Trace Elements and Organic Compounds in

Bed Sediment from Selected Streams in

Southern Louisiana, 1998

National Water-Quality Assessment Program

Water-Resources Investigations Report 02-4089

U.S. Geological Survey

U.S. Department of the Interior
0

Front cover:

Upper left: Crawfish; Upper right: Amite River, Louisiana; 

Lower left: Bayou Lacassine, Louisiana; Lower right: Bayou Boeuf, Louisiana

(Photographs by Dennis K. Demcheck, U.S. Geological Survey)

Center: Bed sediment subsample

(Photograph by Douglas A. Harned, U.S. Geological Survey)
i

Trace Elements and Organic Compounds in 

Bed Sediment from Selected Streams in 

Southern Louisiana, 1998

By Stanley C. Skrobialowski

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 02-4089

National Water-Quality Assessment Program

Baton Rouge, Louisiana

2002
ii

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information contact: Copies of this report can be purchased

from:

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the Internet via the World Wide Web. You may connect to the NAWQA Home Page using the 

Universal Resource Locator (URL) at:

http://water.usgs.gov/nawqa
iii

FOREWORD

The U.S. Geological Survey (USGS) is committed 

to serve the Nation with accurate and timely scientific information that helps enhance and protect the 

overall quality of life, and facilitates effective management of water, biological, energy, and mineral 

resources. Information on the quality of the Nation’s 

water resources is of critical interest to the USGS 

because it is so integrally linked to the long-term 

availability of water that is clean and safe for drinking and recreation and that is suitable for industry, 

irrigation, and habitat for fish and wildlife. Escalating population growth and increasing demands for 

the multiple water uses make water availability, now 

measured in terms of quantity and quality, even 

more critical to the long-term sustainability of our 

communities and ecosystems.

The USGS implemented the National Water-Quality Assessment (NAWQA) Program to support

national, regional, and local information needs and

decisions related to water-quality management and

policy. Shaped by and coordinated with ongoing

efforts of other Federal, State, and local agencies,

the NAWQA Program is designed to answer: What

is the condition of our Nation’s streams and ground

water? How are the conditions changing over time?

How do natural features and human activities affect

the quality of streams and ground water, and where

are those effects most pronounced? By combining

information on water chemistry, physical characteristics, stream habitat, and aquatic life, the NAWQA

Program aims to provide science-based insights for

current and emerging water issues. NAWQA

results can contribute to informed decisions that

result in practical and effective water-resource management and strategies that protect and restore water

quality.

Since 1991, the NAWQA Program has implemented interdisciplinary assessments in more than

50 of the Nation’s most important river basins and

aquifers, referred to as Study Units. Collectively,

these Study Units account for more than 60 percent

of the overall water use and population served by

public water supply, and are representative of the

Nation’s major hydrologic landscapes, priority ecological resources, and agricultural, urban, and natural sources of contamination. 

Each assessment is guided by a nationally consistent study design and methods of sampling and analysis. The assessments thereby build local 

knowledge about water-quality issues and trends in 

a particular stream or aquifer while providing an 

understanding of how and why water quality varies 

regionally and nationally. The consistent, multiscale approach helps to determine if certain types of 

water-quality issues are isolated or pervasive, and 

allows direct comparisons of how human activities 

and natural processes affect water quality and ecological health in the Nation’s diverse geographic and 

environmental settings. Comprehensive assessments on pesticides, nutrients, volatile organic compounds, trace metals, and aquatic ecology are 

developed at the national scale through comparative 

analysis of the Study-Unit findings. 

The USGS places high value on the communication 

and dissemination of credible, timely, and relevant 

science so that the most recent and available knowledge about water resources can be applied in management and policy decisions. We hope this 

NAWQA publication will provide you the needed 

insights and information to meet your needs, and 

thereby foster increased awareness and involvement in the protection and restoration of our 

Nation’s waters. 

The NAWQA Program recognizes that a national 

assessment by a single program cannot address all 

water-resource issues of interest. External coordination at all levels is critical for a fully integrated 

understanding of watersheds and for cost-effective 

management, regulation, and conservation of our 

Nation’s water resources. The Program, therefore, 

depends extensively on the advice, cooperation, and 

information from other Federal, State, interstate, 

Tribal, and local agencies, non-government organizations, industry, academia, and other stakeholder 

groups. The assistance and suggestions of all are 

greatly appreciated.

Robert M. Hirsch

Associate Director for Water
iv
v

CONTENTS

Foreword .............................................................................................................................................iii

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

Introduction......................................................................................................................................... 1

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

Description of Study Unit .............................................................................................................2

Acknowledgments ........................................................................................................................ 2

Factors Influencing Bed-Sediment Quality ........................................................................................ 2

Physio-Chemical Factors .............................................................................................................. 5

Anthropogenic Factors ................................................................................................................. 5

Methods of Study ................................................................................................................................ 5

Sample Collection ........................................................................................................................ 5

Laboratory Methods ..................................................................................................................... 6

Statistical Methods ....................................................................................................................... 6

Comparison Criteria for the Evaluation of Bed Sediment ........................................................... 6

Trace Elements and Organic Compounds in Bed Sediment ............................................................... 8

Trace Elements ............................................................................................................................. 8

Fine-Grained Samples............................................................................................................ 8

Bulk Samples....................................................................................................................... 11

Relation of Physio-Chemical Factors to Sediment-Quality Criteria ...................................14

Total Organic Carbon ...........................................................................................................14

Sediment-Quality Criteria.................................................................................................... 15

Differences Between Fine-Grained and Bulk Samples ....................................................... 15

Historic Comparisons ..........................................................................................................17

Organic Compounds................................................................................................................... 17

Organochlorines................................................................................................................... 19

Polycyclic Aromatic Hydrocarbons .....................................................................................19

Summary and Conclusions ...............................................................................................................22

Selected References ..........................................................................................................................23

Appendixes:

A. Selected trace-element concentrations in bulk bed-sediment samples for selected

sites in the Acadian Pontchartrain Study Unit, southern Louisiana, 1998 .....................26

B. Concentrations of selected trace elements, nutrients, and organic compounds

in bed sediment for selected sites in the Acadian Pontchartrain Study Unit,

southern Louisiana, 1998................................................................................................28

FIGURES

1-3. Maps showing:

1. Location of bed-sediment sampling sites in the Acadian-Pontchartrain

Study Unit, southern Louisiana, 1998.................................................................................... 3

2. Land use, bed-sediment sampling sites, and concentrations of selected

trace elements in fine-grained samples in the Acadian-Pontchartrain Study Unit, 

southern Louisiana, 1998 ........................................................................................................ 9

3. Land use, bed-sediment sampling sites, and concentrations of selected

trace elements in bulk samples in the Acadian-Pontchartrain Study Unit, 

southern Louisiana, 1998 ......................................................................................................12
vi

TABLES

1. Drainage area and land use information for bed-sediment sampling sites in the 

Acadian-Pontchartrain Study Unit, southern Louisiana, 1998 ........................................................ 4

2. Background concentrations, Interim Sediment Quality Guideline concentrations,

and Probable Effects Levels for selected trace elements in bulk freshwater sediment.................. 7

3. Interim Sediment Quality Guideline concentrations and Probable Effects Levels

 for selected organic compounds in bulk freshwater sediment ....................................................... 7

4. Selected trace-element concentrations and number of Interim Sediment Quality

Guidelines (ISQG) and Probable Effects Levels (PEL) exceedances for fine-grained

and bulk bed-sediment samples collected at selected sites in the 

Acadian-Pontchartrain Study Unit, southern Louisiana, 1998 ...................................................... 10

5. Percent fine-grained material, iron, and total organic carbon and manganese

concentrations for bed-sediment sites in the Acadian-Pontchartrain Study Unit, 

southern Louisiana, 1998............................................................................................................... 13

6. P-values for statistical procedures used to compare concentrations of selected

 trace-elements and total organic carbon in fine-grained and bulk bed-sediment samples............ 16

7. Comparison of historic and 1998 data for selected trace-element concentrations in

bed sediment from selected sites in the Acadian-Pontchartrain Study Unit,

southern Louisiana ......................................................................................................................... 18

8. Selected organic compounds and number of Interim Sediment Quality Guidelines

(ISQG) and Probable Effects Level (PEL) exceedances for bed-sediment samples

collected at selected sites in the Acadian-Pontchartrain Study Unit, southern

 Louisiana, 1998............................................................................................................................. 20
1

Trace Elements and Organic Compounds in 

Bed Sediment from Selected Streams in 

Southern Louisiana, 1998

By Stanley C. Skrobialowski

ABSTRACT

Bed-sediment samples from 21 selected streams

in southern Louisiana were collected and analyzed for

the presence of trace elements and organic compounds

during 1998 as part of the U.S. Geological Survey

National Water-Quality Assessment Program. Concentrations of selected trace elements and organic compounds were compared on the basis of sediment-quality

criteria, land use, and grain size; concentrations of

selected trace elements also were compared with concentrations from previous studies. 

Concentrations of seven selected trace elements

and 21 organic compounds were evaluated with sediment-quality criteria established by the Canadian Council of Ministers of the Environment. Concentrations of

selected trace elements and organic compounds were

highest at sites draining urban and agricultural areas and

may result from cumulative effects of relatively high

percentages of fine-grained material, iron, and organic

material. Concentrations exceeding sediment-quality

criteria for the protection of aquatic life occurred most

frequently at Bayou Grosse Tete at Rosedale and Bayou

Lafourche below weir at Thibodaux. Exceedance of

Interim Sediment Quality Guidelines occurred most frequently for arsenic and chromium.

Trace-element concentrations in fine-grained

samples were compared with concentrations in bulk

samples and were determined to be significantly different, and concentrations were generally higher in finegrained sediment. Shapiro-Wilk, paired t-test, and Wilcoxon rank sum statistical procedures, with an alpha of

0.05, were used to compare concentrations of 21 trace

elements, total organic carbon, and total carbon in finegrained and bulk sediment samples for 19 sites. Significant differences were determined between fine-grained

and bulk sediment samples for aluminum, barium,

beryllium, chromium, copper, iron, lithium, nickel,

phosphorus, selenium, titanium, and zinc concentrations. Of 133 paired concentrations, 69 percent were

greater in fine-grained samples, and 23 percent were

greater in bulk samples. Comparisons with data from

previous studies indicate increases by more than 20 percent in concentrations of antimony at Bayou Lafourche

below weir at Thibodaux, arsenic and chromium at

Tickfaw River at Liverpool, lead at Bayou Lafourche

below weir at Thibodaux, and zinc at Bayou Lafourche

below weir at Thibodaux and Vermilion River at Perry.

Historic comparisons also indicate decreases by more

than 20 percent in concentrations of chromium at Bayou

des Cannes near Eunice and mercury at Mermentau

River at Mermentau.

INTRODUCTION

In 1991, the U.S. Geological Survey (USGS)

began implementation of the National Water Quality

Assessment (NAWQA) Program to describe the status

and trends in the quality of the Nation’s surface- and

ground-water resources (Gilliom and others, 1995). The

NAWQA Program consists of more than 50 study units,

including the Acadian-Pontchartrain (ACAD) Study

Unit located in southern Louisiana and southwestern

Mississippi, that incorporate more than 60 percent of the

Nation’s water use and population served by public

water supply. The NAWQA Program integrates chemical, physical, and biological data to assess the quality of

surface and ground water at local, regional, and national

levels (Meador and Gurtz, 1994). The surface-water

and biological components of the NAWQA Program

include characterizing chemical and biological interactions at the bed sediment-water interface. The analysis

of organic compounds and trace elements in water, bedsediment, and biota are combined to describe the source,

transport, and fate of these constituents in the aquatic

environment. 

 Bed sediment are sources and sinks for trace

elements and organic compounds in aquatic systems

and may be considered a source of these contaminants

in the food web (Horowitz, 1991). Understanding bedsediment chemistry in the Acadian-Pontchartrain Study

Unit is important because organisms dwelling or feeding in or near contaminated streambed sediment can

introduce these contaminants into the food web (Hem,

1985; Horowitz, 1991). Currently, several fish con-
2

sumption advisories are in effect in the study unit

area, and bed-sediment chemistry may help explain

uptake in biota in the Gulf Coast area (Louisiana

Department of Environmental Quality, 2001). Concentrations of trace elements and organic compounds in bed sediment and biota can exceed those

of overlying waters by several orders of magnitude,

and bed sediment may be used to evaluate waterquality trends, because bed sediment are integrators

of water quality over time and space (Horowitz,

1991; Horowitz and Elrick, 1988). 

Purpose and Scope

This report describes the occurrence and distribution of selected trace elements and organic

compounds in bed sediment at selected streams in

southern Louisiana in the ACAD Study Unit. Concentrations of selected trace elements were compared with sediment-quality criteria (SQC)

established by the Canadian Council of Ministers of

the Environment (CCME) (1999), dominant land

use, and percent fine-grained sediment. The SQC

used for comparison included background concentrations, Interim Sediment Quality Guidelines

(ISQG’s), and Potential Effects Levels (PEL’s) for

freshwater sediment. Site information, evaluation

criteria, and concentration data for selected trace

elements and organic compounds are presented.

Bed-sediment samples were collected at 21 stream

sites in the ACAD Study Unit between May and

August 1998 and split into subsamples. For all

sites, subsamples were prepared for analysis of trace

elements in fine-grained samples and for analysis of

grain size and organic compounds in bulk samples.

Samples were analyzed for two groups of organic

compounds, organochlorines and polycyclic aromatic hydrocarbons (PAH’s). For 19 of the 21 sites,

a subsample also was prepared for the analysis of

trace elements and total organic carbon in a bulk

sample. Trace-element concentrations from finegrained and bulk samples were compared with land

use, percent iron and organic carbon, and manganese concentrations. Parametric and non-parametric

statistical procedures also were used to compare

concentrations of 21 selected trace elements, total

organic carbon, and total carbon in fine-grained

samples that were detected in bulk samples. Concentrations of 11 selected trace elements in bulk samples were compared to concentrations from previous

studies for sites common to this and previous studies.

Description of Study Unit

The ACAD Study Unit (fig. 1) encompasses

approximately 26,000 square miles and includes parts

of southern Louisiana and southwestern Mississippi,

but excludes the Mississippi River and the Atchafalaya River Swamp. The study unit includes 21

streams discussed in this report, and land use within

the study unit includes urban, forest, agriculture, wetlands, open water, and barren land (table 1). Agriculture in the study unit includes timber; crops such as

rice, soybeans, sugarcane, and corn; and beef production. Aquacultural activities within the study unit are

common, especially for the breeding and production

of catfish and crawfish. Petrochemical and gas exploration and production, and marine transport are the

major nonagricultural industries within the study unit.

Soils within the ACAD Study Unit consist of clay, silt,

and sand with varied drainage characteristics. Soils in

the northern section of the study unit are mostly welldrained sands and gravels that transition to poorlydrained silts and clays (Boniol, 1988) and contain

higher amounts of organic and woody debris in the

southern section of the study area.

Acknowledgments

The author thanks colleagues in the USGS for

collecting samples and reviewing previous drafts of

this report. Roland W. Tollett, Van G. Bergeron, Dennis

K. Demcheck, and Robert B. Fendick assisted in the

collection, processing, and shipping of samples. Patricia J. D’Arconte prepared Geographic Information

System coverages and land-use maps. Critical reviews

by Dennis K. Demcheck, Rodney R. Knight, John A.

Robinson, Verlin C. Stephens, and Michael D. Woodside greatly improved the quality of the manuscript. 

FACTORS INFLUENCING 

BED-SEDIMENT QUALITY

Physio-chemical and anthropogenic factors

influence bed-sediment quality. Physio-chemical factors include weathering, grain size, sediment surface

coatings, geochemical substrate, interstitial-water

chemistry, and hydrologic conditions. Concentrations of some compounds are controlled by overlying

water-quality conditions such as dissolved oxygen,

pH, specific conductance, and oxidation-reduction

potential. Large trace-element concentrations have

been linked with small grain size and presence of

organic matter (Horowitz, 1991). 
Aca

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St. Martinville

Rosedale

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Robert

Westwego

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Bayou Segnette

Figure 1. Location of bed-sediment sampling sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998.

3

Lake 

Pontchartrain

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4

Table 1. Drainage area and land-use information for bed-sediment sampling sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998[Sites were designated as urban when the percentage of urban land use exceeded 25 percent, regardless of the other land-use percentages. <, less than]

Site 

number 

(see fig. 1)

Site name Drainage area, 

in square miles

Land-use

category

Land-use area, in percent1

Urban Forest Agriculture Wetlands Open water 

or barren land

1 Tchefuncte River near Covington 141 Forest <1 60 36 2 22 Bogue Falaya at Lee Road at Covington 130 Forest 1 62 32 <1 33 Tangipahoa River at Robert 647 Forest 2 59 34 3 24 Tickfaw River at Liverpool 87.8 Forest <1 67 29 3 15 Dawson Creek at Bluebonnet Boulevard at 

Baton Rouge 15.1 Urban 78 18 <1 <1 3

6 Amite River at Port Vincent 1,490 Forest 8 62 25 3 27 Bayou Des Allemands at Des Allemands 619 Wetland 2 2 28 62 58 Bayou Lafourche below weir at Thibodaux 4.2 Urban 29 13 47 1 109 Bayou Grosse Tete at Rosedale 118 Agriculture 2 3 58 36 <1

10 Bayou Boeuf at Railroad Bridge at Amelia 1,220 Wetland 3 4 38 51 5

11 Bayou Teche at Keystone Lock and Dam near 

St. Martinville 69.9 Agriculture 8 7 73 11 2

12 Vermilion River at Perry 436 Agriculture 13 5 72 9 <113 Bayou des Cannes near Eunice 142 Agriculture 4 7 85 3 <114 Bayou Nezpique near Basile 505 Forest 2 39 38 19 215 Mermentau River at Mermentau 1,380 Agriculture 3 21 64 10 116 Bayou Que De Tortue at Riceville 216 Agriculture 1 3 93 3 <117 Bayou Lacassine near Lake Arthur 296 Agriculture 2 3 88 7 <118 Whisky Chitto Creek near Oberlin 503 Forest 1 66 8 15 919 Calcasieu River near Kinder 1,720 Forest 1 65 12 16 620 Turtle Bayou north of Bayou Penchant near Amelia 15.6 Wetland <1 <1 <1 74 2621 Bayou Segnette 4.6 miles south of Westwego 23.8 Urban 34 6 <1 54 5

1Percent totals may not equal 100 due to rounding.
5

Physio-Chemical Factors

Grain size, sediment surface coatings, and presence or absence of organic matter are probably the most

important factors influencing trace-element sediment

quality. Horowitz (1991) discussed the interrelation

between surface area and surface coatings that concentrate trace elements. As particle sizes decrease, surface

areas increase, resulting in higher surface area to grainsize ratios for fine-grained material compared to coarsegrained material. Organic matter, silt, and clay constitute the majority of fine-grained material in the study

area. As surface area increases, the potential for traceelement concentrators such as hydrous iron and manganese oxides, and organic carbon to adsorb to particle

surfaces increases. Horowitz (1991) discussed the

importance of organic carbon, iron, and manganese

coatings as concentrators of trace elements in aquatic

systems, and described how trace elements can be physically trapped in particulate organic matter or chemically bound to sediment by organic surface coatings.

Organic matter as coatings and particulates may account

for up to 10 percent dry weight of cobalt, copper, iron,

lead, manganese, molybdenum, nickel, silver, vanadium, and zinc (Horowitz, 1991). Geochemical substrate or parent material influences bed-sediment quality

because surface coatings formed by hydrous iron and

manganese oxides provide surface charges on sediment

particles that tend to increase surface area and concentrate trace elements. 

Hydrologic conditions influence bed-sediment

quality. During periods of high flow, stream velocities

suspend and transport bed sediment. As velocities

decrease, particles may settle on the streambed or continue to move along the streambed as bedload. Transport exposes sediment particles to different waterquality conditions that may facilitate a change in surface

charge or coating. Dissolved oxygen, pH, specific conductance, oxidation-reduction potential, and total

organic carbon may affect bed-sediment quality

(Horowitz, 1991).

Anthropogenic Factors

Anthropogenic factors are associated with land

use and linked directly or indirectly to human activities.

Land-use activities such as agriculture, aquaculture,

mining, construction, industry, transportation, and recreation activities influence bed-sediment quality. Agricultural practices affect bed-sediment quality through the

routine or seasonal application of pesticides and fertilizers on crops and cropland, the maintenance of water

control structures used to irrigate or flood cropland, and

the management of irrigation tailwater. Aquaculture

activities, mainly for the production of catfish and crawfish, may influence bed-sediment chemistry through the

diversion and release of water to and from breeding and

production ponds. Sand mining activities disturb stream

and river bottoms and result in resuspension and exposure of bed sediment to different water-quality conditions. Oil and gas exploration and production activities

may influence bed-sediment quality through incidental

release or spill of drilling fluids or products, and brine

disposal. Construction and land- and lumber-clearing

activities may disturb sediment particles, and make

them more prone to erosion and subsequent suspension

and deposition in streams. Urban activities such as

applying fertilizers and pesticides to lawns, gardens,

golf courses, and other landscaped areas also may influence bed-sediment quality. Industrial, commercial, and

transportation activities influence bed-sediment quality

by introducing into the environment trace elements and

organic compounds that are subsequently trapped chemically or physically in bed sediment. Concentrations of

trace elements may be higher in urban areas because

trace elements, especially lead and zinc, have been

linked to municipal, industrial, and transportation activities (Callender and Rice, 2000).

METHODS OF STUDY

Sample collection, laboratory methods, statistical

methods, and comparison criteria for bed-sediment data

are described in this section. Methods used to collect

and prepare samples for this study followed standard

NAWQA protocols. All samples discussed in this report

were collected and processed by USGS personnel and

analyzed at USGS laboratories.

Sample Collection

Bed-sediment samples were collected and processed according to methods described by Shelton and

Capel (1994). At each site, one bed-sediment sample was

collected, subdivided into appropriate volumes, sieved

and preserved when necessary, and shipped to the appropriate analytical laboratory. Subsamples at 21 stream sites

were analyzed for trace elements in fine-grained sediment, grain size, and organic compounds, and mercury in

bulk sediment. For 19 stream sites, a subsample also was

analyzed for trace elements in bulk sediment.

For each of the 21 sites (table 1), one trace-element sample was wet-sieved through a nylon sieve to

provide a fine-grained sample with particle size smaller

than 63 μm (micrometers) in diameter, according to
6

methods described by Shelton and Capel (1994). Bulk

samples for the analysis of trace elements, total carbon,

and total organic carbon at 19 sites, and for analysis of

grain size at 21 sites, were processed according to methods described by McGee and Demcheck (1995). Bulk

samples were not sieved but were inspected for large

(greater than about 2 millimeters) detritus and debris

prior to shipping. Samples were not analyzed for trace

elements, total carbon, and total organic carbon in bulk

sediment for Whisky Chitto Creek near Oberlin and

Tangipahoa River at Robert. Bulk samples for the analysis of mercury at 21 sites were prepared according to

methods described by Olson and DeWild (1999). Samples for the analysis of organic compounds were prepared according to methods described by Shelton and

Capel (1994). 

Laboratory Methods

Analysis for trace elements in fine-grained samples and organic compounds, total carbon, and total

organic carbon in bulk samples were performed at the

USGS National Water Quality Laboratory (NWQL) in

Denver, Colorado. Methods used by the NWQL for the

analysis of trace elements include total digestion and are

described by Skougstad and others (1979). Methods

used by the NWQL for the analysis of organic compounds and total carbon and total organic carbon are

described by Foreman and others (1995), Furlong and

others (1996), and Arbogast (1990). Particle-size analyses on bulk samples were performed at the USGS Sediment Laboratory in Baton Rouge, Louisiana. Methods

used for the determination of particle size are described

by Guy (1969). Analyses for trace elements (except

mercury), total carbon, and total organic carbon, in bulk

samples were performed at the USGS Sediment Partitioning Research Project Laboratory (SPRL) in Atlanta,

Georgia. Methods used for the determination of traceelement concentrations in bulk samples include a total

digestion and are described by Horowitz and others

(1989). Analyses for mercury in bulk samples were performed at the USGS Wisconsin District Mercury Laboratory (WDML) in Madison, Wisconsin. Methods used

by the WDML for the analysis of mercury are described

by Olson and DeWild (1999). 

Statistical Methods

Parametric and nonparametric statistical procedures were used to compare concentrations of 21 trace

elements, total organic carbon, and total carbon in finegrained and bulk samples from 19 sites. Paired differences were initially tested for normality by using the

Shapiro-Wilk normality testing procedures with an

alpha of 0.05 (SAS Institute, 1990). If the normality

assumption was accepted, a parametric paired t-test with

an alpha of 0.05 was used to determine significance of

difference by comparing the average fine-grained concentration with the average bulk concentration for each

element. If the normality assumption was rejected, the

non-parametric Wilcoxon-Rank Sums procedure with

an alpha of 0.05 was used to test for significant differences (SAS Institute, 1990). Censored values were

included in the procedures and assigned the value of the

detection limit, because trace-element concentrations

determined near the detection limit may vary as much as

100 percent (Kent Elrick, USGS Sediment Partitioning

Research Laboratory, written commun., 2001).

Comparison Criteria for the Evaluation of 

Bed Sediment

Concentrations of trace elements and organic

compounds were compared with Canadian sedimentquality guidelines. Because State and Federal standards

have not been established for concentrations of trace

elements or organic compounds in bed sediment in the

United States, Canadian SQC were used to evaluate

concentrations of 7 selected trace elements (table 2) and

18 organic compounds (table 3) for which guidelines are

available.

Concentrations of seven selected trace elements

in fine-grained and bulk bed-sediment samples were

compared with background concentrations (Persaud and

others, 1993), Interim Sediment Quality Guidelines

(ISQG’s), and Probable Effects Levels (PEL’s) (Canadian Council of Ministers of the Environment, 1999)

listed in table 2. Concentrations of 18 organic compounds were compared with ISQG’s and PEL’s (Canadian Council of Ministers of the Environment, 1999)

listed in table 3. Background concentrations for trace

elements were based on Great Lakes pre-colonial sediment (Persaud and others, 1993). The ISQG’s and

PEL’s were developed for the protection of aquatic life

in bulk (unsieved) bed sediment and are based on associations between chemicals and biological effects and

cause and effect relations. Adverse biological effects

are not expected for concentrations below the ISQG’s.

Occasional adverse biological effects may be observed

for concentrations between ISQG’s and PEL’s, and

adverse biological effects may be expected for concentrations above PEL’s. Although background concen-
7

Table 2. Background concentrations, Interim Sediment Quality Guideline concentrations, and Probable

Effects Levels for selected trace elements in bulk freshwater sediment

[Concentrations are in milligrams per kilogram, dry weight. The ratio of one milligram per kilogram is equal to the ratio of one microgram per gram.]

1

 Source: Persaud and others (1993).

2 Source: Canadian Council of Ministers of the Environment (1999).

Table 3. Interim Sediment Quality Guideline concentrations and Probable Effects Levels for selected

organic compounds in bulk freshwater sediment 

[Concentrations are in milligrams per kilogram, dry weight. Source: Canadian Council of Ministers of the Environment (1999).]

Trace element Background 

concentration1

Interim Sediment Quality 

Guideline concentration2

Probable 

Effects Level2

Arsenic 4.2 5.9 17

Cadmium 1.1 .6 3.5

Chromium 31 37.3 90

Copper 25 35.7 197

Lead 23 35.0 91.3

Mercury .10 .17 .486

Zinc 65 123 315

Organic compound Interim Sediment Quality 

Guideline concentration Probable Effects Level

Organochlorines

Chlordane 4.50 8.87

DDD 3.54 8.51

DDE 1.42 6.75

DDT 1.19 4.77

Dieldrin 2.85 6.67

Total PCB’s 34.1 277

Polycyclic aromatic hydrocarbons

Acenaphthene 6.71 88.9

Acenaphthylene 5.87 128

Anthracene 46.9 245

Benz(a)anthracene 31.7 385

Benzo(a)pyrene 31.9 782

Chrysene 57.1 862

Dibenz(a,h)anthracene 6.22 135

Fluoranthene 111 2,355

Fluorene 21.2 144

Naphthalene 34.6 391

Phenanthrene 41.9 515

Pyrene 53 875
8

trations, ISQG’s, and PEL’s are based on bulk sediment,

these criteria are compared to concentrations in finegrained and bulk samples in this report.

Trace-element and organic-compound concentrations were used to characterize bed-sediment quality for

four land-use categories (urban, forest, agricultural, or

wetland) based on National Land Cover Data (U.S. Geological Survey, 1999). Sites were assigned land-use categories based on the dominant land use in the watershed

(table 1). Sites were designated as urban when the percentage of urban land use exceeded 25 percent, regardless of the other land-use percentages.

TRACE ELEMENTS AND ORGANIC 

COMPOUNDS IN BED SEDIMENT

Bed-sediment samples were collected at 21 sites

and analyzed for selected trace elements and organic

compounds. Concentrations of trace elements in finegrained sediment were determined for 21 sites and in

bulk sediment for 19 sites. Concentrations of trace elements and organic compounds were compared with SQC,

including background concentrations, ISQG’s, and PEL’s

developed by the CCME for bulk-bed sediment. Concentrations of trace elements in bulk and fine-grained

samples and organic compounds in bulk samples were

compared with land use. Trace-element concentrations

also were compared for six sites for which historic data

were available. 

Trace Elements

Concentrations of selected trace elements were

compared with SQC, land use, using parametric and nonparametric statistical procedures, and with data from previous studies. Concentrations of selected trace elements

were determined and compared for fine and bulk sediment because each size fraction represents exposure to

different aquatic biota. Concentrations of trace elements

in fine-grained sediment (smaller than 63 μm in diameter) may be useful in the analysis of compounds in the tissue of aquatic organisms because surficial fine-grained

bed sediment (1) concentrate in depositional zones,

(2) have longer residence times in the water column than

coarse grains when resuspended, and therefore, have a

higher potential for exposure to biota, (3) usually have

higher trace-element concentration than coarse grains,

and (4) may better represent sediment accumulating in

receiving waterbodies such as a lake, reservoir, and estuary. Fine-grained and bulk samples were compared to

SQC because (1) the NAWQA Program protocols require

a fine-grained sample for trace-element analysis (Shelton

and Capel, 1994); (2) concentrations determined from

size-fractions that represent less than 50-70 percent of the

sample may not reflect the true chemical concentrations

(Horowitz, 1991; D.R. Helsel, USGS, written commun.,

2001); (3) SQC were developed for bulk sediment (Canadian Council of Ministers of the Environment, 1999), and

(4) concentrations of trace elements in bulk sediment represent levels of exposure for organisms that dwell in or

near the benthos. 

Fine-Grained Samples

Trace-element concentrations for fine-grained

samples from 21 sites (fig. 2, appendix A) were compared with SQC (table 2). Seven trace elements for

which SQC are available--arsenic, cadmium, chromium,

copper, lead, mercury, and zinc--were evaluated with

background concentrations established by Persaud and

others (1993) and ISQG and PEL concentrations established by CCME (1999).

Arsenic concentrations were detected at all sites

(fig. 2) and ranged from 2 μg/g (micrograms per gram) at

Tchefuncte River near Covington (site 1) to 17 μg/g at

Bayou Grosse Tete at Rosedale (site 9) (table 4).

Arsenic concentrations for 15 sites exceeded the background concentration (4.2 μg/g), and concentrations for

13 sites exceeded the ISQG of 5.9 μg/g. The arsenic concentration for Bayou Grosse Tete at Rosedale (site 9)

equaled the PEL of 17 μg/g. 

Cadmium concentrations were detected at all sites

except Bogue Falaya at Lee Road at Covington (site 2)

and Tickfaw River at Liverpool (site 4) (fig. 2) and

ranged from 0.1 μg/g at Bayou des Cannes near Eunice

(site 13) and Bayou Nezpique near Basile (site 14) to

1.0 μg/g at Bayou Lafourche below weir at Thibodaux

(site 8) (table 4). Only the ISQG and PEL were used to

evaluate cadmium concentrations because the background concentration (1.1 μg/g) is greater than the ISQG

(table 2). Concentrations for Bayou Des Allemands at

Des Allemands, Bayou Lafourche below weir at Thibodaux, and Bayou Grosse Tete at Rosedale (sites 7, 8,

and 9) exceeded the ISQG (0.6 μg/g) with concentrations

of 0.7, 1.0, and 0.9 μg/g, respectively. No cadmium concentrations met or exceeded the PEL (3.5 μg/g).

 Chromium concentrations (fig. 2) were detected

at all sites and ranged from 26 μg/g at Bogue Falaya at

Lee Road at Covington (site 2) to 96 μg/g at Bayou

Lacassine near Lake Arthur (site 17) (table 4). Concentrations for 19 sites exceeded the background concentration (31 μg/g), and concentrations for 17 sites exceeded

the ISQG (37.3 μg/g) (table 2). Chromium concentrations exceeded the PEL (90 μg/g) for Bayou Grosse Tete

at Rosedale (site 9) and Bayou Lacassine near Lake

Arthur (site 17) with concentrations of 95 and 96 μg/g,

respectively. 
0 40

40 80

80 20

20

MILES

0 60

60

KILOMETERS

Gulf of Mexico

Mississippi R r

ive

Mississippi River

Atchafalaya River

Amite River

Lake 

Pontchartrain

Gulf Intracoastal Wate

y

r a w

 93° 92° 91° 90° 

32°

31°

30°

29°

18

19

14 13

15

16

12

11

8

7

9

6

4

1 2

21

3

5

10

20

17

LOUISIANA

MISSISSIPPI

S A

X E T

9

(Source: Canadian Council of M

(Source: Persaud and Others, 19

1

2

Figure 2. Land use, bed-sediment sampling sites, and concentrations of selected trace elements in fine-grained samples in 

Pontchartrain Study Unit, southern Louisiana, 1998.
10

Table 4. Selected trace-element concentrations and number of Interim Sediment Quality Guidelines (ISQG) and Probable Effects Levels (PEL) 

exceedances for fine-grained and bulk bed-sediment samples collected at selected sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998 

[Concentrations in color are noted as follows: blue, greater than or equal to background concentration; red, equals or exceeds the ISQG; purple, is less than the method reporting limit; and green, equals or exceeds 

PEL. Fine, fine-grained sample; Bulk, bulk sample; <, less than; na, not analyzed]

Site 

number 

(see

 fig. 1)

Site name 

	



 



   4     !" #

Fine Bulk Fine Bulk Fine1 Bulk2 Fine1 Bulk2 Fine1 Bulk2 Fine1 Bulk2 Fine1 Bulk2 Fine1 Bulk3 Fine1 Bulk2

1 Tchefuncte River near Covington 1 0 0 0 2 0.9 0.3 0.2 36 11 20 3 25 10 0.27 0.02 65 172 Bogue Falaya at Lee Road at Covington 0 0 0 0 2.5 .3 <.1 .1 26 2 8 <1 22 1 .03 <.01 43 2

3 Tangipahoa River at Robert 0 0 0 0 3.3 na .2 na 31 na 9 na 19 na .04 .02 50 na4 Tickfaw River at Liverpool 1 0 0 0 3.4 1.7 <.1 .1 38 16 14 3 19 10 .04 .02 49 19

5 Dawson Creek at Bluebonnet Boulevard at 

Baton Rouge 3 2 0 0 3.9 3.9 .5 .2 47 40 26 20 57 66 .10 .12 130 110

6 Amite River at Port Vincent 1000 5 3.1 .2 <.1 45 30 20 6 18 15 .03 .03 57 40

7 Bayou Des Allemands at Des Allemands 3300 11 12 .7 .2 75 59 30 24 34 66 .07 .05 120 110

8 Bayou Lafourche below weir at Thibodaux 6601 15 16 1.0 .7 76 63 38 37 67 130 .15 .16 160 220

9 Bayou Grosse Tete at Rosedale 5420 17 14 .9 .7 95 80 46 32 31 26 .07 .08 190 160

10 Bayou Boeuf at Railroad Bridge at Amelia 3300 9.8 10 .5 .1 78 58 32 24 29 32 .05 .05 150 170

11 Bayou Teche at Keystone Lock and Dam 

near St. Martinville 3300 7.8 8.3 .4 .5 74 68 33 32 29 28 .07 .07 130 130

12 Vermilion River at Perry 2300 6.6 7.6 .3 <.1 59 55 22 21 34 42 .07 .09 110 110

13 Bayou des Cannes near Eunice 2200 7.2 8.6 .1 <.1 56 38 18 10 33 27 .03 .02 72 42

14 Bayou Nezpique near Basile 1000 5.4 4.4 .1 .2 49 27 14 5 24 20 .03 .02 59 26

15 Mermentau River at Mermentau 3200 8.9 8.2 .2 .3 83 71 27 22 36 34 .07 .11 120 110

16 Bayou Que De Tortue at Riceville 2300 7.2 8.2 .2 .4 75 74 23 21 33 35 .05 .07 97 96

17 Bayou Lacassine near Lake Arthur 3310 7.8 7.9 .2 .3 96 86 30 22 41 47 .07 .07 110 100

18 Whisky Chitto Creek near Oberlin 1 na 0 0 8.8 na .2 na 34 na 9 na 18 na .03 <.01 48 na19 Calcasieu River near Kinder 1 0 0 0 3.2 .5 .2 .1 38 4 16 1 20 7 .03 <.01 54 5

20 Turtle Bayou north of Bayou Penchant 

near Amelia 2200 6.6 6.7 .3 .4 67 60 29 26 30 31 .09 .09 110 100

21 Bayou Segnette 4.6 miles south of 

Westwego 3200 9.5 13 .5 <.1 54 48 25 23 34 30 .09 .11 127 94

Samples were analyzed by one of the following U.S. Geological Survey laboratories: 1National Water Quality Laboratory, 2Sediment Research Partitioning Laboratory, 

or 3Wisconsin District Mercury Laboratory.

4ISQG concentration is less than background concentration.
11

 Copper concentrations were detected at all sites

(fig. 2) and ranged from 8 μg/g at Bogue Falaya at Lee

Road at Covington (site 2) to 46 μg/g at Bayou Grosse

Tete at Rosedale (site 9) (table 4). Concentrations for

nine sites exceeded the background concentration

(25 μg/g), and concentrations exceeded the ISQG

(35.7 μg/g) (table 2) at Bayou Lafourche below weir at

Thibodaux and Bayou Grosse Tete at Rosedale (sites 8

and 9). No copper concentrations met or exceeded the

PEL (197 μg/g). 

Lead concentrations (fig. 2) were detected at all

sites and ranged from 18 μg/g at Amite River at Port

Vincent and Whisky Chitto Creek near Oberlin (sites 6

and 18) to 67 μg/g at Bayou Lafourche below weir at

Thibodaux (site 8) (table 4). Concentrations for 15 sites

exceeded the background concentration (23 μg/g)

(table 2), and concentrations for Dawson Creek at Bluebonnet Boulevard at Baton Rouge (site 5), Bayou

Lafourche below weir at Thibodaux (site 8), Mermentau

River at Mermentau (site 15), and Bayou Lacassine near

Lake Arthur (site 17) exceeded the ISQG (35 μg/g) with

concentrations of 57, 67, 36, and 41 μg/g, respectively

(table 4). No lead concentrations met or exceeded the

PEL (91.3 μg/g). 

Mercury concentrations (fig. 2) were detected at

all sites and ranged from 0.03 μg/g at Bogue Falaya at

Lee Road at Covington, Amite River at Port Vincent,

Bayou des Cannes near Eunice, Bayou Nezpique near

Basile, Whisky Chitto Creek near Oberlin, and Calcasieu River near Kinder (sites 2, 6, 13, 14, 18, and 19) to

0.27 μg/g at Tchefuncte River near Covington (site 1)

(table 4). Concentrations for Dawson Creek at Bluebonnet Boulevard at Baton Rouge (site 5) and Bayou

Lafourche below weir at Thibodaux (site 8) met or

exceeded the background concentration (0.10 μg/g)

(table 2). The concentration for Tchefuncte River near

Covington (site 1) (0.27 μg/g), exceeded the background concentration and the ISQG (0.17 μg/g). No

mercury concentrations met or exceeded the PEL

(0.486 μg/g). 

Zinc concentrations (fig. 2) were detected at all

sites and ranged from 43 μg/g at Bogue Falaya at Lee

Road at Covington (site 2) to 190 μg/g at Bayou Grosse

Tete at Rosedale (site 9) (table 4). Concentrations for

14 sites met or exceeded the background concentration

(65 μg/g) (table 2). Concentrations for Dawson Creek

at Bluebonnet Boulevard at Baton Rouge, Bayou

Lafourche below weir at Thibodaux, Bayou Grosse Tete

at Rosedale, Bayou Boeuf at Railroad Bridge at Amelia,

Bayou Teche at Keystone Lock and Dam near St. Martinville, and Bayou Segnette 4.6 miles south of

Westwego (sites 5, 8, 9, 10, 11, and 21) exceeded the

ISQG (123 μg/g) (table 4). No zinc concentrations met

or exceeded the PEL (315 μg/g).

The ISQG and PEL exceedances in fine-grained

sediment may be linked to land use and grain size. The

ISQG was met or exceeded for arsenic at 13 sites, cadmium at 3 sites, chromium at 17 sites, copper at 2 sites,

lead at 4 sites, mercury at 1 site, and zinc at 6 sites.

Concentrations of seven selected trace elements

occurred at or below background concentrations at

Bogue Falaya at Lee Road at Covington (site 2) and

Tangipahoa River at Robert (site 3). These sites drain

forested areas and had the lowest percentages of finegrained material (table 5). 

The most ISQG exceedances occurred at Bayou

Lafourche below weir at Thibodaux and Bayou Grosse

Tete at Rosedale (sites 8 and 9). Arsenic, cadmium,

chromium, copper, lead, and zinc concentrations

exceeded the ISQG at Bayou Lafourche below weir at

Thibodaux (site 8). Arsenic, cadmium, chromium, copper, and zinc concentrations exceeded the ISQG, and

arsenic and chromium exceeded the PEL, at Bayou

Grosse Tete at Rosedale (site 9). These bayous drain

areas adjacent to roads and rural residences consistent

with urban settings and have soils that consist of sandy

and clayey alluvium. 

Bulk Samples

Trace-element concentrations for bulk samples

from 19 sites (fig. 3, appendix B) were evaluated with

SQC (table 2). Seven trace elements for which SQC are

available--arsenic, cadmium, chromium, copper, lead,

mercury, and zinc--were compared with background

concentrations established by Persaud and others (1993)

and ISQG and PEL concentrations established by

CCME (1999) (table 2).

Arsenic concentrations (fig. 3) were detected at

all sites and ranged from 0.3 μg/g at Bogue Falaya at

Lee Road at Covington (site 2) to 16 μg/g at Bayou

Lafourche below weir at Thibodaux (site 8) (table 4).

Concentrations for 13 sites exceeded the background

concentration (4.2 μg/g) and for 12 sites exceeded the

ISQG (5.9 μg/g) (table 2). No arsenic concentrations

met or exceeded the PEL (17 μg/g). 

Cadmium concentrations (fig. 3) were detected

at 15 sites and ranged from less than 0.1 μg/g at Amite

River at Port Vincent, Vermilion River at Perry, Bayou

des Cannes near Eunice, and Bayou Segnette 4.6 miles

south of Westwego (sites 6, 12, 13, and 21) to 0.7 μg/g

at Bayou Lafourche below weir at Thibodaux and

Bayou Grosse Tete at Rosedale (sites 8 and 9) (table 4).

Concentrations at Bayou Lafourche below weir at Thibodaux and Bayou Grosse Tete at Rosedale exceeded

the ISQG (0.6 μg/g, table 2). No cadmium concentrations met or exceeded the PEL (3.5 μg/g). 
0 40

40 80

80 20

20

MILES

0 60

60

KILOMETERS

Gulf of Mexico

Mississippi R r

ive

Mississippi River

Atchafalaya River

Amite River

Lake 

Pontchartrain

Gulf Intracoastal Wate

y

r a w

 93° 92° 91° 90° 

32°

31°

30°

29°

LOUISIANA

MISSISSIPPI

S A

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12

(Source: Canadian Council of M

(Source: Persaud and Others, 19

1

2

13

16

1 2

21

4

3

7

20

8

9

6

5

10

19

18

14

15

17 12

11

Figure 3. Land use, bed-sediment sampling sites, and concentrations of selected trace elements in bulk samples in the Ac

Pontchartrain Study Unit, southern Louisiana, 1998.
13

Table 5. Percent fine-grained material, iron, and total organic carbon and manganese concentrations for bed-sediment sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998 [fine, fine-grained; μg/g, micrograms per gram; na, not available]

Site 

number

 (see fig. 1)

Site name Land-use 

category

Percent

 fine-grained 

material

Percent iron Percent total organic carbon Manganese (μg/g)

Fine Bulk Fine Bulk Fine Bulk

1 Tchefuncte River near Covington Forest 28.7 1.0 0.4 1.9 0.7 250 1202 Bogue Falaya at Lee Road at Covington Forest 1.8 .92 .1 1.3 .1 190 193 Tangipahoa River at Robert Forest 3.2 1.4 na 1.4 na 770 na4 Tickfaw River at Liverpool Forest 8.7 1.3 .6 1.5 1.3 1,200 6205 Dawson Creek at Bluebonnet Boulevard at 

Baton Rouge Urban 86.6 2.0 1.7 .8 1.6 300 330

6 Amite River at Port Vincent Forest 67.8 1.6 1.3 .8 .7 930 5707 Bayou Des Allemands at Des Allemands Wetland 93.6 4.1 3.8 5.7 5.9 1,000 1,1008 Bayou Lafourche below weir at Thibodaux Urban 78.8 3.4 2.9 1.7 2.7 640 6109 Bayou Grosse Tete at Rosedale Agriculture 93.6 4.9 4.3 2.1 2.7 570 660

10 Bayou Boeuf at Railroad Bridge at Amelia Wetland 86.4 3.8 3.2 1.9 1.7 890 860

11 Bayou Teche at Keystone Lock and Dam 

near St. Martinville

Agriculture 98.6 3.5 3.4 1.8 2.0 530 610

12 Vermilion River at Perry Agriculture 93.2 2.4 2.6 1.4 1.8 440 58013 Bayou des Cannes near Eunice Agriculture 25.8 2.7 2.2 .7 .6 830 84014 Bayou Nezpique near Basile Forest 57.0 2.2 1.3 1.1 .6 780 44015 Mermentau River at Mermentau Agriculture 96.8 4.0 3.5 2.3 2.6 820 83016 Bayou Que De Tortue at Riceville Agriculture 99.4 3.3 3.3 1.9 2.3 480 58017 Bayou Lacassine near Lake Arthur Agriculture 99.2 4.0 3.6 2.9 3.1 490 49018 Whisky Chitto Creek near Oberlin Forest 16.1 2.9 na 2.3 na 730 na19 Calcasieu River near Kinder Forest 3.7 1.6 .1 1.3 .1 830 16020 Turtle Bayou north of Bayou Penchant 

near Amelia

Wetland 99.4 3.3 3.1 14.0 16.2 560 580

21 Bayou Segnette 4.6 miles south of 

Westwego

Urban 94.6 3.0 3.0 8.1 11.2 700 850
14

Chromium concentrations (fig. 3) were detected

at all sites and ranged from 2 μg/g at Bogue Falaya at

Lee Road at Covington (site 2) to 86 μg/g at Bayou

Lacassine near Lake Arthur (site 17). Chromium concentrations for 13 sites (table 4) exceeded the background concentration (31 μg/g) and the ISQG

(37.3 μg/g) (table 2). No chromium concentrations met

or exceeded the PEL (90 μg/g).

Copper concentrations (fig. 3) were detected at

18 sites and ranged from less than 1 μg/g at Bogue

Falaya at Lee Road at Covington (site 2) (table 4) to

37 μg/g at Bayou Lafourche below weir at Thibodaux

(site 8). Copper concentrations exceeded the background concentration (25 μg/g) at Bayou Lafourche

below weir at Thibodaux, Bayou Grosse Tete at

Rosedale, Bayou Teche at Keystone Lock and Dam near

St. Martinville, and Turtle Bayou north of Bayou Penchant near Amelia (sites 8, 9, 11, and 20). The copper

concentration at Bayou Lafourche below weir at Thibodaux (site 8) exceeded the ISQG (35.7 μg/g) (table 2),

and no copper concentrations met or exceeded the PEL

(197 μg/g).

Lead concentrations (fig. 3) were detected at all

sites and ranged from 1 μg/g at Bogue Falaya at Lee

Road at Covington (site 2) to 130 μg/g at Bayou

Lafourche below weir at Thibodaux (site 8) (table 4).

Lead concentrations for 13 sites exceeded the background concentration (23 μg/g), and concentrations for

Dawson Creek at Bluebonnet Boulevard at Baton

Rouge, Bayou Des Allemands at Des Allemands, Bayou

Lafourche below weir at Thibodaux, Vermilion River at

Perry, Bayou Que de Tortue at Riceville, and Bayou

Lacassine near Lake Arthur (sites 5, 7, 8, 12, 16, and 17)

met or exceeded the ISQG (35 μg/g) (table 2). The lead

concentration for Bayou Lafourche below weir at Thibodaux (site 8) exceeded the PEL (91.3 μg/g). 

Mercury concentrations (fig. 3) were detected at

all sites (table 4) and ranged from less than 0.1 μg/g at

Bogue Falaya at Lee Road at Covington, Whisky Chitto

Creek near Oberlin, and Calcasieu River near Kinder

(sites 2, 18, and 19), to 0.16 μg/g at Bayou Lafourche

below weir at Thibodaux (site 8). Concentrations for

Dawson Creek at Bluebonnet Boulevard at Baton

Rouge, Bayou Lafourche below weir at Thibodaux,

Mermentau River at Mermentau, and Bayou Segnette

4.6 miles south of Westwego (sites 5, 8, 15, and 21)

exceeded the background concentration (0.10 μg/g). No

concentrations met or exceeded the ISQG (0.17 μg/g) or

PEL (0.486 μg/g) for mercury. 

Zinc concentrations (fig. 3) were detected at all

sites and ranged from 2 μg/g at Bogue Falaya at Lee

Road at Covington (site 2) to 220 μg/g at Bayou

Lafourche below weir at Thibodaux (site 8) (table 4).

Concentrations for 12 sites exceeded the background

concentration (65 μg/g), and concentrations for Bayou

Lafourche below weir at Thibodaux, Bayou Grosse Tete

at Rosedale, Bayou Boeuf at Railroad Bridge at Amelia,

and Bayou Teche at Keystone Lock and Dam near

St. Martinville (sites 8, 9, 10, and 11) exceeded the

ISQG (123 μg/g) (table 2). No zinc concentrations met

or exceeded the PEL (315 μg/g).

ISQG and PEL exceedances in bulk samples may

be linked to land use and grain size. The ISQG for

arsenic was met or exceeded at 12 sites, cadmium at

2 sites, chromium at 13 sites, copper at 1 site, lead at

5 sites, and zinc at 4 sites. Concentrations of seven

selected trace elements occurred below background concentrations at the Tchefuncte River near Covington,

Bogue Falaya at Lee Road at Covington, Tickfaw River

at Liverpool, Amite River at Port Vincent, and Calcasieu River near Kinder (sites 1, 2, 4, 6, and 19). The forested drainage areas for these sites contain sandy and

thick loess soils in forested areas (fig. 3), and, except for

Amite River at Port Vincent, bed sediment had less than

30 percent fine-grained material (table 5). Concentrations of arsenic, cadmium, chromium, copper, lead, and

zinc exceeded the ISQG or PEL at Bayou Lafourche

below weir at Thibodaux. Concentrations of arsenic,

cadmium, chromium, and zinc exceeded the ISQG or

PEL at Bayou Grosse Tete at Rosedale (site 9).

Relation of Physio-Chemical Factors to 

Sediment-Quality Criteria 

Concentrations of selected trace elements in finegrained and bulk samples were compared with concentrations of total carbon, total organic carbon, and SQC,

and tested for significant differences. Concentrations

also were compared with each other and land use. Percentages of fine-grained material, iron, and total organic

carbon, and manganese concentrations in fine-grained

samples were compared to those in bulk samples.

Horowitz (1991) discussed iron and manganese oxide

coating and their importance as trace-element concentrators and described the dual role of organic matter in

sediment trace-element chemistry. Organic coatings on

fine-grained material may concentrate trace elements at

the molecular level; for example, organic compounds

may coat a silt particle and attract trace elements.

Organic matter functions as a trace-element diluent at

the particulate level; for example, partially-decomposed

vegetation may trap trace elements.

Total Organic Carbon

 Sites with percentages of fine-grained material

less than 70 percent had higher total organic carbon

(TOC) percentages in fine-grained samples than bulk

samples (table 5). With the exception of wetlands, TOC
15

percentages generally increased with respect to land use

intensity. Percent TOC minima and maxima in each landuse category for bulk samples, and maxima for fine samples, increased in the following order of land use: forest,

agriculture, urban, and wetland. High TOC percentages

in wetlands (table 5) probably result from deposition of

detritus common to wetlands and from sediment in

receiving waters. 

Sediment-Quality Criteria

More ISQG exceedances occurred in fine-grained

samples than bulk samples. Of 133 paired samples for

which ISQG criteria are available, 69 percent of the concentrations were greater in fine-grained samples; 23 percent of the concentrations were greater in bulk samples;

and 8 percent of the concentrations were similar. Concentrations exceeding ISQG’s were most common for

arsenic and chromium. The ISQG for arsenic, cadmium,

chromium, copper, lead, and zinc was exceeded in both

fine-grained and bulk samples at least once. Although

trace-element concentrations were usually higher in finegrained samples than in bulk samples, lead concentrations in the bulk samples for Bayou Lafourche below

weir at Thibodaux (site 8) and Bayou Des Allemands at

Des Allemands (site 7) were almost twice the concentration in the fine-grained sample. Arsenic, chromium, lead,

mercury, and zinc concentrations were detected in all

bulk and fine-grained samples; copper was detected in all

fine-grained samples. 

Trace-element concentrations and exceedances of

ISQG’s may be linked to land use, grain size, and trace

elements concentrators such as iron and manganese (as

grain coating of hydrous iron and manganese oxides) and

organic matter (table 5). Fewer ISQG exceedances

occurred in forested areas than in other land-use types.

Forested sites have relatively low iron (less than three

percent) and fine-grained percentages (less than 70 percent) (table 5). Low manganese concentrations and low

percentages of iron, total organic carbon, and finegrained material may limit the concentration of other

trace elements (Horowitz, 1991). Bogue Falaya at Lee

Road at Covington, Tangipahoa River at Robert, and Calcasieu River near Kinder (sites 2, 3, and 19) had no ISQG

exceedances in fine-grained or bulk samples and had less

than 3.5 percent fine-grained material. Sites with three or

more ISQG exceedances in fine-grained or bulk samples

have more than 78 percent fine-grained material, drain

wetlands, agricultural and urban areas, and may result

from the cumulative effects of relatively high percentages

of fine-grained material, grain coatings such as hydrous

iron and manganese oxide, and organic material (Horowitz and others, 1989). Manganese coatings probably are

not a substantial concentrator of trace elements in forested areas of the ACAD Study Unit. The highest and

lowest manganese concentrations, for both fine-grained

and bulk bed-sediment samples in all land-use categories,

occurred in forested areas. Detected manganese concentrations ranged between 190 and 1,200 μg/g (micrograms per gram) in fine-grained samples and between

120 and 19 μg/g in bulk samples. 

More PEL exceedances occurred for fine-grained

samples than for bulk samples, but the concentrations in

fine-grained samples did not always exceed that of bulk

samples. PEL’s were met or exceeded in fine-grained

samples at Bayou Grosse Tete at Rosedale (site 9) for

arsenic and chromium, and at Bayou Lacassine near Lake

Arthur (site 17) for chromium. Although the lead concentration in the bulk sample at Bayou Lafourche below

weir at Thibodaux (site 8) exceeded the PEL, the concentration in the fine-grained sample was less than the PEL

but exceeded the ISQG. Bayou Lafourche below weir at

Thibodaux and Bayou Grosse Tete at Rosedale (site 9)

drain areas with rural residences immediately adjacent to

the receiving water body; Bayou Lafourche below weir at

Thibodaux also receives water and suspended sediment

from the Mississippi River (fig. 2).

Differences Between Fine-grained and Bulk 

Samples

Results from statistical procedures indicate concentrations of some trace elements are significantly different in fine-grained and bulk samples (table 6). Parametric

and nonparametric statistical procedures were used to

compare concentrations of 21 trace elements, total organic

carbon, and total carbon in fine-grained and bulk bed-sediment samples. The Shapiro-Wilk procedure (with alpha

at 0.05) was used to test sample data for normality. If the

normality assumption was accepted, a parametric twotailed paired t-test (with alpha at 0.05) was used to compare sample groups for significance of difference. If the

normality assumption was rejected, the Wilcoxon rank

sum procedure (with alpha at 0.05) was used to compare

sample groups for significance of difference. Concentrations of 21 trace elements, total organic carbon, and total

carbon for 19 sites and mercury for 21 sites were compared

for fine-grained and bulk samples. Results from the statistical procedures indicate no significant differences

between sample groups for antimony, arsenic, cadmium,

cobalt, lead, manganese, mercury, strontium, vanadium,

total organic carbon, and total carbon. Statistical results

indicate significant differences between sample groups for

aluminum, barium, beryllium, chromium, copper, iron,

lithium, nickel, phosphorus, selenium, titanium, and zinc. 
16

Table 6. P-values for statistical procedures used to compare concentrations of selected trace-elements and 

total organic carbon in fine-grained and bulk bed-sediment samples

[Shapiro-Wilk values in bold indicate the Wilcoxon rank sum procedure was used to determine significance of difference. Paired t-test and 

Wilcoxon rank sum values in bold indicate significance of difference. alpha=0.05; Y, yes; N, no]

Constituent Accepted

normal

P-value (0.05) Fine and bulk 

samples 

significantly 

different 

Shapiro-Wilk Paired t-test Wilcoxon rank 

sum

Aluminum Y 0.0529 0.0004 0.0020 Y

Antimony N .0001 .3255 .3303 N

Arsenic Y .5688 .5531 .6168 N

Barium N .0001 .1174 .0001 Y

Beryllium Y .5885 .0006 .0044 Y

Cadmium Y .1654 .0805 .1150 N

Chromium Y .7527 .0001 .0001 Y

Cobalt N .0014 .0984 .1265 N

Copper Y .1463 .0001 .0001 Y

Iron Y .3838 .0001 .0001 Y

Lead N .0002 .6162 .6577 N

Lithium Y .2628 .0001 .0001 Y

Manganese N .0013 .1459 .5154 N

Mercury N .0001 .5154 .8420 N

Nickel Y .2044 .0040 .0040 Y

Phosphorus Y .2812 .0001 .0001 Y

Selenium Y .3308 .0001 .0010 Y

Strontium Y .3031 .3752 .3978 N

Titanium Y .1706 .0095 .0086 Y

Vanadium Y .7126 .5331 .5572 N

Zinc N .0376 .0172 .0115 Y

Total organic carbon N .0001 .5939 .5301 N

Total carbon N .0001 .8403 .8495 N
17

Results from the statistical procedures indicate

that the purpose for which bed-sediment data are to be

used may influence the type of sample, fine or bulk, to be

collected for trace-element analysis in future studies.

Trace-element concentrations determined from finegrained or bulk samples may be acceptable, if no significant differences exist between sample types. For example, aluminum concentrations were determined to be

significantly different, and concentrations may be different depending upon the sample type collected, but sample

type may not be relevant for antimony concentrations. 

 Historic Comparisons

Temporal and spatial trends in bed-sediment

trace-element concentrations were difficult to discern,

because data are limited and errors are associated with

sampling and analytical accuracy. Only six sites with

historic data and concentrations for 11 trace elements are

common to this study and available for comparison

(table 7). McGee and Demcheck (1995) studied trace

element concentrations and estimated background concentrations, using stepwise regression, in bed sediment

for Tickfaw River at Liverpool, Bayou Lafourche below

weir at Thibodaux, and Vermilion River at Perry (sites 4,

8, and 12). Demcheck (1994) studied trace-element concentrations in bed sediment for Bayou des Cannes near

Eunice, Mermentau River at Mermentau, and Bayou

Lacassine near Lake Arthur (sites 13, 15, and 17). Concentrations for both studies were determined at SPRL

with similar methods. Concentrations of antimony,

arsenic, cadmium, chromium, cobalt, copper, lead, mercury, nickel, selenium, and zinc were compared for these

sites (table 7). Analytical accuracy for trace elements in

bulk samples is plus or minus 10 percent, and sampling

error may be greater than analytical accuracy (Horowitz,

1991; A.J. Horowitz, U.S. Geological Survey, oral commun., 2001). Because trace-element concentrations may

vary within a sample, concentrations were considered

different if the concentration for this study differed by

more than 20 percent with the concentration for the previous study (A.J. Horowitz, U.S. Geological Survey, oral

commun., 2001). 

No trace element had a significant increase or

decrease throughout the study unit, although increases or

decreases greater than 20 percent were observed for specific sites. Antimony concentrations more than quadrupled at Bayou Lafourche below weir at Thibodaux (site 8).

Arsenic concentrations increased by more than 20 percent

at Tickfaw River at Liverpool, Mermentau River at Mermentau, and Bayou Lacassine near Lake Arthur (sites 4,

15, and 17). Chromium concentrations increased by more

than 20 percent at Tickfaw River at Liverpool. Lead concentrations increased at Tickfaw River at Liverpool and

Vermilion River at Perry (site 12), and more than doubled

at Bayou Lafourche below weir at Thibodaux. Zinc concentrations more than tripled at Tickfaw River at Liverpool and increased at Bayou Lafourche below weir at

Thibodaux. Chromium concentrations decreased by more

than 20 percent at Bayou des Cannes near Eunice. Mercury concentrations decreased at Mermentau River at

Mermentau, and zinc concentrations decreased at Bayou

des Cannes near Eunice (site 13).

Trends in trace-element concentrations probably

are caused by changes in land and water use. Changes in

antimony, arsenic, and lead concentrations may result

from ammunition used in waterfowl hunting activities

(Weast, 1983). Increases in arsenic at Mermentau River

at Mermentau (site 15) and Bayou Lacassine near Lake

Arthur (site 17) may be from industrial and petrochemical support activities. The drainage area for Bayou

Lafourche near Thibodaux (site 8) is 4.2 square miles

(table 1). Flow for this site is maintained by diverting

200 to 300 cubic feet per second from the Mississippi

River (Goree and others, 2000, p. 296). Thus, Bayou

Lafourche receives water from both a small basin as well

as 1.25 million square miles of the Mississippi River

Basin. Differences in trace-element concentrations may

be attributed to dilution or concentration effects caused

by the source water diversion or activities in the basin

associated with land use. 

Organic Compounds

Bed-sediment samples collected from 21 sites

were analyzed for 111 organic compounds. Concentrations of 6 organochlorines and 12 polycyclic aromatic

hydrocarbons (PAH’s) (table 8) were compared with

SQC (ISQG’s and PEL’s) (table 3). Endrin, heptachlor

epoxide, lindane, and toxaphene were not detected in any

of the samples. Tangipahoa River near Robert, Tickfaw

River at Liverpool, and Whisky Chitto Creek near Oberlin (sites 3, 4, and 18) drain forested areas and had no

detectable concentrations of organic compounds for

which SQC are available. No ISQG exceedances

occurred at Tchefuncte River at Covington, Bogue

Falaya at Lee Road at Covington, Amite River at Port

Vincent, Bayou Nezpique near Basile, and Calcasieu

River near Kinder (sites 1, 2, 6, 14, and 19), which drain

forested areas, and Bayou Que De Tortue at Riceville and

Bayou Lacassine near Lake Arthur (sites 16 and 17),

which drain agricultural areas.

Of the 130 detected concentrations, 72 exceeded

ISQG’s at 11 sites, and 12 concentrations exceeded

PEL’s at 5 sites. All PEL exceedances occurred at sites

with seven or more ISQG exceedances: Dawson Creek

at Bluebonnet Boulevard at Baton Rouge, Bayou

Lafourche below weir at Thibodaux, Bayou Boeuf at

Railroad Bridge at Amelia, Bayou Teche at Keystone

Lock and Dam near St. Martinville, and Vermilion

River at Perry (sites 5, 8, 10, 11, and 12). The most 
18

Site number(see fig. 1)

Site name

Antimony Arsenic Cadmium Chromium Cobalt

Historic 1998 Historic 1998 Historic 1998 Historic 1998 Historic 1998 

4 Tickfaw River at Liverpool1 0.1 0.3 0.7 1.7 na 0.1 3 16 3 5

8 Bayou Lafourche below weir 

at Thibodaux1

.8 4.0 16 16 na .7 70 63 13 11

12 Vermilion River at Perry1 .5 .9 7.2 7.6 na <.1 49 55 9 1013 Bayou des Cannes near 

Eunice2

.8 .8 9.5 8.6 <0.5 <.1 50 38 12 11

15 Mermentau River at 

Mermentau2

.9 1.0 5 8.2 <.5 .3 77 71 13 13

17 Bayou Lacassine near Lake 

Arthur2

1.1 1.1 5.3 7.9 <.5 .3 93 86 14 17

Site number(see fig. 1)

Site name 

Copper Lead Mercury Nickel Selenium Zinc

Historic 1998 Historic 1998 Historic 1998 Historic 1998 Historic 1998 Historic 1998 

4 Tickfaw River at Liverpool1 3 3 5 10 0.02 0.02 3 7 0.2 0.2 6 19

8 Bayou Lafourche below weir 

at Thibodaux1

31 37 50 130 .09 .10 35 28 .9 .6 153 220

12 Vermilion River at Perry1 23 21 25 42 .06 .04 23 23 .4 .3 117 110

13 Bayou des Cannes near 

Eunice2

15 10 31 27 .03 .03 15 16 .3 .1 52 42

15 Mermentau River at 

Mermentau2

23 22 34 34 .17 .11 24 28 .6 .5 105 110

17 Bayou Lacassine near Lake 

Arthur2

22 22 46 47 .10 .09 27 31 .7 .6 105 100

1Historic data from McGee and Demcheck (1995). 2Historic data from Demcheck (1994).

Table 7. Comparison of historic and 1998 data for selected trace-element concentrations in bed sediment from selected sites in the Acadian-Pontchartrain Study 

Unit, southern Louisiana

[Concentrations are in micrograms per gram. Value in bold differs by more than 20 percent of the 1998 concentration. na, not analyzed; <, less than]
19

ISQG exceedances occurred at sites on streams draining

urban areas, Dawson Creek at Bluebonnet Boulevard at

Baton Rouge and Bayou Lafourche below weir at Thibodaux. The most PEL exceedances occurred at a site

draining an urban area, Bayou Lafourche below weir at

Thibodaux, and a site draining wetlands where support

for petrochemical and marine activities occur, Bayou

Boeuf at Railroad Bridge at Amelia.

Organochlorines

Organochlorine compounds, especially DDT and

polychlorinated biphenyls (PCB’s), have gained public

awareness because they are persistent, hydrophobic, and

concentrate in biota. In this report, the terms DDT,

DDD, and DDE refer to the sum of o′p′ and p′p′ isomers; the term total DDT refers to DDT and all metabolites; and the term total chlordane refers to the sum of all

chlordane metabolites (CIS- and trans-chlordane, and

CIS- and trans-nonachlor). Nowell and others (1999)

found detectable concentrations of organochlorine compounds in bed sediment may not be indicative of recent

application, but may be the result of recent erosion or

disturbance of contaminated soils associated with agricultural practices and urban activities. According to

Nowell and others (1999), ratios of DDT to total DDT

greater than 10 percent indicate DDT-contaminated soils

have recently entered the hydrologic system. 

Organochlorine compounds were detected at

10 sites and compared with ISQG’s and PEL’s. Detections occurred most frequently at Bayou Lafourche

below weir at Thibodaux (site 8). Dieldrin concentrations were detected at Dawson Creek at Bluebonnet

Boulevard at Baton Rouge (site 5) and Bayou Lafourche

below weir at Thibodaux, but did not exceed the ISQG.

Concentrations of DDD were detected at five sites and

exceeded the ISQG only at Bayou Lafourche below

weir at Thibodaux. Concentrations of DDE were

detected at 9 sites and exceeded the ISQG at 7 sites.

The PEL for DDE was exceeded at Bayou Teche at Keystone Lock and Dam near St. Martinville (site 6) and

Vermilion River at Perry (site 12). DDT only was

detected at Bayou Lafourche below weir at Thibodaux

and the concentration exceeded the ISQG. The ratio of

DDT to total DDT was 25 percent and indicates possible

disturbance or recent erosion of DDT-contaminated soil.

Total chlordane concentrations were detected at four

sites; concentrations at Dawson Creek at Bluebonnet

Boulevard at Baton Rouge and Bayou Lafourche below

weir at Thibodaux exceeded the PEL. PCB’s were

detected at Bayou Lafourche below weir at Thibodaux

and exceeded the ISQG. 

Polycyclic Aromatic Hydrocarbons

Concentrations of 12 PAH’s were detected at 18

sites and compared with ISQG’s and PEL’s. Exceedances occurred most frequently at Bayou Lafourche

below weir at Thibodaux (site 8). Anthracene concentrations were detected at more than one-half the sites,

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

pyrene concentrations exceeded the ISQG’s in samples

collected from at least one-third of the sites. More than

eight ISQG’s were exceeded at sites on Dawson Creek

at Bluebonnet Boulevard at Baton Rouge, Bayou

Lafourche below weir at Thibodaux, Bayou Boeuf at

Railroad Bridge at Amelia, Bayou Teche at Keystone

Lock and Dam near St. Martinville, and Vermilion River

at Perry (sites 5, 8, 10, 11, and 12). Benz(a)anthracene,

acenaphthene, anthracene, phenanthrene, and pyrene

account for all PEL exceedances in PAH’s. The PEL’s

for benz(a)anthracene and phenanthrene were exceeded

at Bayou Lafourche below weir at Thibodaux (site 8)

and Bayou Boeuf at Railroad Bridge at Amelia (site 10),

for acenaphthene and anthracene at Bayou Boeuf at

Railroad Bridge at Amelia, and for pyrene at Bayou

Lafourche below weir at Thibodaux.

Anthropogenic organic compounds in the environment are the direct result of human activity and

dominant land use. Organic compounds were not

detected at three forested sites--Tangipahoa River at

Robert (site 3), Tickfaw River at Liverpool (site 4), and

Whisky Chitto Creek near Oberlin (site 18). The highest concentrations of organic compounds occurred at

sites on streams that drain areas of land use characterized by intense human activity. Bayou Lafourche

below weir at Thibodaux (site 8) drains mostly urban

land, and Bayou Boeuf at Railroad Bridge at Amelia

(site 10) is in a tidally-affected area that supports petrochemical and marine transport activities. Bayou Teche

at Keystone Lock and Dam near St. Martinville (site

11) and Vermilion River at Perry (site 12) drain mostly

agricultural land. Dawson Creek at Bluebonnet Boulevard at Baton Rouge (site 5) drains urban land, had 10

ISQG exceedances of organic compounds, and is

entirely within the drainage area of the Amite River at

Port Vincent (site 6), which drains mostly forested land

and had no ISQG exceedances. Organic compounds

detected at Dawson Creek at Bluebonnet Boulevard at

Baton Rouge may be assimilated by fish or algae,

metabolized by bacteria, diluted, or chemically bound

to trapped sediment or sediment that have not yet been

transported and, therefore, not yet detected at Amite

River at Port Vincent. 
20

Site

 number 

(see fig. 1)

Site name 

Number of times 

equaled or 

exceeded

Concentration, in micrograms per gram

ISQG PEL Total chlordane DDD DDE DDT Dieldrin Total PCB’s Pyrene Benzo(a) pyrene

1 Tchefuncte River near Covington 0 0 2.6 <1 <1 <1 <1 <50 E20 E30

2 Bogue Falaya at Lee Road at Covington 0 0 <1 <1 <1 <1 <1 <50 <50 <503 Tangipahoa River at Robert 0 0 <1 <1 <1 <1 <1 <50 <50 <504 Tickfaw River at Liverpool 0 0 <1 <1 <1 <1 <1 <50 <50 <505 Dawson Creek at Bluebonnet Boulevard at 

Baton Rouge 12 1 28.2 3 2.6 <1 1.3 <50 240 110

6 Amite River at Port Vincent 0 0 <1 <1 <1 <1 <1 <50 E20 E10

7 Bayou Des Allemands at Des Allemands 5 0 <1 <1 0.4 <1 <1 <50 110 E50

8 Bayou Lafourche below weir at Thibodaux 17 5 27.5 6.5 4.3 3.6 1.8 70 1,200 640

9 Bayou Grosse Tete at Rosedale 1 0 <1 1.3 3.4 <1 <1 <50 E10 <50

10 Bayou Boeuf at Railroad Bridge at Amelia 11 4 <1 <1 <1 <1 <1 <50 780 320

11 Bayou Teche at Keystone Lock and Dam near 

St. Martinville 9 1 <1 <1 20 <1 <1 <50 570 60

12 Vermilion River at Perry 9 1 1.3 2.9 17 <1 <1 <50 240 50

13 Bayou des Cannes near Eunice 1 0 <1 1.8 4.6 <1 <1 <50 50 E20

14 Bayou Nezpique near Basile 0 0 <1 <1 <1 <1 <1 <50 E10 <50

15 Mermentau River at Mermentau 2 0 <1 <1 2 <1 <2 <100 60 <50

16 Bayou Que De Tortue at Riceville 0 0 <1 <1 <1 <1 <1 <50 E10 <50

17 Bayou Lacassine near Lake Arthur 0 0 <1 <1 1.2 <1 <1 <50 E40 <5018 Whisky Chitto Creek near Oberlin 0 0 <1 <1 <1 <1 <1 <50 <50 <50

19 Calcasieu River near Kinder 0 0 <1 <1 <1 <1 <1 <50 M <50

20 Turtle Bayou north of Bayou Penchant near Amelia 3 0 <1 <1 <1 <1 <6 <300 90 E50

21 Bayou Segnette 4.6 miles south of Westwego 3 0 <1 <1 <1 <1 <2 <100 140 <50

Table 8. Selected organic compounds and number of Interim Sediment Quality Guidelines (ISQG) and Probable Effects Levels (PEL) exceedances for 

bed-sediment samples collected at selected sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998 

[Concentrations in color are noted as follows: purple, is less than the method reporting limit; green, meets or exceeds PEL; and red, meets or exceeds the ISQG. E, estimated; M, presence of material verified

but not quantified; <, less than; na, not analyzed]
21

Site

 number 

(see fig. 1)

Concentration, in micrograms per gram

Fluorene Naph- thalene Phenanthrene Acenaphthylene Acenaphthene Anthracene Benz(a) anthracene Chrysene Dibenz(a,h) anthracene Fluoran- thene

1 <50 <50 <50 <50 <50 <50 E20 E10 <50 na

2 <50 <50 <50 <50 <50 <50 <50 <50 <50 E20

3 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50

4 <50 <50 <50 <50 <50 <50 <50 <50 <50 <505 <50 <50 130 E20 E20 60 120 150 E30 280

6 <50 <50 M <50 <50 M E10 E10 <50 na

7 <50 E10 E40 <50 <50 M E50 E60 <50 130

8 90 90 880 70 90 200 540 640 100 1,200

9 <50 <50 <50 <50 <50 <50 <50 <50 <50 E40

10 140 <100 770 50 120 320 470 480 60 960

11 60 E20 170 <50 E20 E40 150 170 <50 820

12 E50 E10 260 <50 50 E20 70 80 <50 280

13 <50 <50 E20 <50 <50 E10 E20 E20 <50 7014 <50 <50 E1.5 <50 <50 <50 <50 <50 <50 E30

15 <50 <50 M <50 <50 E10 E30 E30 <50 9016 <50 <50 <50 <50 <50 <50 <50 <50 <50 E20

17 <50 <50 <50 <50 <50 E20 E20 E20 <50 E30

18 <50 <50 <50 <50 <50 <50 <50 <50 <50 <5019 <50 <50 <50 <50 <50 <50 <50 <50 <50 <5020 <50 <50 <50 <50 <50 <50 <50 <50 <50 17021 E10 <50 <50 <50 <50 <E40 E30 E60 <100 150

Table 8. Selected organic compounds and number of Interim Sediment Quality Guidelines (ISQG) and Probable Effects Levels (PEL) 

exceedances for bed-sediment samples collected at selected sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998—Continued
22

SUMMARY AND CONCLUSIONS

Concentrations of selected trace elements and

organic compounds were determined for bed-sediment

samples collected during 1998 at 21 sites in the Acadian-Pontchartrain Study Unit in southern Louisiana.

Concentrations of selected trace elements and organic

compounds were compared with background concentrations, Interim Sediment Quality Guidelines (ISQG’s),

Probable Effects Levels (PEL’s), land use, and grain

size. Parametric and nonparametric statistical procedures were used to compare trace-element concentrations in fine-grained and bulk samples. Fine-grained

and bulk samples were compared to sediment-quality

criteria (SQC) because (1) the National Water-Quality

Assessment Program protocols require a fine-grained

sample for trace elements analysis; (2) concentrations

determined from size-fractions that represent less than

50-70 percent of the sample may not reflect the true

chemical concentrations; (3) SQC were developed for

bulk sediment, and (4) concentrations of trace elements

in bulk sediment represent levels of exposure for organisms that dwell in or near the benthos. Concentrations

of selected trace elements and organic compounds were

compared with land use, and concentrations of selected

trace elements were compared with historic values for

selected sites. 

Grain size, geochemical characteristics, and land

use influence bed-sediment quality. More ISQG

exceedances for trace elements occurred in fine-grained

samples than in bulk samples, and fewer ISQG exceedances occurred at sites with low percentages of iron and

organic carbon and at sites on streams draining forested

areas. The most ISQG exceedances for trace elements

occurred at Bayou Lafourche below weir at Thibodaux.

Exceedance of ISQG’s occurred most frequently for

arsenic and chromium. No ISQG exceedances were

reported for organic compounds at eight sites on streams

draining forested areas and two sites on streams draining agricultural areas. Total PEL exceedances for trace

elements and organic compounds occurred most at one

agricultural site, Bayou Grosse Tete at Rosedale, and

one urban site, Bayou Lafourche below weir at Thibodaux, and may result from several mechanisms,

including land use and relatively high percentages of

fine-grained material, iron, and organic material.

Shapiro-Wilk, paired t-test, and Wilcoxon rank

sum statistical procedures, with an alpha of 0.05, were

used to compare concentrations of 21 trace elements,

total organic carbon, and total carbon in fine-grained

and bulk sediment samples for 19 sites. Although

results from statistical comparisons of fine-grained and

bulk samples indicate significant differences for 12

trace elements, concentrations were generally greater in

fine-grained samples. Results from statistical procedures indicate significant differences between finegrained and bulk samples for aluminum, barium, beryllium, chromium, copper, iron, lithium, nickel, phosphorus, selenium, titanium, and zinc concentrations. Of

133 paired concentrations, 69 percent were greater in

fine-grained samples, and 23 percent were greater in

bulk samples. Comparisons with data from previous

studies for six sites indicate increases by more than 20

percent in concentrations of antimony, arsenic, chromium, lead, and zinc for at least one site.

 Trends in bed-sediment are probably caused by

changes in land and water use. Comparisons with data

from previous studies indicate no trace element had a

significant increase or decrease throughout the study

unit, although increases or decreases greater than

20 percent were observed for specific sites. Comparisons with data from previous studies indicate increases

by more than 20 percent in concentrations of antimony

at Bayou Lafourche below weir at Thibodaux, arsenic

and chromium at Tickfaw River at Liverpool, lead at

Bayou Lafourche below weir at Thibodaux, and zinc at

Bayou Lafourche below weir at Thibodaux and Vermilion River at Perry. Historic comparisons also indicate

decreases by more than 20 percent in concentrations of

chromium at Bayou des Cannes near Eunice and mercury at Mermentau River at Mermentau.

Of the 130 detected concentrations of organic

compounds, 72 exceeded ISQG’s at 11 sites, and 12

concentrations exceeded PEL’s at 5 sites. All PEL

exceedances occurred at sites with seven or more ISQG

exceedances: Dawson Creek at Bluebonnet Boulevard

at Baton Rouge, Bayou Lafourche below weir at Thibodaux, Bayou Boeuf at Railroad Bridge at Amelia,

Bayou Teche at Keystone Lock and Dam near St. Martinville, and Vermilion River at Perry. The most ISQG

exceedances occurred at sites draining urban areas,

Bayou Lafourche below weir at Thibodaux and Dawson

Creek at Bluebonnet Boulevard at Baton Rouge. The

most PEL exceedances occurred at a site draining an

urban area, Bayou Lafourche below weir at Thibodaux,

and a site draining wetlands where support for petrochemical and marine activities occur, Bayou Boeuf at

Railroad Bridge at Amelia.
23

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Horowitz, A.J., Elrick, K.A., and Hooper, R.P., 1989,

The prediction of aquatic sediment-associated

trace element concentrations using selected

geochemical factors—hydrological processes:

New York, John Wiley and Sons, v. 3,

p. 347-364.

Louisiana Department of Environmental Quality, 2001,

accessed February 4, 2002, at URL

http://www.deq.state.la.us/surveillance/mercury/

fishadvi.htm

Meador, M.R., and Gurtz, M.E., 1994, Biology as an

integrated component of the U.S. Geological

Survey’s National Water-Quality Assessment

Program: U.S. Geological Survey Open-File

Report 94-83, 4 p.

McGee, B.D., and Demcheck, D.K., 1995, Occurrence

and estimation of trace elements in bottom

material for selected streams in coastal Louisiana,

1991-92: Louisiana Department of Transportation

and Development Water Resources Technical

Report no. 57, 49 p.
24

Nowell, L.H., Capel, P.D., and Dileanis, P.D., 1999,

Pesticides in stream sediment and aquatic biota—

distribution, trends, and governing factors: Ann

Arbor Press, Inc., 1,001 p.

Olson, M.L., and DeWild, J.F., 1999, Low-level

collection techniques and species-specific

analytical methods for mercury in water,

sediment, and biota: U.S. Geological Survey

Water-Resources Investigations Report 99-4018b,

11 p.

Persaud, D., Jaagumagi, R., and Hayton, A., 1993,

Guidelines for the protection and management of

aquatic sediment quality in Ontario: Ontario,

Canada, Ontario Ministry of Environment and

Energy, Water Resources Branch, 24 p.

SAS Institute Inc., 1990, SAS procedures guide,

version 6, third edition: Cary, N.C., SAS

Institute Inc., 705 p.

Shelton, L.R., and Capel, P.D., 1994, Guidelines for

collecting and processing samples of stream bed

sediment for analysis of trace elements and organic

contaminants for the National Water-Quality

Assessment Program: U.S. Geological Survey

Open-File Report 94-458, 20 p.

Skougstad, M.W., Fishman, M.J., Friedman, L.C.,

Erdmann, D.E., and Duncan, S.S., 1979, Methods

for determination of inorganic substances in water

and fluvial sediments: U.S. Geological Survey

Techniques of Water-Resources Investigations,

book 5, chap. A1, 626 p.

U.S. Geological Survey, 1999, Index of

/pub/data/landcover/states, accessed July 7, 2001,

at URL http://edcwww.cr.usgs.gov/pub/data/

landcover/states/

Weast, R.C., ed., 1983, CRC handbook of chemistry and

physics (63 ed.): Boca Raton, Fla., CRC Press

Inc., 2,381 p.
25

APPENDIXES

Appendix A. Selected trace-element concentrations in bulk bed-sediment samples for selected 

sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed 

sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998
2

6

Appendix A. Selected trace-element concentrations in bulk bed-sediment samples for selected sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998 [Analyses were performed by the USGS Sediment Partitioning Laboratory in Atlanta. Concentrations are in micrograms per gram, except as noted.USGS, U.S. Geological Survey; percent, percent dry weight; <, less than] 

Site

number 

(see 

fig. 1)

Site name USGS station number Aluminum (percent) Antimony Arsenic Barium Beryllium Cadmium Chromium Cobalt Copper Iron (percent)) Lead

1 Tchefuncte River near Covington 07375050 0.9 0.3 0.9 130 0.2 0.2 11 2 3 0.4 102 Bogue Falaya at Lee Road at 

Covington 

07375170 .1 .1 .3 18 <.1 .1 2 <1 <1 .1 1

4 Tickfaw River at Liverpool 07375800 1.5 .3 1.7 200 .5 .1 16 5 3 .6 105 Dawson Creek at Bluebonnet 

Boulevard at Baton Rouge 

07379960 4.0 .9 3.9 520 .9 .2 40 7 20 1.7 66

6 Amite River at Port Vincent 07380120 3.1 .6 3.1 350 .8 <.1 30 6 6 1.3 157 Bayou Des Allemands at Des 

Allemands 

07380300 6.6 .7 12 680 1.7 .2 59 14 24 3.8 66

8 Bayou Lafourche below weir at 

Thibodaux 

07381002 5.4 4 16 1,700 1.4 .7 63 11 37 2.9 130

9 Bayou Grosse Tete at Rosedale 07381440 8.7 .9 14 740 2.2 .7 80 12 32 4.3 26

10 Bayou Boeuf at Railroad Bridge 

at Amelia 

073814675 6.2 1.1 10 720 1.6 .1 58 12 24 3.2 32

11 Bayou Teche at Keystone Lock 

and Dam near St. Martinville 

07385700 7.7 1.1 8.3 660 2 .5 68 13 32 3.4 28

12 Vermilion River at Perry 07386980 5.7 .9 7.6 830 1.4 <.1 55 10 21 2.6 4213 Bayou des Cannes near Eunice 08010000 3.7 .8 8.6 430 1.1 <.1 38 11 10 2.2 2714 Bayou Nezpique near Basile 08012000 2.9 .5 4.4 360 .8 .2 27 6 5 1.3 2015 Mermentau River at Mermentau 08012150 8.5 1 8.2 770 1.9 .3 71 13 22 3.5 3416 Bayou Que De Tortue at Riceville 08012300 8.1 1.1 8.2 860 1.8 .4 74 11 21 3.3 3517 Bayou Lacassine near Lake 

Arthur 

08012470 1.3 1.1 7.9 710 2.3 .3 86 17 22 3.6 47

19 Calcasieu River near Kinder 08015500 .4 .2 .5 170 .1 .1 4 2 1 .1 720 Turtle Bayou north of Bayou 

Penchant near Amelia

293524091041300 5.8 .8 6.7 140 1.5 .4 60 10 26 3.1 31

21 Bayou Segnette 4.6 miles south 

of Westwego 

294957090095300 5.4 1.1 13 330 1.4 <.1 48 11 23 3.0 30
27

Appendix A. Selected trace-element concentrations in bulk bed-sediment samples for selected sites in the Acadian-Pontchartrain Study Unit, southern Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Lithium Manganese Mercury Molyb- denum Nickel Phos- phorus Selenium Silver Strontium (percent) Sulfur (percent) Thallium Titanium (percent) Uranium Vana- dium Zinc Total organic carbon 

(percent)

Total 

carbon 

(percent)

1 6 120 0.05 <5 3 200 0.1 1.0 16 <0.1 <50 0.16 <50 15 17 0.7 0.62 2 19 .01 <5 1 19 <.1 <.5 3 <.1 <50 .04 <50 3 2 .1 <.14 8 620 .02 <5 7 150 .2 <.5 23 <.1 <50 .24 <50 24 19 1.3 1.25 18 330 .17 <5 18 620 .2 1.0 100 <.1 <50 .34 <50 57 110 1.6 1.46 14 570 <.01 <5 12 320 .1 <.5 56 <.1 <50 .35 <50 47 40 .7 .67 36 1,100 .06 <5 34 2,200 .7 <.5 140 .3 <50 .32 <50 120 110 5.9 6.18 29 610 .1 <5 28 1,300 .6 <.5 200 .1 <50 .30 <50 90 220 2.7 3.99 48 660 .07 <5 38 1,800 .6 <.5 120 .1 <50 .4 <50 160 160 2.7 2.3

10 32 860 .06 <5 31 1,100 .3 <.5 220 .2 <50 .34 <50 100 170 1.7 1.9

11 50 610 .07 <5 34 1,000 <.1 <.5 100 <.1 <50 .47 <50 120 130 2 1.9

12 27 580 .04 <5 23 1,200 .3 <.5 100 .1 <50 .42 <50 87 110 1.8 2.113 20 840 .03 <5 16 450 .1 <.5 61 <.1 <50 .29 <50 68 42 .6 .614 16 440 .03 <5 9 280 .2 <.5 53 <.1 <50 .32 <50 43 26 .6 .715 49 830 .11 <5 28 1,200 .5 <.5 92 .1 <50 .55 <50 130 110 2.6 2.616 43 580 .09 <5 26 830 .5 <.5 95 <.1 <50 .59 <50 130 96 2.3 2.217 59 490 .09 <5 31 810 .6 <.5 92 .1 <50 .69 <50 150 100 3.1 3.119 3 160 .01 <5 1 42 <.1 <.5 14 <.1 <50 .07 <50 6 5 .1 <.120 35 580 .13 <5 30 1,100 .6 <.5 140 1.5 <50 .28 <50 110 100 16.2 1.6521 29 850 .09 <5 29 1,500 1 <.5 150 1.1 <50 .26 <50 95 94 11.2 11.8
28

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998

[USGS, U.S. Geological Survey; <63 μm, wet-sieved in field with 0.63-micrometer sieve; percent, percent dry weight; <, less than, <2 mm, wet-sieved in field with 2-millimeter sieve; mg/kg, milligrams per 

kilogram; g/kg, grams per kilogram; μg/kg, micrograms per kilogram; μg/g, micrograms per gram; E, estimated; M, presence of material verified but not quantified; --, not analyzed]

Site

number

(see 

fig. 1)

Site name USGS station number

Calcium

<63 μm

(percent)

Magnesium

<63 μm

(percent)

Potassium

<63 μm 

(percent)

Sodium

<63 μm

(percent)

Sulfur

<63 μm

(percent)

Nitrogen, 

NH4, total

(mg/kg

as N)

Nitrogen, 

NH4 plus 

organic, 

total

(mg/kg

as N)

Nitrogen,

NO2+NO3,

total

(mg/kg

as N)

Phosphorus

<63 μm

(percent)

1 Tchefuncte River near Covington 07375050 0.2 0.12 0.52 0.22 <0.05 200 36 <2 0.062 Bogue Falaya at Covington 07375170 .09 .11 .4 .11 <.05 <20 3.4 5 .033 Tangipahoa River at Robert 07375500 .14 .2 .84 .25 <.05 300 27 8 .064 Tickfaw River at Liverpool 07375800 .13 .19 1.1 .36 <.05 500 16 5 .045 Dawson Creek at Bluebonnet 

Boulevard at Baton Rouge 

07379960 .69 .41 1.4 .72 <.05 1,200 65 2 .05

6 Amite River at Port Vincent 07380120 .2 .18 1 .42 <.05 600 92 <2 .057 Bayou Des Allemands at Des 

Allemands 

07380300 1 1.1 1.7 .47 .35 5,400 380 3 .17

8 Bayou Lafourche below weir

 at Thibodaux 

07381002 3.5 1 1.8 .53 .1 1,500 72 <2 .13

9 Bayou Grosse Tete at Rosedale 07381440 .91 1.4 2.3 .38 .06 2,200 280 8 .18

10 Bayou Boeuf at Railroad Bridge 

at Amelia 

073814675 1.2 1.1 1.9 .54 .29 1,700 150 4 .08

11 Bayou Teche at Keystone Lock 

and Dam near St. Martinville 

07385700 .53 1.3 2.2 .55 .05 500 65 7 .10

12 Vermilion River at Perry 07386980 .47 .58 1.7 .61 <.05 1,200 100 9 .0913 Bayou des Cannes near Eunice 08010000 .42 .51 1.3 .5 <.05 670 13 <2 .0514 Bayou Nezpique near Basile 08012000 .29 .39 1 .41 <.05 610 12 3 .0515 Mermentau River at Mermentau 08012150 .44 .65 1.2 .28 .05 2,100 160 5 .1016 Bayou Que De Tortue at Riceville 08012300 .47 .59 1.2 .31 <.05 2,300 1,500 4 .0717 Bayou Lacassine near Lake Arthur 08012470 .49 .67 1.1 .17 .08 2,900 95 <2 .0818 Calcasieu River near Kinder 08014500 .12 .18 .71 .16 <.05 20 .6 <2 .1119 Turtle Bayou north of 

Bayou Penchant near Amelia

08015500 .13 .17 .57 .16 <.05‘ 80 <.2 <2 .04

20 Bayou Segnette 4.6 miles south

 of Westwego 

293524091041300 1.1 .88 1.3 .26 1.4 14,000 5,200 12 .10

21 Dawson Creek at Bluebonnet 

Boulevard at Baton Rouge 

294957090095300 .82 .91 1.6 .64 .88 8,500 300 10 .14
29

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Phosphorus,

total

(mg/kg

as P)

Carbon,

inorg

<63 μm

(percent)

Carbon,

inorg

 <2 mm

(g/kg)

Carbon,

org +

inorg

<2 mm

(g/kg)

Carbon,

org +

inorg

<63 μm

(percent)

Carbon,

organic

<2 mm

(g/kg)

Carbon,

organic

<63 μm

(percent)

Aluminum

<63 μm

(percent)

Antimony

<63 μm

(μg/g)

Arsenic

<63 μm

(μg/g)

Barium

<63 μm

(μg/g)

Beryllium

<63 μm

(μg/g)

Bismuth

<180

(μg/g)

Cadmium

<63 μm

(μg/g)

Cerium

<63 μm

(μg/g)

1 200 0.01 <0.1 10 1.9 10 1.9 2.9 0.5 2 330 0.9 1 0.3 832 40 .01 <.1 .6 1.3 .6 1.3 3.5 .5 2.5 210 .6 <1 <.1 733 200 .01 <.1 5.3 1.4 5.3 1.4 4.4 .5 3.3 400 1.2 <1 .2 724 100 .01 <.1 7.2 1.5 7.2 1.5 4.9 .5 3.4 520 1.4 <1 <.1 815 470 .08 .7 13 .93 12 .85 4.9 .7 3.9 560 .8 <1 .5 626 290 .01 .7 5.8 .82 5.1 .81 4.1 .6 5 460 1.2 <1 .2 707 1,700 .13 <.1 58 5.8 58 5.7 7.2 .8 11 740 2.1 <1 .7 648 1,100 .88 11 34 2.6 23 1.7 6.7 1.2 15 2,400 2.4 1 1 769 1,500 .02 <.1 24 2.1 24 2.1 9.5 .9 17 820 2.8 <1 .9 70

10 940 .19 1.7 19 2.1 17 1.9 7.5 .9 9.8 6,800 2.4 <1 .5 70

11 740 .01 <.1 18 1.8 18 1.8 7.5 .9 7.8 680 2.5 <1 .4 69

12 960 .01 <.1 20 1.4 20 1.4 6.2 .7 6.6 820 1.4 <1 .3 7313 330 .03 .6 6.7 .75 6.1 .72 5.9 .7 7.2 560 1.4 <1 .1 9114 190 .01 <.1 6.3 1.1 6.3 1.1 5.5 .6 5.4 460 1.4 <1 .1 7915 800 .01 <.1 24 2.3 24 2.3 8.9 .9 8.9 770 2.2 <1 .2 9016 610 .01 <.1 21 1.9 21 1.9 7.8 .9 7.2 830 1.9 <1 .2 8017 570 .01 <.1 29 2.9 29 2.9 10 1 7.8 720 1.8 <1 .2 11018 50 .01 <.1 .2 2.3 .2 2.3 3.7 .5 8.8 410 1.6 <1 .2 6419 40 .01 <.1 1.1 1.3 1.1 1.3 3.8 .8 3.2 370 1.1 <1 .2 6520 590 .03 <.1 160 14 160 14 5.7 .6 6.6 1,400 1.7 <1 .3 4121 1,300 .03 .9 110 8.1 110 8.1 6.3 .8 9.5 760 1.6 <1 .5 52
30

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Chromium

<63 μm

(μg/g)

Cobalt

<63 μm

(μg/g)

Copper

<63 μm

(μg/g)

Europium

<63 μm

(μg/g)

Gallium

<63 μm

(μg/g)

Gold

<63mm

(μg/g)

Holmium

<63 μm

(μg/g)

Iron

<63 μm

(percent)

Lanthanum

<63 μm

(μg/g)

Lead

<63mm

(μg/g)

Lithium

<63 μm

(μg/g)

Manganese

<63 μm

(μg/g)

Mercury

<63 μm

(μg/g)

Molybdenum

<63 μm

(μg/g)

Neodymium

<63 μm

(μg/g)

1 36 5 20 <1 6 <.050 <1 1 34 25 16 250 0.27 0.6 252 26 4 8 <1 8 <1 <1 .92 36 22 15 190 .03 <.5 263 31 7 9 1 9 <1 1 1.4 40 19 19 770 .04 <.5 334 38 9 14 1 10 <1 1 1.3 44 19 22 1,200 .04 .6 355 47 6 26 1 10 <1 1 2 33 57 22 300 .1 .9 296 45 8 20 1 9 <.050 <1 1.6 38 18 19 930 .03 .6 327 75 14 30 1 15 <.050 <1 4.1 36 34 40 1,000 .07 1 308 76 12 38 1 14 <.050 1 3.4 42 67 37 640 .15 1 339 95 12 46 1 24 <1 1 4.9 42 31 54 570 .07 .8 35

10 78 11 32 2 17 <1 1 3.8 40 29 42 890 .05 .7 34

11 74 12 33 1 19 <1 1 3.5 40 29 50 530 .07 .6 35

12 59 8 22 1 14 <1 1 2.4 42 34 28 440 .07 <.5 3613 56 13 18 1 14 <1 1 2.7 47 33 32 830 .03 .6 4014 49 10 14 1 13 <1 1 2.2 41 24 32 780 .03 .6 3515 83 13 27 2 22 <1 2 4 51 36 51 820 .07 .9 4316 75 10 23 2 20 <1 1 3.3 44 33 42 480 .05 .9 3817 96 16 30 2 24 <1 2 4 55 41 63 490 .07 1.2 5118 34 18 9 <1 8 <1 <1 2.9 34 18 19 730 .03 .6 2719 38 12 16 1 8 <1 1 1.6 34 20 22 830 .03 .5 2820 67 10 29 1 16 <1 <1 3.3 24 30 36 560 .09 1 2021 54 10 25 1 14 <1 <1 3 30 34 32 700 .09 .7 25
31

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Nickel

<63 μm

(μg/g)

Niobium

<63 μm

(μg/g)

Scandium

<63 μm

(μg/g)

Selenium

<63 μm

(μg/g)

Silver

<63 μm

(μg/g)

Strontium

<63 μm

(μg/g)

Tantalum

<63 μm

(μg/g)

Thallium,

total

<63 μm 

(μg/g)

Tin

<63 μm

(μg/g)

Titanium 

<63 μm

(percent)

Vanadium

<63 μm

(μg/g)

Ytterbium

<63 μm

(μg/g)

Yttrium<63 μm

(μg/g)

Zinc

<63 μm

(μg/g)

P, P′-

DDE

<2 mm

(μg/kg)

1 10 <4 5 0.4 4.3 41 <1 <1 2 0.4 37 2 17 65 M2 8 6 5 .3 .3 31 <1 <1 2 .48 34 2 12 43 <13 12 6 6 .4 .4 48 <1 <1 1 .44 44 2 17 50 <14 16 8 7 .4 .5 56 <1 <1 1 .54 50 2 20 49 <15 18 7 7 .4 .6 110 <1 <1 3 .34 52 2 18 130 36 16 11 6 .3 .2 64 <1 <1 1 .4 52 2 24 57 <17 41 13 12 .8 .4 110 <1 <1 7 .3 110 3 27 120 M8 37 15 12 .7 .3 200 1 <1 6 .4 100 3 30 160 49 41 12 17 .8 .6 120 1 <1 4 .54 160 3 24 190 3

10 33 12 12 .7 .7 190 1 <1 3 .39 110 3 23 150 <1

11 33 10 12 .5 .6 100 <1 <1 3 .49 100 2 21 130 20

12 22 10 10 .4 .6 100 1 <1 3 .5 73 2 20 110 1713 21 10 9 .5 .6 84 1 <1 2 .52 79 2 22 72 514 16 10 8 .5 .6 69 <1 <1 2 .53 67 2 18 59 <115 30 16 14 .8 .9 90 2 <1 3 .7 120 3 26 120 216 24 12 12 .8 .7 90 1 <1 2 .57 110 2 22 97 <117 34 18 15 .9 .9 90 2 1 3 .62 120 3 28 110 118 13 6 5 .7 .6 40 <1 <1 2 .45 46 2 14 48 <119 11 10 6 .5 .6 45 1 <1 1 .47 47 2 16 54 <120 32 7 9 1.7 .3 120 <1 <1 2 .25 100 2 14 110 <621 28 8 9 1 1.3 140 <1 <1 3 .35 88 2 16 130 <2
32

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

2,2′-bi

quinoline

<2 mm

(μg/kg)

3,5-

xylenol

<2 mm

(μg/kg)

4-bromo

phenyl phenyl

ether

<2 mm

(μg/kg)

4-chloro

phenyl phenyl

ether

<2 mm

(μg/kg)

4H-cyclopenta(def)-

phen 

anthrene

<2 mm

(μg/kg)

9,10-

anthraquinone

<2 mm

(μg/kg)

Fluorene,

1-methyl

<2 mm

(μg/kg)

Fluorene

<2 mm

(μg/kg)

Acenaphthene

<2 mm

(μg/kg)

Acenaphthylene

<2 mm

(μg/kg)

Acridine

<2 mm

(μg/kg)

Aldrin

<2 mm

(μg/kg)

AlphaBHC, D6

surrogate

<2 mm

(percent)

AlphaBH

<2 mm

(μg/kg)

1 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 71 <12 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 67 <13 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 74 <14 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 102 <15 <50 <50 <50 <50 E20 50 <50 <50 E20 E20 E10 <1 91 <16 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 95 <17 <50 <50 <50 <50 E40 <50 <50 <50 <50 <50 <50 <1 71 <18 <50 E30 <50 <50 120 170 E50 90 90 70 <50 <1 91 <19 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 75 <1

10 <100 <100 <100 <100 150 50 E30 140 120 50 E50 <1 91 <1

11 <50 <50 <50 <50 90 <50 <50 60 E20 <50 <50 <1 81 <1

12 <50 <50 <50 <50 E40 60 <50 E50 50 <50 <50 <1 113 <113 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 77 <114 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 74 <115 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <2 74 <216 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 69 <117 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 78 <118 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 69 <119 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <1 70 <120 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <50 <6 74 <621 <100 <100 <100 <100 E40 <100 <100 E10 <100 <100 <100 <2 73 <2
33

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Anthracene,

2-methyl-

<2 mm

(μg/kg)

Anthracene

<2 mm

(μg/kg)

Azobenzene

<2 mm

(μg/kg)

Benz(A)

anthracene

<2 mm

(μg/kg)

Benzene,

1,2,4-trichloro-

<2 mm

(μg/kg)

Benzene,

hexachloro-

<2 mm

(μg/kg)

Benzene,

M-dichloro-

<2 mm

(μg/kg)

Benzene,

nitro-

<2 mm

(μg/kg)

Benzene

nitro-, D5

surrogate

<2 mm

(percent)

Benzene,

O-dichloro-

<2 mm

(μg/kg)

Benzene,

P-dichloro-

<2 mm

(μg/kg)

Benzene,

pentachor,

nitro-

<2 mm

(μg/kg)

Benzo(A)-

pyrene

<2 mm

(μg/kg)

1 <50 <50 <50 E20 <50 <1 <50 <50 86 <50 <50 <50 E302 <50 <50 <50 <50 <50 <1 <50 <50 67 <50 <50 <50 <503 <50 <50 <50 <50 <50 <1 <50 <50 96 <50 <50 <50 <504 <50 <50 <50 <50 <50 <1 <50 <50 41 <50 <50 <50 <505 E20 60 <50 120 <50 <1 <50 <50 51 <50 <50 <50 1106 <50 M <50 E10 <50 1 <50 <50 66 <50 <50 <50 E107 <50 M <50 E50 <50 <1 <50 <50 66 <50 <50 <50 E508 50 200 <50 540 <50 <1 <50 <50 56 <50 E10 <50 6409 <50 <50 <50 <50 <50 <1 <50 <50 92 <50 <50 <50 <50

10 130 320 <100 470 <100 <1 <100 <100 48 <100 <100 <100 320

11 E30 E40 <50 150 <50 <1 <50 <50 42 <50 E10 <50 60

12 <50 E20 <50 70 <50 <1 <50 <50 79 <50 <50 <50 5013 <50 E10 <50 E20 <50 <1 <50 <50 39 <50 <50 <50 E2014 <50 <50 <50 <50 <50 <1 <50 <50 77 <50 <50 <50 <5015 <50 E10 <50 E30 <50 <2 <50 <50 52 <50 <50 <50 <5016 <50 <50 <50 <50 <50 <1 <50 <50 53 <50 <50 <50 <5017 <50 E20 <50 E20 <50 <1 <50 <50 57 <50 <50 <50 <5018 <50 <50 <50 <50 <50 <1 <50 <50 42 <50 <50 <50 <5019 <50 <50 <50 <50 <50 <1 <50 <50 50 <50 <50 <50 <5020 <50 <50 <50 <50 <50 <6 <50 <50 52 <50 <50 <50 <5021 <100 E40 <100 E30 <100 <2 <100 <100 54 <100 620 <100 <100
34

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Benzo(B)-

fluoranthene

<2 mm

(μg/kg)

Benzo(G,H,I)

-perylene

<2 mm

(μg/kg)

Benzo(K)-

fluoranthene

<2 mm

(μg/kg)

Benzo(C) 

cinnoline

<2 mm

(μg/kg)

BetaBHC

<2 mm

(μg/kg)

Biphenl,

2-fluoro,

surrogate

<2 mm

(percent)

Biphenl,

3,5-

dichlor,

surrogate

<2 mm

(percent)

Bis(2-

chloroethyl)

ether

<2 mm

(μg/kg)

Carbazole

<2 mm

(μg/kg)

Chloroneb

<2 mm

(μg/kg)

Chrysene

<2 mm

(μg/kg)

Cischlordane

<2 mm

(μg/kg)

Cisnonachlor

<2 mm

(μg/kg)

1 E30 <50 E20 -- <1 75 89 -- <50 <5 E10 1 <12 <50 <50 <50 <50 <1 65 71 -- <50 <5 <50 <1 <1

3 <50 <50 <50 <50 <1 74 75 -- <50 <5 <50 <1 <14 <50 <50 <50 <50 <1 41 93 -- <50 <5 <50 <1 <15 150 80 110 <50 <1 53 46 <50 E30 <5 150 6 46 E20 E10 E20 -- <1 55 101 -- <50 <5 E10 <1 <1

7 60 E20 E50 -- <1 72 79 -- <50 <5 60 <1 <18 460 E260 1,000 -- <2 61 63 -- 130 <5 640 7 29 E40 <50 E40 <50 <1 68 91 -- <50 <5 <50 <1 <1

10 280 140 300 <100 <1 40 42 <100 100 <5 480 <1 <1

11 90 E20 90 <50 <1 43 89 -- <50 <5 170 <1 <1

12 70 E30 80 <50 <1 55 81 <50 <50 <5 80 <1 <113 E30 <50 E30 <50 <1 55 73 -- <50 <5 E20 <1 <114 <50 <50 <50 <50 <1 61 72 -- <50 <5 <50 <1 <115 E50 <50 50 <50 <2 47 60 -- <50 <10 E30 <2 <216 <50 <50 <50 <50 <1 53 64 -- <50 <5 <50 <1 <117 E50 <50 E30 <50 <1 41 74 <50 <50 <5 E20 <1 <118 <50 <50 <50 <50 <1 39 66 -- <50 <5 <50 <1 <119 <50 E10 <50 <50 <1 42 76 <50 <50 <5 <50 <1 <120 <50 <50 <50 <50 <6 48 63 -- <50 <30 <50 <6 <621 E80 <100 E50 <100 <2 47 80 -- <100 <10 E60 <2 <2
35

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Cispermethrin

<2 mm

(μg/kg)

DCPA

<2 mm

(μg/kg)

Dibenz(A,H), 

anthracene

<2 mm

(μg/kg)

Dieldrin

<2 mm

(μg/kg)

Diphenylamine, 

N-nitroso-

<2 mm

(μg/kg)

Dipropylamine, Nnitroso

 <2 mm

(μg/kg)

Endosulfan I

 <2 mm

(μg/kg)

Endrin

<2 mm

(μg/kg)

Fluoranthene

 <2 mm

(μg/kg)

Heptachlor

epoxide

 <2 mm

(μg/kg)

Heptachlor

<2 mm

(μg/kg)

Indeno-

(1,2,3-cd) 

pyrene 

1-methyl

<2 mm

(μg/kg)

Isodrin

<2 mm

(μg/kg)

1 <5 <5 <50 <1 <50 <50 <1 <2 -- <1 <1 E20 <12 <5 <5 <50 <1 <50 <50 <1 <2 E20 <1 <1 <50 <13 <5 <5 <50 <1 <50 <50 <1 <2 <50 <1 <1 <50 <14 <5 <5 <50 <1 <50 <50 <1 <2 <50 <1 <1 <50 <15 <5 <5 E30 1 <50 <50 <1 <2 280 <1 <1 90 <16 <5 <5 <50 <1 <50 <50 <1 <2 -- <1 <1 E10 <17 <5 <5 <50 <1 <50 <50 <1 <2 130 <1 <1 E30 <18 <5 <5 100 2 <50 <50 <1 <2 1,200 <1 E4 E320 <19 <5 <5 <50 <1 <50 <50 <1 <2 E40 <1 <1 <50 <1

10 <5 <5 60 <1 <100 <100 <1 <2 960 <1 <1 160 <1

11 <5 <5 <50 <1 <50 <50 <1 <2 820 <1 <1 E30 <1

12 <5 <5 <50 <1 <50 <50 <1 <2 280 <1 <1 <50 <113 <5 <5 <50 <1 <50 <50 <1 <2 70 <1 <1 <50 <114 <5 <5 <50 <1 <50 <50 <1 <2 E30 <1 <1 <50 <115 <10 <10 <50 <2 <50 <50 <2 <4 90 <2 <2 <50 <216 <5 <5 <50 <1 <50 <50 <1 <2 E20 <1 <1 <50 <117 <5 <5 <50 <1 <50 <50 <1 <2 E30 <1 <1 <50 <118 <5 <5 <50 <1 <50 <50 <1 <2 <50 <1 <1 <50 <119 <5 <5 <50 <1 <50 <50 <1 <2 <50 <1 <1 <50 <120 <30 <30 <50 <6 <50 <50 <6 <12 170 <6 <6 <50 <621 <10 <10 <100 <2 <100 <100 <2 <4 150 <2 <2 <100 <2
36

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Isophorone

<2 mm

(μg/kg)

Isoquinoline,

<2 mm

(μg/kg)

Lindane

<2 mm

(μg/kg)

M-cresol, 

4-chloro-

<2 mm

(μg/kg)

Methane 

bis(2-chloro

ethoxy)

<2 mm

(μg/kg)

Methoxychlor,

O,P′-,

<2 mm

(μg/kg)

Methoxychlor, P,P′-,

<2 mm

(μg/kg)

Mirex,

 <2 mm

(μg/kg)

Napthalene, 

1,2-

dimethyl

 <2 mm

(μg/kg)

Napthalene, 

1,6-

dimethyl

 <2 mm

(μg/kg)

Napthalene, 

2,3,6-

trimethyl

<2 mm

(μg/kg)

Napthalene, 

2,6-

dimethyl

<2 mm

(μg/kg)

1 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <502 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <503 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <504 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <505 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 E506 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <507 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 708 <50 <50 <1 <50 <50 <5 <5 <1 E20 50 70 1209 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 E20

10 <100 <100 <1 <100 <100 <5 <5 <1 <100 E20 E10 90

11 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 E10

12 <50 <50 <1 <50 <50 <5 <5 <1 <50 E20 E20 E2013 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <5014 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <5015 <50 E40 <2 70 <50 <10 <10 <2 <50 E20 <50 E4016 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <5017 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 E4018 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <5019 <50 <50 <1 <50 <50 <5 <5 <1 <50 <50 <50 <5020 <50 <50 <6 <50 <50 <30 <30 <6 <50 <50 <50 44021 <100 <100 <2 <100 <100 <10 <10 <2 <100 <100 <100 120
37

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Napthalene, 

2-chloro-

<2 mm

(μg/kg)

Napthalene, 

2-ethyl-

 <2 mm

(μg/kg)

Naphthalene,

 <2 mm

(μg/kg)

O, P′-

DDD,

 <2 mm

(μg/kg)

O, P′-

DDE,

 <2 mm

(μg/kg)

O, P′-

DDT,

<2 mm

(μg/kg)

Octachlorobiphenyl,

surrogate

<2 mm

(percent)

Oxychlordane,

<2 mm

(μg/kg)

P, P′-

DDD,

<2 mm

(μg/kg)

P, P′-

DDT,

<2 mm

(μg/kg)

PCB

<2 mm

(μg/kg)

P-cresol

<2 mm

(μg/kg)

Pentachloroanisole

 <2 mm

(μg/kg)

1 <50 <50 <50 <1 <1 <2 91 <1 <1 <2 <50 <50 <12 <50 <50 <50 <1 <1 <2 79 <1 <1 <2 <50 <50 <13 <50 <50 <50 <1 <1 <2 83 <1 <1 <2 <50 270 <14 <50 <50 <50 <1 <1 <2 92 <1 <1 <2 <50 60 <15 <50 <50 <50 <1 <1 <2 64 <1 3 <2 <50 230 <16 <50 <50 <50 <1 <1 <2 98 <1 <1 <2 <50 140 <17 <50 <50 E10 <1 <1 <2 91 <1 <1 <2 <50 E40 <18 <50 E40 90 <1 <1 <2 95 <1 E6 4 70 160 <19 <50 <50 <50 <1 <1 <2 76 <1 1 <2 <50 520 <1

10 <100 <100 <100 <1 <1 <2 60 <1 <1 <2 <50 810 <1

11 <50 M E20 <1 <1 <2 92 <1 <1 <2 <50 50 <1

12 <50 E10 E10 <1 <1 <2 79 <1 3 <2 <50 610 <113 <50 <50 <50 <1 <1 <2 85 <1 2 <2 <50 <50 <114 <50 <50 <50 <1 <1 <2 88 <1 <1 <2 <50 <50 <115 <50 <50 <50 <2 <2 <4 88 <2 <2 <4 <100 <50 <216 <50 <50 <50 <1 <1 <2 86 <1 <1 <2 <50 <50 <117 <50 <50 <50 <1 <1 <2 94 <1 <1 <2 <50 <50 <118 <50 <50 <50 <1 <1 <2 84 <1 <1 <2 <50 <50 <119 <50 <50 <50 <1 <1 <2 86 <1 <1 <2 <50 <50 <120 <50 <50 <50 <6 <6 <12 84 <6 <6 <12 <300 6,100 <621 <100 <100 <100 <2 <2 <4 66 <2 <2 <4 <100 6,100 <2
38

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Phenanthrene,

1-methyl

<2 mm

(μg/kg)

Phenanthrene

 <2 mm

(μg/kg)

Phenanthridine

<2 mm

(μg/kg)

Phenol

 <2 mm

(μg/kg)

Phenol,

C8-alkyl-

<2 mm

(μg/kg)

Phenol,

2-chloro

<2 mm

(μg/kg)

Phthalate,

bis(2-ethyl 

hexyl)-

<2 mm

(μg/kg)

Phthalate, 

butyl benzyl

<2 mm

(μg/kg)

Phthalate,

dibutyl

<2 mm

(μg/kg)

Phthalate, 

diethyl

<2 mm

(μg/kg)

Phthalate, 

dimethyl

<2 mm

(μg/kg)

Phthalate, 

dioctyl

<2 mm

(μg/kg)

Pyrene,

1-methyl

<2 mm

(μg/kg)

1 <50 <50 -- <50 <50 -- 340 <50 E50 E40 <50 <50 <502 <50 <50 <50 <50 <50 <50 E40 <50 60 E40 <50 <50 <503 <50 <50 <50 <50 <50 <50 60 <50 E50 50 <50 <50 <504 <50 <50 <50 <50 <50 <50 <50 <50 E30 E10 <50 <50 <505 E10 130 E10 E10 <50 <50 530 E40 E40 <50 <50 <50 E106 E10 M -- E10 <50 -- 110 <50 E20 E20 E10 <50 <507 <50 E40 -- M <50 -- 80 <50 60 80 <50 <50 <508 70 880 -- 50 <50 -- 140 <50 E20 <50 <50 <50 809 <50 <50 <50 <50 <50 <50 90 <50 70 <50 <50 <50 <50

10 90 770 E40 <100 <100 <100 160 120 60 <100 <100 E40 E50

11 E10 170 <50 <50 <50 <50 80 <50 50 E30 <50 <50 E20

12 E20 260 <50 E10 <50 <50 100 <50 E40 E20 <50 <50 E2013 <50 E20 <50 <50 <50 <50 E40 E20 E40 <50 <50 <50 <5014 <50 M <50 <50 <50 <50 E20 <50 E40 <50 <50 <50 <5015 <50 E10 <50 <50 <50 <50 90 <50 60 <50 <50 <50 <5016 <50 <50 <50 <50 <50 <50 <50 <50 E50 <50 <50 <50 <5017 <50 <50 <50 <50 <50 <50 E40 <50 60 E20 E20 <50 <5018 <50 <50 <50 <50 <50 <50 E10 E10 E20 <50 <50 <50 <5019 <50 <50 <50 <50 <50 <50 E10 <50 E20 E10 <50 <50 <5020 <50 60 <50 <50 <50 <50 330 <50 240 <50 <50 <50 <5021 <100 E30 <100 220 <100 <100 130 <100 E90 E50 <100 <100 <100
39

Appendix B. Concentrations of selected trace elements, nutrients, and organic compounds in bed-sediment for selected sites in the Acadian-Pontchartrain Study Unit, southern 

Louisiana, 1998—Continued

Site 

number 

(see 

fig. 1)

Pyrene

<2 mm

(μg/kg)

Quinoline

<2 mm

(μg/kg)

Terphenyl, 

D14-

surrogate

<2 mm

(percent)

Thiophene,

dibenzo-

<2 mm

(μg/kg)

Toluene, 

2,4-dinitro-

<2 mm

(μg/kg)

Toluene, 

2,6-dinitro-

<2 mm

(μg/kg)

Toxaphene

<2 mm

(μg/kg)

Transchlordane

<2 mm

(μg/kg)

Transnonachlor

<2 mm

(μg/kg)

Transpermethrin

<2 mm

(μg/kg)

Thorium

<63 μm

(μg/g)

Uranium

<63 μm

(μg/g)

1 E20 <50 88 <50 <50 <50 <200 E1 E1 <5 8 2.22 <50 <50 72 <50 <50 <50 <200 <1 <1 <5 9 2.73 <50 <50 83 <50 <50 <50 <200 <1 <1 <5 9 34 <50 <50 64 <50 <50 <50 <200 <1 <1 <5 10 3.45 240 <50 68 <50 <50 <50 <200 7 10 <5 9 2.76 E20 <50 96 <50 <50 <50 <200 <1 <1 <5 9 2.57 110 <50 82 <50 <50 <50 <200 <1 <1 <5 11 2.68 1,200 <50 69 60 <50 <50 <200 14 5 <5 11 2.99 E10 <50 81 <50 <50 <50 <200 <1 <1 <5 13 4

10 780 <100 54 50 <100 <100 <200 <1 <1 <5 12 3

11 570 <50 62 <50 <50 <50 <200 <1 <1 <5 11 3.6

12 240 <50 57 E10 <50 <50 <200 1 <1 <5 11 3.113 50 <50 78 <50 <50 <50 <200 <1 <1 <5 12 3.914 E10 <50 87 <50 <50 <50 <200 <1 <1 <5 11 3.615 60 <50 68 <50 <50 <50 <400 <2 <2 <10 14 4.916 E10 <50 89 <50 <50 <50 <200 <1 <1 <5 13 4.817 E40 <50 65 <50 <50 <50 <200 <1 <1 <5 17 518 <50 <50 66 <50 <50 <50 <200 <1 <1 <5 9 2.819 M <50 66 <50 <50 <50 <200 <1 <1 <5 11 3.320 90 <50 64 <50 <50 <50 <1,200 <6 <6 <30 7 3.821 140 <100 61 <100 <100 <100 <400 <2 <2 <10 9 3.5