (32–139)Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 78.09 86.97 87.47 88.93CRM 362, percent recovered (acceptable range) 101.14 (43–125) 98.50 (32–139)Lab blank <5 <5 E.61 E.62 <5 <5 <5Lab spike, percent recovered 70.46 73.63 76.05 74.05CRM 362, percent recovered (acceptable range) 92.75 (43–125) 89.41 (32–139)
72 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued Sample ID C1-202 isomers, methylated Fluoranthene/ pyrenes C2-202 isomers, C2-alkylated Fluoranthene/ pyrenes C5-178 isomers, C5-alkylated Phenanthrene/ anthracenes Benz(a)- anthra- cene Chrysene C3-202 isomers, C3-alkylated Fluoranthene/ pyrenes C1-228 isomers, methylated Benzo(a)- anthracene/ chrysenes CDO.HB 4–5 <65 <150 <65 E18.9 E21.6 <65 <65 CDO.HB 4–5 env dup <65 <100 <65 E17.9 E20.3 <65 <65 Median RPD of sample = 6.7 5.4 6.2 CDO.HB 19–20 <40 <30 <30 E13.3 E18.8 <30 <30 CDO.HB 19–20 lab dup <40 <30 <30 E13.8 E19.6 <30 <30 Median RPD of sample = 4.2 3.7 4.2 CDO.MD 11–12 <10 <10 <10 E3.2 E5.3 <10 <10 CDO.MD 11–12 lab dup <10 <10 <10 <10 E4.7 <10 <10 Median RPD of sample = 9.1 12.0 CDO.CR 7–8 <60 <60 <60 <60 E14.2 <400 <60 CDO.CR 7–8 env dup <60 <60 <60 <60 E14.3 <300 <60 Median RPD of sample = 18.8 .7 Lab blank <5 <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 80.71 78.60 CRM 354, percent recovered (acceptable range) 210.60 (42–89) Lab blank <5 <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 74.41 69.48 CRM 362, percent recovered (acceptable range) 64.24 (42–126) Lab blank <5 <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 90.00 84.20 CRM 362, percent recovered (acceptable range) 97.21 (42–126)

Lab blank <5 <5 <5 <5 E.28 <5 <5Lab spike, percent recovered 80.14 77.29CRM 362, percent recovered (acceptable range) 84.19 (42–126)
Appendix 3.3 73

Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued 

Sample ID

C4-202

isomers,

C4-alkylated

Fluoranthene/

pyrenes

C5-202

isomers,

C5-alkylated

Fluoranthene/

pyrenes

C2-228

isomers,

C2-alkylated

Benzo(a)-

anthracene/

chrysenes

Benzo(b)-

fluoranthene

Benzo(k)-

fluoranthene Benzo(e)- pyrene Benzo(a)- pyrene

CDO.HB 4–5 <65 <65 <65 E38.5 E18.0 E18.3 E20.1CDO.HB 4–5 env dup <65 <65 <65 E34.1 E19.9 E18.1 E19.6Median RPD of sample = 6.7 12.1 10.0 1.1 2.5CDO.HB 19–20 <30 <30 <30 32.0 E16.5 E16.3 E15.2CDO.HB 19–20 lab dup <30 <30 <30 33.1 E18.1 E16.1 E15.0Median RPD of sample = 4.2 3.4 9.2 1.2 1.3CDO.MD 11–12 <10 <10 <10 E7.2 E6.1 E4.9 E3.9CDO.MD 11–12 lab dup <10 <10 <10 E8.2 E3.8 E5.0 E3.8Median RPD of sample = 9.1 13.0 46.5 2.0 2.6CDO.CR 7–8 <60 <60 <60 E33.8 E19.3 E16.3 E20.6CDO.CR 7–8 env dup <60 <60 <60 E27.3 E14.4 E13.5 E18.3Median RPD of sample = 18.8 21.3 29.1 18.8 11.8Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 74.72 79.54 59.28 71.93CRM 354, percent recovered (acceptable range) 69.88 (42–89)Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 67.29 77.45 53.99 69.54CRM 362, percent recovered (acceptable range) 66.75 (37–128) 40.23 (39–104)Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 82.42 94.65 64.58 78.11CRM 362, percent recovered (acceptable range) 96.93 (37–128) 57.96 (39–104)Lab blank <5 <5 <5 <5 <5 <5 <5Lab spike, percent recovered 71.96 84.07 73.93 75.01CRM 362, percent recovered (acceptable range) 85.23 (37–128) 56.67 (39–104)
74 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued Sample ID C1-252 isomers, C1-methylated Benzopyrene/ perylenes C3-228 isomers, C3-Benzo(a)- anthracene/ chrysenes C2-252 isomers, C2-alkylated Benzopyrene/ perylenes C4-228 isomers, C4-Benzo(a)- anthracene/ chrysenes Benzo- (g,h,i)- perylene Indeno- (1,2,3-c,d)- pyrene CDO.HB 4–5 <65 <65 <65 <65 <65 E39.1 CDO.HB 4–5 env dup <65 <65 <65 <65 E26.4 E37.4 Median RPD of sample = 6.7 4.4 CDO.HB 19–20 <30 <30 <30 <30 E20.4 E28.2 CDO.HB 19–20 lab dup E7.2 <30 <30 <30 E18.4 E24.8 Median RPD of sample = 4.2 10.3 12.8 CDO.MD 11–12 36.3 <10 <10 <10 E6.9 E7.9 CDO.MD 11–12 lab dup 61.4 <10 <10 <10 10.2 E7.3 Median RPD of sample = 9.1 51.4 38.6 7.9 CDO.CR 7–8 71.1 <60 <60 <60 <60 E37.4 CDO.CR 7–8 env dup E53.3 <60 <60 <60 E24.6 E31.3 Median RPD of sample = 18.8 28.6 17.8 Lab blank <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 71.61 73.25 CRM 354, percent recovered (acceptable range) Lab blank <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 70.14 79.70 CRM 362, percent recovered (acceptable range) Lab blank <5 <5 <5 <5 <5 <5 Lab spike, percent recovered 86.59 95.82 CRM 362, percent recovered (acceptable range)

Lab blank <5 <5 <5 <5 <5 <5Lab spike, percent recovered 82.99 86.97CRM 362, percent recovered (acceptable range)
Appendix 3.3 75

Appendix 3.3. Quality-control samples for polycyclic aromatic hydrocarbons—Continued 

Sample ID Dibenzo(a,h)- anthracene

C3-252 isomers,

C3-alkylated

Benzopyrene/

perylenes

C4-252 isomers,

C4-alkylated

Benzopyrene/

perylenes

C5-228 isomers,

C5-Benzo(a)-

anthracene/

chrysenes

C5-252 isomers,

C5-alkylated

Benzopyrene/

perylenes

Coronene

CDO.HB 4–5 <65 <65 <65 <65 <65 E15.6CDO.HB 4–5 env dup E23.6 <65 <65 <65 <65 E15.0Median RPD of sample = 6.7 3.9CDO.HB 19–20 E12.1 <30 <30 <30 <30 E14.1CDO.HB 19–20 lab dup E10.6 <30 <30 <30 <30 E10.0Median RPD of sample = 4.2 13.2 34.0CDO.MD 11–12 E3.1 <10 <10 <10 <10 E3.3CDO.MD 11–12 lab dup E3.0 <10 <10 <10 <10 <10Median RPD of sample = 9.1 3.3CDO.CR 7–8 <60 <60 <60 <60 <60 <60CDO.CR 7–8 env dup E18.1 <60 <60 <60 <60 E19.2Median RPD of sample = 18.8Lab blank <5 <5 <5 <5 <5 <5Lab spike, percent recovered 73.36 E42.03CRM 354, percent recovered (acceptable range)Lab blank <5 <5 <5 <5 <5 <5Lab spike, percent recovered 90.49 E45.15CRM 362, percent recovered (acceptable range)Lab blank <5 <5 <5 <5 <5 <5Lab spike, percent recovered 98.69 E79.66CRM 362, percent recovered (acceptable range)Lab blank <5 <5 <5 <5 <5 <5Lab spike, percent recovered 96.54 E96.58CRM 362, percent recovered (acceptable range)
76 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.4 Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued Sample ID Group number Total carbon (percent) Inorganic carbon, as CO3 (percent) Organic carbon (percent) Alumi- num Calcium Iron Magne- sium Potas- sium Phos- phorus CDO.GP 9–10 3958 12.8 0.04 12.8 77,100 3,070 26,000 2,740 6,740 1,050 CDO.GP 9–10 lab dup 3958 12.5 .04 12.5 76,100 3,030 26,000 2,800 6,720 1,050 Median RPD of sample = 1.2 RPD of element = 2.37 0 2.37 1.31 1.31 0 2.17 .30 0 CDO.GP 15–16 3958 9.03 .03 9.00 69,000 2,410 25,000 3,000 7,130 698 CDO.GP 15–16 lab tri 1 3958 na na na 71,900 2,490 25,500 2,930 7,190 754 RPD of element = -- -- -- 4.12 3.27 1.98 2.36 .84 7.71 CDO.GP 15–16 3958 9.03 .03 9.00 69,000 2,410 25,000 3,000 7,130 698 CDO.GP 15–16 lab tri 2 3958 na na na 71,000 2,420 25,300 2,790 7,120 744 RPD of element = -- -- -- 2.86 .41 1.19 7.25 .14 6.38 CDO.GP 15–16 lab tri 1 3958 na na na 71,900 2,490 25,500 2,930 7,190 754 CDO.GP 15–16 lab tri 2 3958 na na na 71,000 2,420 25,300 2,790 7,120 744 Median RPD of sample = 3.0 RPD of element = -- -- -- 1.26 2.85 .79 4.90 .98 1.34 CDO.HB 4–5 3958 11.6 .07 11.5 69,900 3,360 39,800 3,810 8,200 1,340 CDO.HB 4–5 lab dup 3958 11.2 .07 11.1 70,500 3,360 39,900 3,820 8,190 1,360 Median RPD of sample = 0.9 RPD of element = 3.51 0 3.54 .85 0 .25 .26 .12 1.48 CDO.CR 0–0.5 3959 1.2 10.6 10.5 67,900 3,180 46,000 2,960 6,260 1,600 CDO.CR 0–0.5 lab tri 1 3959 1.1 na na 75,600 3,330 49,000 2,810 6,700 1,700 RPD of element = 8.70 -- -- 10.73 4.61 6.32 5.20 6.79 6.06 CDO.CR 0–0.5 3959 1.2 10.6 10.5 67,900 3,180 46,000 2,960 6,260 1,600 CDO.CR 0–0.5 lab tri 2 3959 1.3 na na 74,700 3,400 49,000 2,840 6,770 1,700 RPD of element = 8.00 -- -- 9.54 6.69 6.32 4.14 7.83 6.06 CDO.CR 0–0.5 lab tri 1 3959 1.1 na na 75,600 3,330 49,000 2,810 6,700 1,700 CDO.CR 0–0.5 lab tri 2 3959 1.3 na na 74,700 3,400 49,000 2,840 6,770 1,700 Median RPD of sample = 2.8 RPD of element = 16.67 -- -- 1.20 2.08 0 1.06 1.04 0 CDO.CR 13–14 3959 1.2 9.46 9.37 78,000 3,270 56,000 2,760 6,690 3,000

CDO.CR 13–14 lab dup 3959 1.1 10.0 9.91 72,400 4,020 55,000 2,720 6,430 3,700Median RPD of sample = 4.7 RPD of element = 8.70 5.55 5.60 7.45 20.58 1.80 1.46 3.96 20.90CDO.CR 19–20 3959 1.2 8.53 8.44 83,800 2,570 66,000 3,030 7,230 1,600CDO.CR 19–20 lab dup 3959 1.2 8.45 8.37 83,600 2,560 65,000 3,030 7,240 1,600Median RPD of sample = 0.8 RPD of element = 0 .94 .83 .24 .39 1.53 0 .14 0

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements[In micrograms per gram, except as noted; ID, identifier; lab dup, laboratory duplicate; lab tri, laboratory triplicate; RPD, relative percent difference; na, not analyzed; --, not calculated; <, less than; HNO3 blank, dionized water with nitric acid preservative; MAG–1, USGS Marine Sediment; NIST 2704, National 

Institute of Standards and Technology Buffalo River Sediment; SCO–1, USGS Cody Shale; GSD–8, Chinese Quangxi Province Stream Sediment; MESS–1, 

National Research Council Canada Marine Estuarine Sediment; SRM, standard reference material; ?, uncertain] 
Appendix 3.4 77

HNO3 blank 3959 na na na <8 <20 <50 <0.3 <20 <8

HNO3 blank 3959 na na na <8 <20 <50 <.3 <20 <8HNO3 blank 3959 na na na <8 <20 <50 <.3 <20 <8HNO3 blank 3959 na na na <8 <20 <50 <.3 <20 <8MAG–1 found 3959 na na na 89,600 10,600 50,000 19,200 30,900 760MAG–1 true (Potts and others, 1992) na na na 86,660 9,790 47,600 18,090 29,500 711RPD of element -- -- -- 3.34 7.95 4.92 5.95 4.64 6.66

NIST 2704 found 3959 na na na 62,800 27,200 42,000 12,600 20,300 1,000NIST 2704 true (Potts and others, 1992) na na na 61,090 26,000 41,100 12,000 20,000 1,000RPD of element -- -- -- 2.76 4.51 2.17 4.88 1.49 0

SCO–1 found 3959 na na na 76,800 19,600 37,000 17,500 23,200 960SCO–1 true (Potts and others, 1992) na na na 72,370 18,700 35,900 16,400 23,000 899RPD of element -- -- -- 5.94 4.70 3.02 6.49 .87 6.56GSD–8 found 3959 na na na 42,200 1,570 16,000 1,530 24,300 120GSD–8 true (Potts and others, 1992) na na na 40,800 1,790 15,380 1,510 23,500 130RPD of element -- -- -- 3.37 13.10 3.95 1.32 3.35 8.00MESS–1 found 3959 na na na 57,100 5,010 30,000 8,550 18,200 690MESS–1 true (Potts and others, 1992) na na na 58,391 4,818 30,490 8,685 18,589 637RPD of element -- -- -- 2.24 3.91 1.62 1.57 2.12 7.94MAG–1 found 3959 na na na 90,300 10,500 50,000 18,600 31,600 730MAG–1 true (Potts and others, 1992) na na na 86,660 9,790 47,600 18,090 29,500 711RPD of element -- -- -- 4.11 7.00 4.92 2.78 6.87 2.64NIST 2704 found 3959 na na na 61,700 27,000 41,000 12,400 20,200 1,000NIST 2704 true (Potts and others, 1992) na na na 61,090 26,000 41,100 12,000 20,000 1,000RPD of element -- -- -- .99 3.77 .24 3.28 1.00 0

Median RPD of SRMs = 5.3

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Group number Total carbon (percent) Inorganic carbon, as CO3 (percent) Organic carbon (percent) Alumi- num Calcium Iron Magne- sium Potas- sium Phos- phorus
78 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 HNO3 blank 3958 na na na <8 <20 <50 <0.3 <20 <8 HNO3 blank 3958 na na na <8 <20 <50 <.3 <20 <8 HNO3 blank 3958 na na na <8 <20 <50 <.3 <20 <8 MAG–1 found 3958 na na na 91,700 10,500 50,500 19,200 32,000 772 MAG–1 true (Potts and others, 1992) na na na 86,660 9,790 47,600 18,090 29,500 711 RPD of element -- -- -- 5.65 7.00 5.91 5.95 8.13 8.23 NIST 2704 found 3958 na na na 62,200 26,200 41,500 12,500 20,200 974 NIST 2704 true (Potts and others, 1992) na na na 61,090 26,000 41,100 12,000 20,000 1,000 RPD of element -- -- -- 1.80 .77 .97 4.08 1.00 2.63 SCO–1 found 3958 na na na 72,600 18,600 35,700 16,100 22,500 890 SCO–1 true (Potts and others, 1992) na na na 72,370 18,700 35,900 16,400 23,000 899 RPD of element -- -- -- .32 .54 .56 1.85 2.20 1.01 GSD–8 found 3958 na na na 40,300 1,490 15,300 1,450 24,000 125 GSD–8 true (Potts and others, 1992) na na na 40,800 1,790 15,380 1,510 23,500 130 RPD of element -- -- -- 1.23 18.29 .52 4.05 2.11 3.92 MAG–1 found 3958 na na na 89,800 10,400 49,900 18,900 31,200 763 MAG–1 true (Potts and others, 1992) na na na 86,660 9,790 47,600 18,090 29,500 711 RPD of element -- -- -- 3.56 6.04 4.72 4.38 5.60 7.06 NIST 2704 found 3958 na na na 61,500 26,300 41,300 12,600 20,000 1,000 NIST 2704 true (Potts and others, 1992) na na na 61,090 26,000 41,100 12,000 20,000 1,000 RPD of element -- -- -- .67 1.15 .49 4.88 0 0 SCO–1 found 3958 na na na 70,600 18,300 35,000 16,400 22,200 916 SCO–1 true (Potts and others, 1992) na na na 72,370 18,700 35,900 16,400 23,000 899 RPD of element -- -- -- 2.48 2.16 2.54 0 3.54 1.87 GSD–8 found 3958 na na na 40,600 1,500 15,300 1,500 24,100 125

GSD–8 true (Potts and others, 1992) na na na 40,800 1,790 15,380 1,510 23,500 130RPD of element -- -- -- .49 17.63 .52 .66 2.52 3.92

Median RPD of SRMs = 4.7

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Group number Total carbon (percent) Inorganic carbon, as CO3 (percent) Organic carbon (percent) Alumi- num Calcium Iron Magne- sium Potas- sium Phos- phorus
Appendix 3.4 79

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Sodium Titanium Anti- mony Ar- senic Barium Beryl- lium Cad- mium Cerium Chro- mium Cobalt

CDO.GP 9–10 790 3,020 0.977 7.76 416 1.40 0.238 56.0 67.1 14.1CDO.GP 9–10 lab dup 826 3,180 .977 7.98 413 1.42 .233 56.1 67.6 14.1Median RPD of sample = 1.2 4.46 5.16 0 2.80 .72 1.42 2.12 .18 .74 0CDO.GP 15–16 1,130 3,260 1.01 8.29 435 1.53 .319 64.1 69.5 15.0CDO.GP 15–16 lab tri 1 1,140 3,380 1.02 8.11 437 1.63 .373 65.5 71.4 15.0

.88 3.61 .99 2.20 .46 6.33 15.61 2.16 2.70 0

CDO.GP 15–16 1,130 3,260 1.01 8.29 435 1.53 .319 64.1 69.5 15.0CDO.GP 15–16 lab tri 2 1,080 3,490 1.06 8.24 430 1.61 .344 62.5 70.1 14.9

4.52 6.81 4.83 .60 1.16 5.10 7.54 2.53 .86 .67

CDO.GP 15–16 lab tri 1 1,140 3,380 1.02 8.11 437 1.63 .373 65.5 71.4 15.0CDO.GP 15–16 lab tri 2 1,080 3,490 1.06 8.24 430 1.61 .344 62.5 70.1 14.9Median RPD of sample = 3.0 5.41 3.20 3.85 1.59 1.61 1.23 8.09 4.69 1.84 .67CDO.HB 4–5 1,140 2,810 .711 8.00 507 2.24 .498 69.9 57.6 27.0CDO.HB 4–5 lab dup 1,100 2,810 .705 8.24 508 2.18 .501 71.1 58.0 27.1Median RPD of sample = 0.9 3.57 0 .85 2.96 .20 2.71 .60 1.70 .69 .37CDO.CR 0–0.5 892 2,600 .86 12 432 3.1 .76 122 59.3 46.7CDO.CR 0–0.5 lab tri 1 841 2,800 .90 12 436 3.1 .77 122 62.2 48.1

5.89 7.41 4.55 0 .92 0 1.31 0 4.77 2.95

CDO.CR 0–0.5 892 2,600 .86 12 432 3.1 .76 122 59.3 46.7CDO.CR 0–0.5 lab tri 2 855 2,800 .84 13 437 3.2 .78 125 61.8 48.4

4.24 7.41 2.35 8.00 1.15 3.17 2.60 2.43 4.13 3.58

CDO.CR 0–0.5 lab tri 1 841 2,800 .90 12 436 3.1 .77 122 62.2 48.1CDO.CR 0–0.5 lab tri 2 855 2,800 .84 13 437 3.2 .78 125 61.8 48.4Median RPD of sample = 2.8 1.65 0 6.90 8.00 .23 3.17 1.29 2.43 .65 .62CDO.CR 13–14 726 3,200 .91 15 481 3.2 .83 134 64.5 53.0CDO.CR 13–14 lab dup 781 3,100 .88 14 501 3.2 .78 128 61.5 53.7Median RPD of sample = 4.7 7.30 3.17 3.35 6.90 4.07 0 6.21 4.58 4.76 1.31CDO.CR 19–20 764 3,200 .92 14 458 3.5 .79 125 67.5 44.2CDO.CR 19–20 lab dup 782 3,400 .96 14 454 3.4 .81 122 66.3 44.0Median RPD of sample = 0.8 2.33 6.06 4.26 0 .88 2.90 2.50 2.43 1.79 .45

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued
80 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 HNO3 blank <6 <40 <0.02 <0.1 <0.5 <0.001 <0.003 <0.5 <0.2 <0.1 HNO3 blank <6 <40 <.02 .1 <.5 .007 <.003 <.5 <.2 <.1 HNO3 blank <6 <40 <.02 .2 <.5 .003 <.003 <.5 <.2 <.1 HNO3 blank <6 <40 <.02 <.1 <.5 .006 <.003 <.5 <.2 <.1 MAG–1 found 29,300 4,300 .91 10 508 3.4 .22 89.4 112 22.5 MAG–1 true (Potts and others, 1992) 28,400 4,500 .96 9.2 479 3.20 .20 88.0 97 20.4 RPD of element 3.12 4.55 5.35 8.33 5.88 6.06 8.53 1.58 14.35 9.79 NIST 2704 found 5,800 3,400 3.5 22 421 1.8 3.6 59.3 146 13.9 NIST 2704 true (Potts and others, 1992) 5,470 4,580 3.79 23.4 414 na 3.45 72.0 135 14.0 RPD of element 5.86 29.57 7.96 6.17 1.68 -- 4.26 19.35 7.83 .72 SCO–1 found 6,890 3,600 2.6 13 588 1.9 .16 55.8 69.7 11.7 SCO–1 true (Potts and others, 1992) 6,670 3,760 2.50 12.4 570 1.84 .14 62.0 68.0 10.5 RPD of element 3.24 4.35 3.92 4.72 3.11 3.21 13.33 10.53 2.47 10.81 GSD–8 found 3,220 3,600 .2 2 450 2.0 .01 52.7 5.4 3.4 GSD–8 true (Potts and others, 1992) 3,490 3,660 .24 2.4 480 2.00 .08 54.0 7.60 3.6 RPD of element 8.05 1.65 18.18 18.18 6.45 0 156.04 2.44 33.85 5.71 MESS–1 found 17,500 3,500 .67 12 298 2.3 .66 69.7 63.1 11.6 MESS–1 true (Potts and others, 1992) 18,546 5,426 .73 10.6 na 1.9 .59 na 71 10.8 RPD of element 5.80 43.15 8.57 12.39 -- 19.05 11.20 -- 11.78 7.14 MAG–1 found 29,100 4,000 .81 9.9 491 3.2 .21 81.3 101 22.2 MAG–1 true (Potts and others, 1992) 28,400 4,500 .96 9.2 479 3.20 .20 88.0 97 20.4 RPD of element 2.43 11.76 16.95 7.33 2.47 0 3.88 7.91 4.04 8.45 NIST 2704 found 5,650 3,100 3.2 22 415 2.0 3.5 59.4 143 13.7 NIST 2704 true (Potts and others, 1992) 5,470 4,580 3.79 23.4 414 na 3.45 72.0 135 14.0 RPD of element 3.24 38.54 16.88 6.17 .24 -- 1.44 19.18 5.76 2.17

Median RPD of SRMs = 5.3

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Sodium Titanium Anti- mony Ar- senic Barium Beryl- lium Cad- mium Cerium Chro- mium Cobalt
Appendix 3.4 81

HNO3 blank <6 <40 <0.02 <0.1 <0.5 <0.001 <0.003 <0.5 <0.2 <0.1

HNO3 blank <6 <40 <.02 <.1 <.5 .00800 <.003 <.5 <.2 <.1HNO3 blank <6 <40 <.02 <.1 <.5 .0100 <.003 <.5 <.2 <.1MAG–1 found 29,800 4,350 .926 10.7 509 3.22 .229 86.6 110 22.5MAG–1 true (Potts and others, 1992) 28,400 4,500 .96 9.2 479 3.20 .20 88.0 97 20.4RPD of element 4.81 3.39 3.61 15.08 6.07 .62 12.53 1.60 12.56 9.79NIST 2704 found 5,800 3,500 3.60 20.9 423 1.83 3.45 64.5 135 13.6NIST 2704 true (Potts and others, 1992) 5,470 4,580 3.79 23.4 414 na 3.45 72.0 135 14.0RPD of element 5.86 26.73 5.14 11.29 2.15 -- 0 10.99 0 2.90SCO–1 found 6,630 3,360 2.42 12.1 583 1.81 .142 56.0 71.9 11.1SCO–1 true (Potts and others, 1992) 6,670 3,760 2.50 12.4 570 1.84 .14 62.0 68.0 10.5RPD of element .60 11.24 3.25 2.45 2.25 1.64 1.42 10.17 5.58 5.56GSD–8 found 3,110 3,360 .184 2.73 462 1.93 .068 55.1 5.55 3.34GSD–8 true (Potts and others, 1992) 3,490 3,660 .24 2.4 480 2.00 .08 54.0 7.60 3.6RPD of element 11.52 8.55 26.42 12.87 3.82 3.56 17.45 2.02 31.18 7.49MAG–1 found 29,600 4,280 .943 10.4 490 3.25 .225 85.3 107 22.2MAG–1 true (Potts and others, 1992) 28,400 4,500 .96 9.2 479 3.20 .20 88.0 97 20.4RPD of element 4.14 5.01 1.79 12.24 2.27 1.55 10.77 3.12 9.80 8.45NIST 2704 found 5,840 3,460 3.70 21.6 409 1.96 3.56 62.4 135 13.6NIST 2704 true (Potts and others, 1992) 5,470 4,580 3.79 23.4 414 na 3.45 72.0 135 14.0RPD of element 6.54 27.86 2.40 8.00 1.22 -- 3.14 14.29 0 2.90

SCO–1 found 6,760 3,300 2.45 12.0 557 1.86 .149 54.6 70.4 11.0SCO–1 true (Potts and others, 1992) 6,670 3,760 2.50 12.4 570 1.84 .14 62.0 68.0 10.5RPD of element 1.34 13.03 2.02 3.28 2.31 1.08 6.23 12.69 3.47 4.65GSD–8 found 3,190 3,500 .231 2.71 448 2.03 .015 53.4 8.04 3.33GSD–8 true (Potts and others, 1992) 3,490 3,660 .24 2.4 480 2.00 .08 54.0 7.60 3.6RPD of element 8.98 4.47 3.82 12.13 6.90 1.49 137.50 1.12 5.63 7.79Median RPD of SRMs = 4.7

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Sodium Titanium Anti- mony Ar- senic Barium Beryl- lium Cad- mium Cerium Chro- mium Cobalt
82 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued Sample ID Copper Gallium Lantha- num Lead Lithium Manga- nese Mer- cury Molyb- denum Nickel CDO.GP 9–10 32.9 16.3 28.6 71.8 42.8 479 0.52 2.12 29.9 CDO.GP 9–10 lab dup 33.6 16.2 28.8 72.3 42.3 471 .53 2.19 30.1 Median RPD of sample = 1.2 2.11 .62 .70 .69 1.18 1.68 1.90 3.25 .67 CDO.GP 15–16 35.9 15.4 32.7 111 42.8 314 .76 1.70 30.6 CDO.GP 15–16 lab tri 1 42.4 16.3 33.1 112 45.9 326 na 1.48 30.1 16.60 5.68 1.22 .90 6.99 3.75 -- 13.84 1.65 CDO.GP 15–16 35.9 15.4 32.7 111 42.8 314 .76 1.70 30.6 CDO.GP 15–16 lab tri 2 36.8 16.0 31.5 108 44.5 318 na 1.60 29.9 2.48 3.82 3.74 2.74 3.89 1.27 -- 6.06 2.31 CDO.GP 15–16 lab tri 1 42.4 16.3 33.1 112 45.9 326 na 1.48 30.1 CDO.GP 15–16 lab tri 2 36.8 16.0 31.5 108 44.5 318 na 1.60 29.9 Median RPD of sample = 3.0 14.14 1.86 4.95 3.64 3.10 2.48 -- 7.79 .67 CDO.HB 4–5 24.9 15.7 38.6 24.6 38.9 1,410 .15 1.57 41.2 CDO.HB 4–5 lab dup 24.0 15.9 38.8 24.7 40.2 1,420 .16 1.52 40.6 Median RPD of sample = 0.9 3.68 1.27 .52 .41 3.29 .71 6.45 3.24 1.47 CDO.CR 0–0.5 26.0 16 52.7 28.1 42.2 1,350 .19 3.0 39.8 CDO.CR 0–0.5 lab tri 1 26.8 16 52.1 27.5 42.7 1,430 na 3.0 41.1 3.03 0 1.15 2.16 1.18 5.76 -- 0 3.21 CDO.CR 0–0.5 26.0 16 52.7 28.1 42.2 1,350 .19 3.0 39.8 CDO.CR 0–0.5 lab tri 2 26.7 16 53.6 28.2 43.3 1,430 na 3.0 41.0 2.66 0 1.69 .36 2.57 5.76 -- 0 2.97 CDO.CR 0–0.5 lab tri 1 26.8 16 52.1 27.5 42.7 1,430 na 3.0 41.1 CDO.CR 0–0.5 lab tri 2 26.7 16 53.6 28.2 43.3 1,430 na 3.0 41.0 Median RPD of sample = 2.8 .37 0 2.84 2.51 1.40 0 -- 0 .24 CDO.CR 13–14 24.1 17 56.9 35.0 46.8 1,900 .21 3.2 45.0 CDO.CR 13–14 lab dup 23.7 16 54.5 33.5 44.5 1,970 .18 3.1 44.1 Median RPD of sample = 4.7 1.67 6.06 4.31 4.38 5.04 3.62 15.38 3.17 2.02

CDO.CR 19–20 22.4 18 54.5 41.8 51.1 1,400 .21 1.8 46.1CDO.CR 19–20 lab dup 22.9 18 54.1 40.9 50.7 1,390 .21 1.8 46.0Median RPD of sample = 0.8 2.21 0 .74 2.18 .79 .72 0 0 .22

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued
Appendix 3.4 83

HNO3 blank <0.5 <0.006 <0.3 <0.2 <0.2 <0.2 na <0.1 <1

HNO3 blank <.5 <.006 <.3 <.2 <.2 <.2 na <.1 <1HNO3 blank <.5 <.006 <.3 <.2 <.2 <.2 na <.1 <1HNO3 blank <.5 <.006 <.3 <.2 <.2 <.2 na <.1 <1MAG–1 found 30.1 23 43.4 26.3 78.0 777 na 1.1 49.2MAG–1 true (Potts and others, 1992) 30.0 20.4 43.0 24.0 79.0 760 na 1.60 53.0RPD of element .33 11.98 .93 9.15 1.27 2.21 -- 37.04 7.44

NIST 2704 found 94.8 16 30.6 154 45.2 590 na 3.7 41.9NIST 2704 true (Potts and others, 1992) 98.6 15.0 29.0 161.0 47.5 555 na na 44.1RPD of element 3.93 6.45 5.37 4.44 4.96 6.11 -- -- 5.12

SCO–1 found 29.4 17 33.5 31.6 45.8 409 na 1.2 26.0SCO–1 true (Potts and others, 1992) 28.7 15.0 29.5 31.0 45.0 410 na 1.37 27.0RPD of element 2.41 12.50 12.70 1.92 1.76 .24 -- 13.23 3.77GSD–8 found 5.5 10 27.5 20.6 13.5 347 na .35 1.6GSD–8 true (Potts and others, 1992) 4.1 10.8 30.0 21.0 13.2 310 na .54 2.7RPD of element 29.17 7.69 8.70 1.92 2.25 11.26 -- 42.70 51.16MESS–1 found 25.8 14 38.1 32.8 41.3 532 na 2.1 25.8MESS–1 true (Potts and others, 1992) 25.1 na na 34 44.9 512 na na 29.5RPD of element 2.75 -- -- 3.59 8.35 3.83 -- -- 13.38

MAG–1 found 29.1 23 41.2 26.0 77.4 788 na 1.0 48.3MAG–1 true (Potts and others, 1992) 30.0 20.4 43.0 24.0 79.0 760 na 1.60 53.0RPD of element 3.05 11.98 4.28 8.00 2.05 3.62 -- 46.15 9.28NIST 2704 found 93.6 16 31.7 162 44.4 596 na 3.6 41.1NIST 2704 true (Potts and others, 1992) 98.6 15.0 29.0 161.0 47.5 555 na na 44.1RPD of element 5.20 6.45 8.90 .62 6.75 7.12 -- -- 7.04

Median RPD of SRMs = 5.3

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Copper Gallium Lantha- num Lead Lithium Manga- nese Mer- cury Molyb- denum Nickel
84 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 HNO3 blank <0.5 <0.006 <0.3 <0.2 <0.2 <0.2 na <0.1 <1 HNO3 blank <.5 <.006 <.3 <.2 <.2 <.2 na <.1 <1 HNO3 blank <.5 <.006 <.3 <.2 <.2 <.2 na <.1 <1 MAG–1 found 30.1 22.9 43.6 26.1 79.4 779 na 1.35 49.9 MAG–1 true (Potts and others, 1992) 30.0 20.4 43.0 24.0 79.0 760 na 1.60 53.0 RPD of element 0.33 11.55 1.39 8.38 .51 2.47 -- 16.95 6.03 NIST 2704 found 93.4 15.2 32.0 158 45.8 584 na 3.97 42.2 NIST 2704 true (Potts and others, 1992) 98.6 15.0 29.0 161.0 47.5 555 na na 44.1 RPD of element 5.42 1.32 9.84 1.88 3.64 5.09 -- -- 4.40 SCO–1 found 29.3 16.2 30.0 29.8 43.7 384 na 1.30 24.9 SCO–1 true (Potts and others, 1992) 28.7 15.0 29.5 31.0 45.0 410 na 1.37 27.0 RPD of element 2.07 7.69 1.68 3.95 2.93 6.55 -- 5.24 8.09 GSD–8 found 5.10 10.2 28.6 20.8 13.2 334 na .578 <1 GSD–8 true (Potts and others, 1992) 4.1 10.8 30.0 21.0 13.2 310 na .54 2.7 RPD of element 21.74 5.71 4.78 .96 0 7.45 -- 6.80 -- MAG–1 found 30.1 22.8 43.5 26.0 78.7 766 na 1.32 49.7 MAG–1 true (Potts and others, 1992) 30.0 20.4 43.0 24.0 79.0 760 na 1.60 53.0 RPD of element .33 11.11 1.16 8.00 .38 .79 -- 19.18 6.43 NIST 2704 found 93.8 15.2 32.0 155 45.8 582 na 3.79 42.5 NIST 2704 true (Potts and others, 1992) 98.6 15.0 29.0 161.0 47.5 555 na na 44.1 RPD of element 4.99 1.32 9.84 3.80 3.64 4.75 -- -- 3.70 SCO–1 found 29.5 16.2 29.4 28.7 43.3 377 na 1.27 24.7 SCO–1 true (Potts and others, 1992) 28.7 15.0 29.5 31.0 45.0 410 na 1.37 27.0 RPD of element 2.75 7.69 .34 7.71 3.85 8.39 -- 7.58 8.90

GSD–8 found 5.35 10.3 28.2 20.0 13.1 336 na .586 <1GSD–8 true (Potts and others, 1992) 4.1 10.8 30.0 21.0 13.2 310 na .54 2.7RPD of element 26.46 4.74 6.19 4.88 .76 8.05 -- 8.17 --Median RPD of SRMs = 4.7

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Copper Gallium Lantha- num Lead Lithium Manga- nese Mer- cury Molyb- denum Nickel
Appendix 3.4 85

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Niobium Scan- dium Sele- nium Silver Stron- tium Thorium Uranium Vana- dium Zinc

CDO.GP 9–10 13.6 11.0 1.55 12.2 61.5 9.24 2.61 93.9 122CDO.GP 9–10 lab dup 14.3 11.0 1.70 11.5 61.2 9.15 2.60 95.2 123Median RPD of sample = 1.2 5.02 0 9.23 5.91 .49 .98 .38 1.37 .82CDO.GP 15–16 22.7 10.8 1.37 14.2 57.9 10.2 3.03 89.0 127CDO.GP 15–16 lab tri 1 15.2 10.6 1.51 14.9 60.2 9.95 3.00 92.8 140

39.58 1.87 9.72 4.81 3.90 2.48 1.00 4.18 9.74

CDO.GP 15–16 22.7 10.8 1.37 14.2 57.9 10.2 3.03 89.0 127CDO.GP 15–16 lab tri 2 16.6 10.6 1.33 18.4 58.6 9.65 2.92 91.3 135

31.04 1.87 2.96 25.77 1.20 5.54 3.70 2.55 6.11

CDO.GP 15–16 lab tri 1 15.2 10.6 1.51 14.9 60.2 9.95 3.00 92.8 140CDO.GP 15–16 lab tri 2 16.6 10.6 1.33 18.4 58.6 9.65 2.92 91.3 135Median RPD of sample = 3.0 8.81 0 12.68 21.02 2.69 3.06 2.70 1.63 3.64CDO.HB 4–5 14.7 10.7 1.66 <3 81.4 8.83 2.47 89.4 145CDO.HB 4–5 lab dup 13.4 10.6 1.86 <3 81.8 8.82 2.46 90.5 142Median RPD of sample = 0.9 9.25 .94 11.36 -- .49 .11 .41 1.22 2.09CDO.CR 0–0.5 14 10.1 2.0 na 56.6 9.2 2.5 95.0 235CDO.CR 0–0.5 lab tri 1 13 10.5 2.0 na 58.2 8.6 2.4 99.9 250

7.41 3.88 0 -- 2.79 6.74 4.08 5.03 6.19

CDO.CR 0–0.5 14 10.1 2.0 na 56.6 9.2 2.5 95.0 235CDO.CR 0–0.5 lab tri 2 13 10.7 2.3 na 58.2 8.9 2.5 100 249

7.41 5.77 13.95 -- 2.79 3.31 0 5.13 5.79

CDO.CR 0–0.5 lab tri 1 13 10.5 2.0 na 58.2 8.6 2.4 99.9 250CDO.CR 0–0.5 lab tri 2 13 10.7 2.3 na 58.2 8.9 2.5 100 249Median RPD of sample = 2.8 0 1.89 13.95 -- 0 3.43 4.08 .10 .40

CDO.CR 13–14 14 11.1 2.4 na 61.4 9.5 2.7 106 293CDO.CR 13–14 lab dup 13 10.5 2.2 na 65.3 9.0 2.6 102 281Median RPD of sample = 4.7 7.41 5.56 8.70 -- 6.16 5.41 3.77 3.85 4.18

CDO.CR 19–20 15 11.4 1.8 na 57.0 10.1 2.7 110 299CDO.CR 19–20 lab dup 15 11.4 1.8 na 58.2 9.9 2.6 110 296Median RPD of sample = 0.8 0 0 0 -- 2.08 2.00 3.77 0 1.01

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued
86 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 HNO3 blank <2 <0.3 <0.2 na <0.05 <0.03 <0.02 <0.4 <5 HNO3 blank <2 <.3 <.2 na <.05 <.03 <.02 <.4 <5 HNO3 blank <2 <.3 <.2 na <.05 <.03 <.02 <.4 <5 HNO3 blank <2 <.3 <.2 na <.05 <.03 <.02 <.4 <5 MAG–1 found 20 18.8 1.4 .48 146 12.7 2.7 146 141 MAG–1 true (Potts and others, 1992) 12.0 17.2 1.16 .08 146 11.9 2.70 140 130 RPD of element 50.00 8.89 18.75 142.86 0 6.50 0 4.20 8.12 NIST 2704 found 13 12.6 1.2 .42 123 8.8 2.8 95.6 439 NIST 2704 true (Potts and others, 1992) na 12.0 1.12 na 130 9.2 3.13 95.0 438 RPD of element -- 4.88 6.90 -- 5.53 4.44 11.13 .63 .23 SCO–1 found 14 12.8 .8 .39 172 9.8 2.9 138 109 SCO–1 true (Potts and others, 1992) 11.0 10.8 .890 .134 174 9.7 3.00 131 103 RPD of element 24.00 16.95 10.65 97.71 1.16 1.03 3.39 5.20 5.66 GSD–8 found 37 5.5 <.2 .75 46.6 13.2 2.9 23.6 47.8 GSD–8 true (Potts and others, 1992) 35.0 5.7 .15? .062? 52.0 13.4 3.00 26 43.0 RPD of element 5.56 3.57 -- -- 10.95 1.50 3.39 9.68 10.57 MESS–1 found 15 10.7 .6 .34 88.6 13.3 3.5 73.3 184 MESS–1 true (Potts and others, 1992) na na .34 na na na na 72.4 191 RPD of element -- -- 55.32 -- -- -- -- 1.24 3.73 MAG–1 found 16 18.6 1.3 .38 145 11.8 2.5 145 133 MAG–1 true (Potts and others, 1992) 12.0 17.2 1.16 .08 146 11.9 2.70 140 130 RPD of element 28.57 7.82 11.38 130.43 .69 .84 7.69 3.51 2.28 NIST 2704 found 9.8 12.3 1.0 .37 131 9.3 2.8 93.3 428 NIST 2704 true (Potts and others, 1992) na 12.0 1.12 na 130 9.2 3.13 95.0 438 RPD of element -- 2.47 11.32 -- .77 1.08 11.13 1.81 2.31

Median RPD of SRMs = 5.3

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Niobium Scan- dium Sele- nium Silver Stron- tium Thorium Uranium Vana- dium Zinc
Appendix 3.4 87

HNO3 blank <2 <0.3 <0.2 <3 <0.05 <0.03 <0.02 <0.4 <5

HNO3 blank <2 <.3 <.2 <3 <.05 <.03 <.02 <.4 <5HNO3 blank <2 <.3 <.2 <3 <.05 <.03 <.02 <.4 <5MAG–1 found 22.4 19.3 1.71 <3 150 12.7 2.78 149 139MAG–1 true (Potts and others, 1992) 12.0 17.2 1.16 .08 146 11.9 2.70 140 130RPD of element 60.47 11.51 38.33 -- 2.70 6.50 2.92 6.23 6.69

NIST 2704 found 13.0 12.5 1.04 <3 134 9.55 3.05 95.0 417NIST 2704 true (Potts and others, 1992) na 12.0 1.12 na 130 9.2 3.13 95.0 438RPD of element -- 4.08 7.41 -- 3.03 3.73 2.59 0 4.91

SCO–1 found 13.3 12.3 .951 <3 166 9.72 2.92 134 96.4SCO–1 true (Potts and others, 1992) 11.0 10.8 .890 .134 174 9.7 3.00 131 103RPD of element 18.93 12.99 6.63 -- 4.71 .21 2.70 2.26 6.62

GSD–8 found 38.5 5.48 <.2 <3 48.5 14.5 3.52 24.7 44.5GSD–8 true (Potts and others, 1992) 35.0 5.7 .15? .062? 52.0 13.4 3.00 26 43.0RPD of element 9.52 3.94 -- -- 6.97 7.89 15.95 5.13 3.43

MAG–1 found 22.3 18.7 1.54 <3 148 12.8 2.78 147 138MAG–1 true (Potts and others, 1992) 12.0 17.2 1.16 .08 146 11.9 2.70 140 130RPD of element 60.06 8.36 28.15 -- 1.36 7.29 2.92 4.88 5.97

NIST 2704 found 13.8 12.4 1.36 <3 133 9.63 2.98 94.4 437NIST 2704 true (Potts and others, 1992) na 12.0 1.12 na 130 9.2 3.13 95.0 438RPD of element -- 3.28 19.35 -- 2.28 4.57 4.91 .63 .23

SCO–1 found 14.2 12.1 .899 <3 165 9.46 2.80 132 104SCO–1 true (Potts and others, 1992) 11.0 10.8 .890 .134 174 9.7 3.00 131 103RPD of element 25.40 11.35 1.01 -- 5.31 2.51 6.90 .76 .97

GSD–8 found 36.7 5.34 <.2 <3 48.9 14.1 3.28 24.8 48.5GSD–8 true (Potts and others, 1992) 35.0 5.7 .15? .062? 52.0 13.4 3.00 26 43.0RPD of element 4.74 6.52 -- -- 6.14 5.09 8.92 4.72 12.02

Median RPD of SRMs = 4.7

Appendix 3.4. Quality-control samples for forms of carbon and major and trace elements—Continued

Sample ID Niobium Scan- dium Sele- nium Silver Stron- tium Thorium Uranium Vana- dium Zinc
88 Occurrence of and Trends in Selected Sediment-Associated Contaminants in Caddo Lake, Texas, 1940–2002 Appendix 3.5 Appendix 3.5. Quality-control samples for petroleum biomarkers [In micrograms per kilogram, except as noted; E, estimated; lab dup, laboratory duplicate; <, less than; RPD, relative percent difference; na, not analyzed] Sample ID Group number Nonane (C9) Decane (C10) Unde- cane (C11) Dode- cane (C12) Tridec- ane (C13) Tetra- decane (C14) Penta- decane (C15) Hexa- decane (C16) Hepta- cecane (C17) Pristane CDO.MD 11–12 8217R02171 E3.4 E9.5 E24.5 E3.7 E3.3 E7.1 E7.2 E23.2 73.6 3.2 CDO.MD 11–12 lab dup 8217R02171 <40 E5.0 E12.4 E5.0 E3.1 E5.8 E7.3 E27.0 65.0 3.2 RPD of sample = 12.9 RPD of compound = 62.1 65.6 29.9 6.2 20.2 1.4 15.1 12.4 0 Lab blank 8217R02171 E.76 E5.8 E12.8 E.72 E.57 E1.7 E1.8 E9.5 E1.3 <20 Lab spike, percent recovery 8217R02171 E15.0 47.7 82.7 45.3 56.0 64.3 74.0 125 82.0 70.0 Sample ID Octa- decane (C18) Phytane Nona- decane (C19) Eicosane (C20) Henei- cosane (C21) Docosane (C22) Tricosane (C23) Tetra- cosane (C24) Penta- cosane (C25) 5B (H) cholane Hexa- cosane (C26) n-hepta- cosane (C27) CDO.MD 11–12 E12.8 14.8 97.1 58.6 99.6 E65.1 E278 E87.8 E459 <40 E116 E713 CDO.MD 11–12 lab dup E12.4 13.0 81.9 51.0 91.5 E59.1 E215 E102 E369 <40 E88.2 E538 RPD of sample = 12.9 3.2 12.9 17.0 13.9 8.5 9.7 25.6 15.0 21.7 27.2 28.0 Lab blank E.89 <20 E.92 E1.4 E1.4 E2.1 E4.3 E13.0 E5.3 <20 E5.30 E5.30 Lab spike, percent recovery 82.0 78.8 87.7 102 114 E157 E182 E221 E171 na E152 E148 Sample ID Chole- stane series Octa- cosane (C28) Cholestane

+

Coprostane

4A-methyl

sterane

series

n-nonacosane

(C29)

Hopane

triterpanoid

series

17A(H)

22,29,30

trisnorhopane

4A-C28

methylsterane

n-triacontane

(C30)

n-hentriacontane

(C31)

17B(H)

21A(H) 30

norhopane

CDO.MD 11–12 E36.7 E127 E2.1 1,260 E609 2,000 <40 <40 E104 E523 <40CDO.MD 11–12 lab dup 40.0 E112 E2.3 1,440 E530 1,830 <40 <40 E97.6 E472 <40RPD of sample = 12.9 8.6 12.6 9.1 13.3 13.9 8.9 6.3 10.3Lab blank <20 E5.2 <20 <20 E6.0 <20 <20 <20 E4.5 E4.1 <20Lab spike, percent recovery na E154 106 na E145 na na na E135 E135 na

Sample ID

4A-C30

methylsterane

17A(H)

21B

hopane

n-dotriacontane

(C32)

17B(H)

21A

hopane

n-tritriacontane

(C33)

17B(H)21B(H)

hopane

n-tetratriacontane

(C34)

n-pentatriacontane

(C35)

n-hexatriacontane

(C36)

n-octatriacontane

(C38)

nonatriacontane

(C39)

n-tetracontane

(C40)

CDO.MD 11–12 <40 E27.7 E58.4 <40 E260 E26.9 E32.0 E101 E37.6 <100 E84.8 E56.9CDO.MD 11–12 lab dup <40 E22.2 E57.3 <40 E229 E19.7 E32.6 E101 E31.6 <100 E78.1 E77.1RPD of sample = 12.9 22.0 1.9 12.7 30.9 1.9 0 17.3 8.2 30.1Lab blank <20 <20 E3.1 <20 E2.40 <20 E1.4 E1.3 E1.1 <20 <20 <20Lab spike, percent recovery na na E125 na E120 na E111 E104 E91.3 E90.7 E88.7 E97.3