Prepared in cooperation with the San Antonio River Authority

Occurrence and Concentrations of Selected Trace Elements, 

Halogenated Organic Compounds, and Polycyclic Aromatic 

Hydrocarbons in Streambed Sediment and Results of WaterToxicity Testing in Westside Creeks and the San Antonio 

River, San Antonio, Texas, 2014

Scientific Investigations Report 2016–5136

U.S. Department of the Interior

U.S. Geological Survey
Front cover:

Left, U.S. Geological Survey scientist collecting a stormwater sample at U.S. Geological Survey station 

08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Texas . 

Middle, Looking upstream towards downtown San Antonio from U.S. Geological Survey station 

08178465 San Pedro Creek at West Cevallos Street, San Antonio, Texas. 

Right, U.S. Geological Survey scientist making field notes at U.S. Geological Survey station 08178310 

Alazán Creek at West Laurel Street, San Antonio, Texas. 

Back cover:

Top, U.S. Geological Survey station 08178445 Apache Creek at West Commerce Street, San Antonio, 

Texas. 

Bottom, U.S. Geological Survey station 08178345 Martínez Creek at West Hildebrand Avenue, San 

Antonio, Texas. 
Occurrence and Concentrations of 

Selected Trace Elements, Halogenated 

Organic Compounds, and Polycyclic 

Aromatic Hydrocarbons in Streambed 

Sediment and Results of Water-Toxicity 

Testing in Westside Creeks and the San 

Antonio River, San Antonio, Texas, 2014

By Cassi L. Crow, Jennifer T. Wilson, and James L. Kunz 

Prepared in cooperation with the San Antonio River Authority

Scientific Investigations Report 2016–5136

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

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Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Crow, C.L., Wilson, J.T., and Kunz, J.L., 2016, Occurrence and concentrations of selected trace elements, halogenated 

organic compounds, and polycyclic aromatic hydrocarbons in streambed sediments and results of water-toxicity 

testing in Westside Creeks and the San Antonio River, San Antonio, Texas, 2014: U.S. Geological Survey Scientific 

Investigations Report 2016–5136, 56 p., http://dx.doi.org/10.3133/sir20165136. 

ISSN 2328-031X (print))

ISSN 2328-0328 (online)
iii

Contents

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

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

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

Description of the Study Area and Sampling Sites ........................................................................3

Methods ..........................................................................................................................................................3

Streambed Sample Collection ...........................................................................................................3

Streambed Sediment Analytical Methods .....................................................................................10

Water Quality Toxicity Sample Collection ......................................................................................10

Water Quality Toxicity Analytical Methods ...................................................................................10

Quality Control ....................................................................................................................................11

Inorganic Analysis ....................................................................................................................11

Organic Analysis .......................................................................................................................12

Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic 

Compounds, and Polycyclic Aromatic Hydrocarbons in Streambed Sediment ...............................14

Trace Elements ...................................................................................................................................14

Halogenated Organic Compounds ..................................................................................................16

Pesticides ...................................................................................................................................17

Brominated Flame Retardants ................................................................................................17

Polychlorinated Biphenyls ......................................................................................................22

Polycyclic Aromatic Hydrocarbons ................................................................................................22

Results of Water-Toxicity Testing .............................................................................................................28

Summary .......................................................................................................................................................32

References ...................................................................................................................................................33

Figures

1. Map showing land cover characteristics of the contributing area associated with 

each site where streambed-sediment samples and samples for water-toxicity 

testing were collected from the Westside Creeks (Alazán, Apache, Martínez, and 

San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ................................4

2. Map showing locations of sites where streambed-sediment samples and 

samples for water-toxicity testing were collected from the Westside Creeks 

(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, 2014 ....................................................................................................................6

3. Photographs showing A, streambed-sediment sample collection; B, processing; 

and C, collection of water samples for toxicity-testing used at sites in the 

Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San 

Antonio River, San Antonio, Texas, 2014 ..................................................................................7

4. Graphs showing comparison of consensus-based sediment quality guidelines 

with concentrations of trace elements in streambed-sediment samples collected 

from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro 

Creeks) and San Antonio River, San Antonio, Texas, 2014 ..................................................15
iv

5. Graph showing percentages of organic carbon in streambed-sediment samples 

collected from sites on the Westside Creeks (Alazán, Apache, Martínez, and 

San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ..............................16

6. Bar graph showing detection frequencies of pesticides in streambed-sediment 

samples collected from sites on the Westside Creeks (Alazán, Apache, Martínez, 

and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ......................18

7. Graphs showing comparison of consensus-based sediment quality guidelines 

with concentrations of pesticides in streambed-sediment samples collected 

from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro 

Creeks) and San Antonio River, San Antonio, Texas, 2014 ..................................................19

8. Bar graph showing detection frequencies of 13 brominated flame retardants in 

streambed-sediment samples collected from sites on the Westside Creeks 

(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, 2014 ..................................................................................................................20

9. Graphs showing comparison of select organic-carbon normalized brominated 

flame retardant concentrations and Environment Canada Federal Environmental 

Quality Guidelines (FEQGs) for sediment in streambed-sediment samples 

collected from sites on the Westside Creeks (Alazán, Apache, Martínez, and 

San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ..............................21

10. Bar graph showing detection frequencies of polychlorinated biphenyls (PCBs) 

in streambed-sediment samples collected from sites on the Westside Creeks 

(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, 2014 ..................................................................................................................23

11. Graph showing comparison of consensus-based sediment quality guidelines 

with concentrations of polychlorinated biphenlys (PCBs) in streambed-sediment 

samples collected from sites on the Westside Creeks (Alazán, Apache, Martínez, 

and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ......................24

12. Graphs showing comparison of consensus-based sediment quality guidelines 

with concentrations of polycyclic aromatic hydrocarbons (PAHs) in streambedsediment samples collected from sites on the Westside Creeks (Alazán, Apache, 

Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 

2014 ..............................................................................................................................................25

13. Graphs showing comparison of polycyclic aromatic hydrocarbon (PAH) profiles 

for selected PAH sources summarized in Van Metre and Mahler to PAH profiles 

for average streambed sediment computed from samples collected during 

base-flow and poststorm conditions from sites on the Westside Creeks (Alazán, 

Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, 

Texas, 2014 ..................................................................................................................................27

14. Bar graph showing responses of Pimephales promelas (fathead minnow) in 

7-day exposure to water samples collected during base-flow and poststorm 

conditions from sites on the Westside Creeks (Alazán, Apache, Martínez, and 

San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ..............................29
v

Tables

1. Total length of sampled reach, contributing area, and land use of the contributing 

area to each site where streambed-sediment samples and samples for watertoxicity testing were collected from the Westside Creeks (Alazán, Apache, 

Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ......5

2. Top 10 potential sources of contamination in contributing areas of sites where 

streambed-sediment samples were collected from the Westside Creeks (Alazán, 

Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, 

Texas, 2014 ....................................................................................................................................8

3. Relative percent differences between environmental samples and duplicate 

samples for trace elements measured in streambed-sediment samples collected 

from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro 

Creeks) and San Antonio River, San Antonio, Texas, 2014 ..................................................38

4. Statistical summary of relative percent difference (RPD) between environmental 

and duplicate streambed-sediment samples collected from sites on the Westside 

Creeks (Alazán, Apache, Martínez, and San Pedro Creeks), San Antonio, Texas, 

2014 ..............................................................................................................................................11

5. Results from U.S. Geological Survey National Water Quality Laboratory (NWQL) 

analysis of National Institute of Standards and Technology (NIST) standard 

reference materials 8704 and 1941b .......................................................................................40

6. Relative percent differences between environmental samples and duplicate 

samples for halogenated organic compounds measured in streambed-sediment 

samples collected from sites on the Westside Creeks (Alazán, Apache, Martínez, 

and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ......................42

7. Relative percent differences between environmental samples and duplicate 

samples for polycyclic aromatic hydrocarbons measured in streambed-sediment 

samples collected from sites on the Westside Creeks (Alazán, Apache, Martínez, 

and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014 ......................46

8. Analytical results for halogenated organic compounds found in laboratory set 

blank samples, and set spike data associated with samples collected from sites 

on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and 

San Antonio River, San Antonio, Texas, 2014.........................................................................49

9. Analytical results for polycyclic aromatic hydrocarbons found in laboratory set 

blank samples and set spike data associated with samples collected from sites 

on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and 

San Antonio River, San Antonio, Texas, 2014 ........................................................................55

10. Consensus-based sediment-quality guidelines of MacDonald and others (2000) 

that were used to evaluate the contaminant concentrations in streambedsediment samples collected from sites on the Westside Creeks (Alazán, Apache, 

Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 

2014 ..............................................................................................................................................14

11. Responses of Pimephales promelas (fathead minnow) in 7-day exposure to water 

samples collected during base-flow conditions from sites on the Westside Creeks 

(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, January 2014 ..................................................................................................30

12. Responses of Pimephales promelas (fathead minnow) in 7-day exposure to water 

samples collected during poststorm conditions from sites on the Westside Creeks 

(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, May 2014 .........................................................................................................31
vi

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 929.0 square centimeter (cm2)

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

International System of Units to U.S. customary units

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

meter (m) 1.094 yard (yd) 

Volume

liter (L) 33.81402 ounce, fluid (fl. oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

Pressure

kilopascal (kPa) 0.009869 atmosphere, standard (atm)

kilopascal (kPa) 0.01 bar

kilopascal (kPa) 0.2961 inch of mercury at 60°F (in Hg)

kilopascal (kPa) 0.1450 pound-force per inch (lbf/in) 

kilopascal (kPa) 20.88 pound per square foot (lb/ft2) 

kilopascal (kPa) 0.1450 pound per square inch (lb/ft2) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as °F = (1.8 × 

°C) + 32.

Datum

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).
vii

Supplemental Information

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C). Concentrations of chemical constituents in water are given in milligrams per liter (mg/L). 

Concentrations of chemical constituents in sediment are given in milligrams per kilogram 

(mg/kg), micrograms per kilogram (μg/kg).

Abbreviations

DDD Dichlorodiphenyldichloroethane

DDE Dichlorodiphenyldichloroethylene

DDT Dichlorodiphenyltrichloroethane

FEQG Federal Environmental Quality Guidelines established by Environment Canada

IRL Interim reporting level

NAWQA National Water-Quality Assessment

NIST National Institute of Standards and Technology

NWQL National Water Quality Laboratory

PAH Polycyclic aromatic hydrocarbons

PBDE Polybrominated diphenyl ether

PCB Polychlorinated biphenyl

PEC Probable effect concentration

PSOC Potential source of contamination

RPD Relative percent difference

SARA San Antonio River Authority

SQG Sediment quality guideline

TEC Threshold effect concentration

UV Ultraviolet

USGS U.S. Geological Survey

Occurrence and Concentrations of Selected Trace 

Elements, Halogenated Organic Compounds, and 

Polycyclic Aromatic Hydrocarbons in Streambed Sediment 

and Results of Water-Toxicity Testing in Westside Creeks 

and the San Antonio River, San Antonio, Texas, 2014 

By Cassi L. Crow, Jennifer T. Wilson, and James L. Kunz 

Abstract

Sediment samples and samples for water-toxicity testing 

were collected during 2014 from several streams in San Antonio, Texas, known locally as the Westside Creeks (Alazán, 

Apache, Martínez, and San Pedro Creeks) and from the San 

Antonio River. Samples were collected during base flow and 

after periods of stormwater runoff (poststorm conditions) to 

determine baseline sediment- and water-quality conditions. 

Streambed-sediment samples were analyzed for selected 

constituents, including trace elements and organic contaminants such as pesticides, polychlorinated biphenyls (PCBs), 

brominated flame retardants, and polycyclic aromatic hydrocarbons (PAHs). Potential risks of contaminants in sediment 

were evaluated by comparing concentrations of contaminants 

in sediment to two effects-based sediment-quality guidelines: 

(1) a lower level, called the threshold effect concentration, 

below which, harmful effects to benthic biota are not expected, 

and (2) a higher level, the probable effect concentration (PEC), 

above which harmful effects are expected to occur frequently. 

Samples for water-toxicity testing were collected from each 

stream to provide information about fish toxicity in the study 

area. The trace metal lead was detected at potentially toxic 

concentrations greater than the PEC in both the base-flow and 

poststorm samples collected at two sites sampled on San Pedro 

Creek. The PECs for the pesticides dichlorodiphenyldichloroethane, dichlorodiphenyldichloroethylene, dichlorodiphenyltrichloroethane, and chlordane were exceeded in some of the 

samples at the same two sites on San Pedro Creek. Brominated 

flame retardants and polybrominated diphenyl ether (PBDE) 

85, 153, and 154 were found in all streambed-sediment samples. Federal Environmental Quality Guidelines established 

by Environment Canada for PBDE 99 and PBDE 100 were 

exceeded in all samples in which PBDE 99 was detected and 

in a majority of the samples in which PBDE 100 was detected; 

the greatest concentrations occurred in samples collected at the 

same two sites on San Pedro Creek where the samples containing elevated lead and pesticide concentrations were collected. 

All concentrations of total PCBs (computed as the sum of the 

18 reported PCB congeners) in the individual streambed-sediment samples were less than the threshold effect concentration, but the concentrations were elevated in the two sites on 

San Pedro Creek compared to concentrations at other sites. At 

one site on Apache Creek, 6 of the individual PAHs measured 

in the sample collected during base-flow conditions exceeded 

the PECs and 8 of the 9 PECs were exceeded in the sample 

collected during poststorm conditions. The total PAH concentration in the sample collected at the site during poststorm 

conditions was 3.3 times greater than the PEC developed for 

total PAHs. Average PAH profiles computed for base-flow 

samples and poststorm samples most closely resemble the 

parking lot coal-tar sealcoat dust PAH source profile, defined 

as the average PAH concentrations in dust swept from parking 

lots in six cities in the United States that were sealed with a 

black, viscous liquid containing coal-tar pitch. Six of ten water 

samples collected during base-flow conditions caused reductions in Pimephales promelas (fathead minnow) survival and 

were considered to be toxic.

Introduction

Elevated concentrations of sediment-associated 

contaminants often are measured in urban areas (Rice, 1999; 

Wong and others, 2000; Chalmers and others, 2007). In the 

area of San Antonio, Texas, the seventh most populous city 

in the United States (U.S. Census Bureau, 2016), sedimentassociated contaminants have been detected and documented 

in previous studies. For example, Ging (1999) and Ging and 

others (1999) documented upward trends in zinc, chlordane, 

and polycyclic aromatic hydrocarbon (PAH) concentrations 

in relation to sediment cores collected in an urban lake in 

the San Antonio area. Lead, dichlorodiphenyltrichloroethane 

(DDT), and polychlorinated biphenyls (PCBs) also were 

detected in the lake core samples. Wilson (2011) documented 

concentrations of certain pesticides, PCBs, halogenated 

organic compounds, and PAHs in streambed and suspended 

sediment in selected streams in the San Antonio area. 
2 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Sediment-associated contaminants can influence the health 

of aquatic organisms that ingest particulate matter when 

bioaccumulation of trace elements and organic compounds 

occurs (Forstner and Wittmann, 1979; Luoma, 1983). The 

accumulation of trace elements and organic compounds can 

cause various physiological issues and can ultimately result in 

death of aquatic organisms. Subsequent ingestion of aquatic 

organisms by consumers (organisms that eat other organisms) 

can transfer accumulated fat-soluble (lipophilic) contaminants 

upward through the food chain resulting in biomagnification 

(Neely, 1980; Borga and others, 2004).

The Alazán, Apache, Martínez, and San Pedro Creeks 

in San Antonio, Tex., are part of a network of tributaries to 

the San Antonio River known locally as the Westside Creeks 

(fig. 1). The Westside Creeks flow through some of the oldest 

neighborhoods in San Antonio—an area with a rich cultural 

history that includes the Alamo, Mission Concepción, and 

San José Mission. In 1954, a Federal program known as 

the San Antonio Channel Improvement Project channelized 

several miles of stream reaches in the Westside Creeks 

and San Antonio River within the city limits in an effort 

to reduce urban flooding (San Antonio River Authority, 

2016). In 2008, the San Antonio River Authority (SARA) 

started a community-based effort working to improve the 

environmental condition of 14 miles of channelized sections 

of the Alazán, Apache, Martínez, and San Pedro Creeks, 

while enhancing or maintaining current (2016) flood control 

functions, and increasing recreational opportunities (San 

Antonio River Authority, 2016) (fig. 2). It is anticipated the 

construction activities to improve channelized sections on the 

14 miles of stream channel could appreciably disturb stream 

channel sediments.

There are several constituents of concern in the streambed 

sediments of the Westside Creeks; the constituents that were 

selected for analysis included trace elements, pesticides, 

brominated flame retardants, PCBs, and PAHs. Many of the 

selected constituents of concern have been used historically 

for industrial as well as domestic purposes. These chemicals 

are typically hydrophobic, meaning they do not normally 

remain in the water column but instead bind to sediments; 

hence, sediments can serve as long-term repositories of 

historical contamination. The disruption of sediment during 

the anticipated large-scale construction activities to improve 

channelized sections can create the potential to reintroduce 

these chemicals into the ecosystem where, depending 

on hydrologic and environmental conditions, they could 

become bioavailable and toxic to aquatic life. It is important 

to understand the impact of urbanization on freshwater 

ecosystems, including the possibility of increased frequency 

and delivery of contaminants to neighboring ecosystems 

(Moran and others, 2012). The Westside Creeks are tributaries 

to the San Antonio River, which drains into bays and estuaries 

along the Gulf Coast in Texas. Contaminates mobilized from 

the Westside Creeks during construction activities could affect 

downstream users of water from the San Antonio River and 

ultimately the ecological health of these bays and estuaries. 

Determination of the degree to which contaminants might be 

present in the sediment in areas of long-term urbanization also 

is important because almost all population growth through 

2050 is expected to occur by expansion of existing urban 

areas (United Nations, 2015), and the San Antonio area is 

a prime example of this projection. The degree to which 

contaminants are present in sediments of San Antonio streams 

might increase over time as a result of rapid urbanization. By 

2040, the population of Bexar County is projected to grow 

by 1 million, and the urban area of San Antonio is projected 

to more than double in size from 500 square miles (mi2) to 

more than 1,000 mi2 (San Antonio Express News, 2014). 

As urbanization increases, infrastructure modifications such 

as the replacement of aging or undersized bridges and other 

stream modification projections could lead to mobilization and 

redistribution of contaminants. 

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

SARA, collected sediment samples and samples for watertoxicity testing from sites on Alazán, Apache, Martínez, and 

San Pedro Creeks, and from a site on the San Antonio River 

as part of an initial characterization of selected contaminants 

in the study area. Stream samples also were collected to assess 

toxicity of the streams to fish during base flow and after 

periods of stormwater runoff. 

Purpose and Scope

This report provides an initial characterization of selected 

contaminants in streambed sediments and water-toxicity 

testing results within the boundaries of a planned restoration of 

the Westside Creeks in San Antonio, Tex. (fig. 2). Streambedsediment samples and samples for water-toxicity testing were 

collected in 2014 from the Alazán, Apache, Martínez, and San 

Pedro Creeks, as well as from the main channel of the San 

Antonio River during two periods of sampling representing 

different flow conditions. The first period of sampling was 

during base-flow conditions; the second was completed shortly 

after a stormflow event. 

This report specifically describes the occurrence and 

quantity of selected constituents in streambed sediments 

including trace elements, pesticides, polychlorinated 

biphenyls, brominated flame retardants, and polycyclic 

aromatic hydrocarbons, and water toxicity for aquatic biota 

at selected sites in Westside Creeks and the San Antonio 

River in 2014. Potential risks of contaminants in sediment 

were evaluated by comparing concentrations of contaminants 

in sediment to effects-based sediment-quality guidelines. 

The frequencies with which the organic contaminants were 

detected in the streambed-sediment samples were assessed, 

and comparisons of concentrations among sites were made to 

describe the occurrence and distribution of the contaminants. 

As an indicator of ecological health in relation to mobilized 

(and thus, possibly bioavailable) contaminants in disturbed 

streambed sediments, the toxicity of water samples collected 

from the same locations as sediment samples to the indicator 

species Pimephales promelas (fathead minnow) was evaluated 

by using standard 7-day water-toxicity testing. All analytical 

data are presented in Crow and others (2016).
Methods 3

Description of the Study Area and Sampling 

Sites

The study area encompasses approximately 95 mi2

and consists of the drainage area of San Pedro Creek, its 

tributaries, and one site downstream from the confluence of 

San Pedro Creek with the San Antonio River (fig. 1). The sites 

from which streambed-sediment samples and samples for 

water-toxicity testing were collected were Martínez Creek at 

West Hildebrand Avenue, San Antonio, Tex., (USGS station 

08178345; hereinafter referred to as the “upstream Martínez 

site”; map identifier MTZ-US); Martínez Creek at West 

Poplar Street, San Antonio, Tex., (USGS station 08178375; 

hereinafter referred to as the “downstream Martínez site”; 

map identifier MTZ-DS); Alazán Creek at West Laurel Street, 

San Antonio, Tex., (USGS station 08178310; hereinafter 

referred to as the “upstream Alazán site”; map identifier 

ALZ-US); Alazán Creek at Tampico Street, San Antonio, 

Tex., (USGS station 08178410; hereinafter referred to as the 

“downstream Alazán site”; map identifier ALZ-DS); Apache 

Creek at West Commerce Street, San Antonio, Tex., (USGS 

station 08178445; hereinafter referred to as the “upstream 

Apache site”; map identifier APC-US); Apache Creek at South 

Brazos Street, San Antonio, Tex., (USGS station 08178460; 

hereinafter referred to as the “downstream Apache site”; map 

identifier APC-DS); San Pedro Creek at Santa Rosa Street, San 

Antonio, Tex., (USGS station 08178100; hereinafter referred 

to as the “upstream San Pedro site”; map identifier SPD-US); 

San Pedro Creek at West Cevallos Street, San Antonio, 

Tex., (USGS station 08178465; hereinafter referred to as the 

“middle San Pedro site”; map identifier SPD-MD); San Pedro 

Creek at Probandt Street, San Antonio, Tex., (USGS station 

08178504; hereinafter referred to as the “downstream San 

Pedro site”; map identifier SPD-DS); and San Antonio River 

at Mission Road, San Antonio, Tex., (USGS station 08178515; 

hereinafter referred to as the “San Antonio River site”; map 

identifier SAR) (table 1). 

The contributing area and land use in the contributing 

area in 2011 (fig. 1) of each sampling site are summarized in 

table 1. The contributing areas range in size from 1.8 for the 

upstream San Pedro site to 94.9 mi2 for the San Antonio River 

site, respectively. The entire study area is highly urbanized 

with the contributing areas ranging from 94.3 to 100 percent 

developed land (Homer and others, 2015).

Numerous potential sources of contamination are present 

in the drainage areas of the Westside Creeks. The top 10 

potential sources of contamination (PSOCs) by area in the 

contributing area of each sampling site (the watershed area 

that drains to the location of the sampling site) as identified 

by the Texas Commission on Environmental Quality Source 

Water Assessment Program are shown in table 2 (Texas 

Commission on Environmental Quality, 2009). Abandoned 

municipal solid waste landfills and petroleum storage tanks 

were the most common PSOCs in the study area. In the six 

largest contributing areas, abandoned municipal solid waste 

landfills were the largest PSOCs followed by petroleum 

storage tanks. Petroleum storage tanks were the largest 

PSOC in the two smallest contributing areas (to the upstream 

and middle San Pedro Creek sampling sites [fig. 1; map 

identifiers SPD–US and SPD–MD]) followed by petroleum 

chemical industry and auto repair, sales, salvage, and towing, 

respectively. Petroleum storage tanks also were the largest 

PSOC in the contributing area of the downstream Martínez 

site followed by auto repair, sales, salvage, and towing. 

Abandoned municipal solid waste landfills were the largest 

PSOC in the contributing area of the upstream Martínez site 

followed by pipelines (Texas Commission on Environmental 

Quality, 2009).

Methods

Streambed Sample Collection

Streambed-sediment and water samples were collected 

during base-flow conditions in January 2014 and again in 

May 2014 following a storm event. The streambed-sediment 

sampling sites were along stream reaches with several 

depositional zones that could be sampled by wading the stream 

(fig. 2; table 1). Care was taken to ensure that the streambeds 

were submerged during the sampling from which streambedsediment samples were collected because comparison of wet 

to dry sediment chemistry is unreliable, especially for organic 

compounds (Shelton and Capel, 1994). 

The collection of streambed-sediment samples was based 

on methods of the USGS National Water-Quality Assessment 

(NAWQA) program (Shelton and Capel, 1994). The NAWQA 

streambed-sediment collection guidelines recommend 

collecting fine-grained particulates from 5 to 10 depositional 

zones along a reach of stream approximately 100 meters in 

length. Depositional zones are locations in streams where the 

energy typically is low and fine-grained particles accumulate 

in the streambed (Shelton and Capel, 1994). Each sediment 

sample consisted of 2 to 8 depositional zones along reaches 

of the sampled streams (each reach was approximately 26 

to 1,476 feet in length) (table 1). Some suitable depositional 

zones were not sampled because they were too deeply 

inundated to wade, too widely spaced along the stream reach, 

or inaccessible because of thick vegetation or steep banks. 

All sediment samples were collected by wading the 

stream; each depositional zone was approached by one or 

two field personnel from the downstream direction so as not 

to disturb the streambed sediment (fig. 3A). After rinsing 

precleaned sampling equipment with native water, surficial 

streambed sediment (about 1 centimeter deep) was collected 

from the multiple depositional zones with a Teflon spoon and 

composited in a glass container. The total volume (wet) of 

streambed sediment collected at each stream reach was about 

1 liter (L). Streambed-sediment samples were stored on ice 

immediately after collection and processed in the USGS office 

in San Antonio. 
4 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Base modified from U.S. Geological Survey 1:1,000,000-scale digital data

Albers Equal Area Conic projection

North American Datum of 1983 

281

1604

10

10

10

35

35

37

410

Leon Creek

Apache Creek

Olmos Creek

Leon Creek

Panther Springs Cre ek

Zarzamora Creek

Salado Creek

Alazán Creek

San Antonio River

San Antonio River

San Pedro Creek

Martínez Creek

Leon Creek

Apache Creek

Olmos Creek

San Antonio River

Leon Creek

Panther Springs Cre ek

Zarzamora Creek

Salado Creek

San Pedro Creek

Alazán Creek

San Antonio River

Martínez Creek

EXPLANATION

Land cover

 Water

 Developed, open space

 Developed, low intensity

 Developed, medium

 intensity

 Developed, high intensity

 Barren land

 Deciduous forest

 Evergreen forest

 Mixed forest

 Shrub, scrub

 Grassland, herbaceous

 Pasture/hay

 Cultivated crops

 Woody wetlands

Watershed boundary

U.S. Geological Survey

 sampling site with map

 identifier (table 1)

 where streambed-

 sediment samples and

 samples for water-

 toxicity testing

 were collected

 

SAR

0 1 2 MILES

0 1 2 KILOMETERS

98°35' 98°30' 98°25'

29°35'

29°30'

29°25'

SPD-US

SPD-DS

MTZ-DS

MTZ-US

ALZ-US

APC-US

APC-DS

ALZ-DS

SPD-MD

SAR

SPD-US

SPD-DS

MTZ-DS

MTZ-US

ALZ-US

APC-US

APC-DS

ALZ-DS

SPD-MD

SAR

BEXAR COUNTY

San Antonio

Area enlarged

Study

area

MTZ-US

MTZ-DS

ALZ-US

ALZ-DS

APC-US

APC-DS

SPD-US

SPD-MD

SPD-DS

SAR

Upstream Martínez

Downstream Martínez

Upstream Alazán

Downstream Alazán

Upstream Apache

Downstream Apache

Upstream San Pedro

Middle San Pedro

Downstream San Pedro

San Antonio River

Short name for sampling 

site (table 1)

Map

identifier

BEXAR COUNTY

TEXAS

Figure 1. Land cover characteristics of the contributing area associated with each site where streambed-sediment samples and 

samples for water-toxicity testing were collected from the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San 

Antonio River, San Antonio, Texas, 2014. Land cover data are from Homer and others (2015).
Table 1. Total length of sampled reach, contributing area, and land use of the contributing area to each site where streambed-sediment samples antesting were collected from the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. National Land Cover Database (Homer and others, 2015).[ft, feet; mi2, square miles]

U.S. Geological Survey station 

number and name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Total 

length of 

sampled 

reach 

(ft)

Number 

of 

locations 

sampled 

in reach

Contributing 

area 

(mi2)

Land use

Developed1

(percent)

Forest2

(percent)

Shrub 

and 

scrub 

(percent)

Pasture, 

hay, and 

cultivated 

crops 

(percent)

Grassland, 

herbaceous 

(percent)

W

(p

08178345Martínez Creek at West Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez 

MTZ-US 1,476 5 4.5 100.0 0.0 0.0 0.0 0.0 

08178375Martínez Creek at West Poplar Street, San Antonio, Tex.

Downstream 

Martínez 

MTZ-DS 820 6 7.1 100.0 0.0 0.0 0.0 0.0 

08178310Alazán Creek at West Laurel Street, San Antonio, Tex.

Upstream 

Alazán

ALZ-US 755 7 8.2 98.6 0.6 0.2 0.0 0.0 

08178410Alazán Creek at Tampico Street, San Antonio, Tex.

Downstream 

Alazán

ALZ-DS 295 6 17.5 99.1 0.3 0.1 0.0 0.2 

08178445Apache Creek at West Commerce Street, San Antonio, Tex.

Upstream 

Apache

APC-US 26 2 15.8 96.8 1.3 1.0 0.4 0.3 

08178460Apache Creek at South Brazos Street, San Antonio, Tex.

Downstream 

Apache

APC-DS 266 8 22.6 97.3 0.9 0.8 0.2 0.3 

08178100San Pedro Creek at Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro

SPD-US 318 5 1.8 100.0 0.0 0.0 0.0 0.0 

08178465San Pedro Creek at West Cevallos Street, San Antonio, Tex.

Middle San 

Pedro

SPDMD 384 6 2.7 100.0 0.0 0.0 0.0 0.0 

08178504San Pedro Creek at Probrandt Street, San Antonio, Tex.

Downstream 

San Pedro

SPD-DS 443 7 44.7 98.3 0.6 0.5 0.1 0.3 

08178515San Antonio River at Mission Road, San Antonio, Tex.

San Antonio 

River

SAR 30 2 94.9 94.3 2.8 0.9 0.1 0.4 

1Includes open space and low, medium, and high intensity development.2Includes deciduous, evergreen, and mixed forests.
6 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

JOINT BASE

SAN ANTONIOLACKLAND KELLY

FIELD

ANNEX

JOINT BASE

SAN ANTONIOFT. SAM

HOUSTON

The Alamo

Mission

Concepción

San José

Mission

San Pedro Creek

Alazán Creek

Base modified from City of San Antonio digital data

State Plane Texas South Central Projection

North American Datum of 1983 

Leon Creek

Elmendorf 

Lake

Woodlawn

Lake

San

Antonio

Olmos Creek

River

Apache Cree k

Martínez Creek

San Antonio River

0 1 2 MILES

0 1 2 KILOMETERS

BEXAR COUNTY

TEXAS

HILDEBRAND AVE

CEVALLOS ST

PROBANDT ST

MISSION RD

TAMPICO ST

W LAUREL ST

W POPLAR ST

BRAZOS ST

W COMMERCE ST

SANTA ROSA ST

10

410

10

410

£¤281

35

151

10

37

35

90

BEXAR COUNTY

Study area

Area enlarged

San

Antonio

MTZ-US

ALZ-US

APC-US SPD-US

APC-DS

SPD-MD

ALZ-DS

SPD-DS

SAR

MTZ-DS

98°35'15" 98°32'00" 98°28'45"

29°30'00"

29°26'15"

29°22'30"

EXPLANATION

Military base

Stream segments representing the extent of

 the planned restoration project (San Antonio

 River Authority, 2016)

Study area boundary

Historic site

U.S. Geological Survey sampling site

 with map identifier (table 1) where

 streambed-sediment samples and samples

 for water-toxicity testing were collected

SAR

Figure 2. Locations of sites where streambed-sediment samples and samples for water-toxicity testing were collected from the 

Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. 
A B CFigure 3. A, streambed-sediment sample collection; B, processing (from Wilson, 2016); and C, collection of water samples for toxicity-testing used aCreeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. 
Table 2. Top 10 potential sources of contamination (Texas Commission on Environmental Quality, 2009) in contributing areas of sites where streambecollected from the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. [mi2, square miles; ft2, square feet; TNRCC, Texas Natural Resource Conservation Commission] Map identifier (fig. 1) MTZ-US MTZ-DS ALZ-US ALZ-DS 

Contributing area (mi2) 4.5 7.1 8.2 17.5 

Rank of source Source type Area (ft2) Source type Area (ft2) Source type Area (ft2) Source type Area (ft2) 

1 Municipal solid waste - abandoned 60,000 Petroleum storage tank 95,000 Municipal solid waste - abandoned 180,000 Municipal solid waste - abandoned 240,000 M2 Pipeline 56,000 Auto repair, sales, salvage, towing 66,000 Petroleum storage tank 84,000 Petroleum storage tank 226,000 P3 Petroleum storage tank 52,000 Municipal solid waste - abandoned 60,000 Auto repair, sales, salvage, towing 43,000 Auto repair, sales, salvage, towing 138,000 P4 Auto repair, sales, salvage, towing 28,000 Pipeline 56,000 Pipeline 42,000 Pipeline 98,000 A5 Confined animal feeding operation 25,000 Confined animal feeding operation 25,000 Mined land: active or abandoned 20,000 Pesticide, fertilizer manufacturing, sale, application 35,000 M6 Pesticide, fertilizer manufacturing, sale, application 13,000 Organic Chemical Industry 25,000 Pesticide, fertilizer manufacturing, sale, application 14,000 Confined animal feeding operation 25,000 R7 Tire sales, repair business 5,000 Pesticide, fertilizer manufacturing, sale, application 19,000 Paint shop 10,000 Organic Chemical Industry 25,000 P8 Paint shop 4,000 Paint shop 7,000 Tire sales, repair business 9,000 Paint shop 22,000 C9 Pesticide manufacturing, sale, application 3,000 Pesticide manufacturing, sale, application 7,000 New or used oil site 6,000 Mined land: active or abandoned 20,000 T

10 New or used oil site 2,000 Tire sales, repair 

business

6,000 Chemical storage 5,000 Tire sales, repair 

business

20,000 N
Table 2. Top 10 potential sources of contamination (Texas Commission on Environmental Quality, 2009) in contributing areas of sites where streambecollected from the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued[mi2, square miles; ft2, square feet; TNRCC, Texas Natural Resource Conservation Commission]

Map identifier (fig. 1) APC-DS SPD-US SPD-MD SPD-DS 

Contributing area (mi2) 22.6 1.8 2.7 44.7 

Rank of source Source type Area (ft2) Source type Area (ft2) Source type Area (ft2) Source type Area (ft2) 

1 Municipal 

solid waste - abandoned

660,000 Petroleum storage 

tank

51,000 Petroleum storage 

tank

86,000 Municipal 

solid waste - abandoned

960,000 Mu

sa

2 Petroleum storage 

tank

207,000 Petroleum 

Chemical Industry

25,000 Auto repair, sales, 

salvage, towing

26,000 Petroleum storage 

tank

559,000 Petr

t

3 Auto repair, sales, 

salvage, towing

114,000 Auto repair, sales, 

salvage, towing

17,000 Confined animal 

feeding operation

25,000 Auto repair, sales, 

salvage, towing

296,000 Pip

4 Pipeline 112,000 Paint shop 5,000 Petroleum 

Chemical Industry

25,000 Pipeline 280,000 Aut

s

5 Mined land: active 

or abandoned

40,000 Pesticide, 

fertilizer manufacturing, sale, application

4,000 Organic Chemical 

Industry

25,000 Pesticide, fertilizer 

manufacturing, sale, application

61,000 Sep

6 Radiochemical 

site

35,000 Superfund site - 

TNRCC

4,000 Paint shop 6,000 Mined land: active 

or abandoned

60,000 Min

o

7 Treatment plant 25,000 Tire sales, repair 

business

3,000 Radiochemical 

site

5,000 Confined animal 

feeding operation

50,000 Pes

ms

8 Pesticide, fertilizer 

manufacturing, sale, application

21,000 Plastic 

manufacturing, sales

2,000 Tire sales, repair 

business

5,000 Radiochemical site 44,000 Ind

wo

9 Chemical storage 19,000 Site discovery - 

TNRCC

2,000 Pesticide, 

fertilizer manufacturing, sale, application

4,000 Chemical storage 42,000 Che

10 Tire sales, repair 

business

14,000 Radiochemical 

site

1,000 Superfund site - 

TNRCC

4,000 Tire sales, repair 

business

42,000 Pain
10 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Streambed-sediment sample processing (fig. 3B) involved 

mixing and sieving the wet sediment. Sieving the samples 

eliminated the grain-size variability that has been shown to 

affect trace-element and organic-compound concentrations 

in sediment samples (Horowitz and Elrick, 1987; Smith and 

others, 1988), allowing for more informative comparisons 

among samples. About one-half of the sample was sieved 

using a 63-micrometer (mm) nylon-cloth sieve for analysis 

of major and trace elements. Sediment greater than 63 mm 

(the diameter differentiating larger, sand-size particles from 

smaller, clay- and silt-size particles) (Wentworth 1922; Guy, 

1969) was discarded. The fine material (less than 63 mm) 

was transferred into 125 milliliter (mL) polypropylene jars 

and transported on ice to the USGS office in Austin where 

they were freeze-dried, pulverized, and shipped to the 

USGS Mineral Resources Program Analytical Laboratories 

in Lakewood, Colorado, for analysis. The other half of the 

sample was sieved by using a 2.0-millimeter (mm) stainlesssteel-mesh sieve on the opening of a 500-mL precleaned glass 

jar and analyzed for organic compounds. Coarse sediment 

(greater than 2.0 mm) was discarded. The samples for 

organic compound analyses were chilled and shipped on ice 

to the USGS National Water Quality Laboratory (NWQL) in 

Lakewood, Colo., for analysis.

Streambed Sediment Analytical Methods

Streambed-sediment samples were analyzed for 

major and trace elements, halogenated organic compounds 

(including pesticides, brominated flame retardants, and PCBs), 

and PAHs. The USGS Mineral Resources Program Analytical 

Laboratories in Lakewood, Colo., analyzed the freeze-dried 

streambed-sediment samples for major and trace elements 

using a variety of analytical methods. Total and inorganic 

carbon was determined by using methods described by Taggart 

(2002). Total carbon was analyzed by combustion with an 

automated carbon analyzer; inorganic carbon was determined 

as carbon dioxide by coulometric titration. Organic carbon 

was then determined as the difference in mass between total 

and inorganic carbon. The percentage of organic carbon in 

the sediment sample is reported. Samples for major and trace 

element analyses were digested completely using a mixture 

of hydrochloric, nitric, perchloric, and hydrofluoric acids and 

analyzed by inductively coupled plasma–mass spectrometry 

(Briggs and Meier, 2002). Concentrations of mercury 

were determined by continuous flow-cold vapor-atomic 

fluorescence spectrometry (Hageman, 2007). 

The NWQL in Lakewood, Colo., analyzed the wet 

streambed-sediment samples for halogenated organic 

compounds and PAHs using a custom analytical method, 

meaning there was not a published method at the time of 

sample analysis. The samples were extracted twice using 

the ASE 200 accelerated solvent extraction system made 

by Dionex (Sunnyvale, California) at a pressure of 13,800 

kilopascals with a water/isopropyl alcohol mixture (50:50, 

volume-to-volume ratio) at 120 degrees Celsius (°C) and then 

a water/isopropyl alcohol mixture (20:80, volume-to-volume 

ratio) at 200 °C for 40 minutes. As explained in Wilson (2016, 

p. 11) “surrogate compounds were added to the sample prior 

to extraction to monitor laboratory preparation, matrix effects 

(Rowe and others, 2005; Geboy and Engle, 2011), and method 

performance.” The extracts were analyzed by capillary-column 

gas chromatography/mass spectrometry (GC/MS) by using 

an Agilent Technologies Model 5975 GS/MS, with the mass 

spectrometer (MS) operated in the electron capture negative 

ion mode using ammonia as the reactant gas. The halogenated 

organic compounds were identified by selected ion monitoring 

using the ions of interest (Mark Burkhardt and Steven Zaugg, 

U.S. Geological Survey National Water Quality Laboratory, 

written commun., July 2007). 

Wet streambed-sediment samples also were analyzed for 

PAHs by the NWQL. The samples were extracted by using 

the ASE 200 accelerated solvent extraction system (Dionex, 

Sunnyvale, Calif.) as described previously for the halogenated 

organic compounds. The constituents of interest then were 

isolated from the extract by using disposable solid-phase 

extraction (SPE) cartridges containing divinylbenzenevinylpyrrolidone copolymer resin. The SPE cartridge was 

dried partially with nitrogen gas, and sorbed compounds were 

eluted with a dichloromethane/diethyl ether mixture (80:20, 

volume-to-volume ratio) and passed through a second SPE 

cartridge, either a sodium sulfate or Florisil SPE cartridge, to 

dry and further “clean up” the extract by removing unwanted 

impurities. The concentrated extract was solvent exchanged 

into ethyl acetate, the solvent volume reduced, internal 

standard compounds added, and then analyzed by capillarycolumn GC/MS on an Agilent Technologies Model 5973, with 

the MS operated in the electron impact, full scan mode (Zaugg 

and others, 2006). 

Water Quality Toxicity Sample Collection

Water samples for use in toxicity testing were collected 

from the nine sites on the Westside Creeks and the site on the 

San Antonio River during base-flow conditions (January 2014) 

and following a storm event (May 2014). Samples for watertoxicity testing were grab samples collected into new 20-L 

carboys (fig. 3C) that were certified for use in metal analyses. 

Samples were chilled immediately to about 4 °C and shipped 

overnight for analysis by the USGS Columbia Environmental 

Research Center (CERC) in Columbia, Missouri. Water 

samples were stored in the dark at a temperature of about 4 °C 

prior to analysis. 

Water Quality Toxicity Analytical Methods

Water samples from the nine sites on the Westside Creeks 

and the site on the San Antonio River were evaluated at the 

CERC in two rounds of standard 7-day water-toxicity testing 

as an indicator of ecological health. Water samples collected 

from the 10 sites during base-flow conditions at the end of 
Methods 11

January 2014 were tested in the first round and 10 additional 

water samples collected in late May 2014 from the same sites 

were tested in the second round. Toxicity endpoints consisted 

of the 7-day survival and biomass of Pimephales promelas

(fathead minnow) that were exposed to either environmental 

water or diluted or undiluted control water starting with 

recently hatched fish larvae that were slightly more than 

48-hours old (U.S. Environmental Protection Agency, 2002). 

Water in the tanks holding the test organisms was replaced 

every 3 days with water from the same sources (and when 

applicable, diluted in the same manner) as the original water 

used to fill the tanks for the experiments. 

At the end of the 7-day exposure, the surviving fish were 

placed in clean control water and exposed to 7.5 microWatts 

per square centimeter (μW/cm2) ultraviolet radiation (UV) 

for 4 hours to evaluate the potential lethality associated with 

photoactivated compounds that may accumulate in the fish 

tissues (Little and others, 2007). Survival of test organisms 

was determined after the 4-hour pulse exposure to UV and 

after a subsequent 20-hour recovery period under ambient 

laboratory lighting conditions. 

Quality Control

Quality-control (QC) samples were collected and 

analyzed to help assess the amount of variability and bias 

found in the environmental sample results (Mueller and 

others, 2015). The QC samples submitted to the analytical 

laboratories by project personnel included four streambedsediment sample duplicates and two reference samples. 

Concurrent duplicate samples were collected, meaning that 

two samples were collected by using identical methodology 

and as closely together in time and space as possible 

(Horowitz and others, 1994). Duplicate sample results can be 

affected by sample heterogeneity, particularly when sediment 

is the sample medium (Pirkey and Glodt, 1998). The relative 

percent difference (RPD) was calculated between each pair of 

duplicate analyses to provide a measure of variability using 

the equation: 

1 2

1 2

| | RPD 100

( ) / 2

C C

C C

− = × + , (1)

where

C1 is the constituent concentration in the 

environmental sample, and 

C2 is the constituent concentration in the 

duplicate sample.

Reference samples contain known concentrations of 

selected analytes and are used to estimate positive or negative 

bias (if the measured value is greater than or less than the 

known concentration). National Institute of Standards and 

Technology (NIST) reference material 8704 (Buffalo River 

Sediment; National Institute of Standards and Technology, 

2000) for selected trace elements and NIST standard reference 

material 1941b (Organics in Marine Sediment; National 

Institute of Standards and Technology, 2015) for selected 

pesticides, PCBs, and PAHs were analyzed by the USGS 

laboratories.

Inorganic Analysis

The RPDs calculated for trace element analytes in the 

four duplicate samples collected in the Westside Creeks during 

2014 (table 3, at end of report) are summarized in table 4. The 

RPDs for the trace element analyses ranged from 0 to 9.7 with 

a median value of 0.58, indicating low variability between 

duplicate streambed-sediment samples. Low variability (high 

precision) between concurrent duplicate samples is indicative 

of proper sampling techniques, which ensures comparability 

between sites and sample sets.

Comparisons of reference material 8704 (Buffalo River 

Sediment) analysis by the USGS Mineral Resources Program 

Analytical Laboratories to the NIST concentration values 

Table 4. Statistical summary of relative percent difference (RPD) between environmental and duplicate streambed-sediment samples 

collected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks), San Antonio, Texas, 2014.

[RPD, relative percent difference]

Category Number of 

samples

Minimum 

RPD

Maximum

RPD

Mean 

RPD

Median

RPD

Trace elements 4 0 9.7 0.90 0.58

Halogenated organic compounds

 Pesticides 4 0 37 6.4 4.6

 Polychlorinated biphenyls (PCBs) 4 0.26 11 5.4 5.0

 Brominated flame retardants 4 0.41 30 5.6 3.3

Polycyclic aromatic hydrocarbons (PAHs) 4 0 17 5.6 3.7

All duplicate samples 4 0 37 3.9 1.9
12 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

generally indicate negligible bias in inorganic constituents 

during environmental sample analyses (table 5, at end of 

report). Results for the analysis were within the range of 

uncertainty (known concentration of a constituent in the NIST 

reference material plus or minus one standard deviation) 

(table 5) for 11 of 22 analytes, greater than the range of 

uncertainty for 4 of the 22 analytes, and less than the range 

of uncertainty for 7 of the 22 analytes. Trace elements for 

which negative bias was observed (results less than the range 

of uncertainty) are of concern because there is the potential 

for false negatives (concentrations reported as less than the 

applicable reporting level when they were likely greater than 

the applicable reporting level) and the possibility that the 

analytes are present in greater, potentially toxic concentrations 

in the environmental samples than reported by the laboratory. 

The concentrations of inorganic analytes in the environmental 

samples were adjusted by factors developed from the results 

of the reference material analysis. Comparisons of the 

environmental sample concentrations among sites, sampling 

events, and to sediment-quality guidelines before and after 

adjustments indicated that the bias had no apparent effect on 

the interpretation of the study results. The concentrations of 

inorganic analytes in the environmental sample results are 

therefore used in this report as received from the laboratory.

Organic Analysis

The RPDs calculated for the four organic duplicate 

samples collected in the Westside Creeks during 2014 

(tables 6 and 7, at end of report) are summarized in table 4. 

The comparisons of duplicate sample results indicate 

greater variability in the halogenated organic compound 

concentrations (RPDs ranged from 0 to 37) than in the 

PAH concentrations (RPDs ranged from 0 to 17). From the 

RPDs calculated for organic compounds, 204 of the 207 

(96 percent), including all of those calculated for PCBs 

and PAHs, were less than 20 percent. One RPD calculated 

for the antimicrobial pesticide triclosan (RPD of 37.0), 

and one each RPD for the brominated flame retardants 

1,2-bis(2,4,6-tribromophenoxy) ethane (TBE) (RPD of 29.9) 

and Bis(hexachlorocyclopentadieno) cyclooctane (trade name 

Dechlorane plus) (RPD of 20.6) exceeded 20 percent, which 

is not unusual when comparing concurrent duplicate sediment 

samples. Overall, variability in the analysis of organic 

compounds was low, which is indicative of proper sampling 

and analytical processes that allow comparability between 

sites and sample sets; no organic environmental data were 

rejected from the dataset based on variability. 

Quality control for the NWQL for the halogenated 

organic compound and PAH analyses consisted of analyzing 

a laboratory reagent blank (hereinafter called a laboratory 

set blank) and a laboratory reagent spike (hereinafter called 

a set spike) with each set of environmental samples. The 

halogenated organic compound samples collected at the 

sites in the Westside Creeks and San Antonio River in 2014 

were analyzed in six different sets (table 8, at end of report); 

PAH samples were analyzed in four different sets (table 9, 

at end of report). Halogenated organic compound and PAH 

concentrations equal to or greater than their respective 

interim reporting levels (IRLs) are hereinafter referred to 

as “detections” or “detected concentrations.” The IRL is a 

temporary reporting level used for new or custom schedules 

when long-term method detection limit data are unavailable 

and a laboratory reporting level has not yet been established 

(U.S. Geological Survey, 2002, table 5). 

Laboratory set blank samples are intended to demonstrate 

processing and analysis by the laboratory are not sources 

of contamination (Mueller and others, 2015). Five to seven 

halogenated organic compounds were detected in each of the 

laboratory set blank samples (table 8). Four to eighteen PAHs 

were detected in each of the laboratory set blank samples 

(table 9). Whenever a halogenated organic compound or 

PAH was detected in its respective laboratory set blank, the 

quantification of that same compound in the environmental 

samples in that same set was marked as estimated with an 

“E” remark code. The value was further qualified with a “v” 

value-qualifier code indicating the sample was associated 

with a laboratory blank in which the compound was detected 

(Childress and others, 1999). Detections of halogenated 

organic compounds and PAHs in laboratory set blank samples, 

particularly at concentrations equal to or greater than their 

IRLs, indicate the possibility of positive bias and false 

positives during environmental sample analyses. Five of the 

six detections of PBDE 47 and two of the six detections of 

PBDE 99 in the halogenated organic compound laboratory 

set blank samples, and one of the three detections of bis(2-

ethylhexyl) phthalate in the PAH laboratory set blank samples 

were present in concentrations greater than their respective 

IRLs. The detections of the compounds in the environmental 

samples were at concentrations of 1.5 to 1,447 times greater 

than the detected concentrations in their respective laboratory 

set blanks; therefore, no environmental data were rejected 

or adjusted on the basis of the results obtained from blank 

samples. All values marked as estimated (E) on the basis of 

laboratory set blank detections were used as reported by the 

laboratory in data analysis including comparisons among sites, 

sampling events, and to sediment-quality guidelines. 

Based on laboratory set spike recoveries, the analytical 

method performance and potential bias indicate the 

environmental sample results can be interpreted as reported by 

the laboratory without adjustment. The overall average spike 

recovery for the halogenated organic compounds was 70.3 

percent and 118 percent for PAHs (tables 8 and 9). The NWQL 

establishes annually acceptable spike recovery ranges on the 

basis of historical spike analyses (D.L. Stevenson and A.R. 

Barnard, U.S. Geological Survey, written commun., 2013). 

Spike recoveries were within acceptable recovery ranges for 

223 of the 234 (95 percent) individual recovery values of the 

spike samples analyzed for halogenated organic compounds 

and for 104 of the 114 (91 percent) of the individual recovery 

values for those analyzed for PAHs. Eight of the eleven 

spike recoveries that were outside of their acceptable ranges 
Methods 13

for halogenated organic compound analysis were less than 

their acceptable ranges (negatively biased), whereas all of 

the spike recoveries that were outside of their acceptable 

ranges for PAH analysis were greater than their acceptable 

ranges (positively biased). The spike recoveries for triclosan 

in all six laboratory set spikes were less than the lower limit 

(14 percent) of the acceptable range and ranged from an 

estimated value of 2.8 percent to an estimated value of 7.6 

percent, indicating a possible large negative bias in triclosan 

concentrations and the possibility of frequent false negatives 

during environmental sample analyses. For this reason, the 

four detections of triclosan in the environmental samples were 

assigned an “E” remark code and further qualified with an 

“m” value-qualifier code indicating the sample was biased on 

the basis of an associated laboratory set spike (Childress and 

others, 1999). Triclosan concentrations are included in the 

dataset as reported by the laboratory, but the concentrations 

were not used in data analysis in this report.

The environmental sample results were adjusted for the 

laboratory set spike recoveries to assess the possible effect of 

the analytical method performance on the data interpretation. 

The environmental sample concentrations were raised or 

lowered as needed to represent a 100-percent spike recovery. 

Comparisons of the environmental sample concentrations 

among sites, sampling events, and to sediment-quality 

guidelines before and after spike adjustments indicated 

that the spike recovery rates had no apparent effect on the 

interpretation of the study results; therefore, the environmental 

sample results are used in this report as received from the 

laboratory. Because laboratory set spikes are prepared using 

reagent water (deionized water that is continuously purged at 

the NWQL with ultrapure nitrogen and assumed to be void of 

the analytes of interest), any possible matrix effects associated 

with any organic matter, and (or) constituents other than the 

target constituent that might be present in the environmental 

samples, are not accounted for by laboratory set spike 

recovery rates (Rowe and others, 2005). 

One sample of reference material 1941b (Organics 

in Marine Sediment; National Institute of Standards and 

Technology, 2015) containing known concentrations of 

a set of organic compounds was submitted to evaluate 

laboratory method performance. A single reference sample, 

while not sufficient to make statistical assessment of overall 

laboratory performance, can be used as a general indicator 

of performance. As with all the environmental samples, a 

set spike was analyzed by the NWQL with the reference 

material sample. Recoveries from that set spike were within 

the acceptable ranges for each constituent for the majority of 

the organic compounds. For completeness, the NIST reference 

material values were compared to both an unadjusted 

concentration (as reported by the laboratory analyzing the 

sample) and an adjusted concentration that was increased or 

decreased as needed to represent a 100-percent spike recovery. 

Comparisons of the reference sample concentrations before 

and after spike adjustments indicated no apparent effect on 

the overall bias distribution in the datasets; therefore, the 

concentrations of the organic compounds in the reference 

sample are used in this report as received from the laboratory. 

The reference material (table 5) contained one 

pesticide (DDT) with NIST certified concentrations 

less than the laboratory IRLs. Concentrations of the 

other six pesticides obtained during analysis by USGS 

laboratories were less than the known concentrations, 

including false negatives (concentrations reported as 

less than the applicable reporting level when they were 

likely greater than the applicable reporting level) in the 

analysis of dichlorodiphenyldichloroethane (DDD) and 

dichlorodiphenyldichloroethylene (DDE). Recoveries from 

USGS laboratory analysis of pesticides in the reference 

material ranged from approximately 2 percent in transnonachlor to approximately 19 percent in cis-nonachlor, 

indicating the possibility of substantial negative bias in 

environmental sample concentrations of these pesticides. 

Concentrations of 16 PCBs obtained during analysis by 

USGS laboratories were less than the known concentrations, 

including false negatives in the analysis of PCB congeners 

49, 52, 70, 110, 138, and 146. PCBs consist of as many as 

209 theoretically possible chlorinated compounds, called 

congeners, with various numbers and positions of chlorine 

atoms attached to the biphenyl structure (U.S. Environmental 

Protection Agency, 2016b). For identification purposes, each 

PCB compound (congener) has been assigned a number from 

1 to 209; the number generally increases with increasing 

chlorination of the biphenyl structure (Ballschmiter and Zell, 

1980, table 2, p. 21). Recoveries from reference material 

analysis of the other 10 PCB congeners by the USGS 

laboratories ranged from approximately 18 percent in PCB 

congener 101 to approximately 66 percent in PCB congener 

170, indicating the possibility of moderate negative bias 

in environmental concentrations. The reference material 

contained four PAH compounds with NIST certified 

values less than their respective laboratory IRLs. Of the 

other 18 PAH compound concentrations obtained during 

analysis by USGS laboratories, 11 were greater than the 

known concentrations, and 5 were less than the known 

concentrations. Recoveries from USGS laboratory analysis 

of PAHs in the reference material ranged from approximately 

38 percent in indenopyrene to approximately 213 percent in 

2,6-dimethlnaphthalene with a median of approximately 115 

percent, indicating a possible positive bias in overall PAH 

concentrations in environmental samples (table 5). 

For completeness and comparison, the concentrations 

of organic compounds in the environmental samples were 

adjusted by factors developed from the results of the reference 

material analysis. Comparisons of the environmental sample 

concentrations among sites, sampling events, and to sedimentquality guidelines before and after adjustments indicated that 

the bias could have had an effect on the concentrations of 

certain halogenated organic compounds. The concentrations 

of organic compounds in the environmental sample results 

are used in this report as received from the laboratory, but 

instances when bias could be a concern are addressed.
14 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Occurrence and Concentrations of 

Selected Trace Elements, Halogenated 

Organic Compounds, and Polycyclic 

Aromatic Hydrocarbons in Streambed 

Sediment 

Concentrations of the contaminants in the streambedsediment samples were compared to the consensus-based 

sediment quality guidelines (SQGs) of MacDonald and others 

(2000) to determine the degree of contamination (table 10). 

The SQGs evaluate the potential toxicity of bed sediments 

to benthic biota (sediment-dwelling organisms). Two SQG 

concentration levels are used: (1) a lower level, called the 

threshold effect concentration (TEC), below which harmful 

effects to benthic biota are not expected, and (2) a higher 

level, the probable effect concentration (PEC), above which 

harmful effects are expected to occur frequently. Samples with 

concentrations between the TEC and PEC are not predicted to 

be toxic or nontoxic to benthic biota. The sediment screening 

levels used by the Texas Commission for Environmental 

Quality’s Ecological Assessment Program (Texas Commission 

for Environmental Quality, 2015) are identical to the PECs of 

MacDonald and others (2000). 

Trace Elements

Trace elements are naturally occurring and typically 

found in sediment samples; they also can be derived from 

anthropogenic sources. The concentrations of arsenic, 

cadmium, chromium, copper, lead, mercury, nickel, and zinc 

in the streambed-sediment samples collected in the Westside 

Creeks and San Antonio River in 2014 were compared to 

their sediment-quality guidelines (fig. 4). The concentrations 

of arsenic, cadmium, mercury, and nickel were less than the 

TEC in all of the samples. Lead and zinc were most frequently 

detected at concentrations greater than the TEC (90 percent 

of all analyses). Concentrations of lead in all four samples 

collected at the upstream San Pedro and middle San Pedro 

sites were greater than the PEC of 128 mg/kg (fig. 4). Lead 

is a toxic metal that has been shown to be strongly related to 

urban land use (Callender and Rice, 2000; U.S. Environmental 

Protection Agency, 2016a). Prior to regulation efforts, lead 

was used as a pigment in paint, in water supply pipes, and 

as a fuel additive. In 2016, the manufacture of automobile 

components, including lead-acid batteries, is one of the most 

common uses of lead in the United States (U.S. Environmental 

Protection Agency, 2016a). Consistent with Callender and 

Rice (2000), land use in the contributing areas of the upstream 

and middle San Pedro sites is highly urbanized and typical 

of the entire study area (table 1). Sources of lead in the 

contributing areas of these sites might include older petroleum 

storage tanks that in the past held leaded fuel or possibly from 

a variety of automobile components used in the numerous 

Table 10. Consensus-based sediment-quality guidelines of 

MacDonald and others (2000) that were used to evaluate the 

contaminant concentrations in streambed-sediment samples 

collected from sites on the Westside Creeks (Alazán, Apache, 

Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, 2014.

[mg/kg, milligrams per kilogram; μg/kg, micrograms per kilogram; DDD, 

dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; 

DDT, dichlorodiphenyltrichloroethane; PCBs, polychlorinated biphenyls; 

PAHs, polycyclic aromatic hydrocarbons]

Constituent Threshold effect 

concentration1

Probable effect 

concentration2

Trace elements (mg/kg)

Arsenic 9.79 33.0

Cadmium 0.99 4.98

Chromium 43.4 111

Copper 31.6 149

Lead 35.8 128

Mercury 0.18 1.06

Nickel 22.7 48.6

Zinc 121 459

Halogenated organic compounds (μg/kg)

Chlordane 3.24 17.6

Dieldrin 1.90 61.8

DDD 4.88 28.0

DDE 3.16 31.3

DDT 4.16 62.9

Total PCBs 59.8 676

Polycyclic aromatic hydrocarbons (μg/kg)

Anthracene 57.2 845

Benz(a)anthracene 108 1,050

Benzo(a)pyrene 150 1,450

Chrysene 166 1,290

Dibenzo(a,h)anthracene 33.0 none

Fluoranthene 423 2,230

Fluorene 77.4 536

Naphthalene 176 561

Phenanthrene 204 1,170

Pyrene 195 1,520

Total PAHs 1,610 22,800

1

Threshold effect concentration is the concentration below which harmful 

effects to benthic biota are not expected.

2

Probable effect concentration is the concentration above which harmful 

effects are expected to occur frequently.

automobile-related businesses in the area (table 2). Other trace 

elements detected at concentrations greater than the TEC but 

less than the PEC were chromium (65 percent of all analyses) 

and copper (35 percent of all analyses). 

On the basis of the percentages of concentrations greater 

than the TEC for all eight trace elements during base-flow 

conditions, the greatest number of trace elements in the 
Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHS 15 SPD-US SPD-MD MTZ-US MTZ-DS ALZ-US ALZ-DS APC-US APC-DS SPD-DS SAR SPD-US SPD-MD MTZ-US MTZ-DS ALZ-US ALZ-DS APC-US APC-DS SPD-DS SAR

Map identifier (table 1) Map identifier (table 1)

0

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Concentration, in milligrams per kilogram

[TEC, threshold effect concentration; PEC, probable effect concentration]

TEC TEC

TEC

TEC

TEC

TEC

TEC

TEC

PEC PEC

PEC

PEC

Lead Mercury

Copper

Zinc

Arsenic Cadmium

Chromium

Nickel

Streambed-sediment sample

 concentration

 Base-flow sample

 Poststorm sample

EXPLANATION

Figure 4. Comparison of consensus-based sediment quality guidelines (MacDonald and others, 2000) with concentrations of trace 

elements in streambed-sediment samples collected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro 

Creeks) and San Antonio River, San Antonio, Texas, 2014. 
16 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

sediments occurred at the upstream Martínez site (50 percent), 

and the smallest number occurred at the San Antonio River 

site (12.5 percent) (fig. 4). During poststorm conditions, the 

greatest number of trace elements in the sediments exceeding 

a TEC occurred at the downstream Martínez site (50 percent), 

and the smallest number occurred at the downstream Apache 

site (25 percent). With the exception of arsenic concentrations, 

which were greater in all base-flow samples collected at the 

10 sites compared to the poststorm samples collected at the 

same sites, there was no discernable pattern observed in the 

trace metal concentrations when comparing base-flow and 

poststorm samples. The reduced concentration of arsenic 

following the storm event could indicate a consistent source 

that is either diluted or subject to flushing during storm runoff.

Halogenated Organic Compounds

Unlike trace elements which can occur naturally, the 

halogenated organic compounds discussed in this report 

are almost always associated with human activities. The 

manufacturing, sale, or use of many of these compounds 

(pesticides, brominated flame retardants, and PCBs) was 

banned or restricted in the United States because of their 

persistence in the environment, detrimental effects on plant and 

animal life, or both (U.S. Environmental Protection Agency, 

1997a). However, many other synthetic halogenated organic 

compounds (pesticides and brominated flame retardants) are 

currently (2016) being produced and used in the Unites States; 

selected pesticides in this group were assessed and referred to 

as “current-use pesticides” in this report. 

Many organic compounds are known to sorb to the organic 

matter in sediments (Chiou and others, 1979; Karickhoff and 

others, 1979). The percentage of organic carbon in streambedsediment samples collected during base-flow conditions was 

greater than the percentages measured in samples collected 

during poststorm conditions at 60 percent of the sampled 

sites (fig. 5). The percentage of organic carbon measured 

during base-flow conditions ranged from 1.2 percent at the 

Map identifier (table 1)

SPD-US

SPD-MD

MTZ-USMTZ-DS

ALZ-US

ALZ-DS

APC-US

APC-DS

SPD-DS

SAR

0

1

2

3

4

5

Organic carbon, in percent

EXPLANATION

Streambed-sediment sample

 concentration

 Base-flow sample

 Poststorm sample

Figure 5. Percentages of organic carbon in streambed-sediment samples collected from sites on the Westside Creeks (Alazán, 

Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.
Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHS 17

San Antonio River site to 3.9 percent at the upstream Apache 

site and from 0.78 percent at the San Antonio River site to 

4.9 percent at the upstream Apache site during poststorm 

conditions, which could affect the organic compound 

concentrations in the different sample types. Some, but not 

all, SQGs are based on concentrations normalized to 1 percent 

organic carbon to overcome differences that could be related 

to different types of samples. The PBDE concentrations were 

normalized by dividing them by the percentage of organic 

carbon in the sample before comparisons among PBDE 

concentrations were made.

Pesticides

The concentrations in streambed-sediment samples of 9 

historical-use and 10 current-use pesticides (all of which are 

synthetic, halogenated organic compounds) were investigated 

in this study (fig. 6). The historical-use pesticides discussed 

in this report are toxic, persistent organic pollutants that have 

either been banned for production, sale, and use in the United 

States, or their production, sale, and use are being phased out 

(Agency for Toxic Substances and Disease Registry, 2016). 

Historical-use pesticides were more frequently detected 

in streambed-sediment samples compared to current-use 

pesticides. Three chlordane compounds (cis-chlordane, transchlordane, and trans-nonachlor), which were banned by the 

U.S. Environmental Protection Agency (EPA) in 1988 (U.S. 

Environmental Protection Agency, 1997b), were detected in all 

of the samples collected during both base-flow and poststorm 

conditions (fig. 6). During base-flow conditions, the number 

of pesticides detected at each site ranged from 4 in the sample 

collected from the upstream Apache site to 12 in the sample 

collected at the downstream Martínez site. During poststorm 

conditions, the number of pesticides detected at each site 

ranged from 7 in the sample collected from the upstream 

Apache site to 13 in the sample collected at the upstream San 

Pedro site (Crow and others, 2016). The pesticides alphaendosulfane, dimethyl tetrachloroterephthalate (DCPA), 

tefluthrin, methyl triclosan, and trifluralin were not detected 

in any samples collected during base-flow conditions but 

were detected in some samples collected during poststorm 

conditions. The most frequently detected (60 percent of 

samples) current-use pesticides in samples collected during 

base-flow conditions were the insecticides lambda-cyhalothrin 

and fipronil sulfide. Cyfluthrin, a synthetic pyrethroid 

insecticide, was the most frequently detected (60 percent of 

samples) current-use pesticide in samples collected during 

poststorm conditions. 

MacDonald and others (2000) published consensus-based 

SQGs for chlordane (sum of cis-chlordane, trans-chlordane, 

cis-nonachlor, and trans-nonachlor), dieldrin, DDD, DDE, 

and DDT (table 10). Most of the pesticide concentrations, as 

reported by the laboratory, were less than their respective PEC 

concentrations (fig. 7). Possible negative bias in laboratory 

results for all four chlordane compounds (cis-chlordane, 

trans-chlordane, cis-nonachlor, and trans-nonachlor), DDD, 

and DDT indicates that true environmental concentrations 

could be greater than those reported by the laboratory, 

meaning the compounds could exist in the environment in 

greater (possibly more toxic) concentrations than indicated 

by the reported laboratory values discussed in this report. 

The majority of the detections of dieldrin (13 of 16) and 

DDT (6 of 9) were at concentrations less than their respective 

TECs. The majority of the detections of chlordane (18 of 20) 

and DDE (15 of 18), as reported by the laboratory, were at 

concentrations greater than their respective TECs but less than 

their PECs. Correction for possible negative laboratory bias 

indicated that the environmental concentrations for chlordane 

could possibly exceed the PEC in all samples. Pesticides 

were most frequently detected in concentrations, as reported 

by the laboratory, greater than their PECs in samples from 

the upstream San Pedro and middle San Pedro sites. During 

base-flow conditions, concentrations of DDD, DDE, and DDT 

exceeded their PECs in the sample collected from the middle 

San Pedro site. During poststorm conditions, concentrations 

of chlordane, DDD, and DDE in samples collected at the 

upstream San Pedro site and concentrations of DDD and DDE 

in samples collected at the middle San Pedro site exceeded 

their PECs. Correction for possible negative laboratory bias 

indicated that the number and distribution of environmental 

concentrations exceeding the PEC did not change for DDD; 

however, the concentrations of DDE in as many as seven 

additional samples (five collected during base-flow and two 

collected during poststorm conditions) could have exceeded 

the PEC.

Brominated Flame Retardants

Brominated flame retardants are halogenated organic 

compounds that are added to plastics, foams, and fabrics to 

increase the fire resistance of products such as electronics, 

automobiles, clothing, and furniture. The chemicals are not 

chemically bound to the products to which they are added, 

making them likely to leach out of these products (Shaw and 

others, 2010). Brominated flame retardants are persistent 

in the environment and have been shown to be toxic and to 

bioaccumulate (U.S. Environmental Protection Agency, 2010). 

In 2005, the EPA restricted the manufacturing, importing, 

or processing of pentabromodiphenyl ether (pentaBDE) and 

octabromodiphenyl ether (octaBDE), which are commercial 

mixtures of PDBE congeners (U.S. Environmental Protection 

Agency, 2015). The streambed-sediment samples collected 

from the Westside Creeks and San Antonio River in 2014 

were analyzed for several polybrominated diphenyl ether 

(PBDE) congeners plus three other brominated flame 

retardants: Dechlorane Plus, pentabromotoluene, and 1,2-bis 

(2,4,6-tribromophenoxy) ethane (TBE). Brominated flame 

retardants were found at every site where streambed-sediment 

samples were collected (fig. 8). PBDEs 85, 153, and 154 were 

found in all streambed-sediment samples. Brominated flame 
Detections, in percent 0 10 20 30 40 50 60 70 80 90 

Dieldrin cis-Chlordane trans-Chlordane cis-Nonachlor trans-Nonachlor DDT DDD DDE alpha-Endosulfane Chlorpyrifos Cyfluthrin DCPA lambda-Cyhalothrin Tefluthrin Triclosan Methyl triclosan Desulfinylfipronil Fipronil sulfide Trifluralin

Pesticides

[DDT, dichlorodiphenyltrichloroethane; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DCPA, dimethyl tetrachloroterephthalate]

EXPLANATION

Streambed-sediment sample Base-flow detection Poststorm detection

ND No detection

NDNDNDNDND

Figure 6. Detection frequencies of pesticides in streambed-sediment samples collected from sites on the Westside Creeks (Alazán, Apache, Martínand San Antonio River, San Antonio, Texas, 2014.
Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHS 19

Pesticide concentration, in micrograms per kilogram

0.0

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Map identifier (table 1) SPD-US

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Map identifier (table 1) SPD-US

SPD-MD

MTZ-US

MTZ-DS

ALZ-US

ALZ-DS

APC-US

APC-DS

SPD-DS

SAR

(PEC = 61.8)

(26.7)

(162)

(1,120) (41.5) (204)

(61.2)

(142)

EXPLANATION

Sediment quality guidelines

 Probable effect concentration (PEC)

 Threshold effect concentration (TEC)

Streambed-sediment sample concentration

 Base-flow sample, detection

 Poststorm sample, detection

 Base-flow sample, nondetection at interim reporting level

 Poststorm sample, nondetection at interim reporting level

Concentration value off scale

 

[DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene;

DDT, dichlorodiphenyltrichloroethane]

(26.7)

Chlordane Dieldrin

DDT

DDD DDE

Figure 7. Comparison of consensus-based sediment quality guidelines (MacDonald and others, 2000) with concentrations of 

pesticides in streambed-sediment samples collected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro 

Creeks) and San Antonio River, San Antonio, Texas, 2014.
20 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

retardants were more frequently detected in samples collected 

during poststorm conditions (75 percent of the analyses) than 

in those collected during base-flow conditions (67 percent 

of the analyses), with the greatest increase in the number of 

brominated flame retardants detected when comparing samples 

collected from the San Pedro Creek sites during base-flow and 

poststorm conditions.

To protect benthic and pelagic aquatic life, Environment 

Canada has established guidelines referred to as “Federal 

Environmental Quality Guidelines” (FEQGs) for the 

concentrations of PBDE 99 and PBDE 100 in stream 

sediments. According to Environment Canada (2013, p. 2), 

the FEQGs “provide benchmarks for the quality of the 

ambient environment. Where the FEQG is met there is 

low likelihood of adverse effects on the aquatic life or the 

wildlife that may consume them.” The FEQGs (normalized 

to 1 percent organic carbon in sediments) for PBDE 99 and 

PBDE 100 are 0.4 mg/kg (Environment Canada, 2013). 

The concentrations of PBDE 99 and PBDE 100 measured 

in the sediment samples collected during this study were 

normalized to 1 percent organic carbon to compare them to 

the FEQGs. The organic-carbon normalized concentrations 

of PBDE 99 exceeded the FEQG in the 19 streambedsediment samples in which PBDE 99 was detected (fig. 9). 

Organic-carbon normalized concentrations of PBDE 99 

ranged from 0.5 mg/kg in the sample collected during baseflow conditions at the middle San Pedro site to 8.5 mg/kg 

in the sample collected during base-flow conditions at the 

upstream Apache site (fig. 9). The organic-carbon normalized 

concentrations of PBDE 100 exceed the FEQG in 13 of the 

19 streambed-sediment samples in which PBDE 100 was 

detected. Similar to the results for PBDE 99 and PBDE 100, 

the remaining brominated flame retardants that were analyzed 

were also found in the streambed sediments collected from 

all 10 sites at similar concentrations. The organic-carbon 

normalized concentrations of the three most frequently 

Detections, in percent 

0 10 20 30 40 50 60 70 80 90 100

Map identifier (table 1)

SPD-US

SPD-MD

ALZ-US

ALZ-DS

APC-US

APC-DS

MTZ-US

MTZ-DS

SPD-DS

SAR

EXPLANATION

Brominated flame retardants detected

 in streamflow-sediment sample

 Base-flow detection

 Poststorm detection

Figure 8. Detection frequencies of 13 brominated flame retardants in streambed-sediment samples collected from sites on the 

Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. 
Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHS 21 SPD-US SPD-MD MTZ-US MTZ-DS ALZ-US ALZ-DS APC-US APC-DS SPD-DS SAR

Map identifier (table 1)

Brominated flame retardant concentration, in micrograms per kilogram, divided by organic carbon concentration, in percent

0

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EXPLANATION

Environment Canada Federal Environmental Quality

 Guidelines for sediment (Environment Canada, 2013)

Streambed-sediment sample concentration

 Base-flow sample, detection

 Poststorm sample, detection

 Base-flow sample, nondetection at interim reporting level

[PBDE, Polybrominated diphenyl ether]

PBDE 100

PBDE 99

PBDE 85

PBDE 153 

PBDE 154

Figure 9. Comparison of select organic-carbon normalized brominated flame retardant concentrations and Environment Canada 

Federal Environmental Quality Guidelines (FEQGs) for sediment (Environment Canada, 2013) in streambed-sediment samples collected 

from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.
22 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

detected compounds, PBDE 85, PBDE 153, and PBDE 154, 

were compared among the sample collection sites (fig. 9). 

The concentration variations of PBDEs 85, 153, and 154 were 

similar to those of PBDE 99 and PBDE 100. The greatest 

concentrations of organic-carbon normalized PBDEs 85, 

99, 100, 153, and 154 were observed in samples collected 

during base-flow conditions at the upstream Apache site. 

Concentrations of these compounds in the samples collected at 

the same site during poststorm conditions were substantially 

reduced from the base-flow sample concentrations, possibly 

indicating a source that is diluted during rainfall events.

Polychlorinated Biphenyls

Polychlorinated biphenyls were first synthesized in the 

early 1930s and have had widespread industrial uses, primarily 

as plasticizers, hydraulic lubricants, and dielectric fluids in 

electrical capacitors (Smith and others, 1988). Adverse human 

health effects and cancer in animals have been associated with 

exposure to PCBs. Polychlorinated biphenyls have not been 

manufactured in the United States since 1977, and their use 

was generally banned in 1979 (the EPA issues exemptions 

that allow the importation of PCBs by a petition process) 

(Agency for Toxic Substances and Disease Registry, 2000). 

The tendency for PCB congeners to volatilize or sorb strongly 

to solids depends on the degree of chlorination. The larger 

numbered PCB congeners with at least four chlorine atoms 

tend to sorb strongly to solids such as sediments, whereas the 

smaller numbered PCB congeners with three chlorine atoms or 

less are more likely to volatilize (Eisenreich and others, 1983; 

Eisenreich and others, 1992; Pearson and others, 1996; Puri 

and others, 1997). 

The NWQL quantified 18 common PCB congeners 

in the streambed-sediment samples collected from the 

Westside Creeks and San Antonio River in 2014. The two 

smallest PCB congeners (49 and 52) were not detected in 

any of the streambed-sediment samples (Crow and others, 

2016). Polychlorinated biphenyl 70 was detected in only two 

samples collected during base-flow conditions (upstream and 

downstream Apache sites) (fig. 10). Polychlorinated biphenyls 

174, 187, and 194 were found in every streambed-sediment 

sample collected during both base-flow and poststorm 

conditions. The median number of detections of the 18 

common PCB congeners in the individual samples collected 

during both base-flow and poststorm conditions was 12.5; the 

number of detections ranged from 5 in the sample collected 

from the upstream Apache site during base-flow conditions 

to 15 in the sample collected from the middle San Pedro site 

during poststorm conditions. 

MacDonald and others (2000) published a consensusbased SQG for total PCBs (table 10). Total PCBs in 

streambed-sediment samples collected from the Westside 

Creeks and San Antonio River in 2014 were computed as 

the sum of the 18 reported congeners (Crow and others, 

2016) by using the Kaplan-Meier method for computing 

summations that include nondetections (Helsel, 2009). The 

Kaplan-Meier method is a nonparametric statistical method 

that was developed for evaluating right-censored survival 

data of people older than a certain age in medical and 

industrial statistics that has been modified for left-censored 

environmental data where nondetections are common. Total 

environmental PCB concentrations adjusted for negative bias 

(on the basis of organic reference material analysis) indicated 

that although some adjusted concentrations could possibly 

exceed the TEC (59.8 mg/kg; table 10) for total PCBs, 

the negative bias was not great enough to cause adjusted 

concentrations to exceed the PEC (676 mg/kg; table 10) and 

thus be possibly toxic to aquatic biota. All concentrations 

of total PCBs in the individual streambed-sediment samples 

were less than the TEC (fig. 11). The concentrations of total 

PCBs in the samples collected during base-flow conditions 

ranged from an estimated 2.9 mg/kg in the sample collected 

at the upstream Alazán site to an estimated 35 mg/kg at the 

middle San Pedro site; the median concentration of total PCBs 

was an estimated 7.5 mg/kg (Crow and others, 2016). During 

poststorm conditions, the concentrations of total PCBs in the 

samples ranged from an estimated 3.8 mg/kg in the sample 

collected at the downstream Apache site to an estimated 

49 mg/kg in the sample collected at the upstream San Pedro 

site, and the median total PCB concentration was an estimated 

6.6 mg/kg. The concentrations of total PCBs in the samples 

collected during base-flow and poststorm conditions from the 

upstream and middle San Pedro sites were greater than the 

concentrations in the samples collected from the other study 

sites. 

Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons are ubiquitous in 

the urban environment and are derived from numerous 

sources. Common sources in urban settings include coaltar-based sealcoat; automobile exhaust; used motor oil; 

automobile tire particles; and burning wood, oil, coal, or other 

combustibles for cooking, heating, or energy production. 

Coal-tar-based sealcoat contains elevated concentrations 

of PAHs and has been identified as the predominant source 

of PAHs in many urban environments (Mahler and others, 

2005; Van Metre and Mahler, 2010). PAHs rarely occur in 

the environment as individual compounds but are present 

as complex mixtures. PAHs are potential human health 

hazards; several PAH compounds, known as B2 PAHs, have 

been identified as probable carcinogens (U.S. Environmental 

Protection Agency, 1993). In this report, total PAH is the 

sum of 12 compounds: acenaphthene, acenaphthylene, 

anthracene, benzo(a)anthracene, benzo(a)pyrene, chrysene, 

dibenzo(a,h)anthracene, fluoranthene, fluorene, naphthalene, 

phenanthrene, and pyrene (Ingersoll and others, 2001; 

2-methylnaphthalene not included because not measured 

by the NWQL). The greatest total PAH concentration 

(99,000 μg/kg) was measured in the poststorm sample 
Detections, in percent 0 10 20 30 40 50 60 70 80 90 

PCB 49PCB 52PCB 70

PCB 101PCB 110PCB 118PCB 138PCB 146PCB 149PCB 151PCB 170PCB 174PCB 177PCB 180PCB 183PCB 187PCB 194PCB 206

Polychlorinated biphenyl (PCB) congeners

EXPLANATION

Streambed-sediment sample Base-flow detection Poststorm detection

ND No detection

NDNDNDNDND

Figure 10. Detection frequencies of polychlorinated biphenyls (PCBs) in streambed-sediment samples collected from sites on the Westside Creeks (and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.
24 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs Total polychlorinated biphenylsoncentration, in micrograms per kilogram

0

10

20

30

40

50

60

70

Map identifier (table 1)

SPD-US

SPD-MD

MTZ-US

MTZ-DS

ALZ-US

ALZ-DS

APC-US

APC-DS

SPD-DS

SAR

[Probable effect concentration of 676 migrograms per kilograpm is not shown on graph]

Sediment quality guidelines

 Threshold effect concentration

Streambed-sediment sample concentration

 Base-flow sample

 Poststorm sample

EXPLANATION

Figure 11. Comparison of consensus-based sediment quality guidelines (MacDonald and others, 2000) with concentrations of 

polychlorinated biphenlys (PCBs) in streambed-sediment samples collected from sites on the Westside Creeks (Alazán, Apache, 

Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.

collected at the upstream Apache site (Crow and others, 2016). 

The total PAH concentration in the sample collected at the 

same site during base-flow conditions (20,000 μg/kg) was 

also the greatest total PAH concentration measured during 

base-flow conditions. Land use in the contributing area of 

the upstream Apache site is typical of the study area (table 1) 

and therefore provides no insight to the relatively high PAH 

concentrations measured in the streambed-sediment samples 

collected from the site compared to all the other sites. The 

smallest total PAH concentration (750 μg/kg) was measured in 

the poststorm sample collected at the downstream San Pedro 

site (Crow and others, 2016). 

Streambed-sediment samples were compared to the 

consensus-based SQGs developed for several individual 

PAH compounds (anthracene, benz(a)anthracene, benzo(a)

pyrene, chrysene, dibenzo(a,h)anthracene, fluoranthene, 

fluorene, naphthalene, phenanthrene, and pyrene) and total 

PAHs (MacDonald and others, 2000) (fig. 12). Total PAHs and 

each of the 10 individual PAHs were analyzed in 20 samples 

resulting in a total of 220 analyses. The TECs of the PAHs 

for which SQGs were developed were exceeded in 161 of 

220 analyses (73 percent); PECs were exceeded in 30 of 220 

analyses (14 percent), of which 9 (30 percent) were analyses 

from the sample collected during poststorm conditions at 

the upstream Apache site. At the upstream Apache site, 6 

of the individual PAHs measured in the sample collected 

during base-flow conditions exceeded the 9 PECs developed 

by MacDonald and others (2000) and 8 of the 9 PECs were 

exceeded in the sample collected during poststorm conditions. 

The total PAH concentration in the sample collected during 

poststorm conditions (99,000 mg/kg) at the upstream Apache 

Creek site was 3.3 times greater than the PEC developed for 

total PAHs (22,800 mg/kg), making it the most contaminated 

site in regards to total PAHs in the study area. In general, 

TECs were exceeded in a greater number of analyses in 

samples collected during base-flow conditions (76 percent) 

than in those collected during poststorm conditions 

(70 percent). The PECs were exceeded in a greater number 

of analyses during poststorm conditions (17 percent) than in 

those collected during base-flow conditions (11 percent). The 
Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHS 25

0

200

400

600

800

1,000

1,200

1,400

1,600

0

200

400

600

800

1,000

1,200

1,400

0

400

800

1,200

1,600

2,000

2,400

0

100

200

300

400

500

600

0

200

400

600

800

1,000

1,200

1,400

1,600

0

4,000

8,000

12,000

16,000

20,000

24,000

0

200

400

600

800

1,000

0

200

400

600

800

1,000

1,200

0

50

100

150

200

250

300

350

400

0

100

200

300

400

500

600

0

200

400

600

800

1,000

1,200

Polycyclic aromatic hydrocarbon (PAH) concentration, in micrograms per kilogram

Map identifier (table 1) SPD-US SPD-MD

MTZ-US

MTZ-DS

ALZ-US

ALZ-DS

APC-US

APC-DS

SPD-DS

SAR

Map identifier (table 1) SPD-US SPD-MD

MTZ-US

MTZ-DS

ALZ-US

ALZ-DS

APC-US

APC-DS

SPD-DS

SAR

(PEC not established)

(3,000)

(2,300)

(7,900) (2,800)

(2,300)

(2,100)

(10,000) (2,800)

(2,000) (3,700)

(13,000) (4,200)

(3,100)

(5,000)

(26,000) (7,400)

(5,000)

(2,000)

(14,000) (2,700)

(1,700)

(1,200)

(4,000)

(20,000) (6,200)

(1,700) (4,100)

(99,000) (27,000)

(1,400)

(7,900)

EXPLANATION

Sediment quality guidelines

 Probable effect concentration (PEC)

 Threshold effect concentration (TEC)

Streambed-sediment sample concentration

 Base-flow sample, detection

 Poststorm sample, detection

 Base-flow sample, nondetection at interim reporting level

 Poststorm sample, nondetection at interim reporting level

 Poststorm sample, presence verified but not quantified

Concentration value off scale

Anthracene Benzo(a)pyrene

Benzo(a)anthracene Chrysene

Dibenzo(a,h)anthracene Fluoranthene

Fluorene Naphthalene

Phenanthrene Pyrene

Total PAH

Figure 12. Comparison of consensus-based sediment quality guidelines (MacDonald and others, 2000) with concentrations of 

polycyclic aromatic hydrocarbons (PAHs) in streambed-sediment samples collected from sites on the Westside Creeks (Alazán, Apache, 

Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.
26 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

percentage by which a given PAH exceeded its PEC ranged 

from less than 1 percent for chrysene in the sample collected 

during poststorm conditions at the upstream Martínez site 

(chrysene concentration of 1,300 μg/kg; the PEC for chrysene 

is 1,290 μg/kg) to greater than 1,200 percent for pyrene in the 

sample collected during poststorm conditions at the upstream 

Apache Creek site (20,000 μg/kg pyrene concentration; 

the PEC for pyrene is 1,520 μg/kg). The greatest degree of 

PEC exceedance (an average of nearly 700 percent from 

nine analyses) was observed in the sample collected during 

poststorm conditions at the upstream Apache site. 

Van Metre and Mahler (2010, p. 337, table 1) compiled 

PAH source profiles documented in the literature to compare 

to bottom sediments deposited post 1990 in lakes across 

the United States. They normalized the concentrations of 

12 selected PAH compounds (phenanthrene, anthracene, 

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

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

pyrene, indenopyrene, and benzo(g,h,i)perylene) to the 

sum of the 12 compounds to describe the variability of the 

PAH mixtures. The same 12 PAHs described by Van Metre 

and Mahler (2010) were normalized by their sum for the 

streambed-sediment samples collected during base-flow 

conditions and for those collected during poststorm conditions 

at the nine sites on the Westside Creeks and the site on 

the San Antonio River. Average PAH profiles for samples 

collected during base-flow and stormflow conditions at sites 

in the study area were computed by averaging each of the 

12 normalized compounds in the 10 samples collected during 

each hydrologic condition. Average PAH profiles computed 

for base-flow samples and poststorm samples were each 

compared to seven PAH source profiles compiled by Van 

Meter and Mahler (2010) (fig. 13). The seven PAH profiles 

selected for comparison include parking lot coal-tar sealcoat 

dust, automobile emissions measured in tunnels, emissions 

from diesel-powered automobiles, emissions from gasolinepowered automobiles, emissions from coal-fired powerplants, 

used automobile motor oil, and automobile tire particles. 

These seven PAH profiles were determined by Wilson (2011) 

to be the most common contributors of PAHs to sediments in 

Bexar County, Tex., based on results from a chemical mass 

balance source-receptor model. The PAH profiles of both 

the average base-flow and poststorm streambed-sediment 

samples indicated low concentrations of anthracene, benzo(a)

anthracene, benzo(k)fluoranthene, indenopyrene, and 

benzo(g,h,i)perylene and high concentrations of fluoranthene, 

pyrene, and benzo(b)fluoranthene relative to the overall PAH 

mixture. The base-flow and poststorm average concentrations 

of the PAHs were generally the same (within one standard 

deviation) with the exception of benzo(b)fluoranthene. 

The graphical representations of the average base-flow 

and average poststorm streambed-sediment PAH profiles 

most closely resemble that of the parking lot coal-tar sealcoat 

dust PAH source profile (fig. 13), indicating this PAH source 

could be the largest contributor of PAHs in the averaged 

samples. Parking lot coal-tar sealcoat is a black, viscous liquid 

containing coal-tar pitch that is sprayed or painted on asphalt 

pavement and marketed to improve the appearance and extend 

the life of asphalt (U.S. Environmental Protection Agency, 

2012). The source profile of parking lot coal-tar sealcoat 

dust is defined as the average of dust swept from coal-tar 

sealcoated parking lots from six cities in the United States: 

Minneapolis, Minn., Chicago, Ill., Detroit, Mich., Washington, 

D.C., New Haven, Conn., and Austin, Tex. (Mahler and others, 

2005; Van Metre and others, 2009). 

As one of the oldest inhabited areas of San Antonio, the 

Westside Creeks area has been subjected to urban influences 

for many years, and the effect of urbanization was evident 

in the sediment record in the streams. The sediment samples 

collected at all 10 sites sampled for this characterization 

contained elevated concentrations of numerous trace elements, 

pesticides, brominated flame retardants, PCBs, and PAHs; 

often at concentrations greater than the TECs, and sometimes 

greater than the PECs established for those constituents. The 

upstream and middle San Pedro sites were of specific concern 

because during base-flow and poststorm conditions, elevated 

concentrations of lead and historical-use pesticides were 

detected in the sediment samples collected at these sites—

concentrations that consistently exceeded applicable PECs. 

The total PCB concentrations at the upper and middle San 

Pedro sites, although less than the TEC, were the largest total 

PCB concentrations measured among all of the sites in the 

study area. During both base-flow and poststorm conditions, 

six individual PAHs were greater than their PECs, and 

total PAHs were greater than the PEC in samples collected 

during poststorm conditions at the upstream San Pedro site. 

The sediment collected from the upstream Apache site also 

contained high concentrations of PAHs. Greater concentrations 

of the detected PAHs in the poststorm samples compared to 

the base-flow samples collected at both the upstream San 

Pedro and upstream Apache sites indicate there are likely 

active sources of PAHs in the upper reaches of the San Pedro 

and Apache Creeks.
Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHS 27

Phenanthrene

Anthracene

Fluoranthene

Pyrene

Benzo(a)anthracene

Chrysene

Benzo(b)fluoranthene

Benzo(k)fluoranthene

Benzo(e)pyreneBenzo(a)pyrene

Indenopyrene

Benzo(ghi)perylene

Phenanthrene

Anthracene

Fluoranthene

Pyrene

Benzo(a)anthracene

Chrysene

Benzo(b)fluoranthene

Benzo(k)fluoranthene

Benzo(e)pyreneBenzo(a)pyrene

Indenopyrene

Benzo(ghi)perylene

Individual PAH

Individual PAH

0

0.05

0.10

0.15

0.20

0.25

0.30

0

0.05

0.10

0.15

0.20

0.25

0.30

0

0.05

0.10

0.15

0.20

0.25

0.30

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Ratio of individual PAH to total PAHs

0

0.05

0.10

0.15

0.20

0.25

0.30

0

0.05

0.10

0.15

0.20

0.25

0.30

0

0.05

0.10

0.15

0.20

0.25

0.30

Polycyclic aromatic hydrocarbon (PAH) source

Average base-flow streambed sediment

 1 standard deviation error bar

Average poststorm streambed sediment

 1 standard deviation error bar

EXPLANATION

Parking lot coal-tar

sealcoat dust

Automobile emissions

measured in tunnels

Emissions from

diesel-powered

automobiles

Emissions from

gasoline-powered

automobiles

Emissions from

coal-fired

powerplants

Used automobile

motor oil

Automobile

tire particles

Figure 13. Comparison of polycyclic aromatic hydrocarbon (PAH) profiles for selected PAH sources summarized in Van Metre and 

Mahler (2010, table 1, p. 337) to PAH profiles for average streambed sediment computed from samples collected during base-flow and 

poststorm conditions from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, 2014.
28 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Results of Water-Toxicity Testing

The survival and biomass of fathead minnows were 

assessed in water collected from each of the 10 sampling sites 

during base-flow and poststorm conditions and in two types 

of control water. The control water used for survival testing 

consisted of diluted and undiluted groundwater (hereinafter 

referred to as “well water”) from a well at the USGS Columbia 

Environmental Research Center. The hardness of the undiluted 

well water was 300 milligrams per liter (mg/L). The undiluted 

well water was mixed with deionized water to produce diluted 

well water with a hardness of 100 mg/L. 

First, survival of the fathead minnows following exposure 

to water collected during base-flow conditions was evaluated.

Comparisons were made between the survival and biomass of 

fathead minnows exposed to base-flow environmental water 

samples or to well water (diluted and undiluted) used in the 

accompanying control experiments. Control experiments 

assessing the survival and biomass of fathead minnows in 

diluted and undiluted well water were run concurrently with 

the experiments assessing survival and biomass of fathead 

minnows in water samples collected during base-flow 

conditions from the nine Westside Creeks sites and from 

the site on the San Antonio River. The results of the control 

experiments greatly exceeded the test acceptability criterion 

of greater than 80 percent survival (U.S. Environmental 

Protection Agency, 2002) as the survival of fathead minnows 

was greater than or equal to 95 percent in both the diluted and 

undiluted well water. Survival and mean biomass did not differ 

between the control experiments using diluted or undiluted 

well water. 

Six of the ten environmental water samples collected 

during base-flow conditions resulted in appreciably reduced 

survival and biomass relative to the control experiments. The 

water samples collected from the downstream Martínez site, 

the upstream and downstream Alazán sites, the downstream 

Apache site, and from the middle and downstream San 

Pedro sites proved most toxic to the fathead minnows, with 

survival rates ranging from 35 to 68 percent compared to 95 

to 98 percent survival rates in the control experiments. The 

water sample from the downstream San Pedro site caused 

the greatest reductions in both survival and mean biomass 

compared to the control experiments (fig. 14; table 11). The 

4-hour pulse exposure to elevated UV in clean control water 

following initial exposure did not result in any subsequent 

mortality, either during the pulse or after the 20-hour recovery 

period.

Second, survival of the fathead minnows following 

exposure to water collected during poststorm conditions was 

evaluated. Survival of fathead minnows was 100 percent 

in both the diluted and undiluted well water control tests 

that were done in conjunction with the exposure tests using 

water collected during poststorm conditions. As in the 

exposure tests using water collected during base flow, the 

survival exposure experiments using water collected during 

poststorm conditions were done concurrently with the survival 

experiments using diluted and undiluted well water collected 

from the same well used to provide control water in the baseflow exposure tests. Water samples representing poststorm 

conditions were collected from the same 10 sites that were 

used in the exposure experiments using water collected 

during base-flow conditions. The 100-percent survival of 

fathead minnows in diluted and undiluted well water that 

was determined in conjunction with the poststorm sample 

exposure tests greatly exceeded the criterion of greater than 

80 percent survival specified for control tests. Survival and 

biomass did not differ between the two controls. Significant 

differences between control samples and water collected 

from the sampling sites were determined by one-way analysis 

of variance with pairwise comparison using Williams’ test 

(Williams, 1972). If data were not normally distributed or did 

not have equal variances, Steel’s many-one rank test (Steel, 

1959) or Wilcoxon rank sum test with Bonferroni adjustment 

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

level of statistical significance was set at p = 0.05. Results of 

the 7-day exposure tests indicated that exposure of the fish 

to water collected from the sampling sites during poststorm 

conditions did not significantly reduce survival or biomass 

relative to exposure of the fish to the diluted or undiluted 

water used in the control experiments. Survival for fish in all 

10 environmental water samples during poststorm conditions 

was greater than or equal to 97 percent (fig. 14; table 12). The 

4-hour pulse exposure to elevated UV in clean water following 

initial exposure did not result in subsequent mortality, either 

during the pulse or after the 20-hour recovery period. 

Periodically during the toxicity testing, dissolved oxygen 

concentrations, pH, specific conductance, hardness, alkalinity, 

and total and unionized ammonia concentrations were 

measured in the water samples (Crow and others, 2016).The 

samples were also periodically analyzed for the concentrations 

of select major ions (calcium, potassium, magnesium, 

sodium, sulfate, and chloride) during testing (Crow and 

others, 2016). Both ammonia and major-ions concentrations 

were considered as potential contributors to fathead minnow 

toxicity observed during exposure to samples collected during 

base-flow conditions. Concentrations of ammonia were low 

(for example, total ammonia less than 0.45 mg/L) relative 

to published toxicity thresholds for fathead minnows (159.2 

mg/L for acute exposure and 9.187 mg/L for chronic exposure) 

(U.S. Environmental Protection Agency, 2013). The relations 

between fathead minnow survival and concentrations of major 

ions (for example, sodium, sulfate, chloride, and specific 

conductance) in the water samples also were examined, and no 

appreciable correlations were observed. It is unlikely that the 

observed toxicity to fathead minnows from the water samples 

collected during base-flow conditions at the downstream 

Martínez, upstream Alazán, downstream Alazán, downstream 

Apache, middle San Pedro Creek, and downstream San Pedro 

Creek sites was the result of environmental stressors on the 

organisms caused by differences in water-quality constituents 

routinely monitored during toxicity testing (major-ion 

concentrations, dissolved oxygen concentration, pH, specific 

conductance, hardness, alkalinity, and total and unionized 

ammonia concentrations). 
Results of Water-Toxicity Testing 29

SPD-US

SPD-MD

MTZ-USMTZ-DS

ALZ-US

ALZ-DS

APC-USAPC-DS

SPD-DS

SAR

Control Sample 1Control Sample 2

Map identifier (table 1)

0

20

40

60

80

100

120

10

30

50

70

90

110

Fathead minnow survival, in percent

EXPLANATION

Water sample with 1 standard deviation error bar—Base-flow condition

 Sample nontoxic to fathead minnows

 Sample toxic to fathead minnows

Water sample with 1 standard deviation error bar—Poststorm condition.

 Sample nontoxic to fathead minnows

Figure 14. Responses of Pimephales promelas (fathead minnow) in 7-day exposure to water samples collected during base-flow and 

poststorm conditions from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San 

Antonio, Texas, 2014.

The relations between fathead minnow survival and 

concentrations of selected constituents in the streambedsediment samples collected during base-flow conditions also 

were examined to determine if any correlations might exist. 

Fathead minnow survival was compared to concentrations 

in streambed sediments of lead; the pesticides dieldrin, 

chlordane, and DDE; the brominated flame retardants PBDE 

85, 153, and 154 and Dechlorane Plus, total PCBs; and total 

PAHs. A sufficient number of detections in the pesticides 

DDD or DDT were not detected to make a comparison; 

additionally, the brominated flame retardants PBDE 99 

and 100 were not compared because neither compound 

was detected in the streambed-sediment sample collected 

in conjunction with the water sample with the smallest 

survival rate. Linear regression analysis and the coefficient of 

determination (R2) are commonly used to assess the relation 

between two variables of interest; R2 values range from 0 to 

1 and represent the fraction of the variance explained by the 

linear regression (Helsel and Hirsch, 2002). Linear regression 

analysis did not indicate a strong relation between fathead 

minnow survival and any of the examined streambed-sediment 

constituents. The R2

 values for the relations of survival to the 

selected streambed-sediment constituents ranged from 0.01 

for concentrations of lead, DDE, and total PCBs to 0.44 for 

concentrations of total PAH.
Table 11. Responses of Pimephales promelas (fathead minnow) in 7-day exposure to water samples collected during base-flow conditions from site(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, January 2014. [Mean initial weight and standard deviation at the beginning of the test was 0.925 ± 0.126 (sample size = 40); UV, ultraviolet; mg, milligrams; --, not applicable; mg/L, milligram

U.S. Geological Survey station number U.S. Geological Survey station name Short name for sampling site Map identifier (fig. 1) Sample date Control sample identifier Mean survival (percent) Survival standard deviation (percent) UV Surv

(perce

-- -- -- -- -- Control 1 (hardness 100 mg/L) 98 4 100 -- -- -- -- -- Control 2 (hardness 300 mg/L) 95 8 100 08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Tex. Upstream Martínez MTZ-US 1/27/2014 -- 92 10 100 08178375 Martínez Creek at West Poplar Street, San Antonio, Tex. Downstream Martínez MTZ-DS 1/27/2014 -- 260 27 100 08178310 Alazán Creek at West Laurel Street, San Antonio, Tex. Upstream Alazán ALZ-US 1/27/2014 -- 257 16 100 08178410 Alazán Creek at Tampico Street, San Antonio, Tex. Downstream Alazán ALZ-DS 1/29/2014 -- 255 18 100 08178445 Apache Creek at West Commerce Street, San Antonio, Tex. Upstream Apache APC-US 1/29/2014 -- 92 17 100 08178460 Apache Creek at South Brazos Street, San Antonio, Tex. Downstream Apache APC-DS 1/29/2014 -- 270 20 100 08178100 San Pedro Creek at Santa Rosa Street, San Antonio, Tex. Upstream San Pedro SPD-US 1/29/2014 -- 98 4 100 08178465 San Pedro Creek at West Cevallos Street, San Antonio, Tex. Middle San Pedro SPD-MD 1/31/2014 -- 257 16 100 08178504 San Pedro Creek at Probandt Street at San Antonio, Tex. Downstream San Pedro SPD-DS 1/31/2014 -- 235 35 100 08178515 San Antonio River at Mission Road, San Antonio, 

Tex.

San Antonio 

River

SAR 1/31/2014 -- 85 19 100 

1Survival after the 20-hour recovery period under ambient laboratory lighting conditions.2Significant reduction in an endpoint relative to both controls (p<0.05).
Table 12. Responses of Pimephales promelas (fathead minnow) in 7-day exposure to water samples collected during poststorm conditions from site(Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, May 2014. [Mean initial weight and standard deviation at the beginning of the test was 1.21 plus or minus 0.21 (sample size = 40); UV, ultraviolet; mg, milligrams; --, not applicable; mg/L

U.S. 

Geological 

Survey 

station 

number

U.S. Geological Survey station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Control 

sample 

identifier

Mean 

survival 

(percent)

Survival 

standard 

deviation 

(percent)

UV 

surviva

(percen

-- -- -- -- -- Control 1 

(hardness 100 mg/L)

100 -- 100 

-- -- -- -- -- Control 2 

(hardness 300 mg/L)

100 -- 100 

08178345 Martínez Creek at West Hildebrand Avenue, 

San Antonio, Tex.

Upstream 

Martínez 

MTZ-US 5/28/2014 -- 100 -- 100 

08178375 Martínez Creek at West Poplar Street, San 

Antonio, Tex.

Downstream 

Martínez 

MTZ-DS 5/28/2014 -- 98 4 100 

08178310 Alazán Creek at West Laurel Street, San 

Antonio, Tex.

Upstream 

Alazán

ALZ-US 5/29/2014 -- 100 -- 100 

08178410 Alazán Creek at Tampico Street, San Antonio, 

Tex.

Downstream 

Alazán

ALZ-DS 5/29/2014 -- 100 -- 100 

08178445 Apache Creek at West Commerce Street, San 

Antonio, Tex.

Upstream 

Apache

APC-US 5/29/2014 -- 100 -- 100 

08178460 Apache Creek at South Brazos Street, San 

Antonio, Tex.

Downstream 

Apache

APC-DS 5/29/2014 -- 97 5 100 

08178100 San Pedro Creek at Santa Rosa Street, San 

Antonio, Tex.

Upstream 

San Pedro

SPD-US 5/28/2014 -- 100 -- 100 

08178465 San Pedro Creek at West Cevallos Street, San 

Antonio, Tex.

Middle San 

Pedro

SPD-MD 5/29/2014 -- 100 -- 100 

08178504 San Pedro Creek at Probandt Street at San 

Antonio, Tex.

Downstream 

San Pedro

SPD-DS 5/28/2014 -- 100 -- 100 

08178515 San Antonio River at Mission Road, San 

Antonio, Tex.

San Antonio 

River

SAR 5/28/2014 -- 98 4 100 

1Survival after the 20-hour recovery period under ambient laboratory lighting conditions.
32 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Summary

Elevated concentrations of sediment-associated 

contaminants often are measured in urban areas and in San 

Antonio, Texas, the seventh most populous city in the United 

States, sediment-associated contaminants have been detected 

and documented in previous studies. Sediment-associated 

contaminants can influence the health of aquatic organisms 

that ingest particulate matter when bioaccumulation of trace 

elements and organic compounds occurs. The accumulation 

of trace elements and organic compounds can cause various 

physiological issues and can ultimately result in death of 

aquatic organisms. Subsequent ingestion of aquatic organisms 

can transfer the accumulated contaminants upward through the 

food chain resulting in biomagnification.

The Alazán, Apache, Martínez, and San Pedro Creeks 

in San Antonio, Tex., are part of a network of tributaries 

to the San Antonio River known locally as the Westside 

Creeks. The Westside Creeks flow through some of the 

oldest neighborhoods in San Antonio. In 2008, the San 

Antonio River Authority (SARA) started a communitybased restoration effort working to restore the environmental 

condition of 14 miles of channelized sections of the Alazán, 

Apache, Martínez, and San Pedro Creeks, while enhancing or 

maintaining current flood control components and increasing 

recreational opportunities. It is anticipated the construction 

activities on the 14 miles of stream channel could appreciably 

disturb stream channel sediments.

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

SARA, collected sediment samples and samples for watertoxicity testing from sites on Alazán, Apache, Martínez, and 

San Pedro Creeks, and from a site on the San Antonio River 

as part of an initial characterization of selected contaminants 

in the study area. Sediment samples were analyzed for 

selected constituents, including trace elements and organic 

contaminants such as pesticides, polychlorinated biphenyls 

(PCBs), brominated flame retardants, and polycyclic aromatic 

hydrocarbons (PAHs). The frequencies with which the organic 

contaminants were detected in the streambed-sediment 

samples were assessed, and comparisons of concentrations 

among sites were made to describe the occurrence and 

distribution of the contaminants. As an indicator of 

ecological health in relation to mobilized (and thus, possibly 

bioavailable) contaminants in disturbed streambed sediments, 

the toxicity of water samples collected from the same locations 

as sediment samples to the indicator species Pimephales 

promelas (fathead minnow) was evaluated by using standard 

7-day water-toxicity testing.

Potential risks of contaminants in streambed-sediment 

samples were evaluated by comparing concentrations of 

contaminants in sediment to effects-based sediment quality 

guidelines (SQGs). The SQGs evaluate the potential toxicity 

of bed sediments to benthic biota. Two SQG concentration 

levels were used: (1) a lower level, called the threshold effect 

concentration (TEC), below which harmful effects to benthic 

biota are not expected, and (2) a higher level, the probable 

effect concentration (PEC), above which harmful effects are 

expected to occur frequently. 

The concentrations of the trace elements arsenic, 

cadmium, mercury, and nickel were less than the TEC in all 

of the samples. Lead and zinc were most frequently detected 

at concentrations greater than the TEC. Concentrations of lead 

in all four samples collected from the upper and middle San 

Pedro Creek sites were greater than the PEC. Sources of the 

potentially toxic lead concentrations in the contributing areas 

of these two sites might include older petroleum storage tanks 

that in the past could have held leaded fuel or possibly from 

a variety of automobile components used in the numerous 

automobile-related businesses in the area.

Some SQGs for organic compounds are for 

concentrations that are normalized by dividing them by the 

percentage of organic carbon. Normalizing the concentrations 

in this manner compensates for differences in concentrations 

of the organic compounds that could be related to differences 

in the amount of organic carbon in the samples. The 

percentages of organic carbon in streambed-sediment samples 

collected during base flow were greater than the percentages 

measured in samples collected during poststorm conditions 

at a majority of the sites. To account for variations in the 

percentage of organic carbon in the sediment sample, the 

polybrominated diphenyl ether (PBDE) concentrations were 

normalized by dividing them by the percentage of organic 

carbon before comparisons between sites were made.

Of the 19 pesticides investigated in this study, 

historical-use pesticides that have been banned or are being 

phased out because of their toxicity and persistence in the 

environment were more frequently detected in streambedsediment samples compared to current-use pesticides. Three 

chlordane compounds (cis-chlordane, trans-chlordane, 

and trans-nonachlor) were detected in all of the samples 

collected during both base-flow and poststorm conditions. 

Pesticides were most frequently detected in concentrations 

greater than their PECs in samples from the upstream 

and middle San Pedro sites. During base-flow conditions, 

concentrations of dichlorodiphenyldichloroethane 

(DDD), dichlorodiphenyldichloroethylene (DDE), and 

dichlorodiphenyltrichloroethane (DDT) exceeded their PECs 

in the sample collected from the middle San Pedro site. 

During poststorm conditions chlordane, DDD, and DDE 

concentrations in samples collected at the upstream San Pedro 

site, and DDD and DDE concentrations at the middle San 

Pedro site exceeded their PECs.

Brominated flame retardants were found at every 

site where streambed-sediment samples were collected; 

available guidelines indicate the measured concentrations 

were frequently large enough to potentially cause adverse 

effects on aquatic life. Brominated flame retardants were 

more frequently detected in samples collected during 

poststorm conditions than in those collected during baseflow conditions, with the greatest increase in the number 

of brominated flame retardants detected when comparing 

samples collected from the San Pedro Creek sites during 
References 33

base-flow and poststorm conditions. PBDEs 85, 153, and 

154 were found in all streambed-sediment samples. The 

organic-carbon normalized concentrations of PBDE 99 and 

PBDE 100 were compared to Federal Environmental Quality 

Guidelines (FEQGs) developed by Environment Canada. 

The organic-carbon normalized concentrations of PBDE 99 

exceeded the FEQG developed for this constituent in all 19 

streambed-sediment samples in which PBDE 99 was detected. 

The organic-carbon normalized concentrations of PBDE 100 

exceeded the FEQG for PBDE 100 in 13 of the 19 streambedsediment samples in which PBDE 100 was detected. The 

organic-carbon normalized concentrations of the three most 

frequently detected compounds, PBDE 85, PBDE 153, and 

PBDE 154, were compared among the sample collection 

sites. The concentration variations of PBDEs 85, 153, and 

154 were similar to those of PBDEs 99 and 100. The greatest 

concentrations of organic-carbon normalized PBDEs 85, 

99, 100, 153, and 154 were observed in samples collected 

during base-flow conditions at the upstream Apache site. 

Concentrations of these compounds in the samples collected at 

the same site during poststorm conditions were substantially 

reduced from the base-flow sample concentrations, possibly 

indicating a source that is diluted during rainfall events.

Eighteen common PCB congeners were analyzed in the 

streambed-sediment samples collected from the 10 sites. PCBs 

174, 187, and 194 were found in every streambed-sediment 

sample collected during both base-flow and poststorm 

conditions. The concentrations of total PCBs, computed as the 

sum of the 18 reported congeners, did not exceed the TEC in 

any of the samples. The concentrations of total PCBs in the 

samples collected during base-flow and poststorm conditions 

from the upstream and middle sites on San Pedro Creek were 

greater than the concentrations in the samples collected from 

the other study sites.

A majority of the 10 individual PAHs and total PAH 

exceeded their TECs, and the PECs were exceeded in 30 of 

220 analyses. In general, TECs were exceeded in a greater 

number of analyses in samples collected during base-flow 

conditions than in those collected during poststorm conditions; 

whereas, PECs were exceeded in a greater number of analyses 

during poststorm conditions than in those collected during 

base-flow conditions. At the upstream Apache site, 6 of the 

individual PAHs measured in the sample collected during 

base-flow conditions exceeded the 9 established PECs and 8 

PECs were exceeded in the sample collected during poststorm 

conditions. The total PAH concentration in the sample 

collected during poststorm conditions was 3.3 times greater 

than the PEC developed for total PAHs, making it the most 

contaminated site in regards to total PAHs in the study area.

Average PAH profiles for samples collected during baseflow and stormflow conditions at sites in the study area were 

computed by averaging each of the 12 normalized (to the sum 

of the 12 compounds) compounds in the 10 samples collected 

during each hydrologic condition. Average PAH profiles 

computed for base-flow samples and poststorm samples 

were compared to seven published PAH source profiles. The 

graphical representations of the average base-flow and average 

poststorm streambed-sediment PAH profiles most closely 

resembled that of the published parking lot coal-tar sealcoat 

dust PAH source profile, indicating this PAH source, which 

is a black, viscous liquid containing coal-tar pitch that is 

sprayed or painted on asphalt pavement to create a protective 

seal, could be the largest contributor of PAHs in the averaged 

samples. 

Six of the environmental water samples collected during 

base-flow conditions at the 10 sites were toxic to the fathead 

minnow relative to both of the controls (reduced survival or 

biomass). The water samples from five sites caused lowered 

survival rates ranging from 35 to 68 percent in fathead 

minnow populations. The 4-hour pulse exposure to elevated 

ultraviolet radiation (UV) in clean water following initial 

exposure did not result in subsequent mortality, either during 

the pulse or after the 20-hour recovery period. The relations 

between fathead minnow survival and concentrations of major 

ions measured in the water samples were examined and no 

appreciable correlations were observed. The relations between 

fathead minnow survival and concentrations of selected 

constituents in the streambed-sediment samples collected 

during base-flow conditions also showed no significant 

correlations. 

Survival for fathead minnow in all 10 environmental 

water samples collected during poststorm conditions was 

greater than or equal to 97 percent. The 4-hour pulse exposure 

to elevated UV in clean water following initial exposure did 

not result in subsequent mortality, either during the pulse or 

after the 20-hour recovery period.

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Methods, book 5, chap. B3, 44 p.
Tables 3 and 5–9
Table 3. Relative percent differences between environmental samples and duplicate samples for trace elements measured in streambed-sediment son the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. [mg/kg, milligrams per kilogram; ENV, environmental sample; DUP, duplicate sample; RPD, relative percent difference; <, less than; --, no data] U.S. Geological Survey station number U.S. Geological Survey station name Short name for sampling site Map identifier (fig. 1) Sample date Sample type Thallium (mg/kg) Anti- mony (mg/kg) Arsenic (mg/kg) Barium (mg/kg) Beryl- lium (mg/kg) Bismuth (mg/kg) 

08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Tex. Upstream Martínez MTZ-US 1/27/2014 ENV 0.42 1.9 5.2 258 1.2 0.3 

DUP 0.41 1.9 5.2 260 1.2 0.3 RPD 0.60 0.0 0.0 0.19 0.0 0.0 

08178460 Apache Creek at South Brazos Street, San Antonio, Tex. Downstream Apache APC-DS 1/29/2014 ENV 0.39 1.2 6.4 316 1.2 1.22 

DUP 0.40 1.1 6.6 311 1.1 1.08 

RPD 0.63 2.2 0.8 0.40 2.2 3.04 

08178410 Alazán Creek at Tampico Street, San Antonio, Tex. Downstream Alazán ALZ-DS 5/29/2014 ENV 0.47 1.3 5.3 374 1.6 0.3 

DUP 0.50 1.3 5.2 399 1.6 0.3 

RPD 1.55 0.0 0.5 1.62 0.0 0.0 

08178100 San Pedro Creek at Santa Rosa Street, San Antonio, Tex. Upstream San Pedro SPD-US 5/28/2014 ENV 0.40 1.9 2.9 285 0.92 0.34 

DUP 0.40 2.0 2.8 282 0.94 0.31 RPD 0.00 1.3 0.9 0.26 0.54 2.31 

U.S. Geological Survey station number U.S. Geological Survey station name Short name for sampling site Map identifier (fig. 1) Sample date Sample type Copper (mg/kg) Gallium (mg/kg) Lead (mg/kg) Lithium (mg/kg) Manga- nese (mg/kg) Molyb- denum (mg/kg) 

08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Tex. Upstream Martínez MTZ-US 1/27/2014 ENV 34.9 11.0 78.5 27.6 203 1.5 

DUP 34.9 11.1 76.3 28.7 203 1.6 

RPD 0.00 0.23 0.71 0.98 0.00 1.6 

08178460 Apache Creek at South Brazos Street, San Antonio, Tex. Downstream Apache APC-DS 1/29/2014 ENV 38.0 9.90 58.8 24.6 281 1.1 

DUP 35.1 10.2 58.0 24.0 289 1.1 

RPD 1.98 0.75 0.34 0.62 0.70 0.0 

08178410 Alazán Creek at Tampico Street, San Antonio, Tex. Downstream Alazán ALZ-DS 5/29/2014 ENV 27.1 13.8 53.1 34.7 325 1.1 

DUP 26.9 14.0 51.9 33.9 330 1.0 

RPD 0.19 0.36 0.57 0.58 0.38 2.4 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 44.7 7.9 238 24.5 198 1.6 

DUP 50.6 7.6 222 21.5 186 1.6 

RPD 3.10 1.0 1.74 3.26 1.56 0.0 
Table 3. Relative percent differences between environmental samples and duplicate samples for trace elements measured in streambed-sediment son the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued[mg/kg, milligrams per kilogram; ENV, environmental sample; DUP, duplicate sample; RPD, relative percent difference; <, less than; --, no data]

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

Silver 

(mg/kg)

Strontium 

(mg/kg)

Tantalum 

(mg/kg)

Thorium 

(mg/kg)

Uranium 

(mg/kg)

Vanadium 

(mg/kg)

Zin

(mg/

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV 0.243 239 0.63 8.37 3.00 66.8 208 DUP 0.238 237 0.63 8.85 3.09 68.2 209 RPD 0.52 0.21 0.00 1.39 0.74 0.52 0.

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV 0.453 300 0.58 8.83 2.82 60.5 198 DUP 0.460 300 0.60 8.92 2.87 59.0 183 RPD 0.38 0.00 0.85 0.25 0.44 0.63 1.

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <0.02 266 -- 9.45 2.48 82.2 150 DUP <0.02 268 -- 9.61 2.51 87.0 151 RPD -- 0.19 -- 0.42 0.30 1.42 0.

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV <0.02 334 -- 6.44 2.51 41.9 300 DUP <0.02 338 -- 6.80 2.73 41.8 311 RPD -- 0.30 -- 1.36 2.10 0.06 0.

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

Cesium 

(mg/kg)

Iron 

(mg/kg)

Magnesium 

(mg/kg)

Phosphorus 

(mg/kg)

Potassium 

(mg/kg)

Rub

(mg

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV 5.4 19,200 6,550 789 11,500 66DUP 5.4 19,100 6,590 726 11,500 66RPD 0.0 0.13 0.15 2.08 0.00 0

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV 4.8 17,700 7,370 875 8,410 55DUP 5.1 17,500 7,220 799 8,390 56RPD 1.5 0.28 0.51 2.27 0.06 0

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV 10.0 23,100 8,730 625 11,900 75DUP 14.8 23,400 8,740 635 11,900 76RPD 9.68 0.32 0.03 0.40 0.00 0

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 8.0 14,400 5,950 884 9,180 50DUP 9.7 14,000 6,100 851 8,800 49RPD 4.8 0.70 0.62 0.95 1.06 0
40 Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs

Table 5

Table 5. Results from U.S. Geological Survey National Water Quality Laboratory (NWQL) analysis of National Institute of Standards and 

Technology (NIST) standard reference materials 8704 and 1941b.—Continued

[±, plus or minus; --, no data; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, 

polychlorinated biphenyls; <, less than; E, estimated]

Constituent, units NIST concentration with 

standard deviation

NWQL 

concentration

NWQL set spike 

recovery, percent

NWQL concentration 

adjusted for set 

spike recovery

Calcium, milligrams per kilogram 2.641 ± 0.083 2.63 -- --

Magnesium, milligrams per kilogram 1.2 ± 0.018 1.14 -- --

Potassium, milligrams per kilogram 2.001 ± 0.041 1.92 -- --

Sodium, milligrams per kilogram 0.553 ± 0.015 0.57 -- --

Carbon (inorganic plus organic), percent 3.351 ± 0.017 3.33 -- --

Aluminum, milligrams per kilogram 6.1 ± 0.18 5.91 -- --

Barium, milligrams per kilogram 413 ± 13 397 -- --

Cadmium, milligrams per kilogram 2.94 ± 0.29 2.90 -- --

Cesium, milligrams per kilogram 5.83 ± 0.12 6.10 -- --

Chromium, milligrams per kilogram 121.9 ± 3.8 116.0 -- --

Cobalt, milligrams per kilogram 13.57 ± 0.43 13.30 -- --

Iron, milligrams per kilogram 3.97 ± 0.1 3.85 -- --

Lead, milligrams per kilogram 150 ± 17 159 -- --

Manganese, milligrams per kilogram 544 ± 21 551 -- --

Nickel, milligrams per kilogram 42.9 ± 3.7 41.9 -- --

Scandium, milligrams per kilogram 11.26 ± 0.19 11.20 -- --

Titanium, milligrams per kilogram 0.457 ± 0.02 0.31 -- --

Vanadium, milligrams per kilogram 94.6 ± 4 93.4 -- --

Zinc, milligrams per kilogram 408 ± 15 401 -- --

Antimony, milligrams per kilogram 3.07 ± 0.32 2.90 -- --

Arsenic, milligrams per kilogram 17.0 16.6 -- --

cis-Chlordane, micrograms per kilogram 0.85 ± 0.11 0.08 77.5 0.11

cis-Nonachlor, micrograms per kilogram 0.378 ± 0.053 0.071 82.6 0.086

DDD, micrograms per kilogram 4.66 ± 0.46 <2.18 89.1 --

DDE, micrograms per kilogram 3.22 ± 0.28 <1 76 --

DDT, micrograms per kilogram 1.12 ± 0.42 <4 96.9 --

trans-Chlordane, micrograms per kilogram 0.566 ± 0.093 0.059 81.5 0.072

trans-Nonachlor, micrograms per kilogram 0.438 ± 0.073 0.009 83.1 0.011

PCB congener 49, micrograms per kilogram 4.34 ± 0.28 <3.52 75.1 --

PCB congener 52, micrograms per kilogram 5.24 ± 0.28 <1 69.1 --

PCB congener 70, micrograms per kilogram 4.99 ± 0.29 <2 78.8 --

PCB congener 101, micrograms per kilogram 5.11 ± 0.34 0.909 79.2 1.15

PCB congener 110, micrograms per kilogram 4.62 ± 0.36 <1 80.2 --

PCB congener 118, micrograms per kilogram 4.23 ± 0.19 2.03 74.8 2.71

PCB congener 138, micrograms per kilogram 3.6 ± 0.28 <2.02 76.0 --

Table 5. Results from U.S. Geological Survey National Water Quality Laboratory (NWQL) analysis of National Institute of Standards and 

Technology (NIST) standard reference materials 8704 and 1941b.

[±, plus or minus; --, no data; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, 

polychlorinated biphenyls; <, less than; E, estimated]
Table 5 41

Table 5. Results from U.S. Geological Survey National Water Quality Laboratory (NWQL) analysis of National Institute of Standards and 

Technology (NIST) standard reference materials 8704 and 1941b.—Continued

[±, plus or minus; --, no data; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, 

polychlorinated biphenyls; <, less than; E, estimated]

Constituent, units NIST concentration with 

standard deviation

NWQL 

concentration

NWQL set spike 

recovery, percent

NWQL concentration 

adjusted for set 

spike recovery

PCB congener 146, micrograms per kilogram 1.22 ± 0.12 <0.524 75.2 --

PCB congener 149, micrograms per kilogram 4.35 ± 0.26 2.06 72.9 2.83

PCB congener 170, micrograms per kilogram 1.35 ± 0.09 0.886 74.3 1.19

PCB congener 174, micrograms per kilogram 1.51 ± 0.39 0.743 72.3 1.03

PCB congener 180, micrograms per kilogram 3.24 ± 0.51 1.69 75.0 2.25

PCB congener 183, micrograms per kilogram 0.979 ± 0.087 0.42 72.0 0.58

PCB congener 187, micrograms per kilogram 2.17 ± 0.22 1.07 71.7 1.49

PCB congener 194, micrograms per kilogram 1.04 ± 0.06 0.471 75.1 0.63

PCB congener 206, micrograms per kilogram 2.42 ± 0.19 1.29 74.4 1.73

1-Methylphenanthrene, micrograms per kilogram 73.2 ± 5.9 <117.25 -- --

1-Methylpyrene, micrograms per kilogram 52.5 ± 2.3 <117.25 -- --

2,6-Dimethlnaphthalene, micrograms per kilogram 75.9 ± 4.5 162 77.8 208

2-Methylanthracene, micrograms per kilogram 36 ± 15 <119 -- --

9H-fluorene, micrograms per kilogram 85 ± 15 89.6 80.4 111

Acenaphthene, micrograms per kilogram 38.4 ± 5.2 31.7 79.6 40

Acenaphthylene, micrograms per kilogram 53.3 ± 6.4 98.5 75.1 131

Anthracene, micrograms per kilogram 184 ± 18 237 85.2 278

Benzo[a]anthracene, micrograms per kilogram 335 ± 25 319 98.7 323

Benzo[a]pyrene, micrograms per kilogram 358 ± 17 264 100 264

Benzo[b]fluoranthene, micrograms per kilogram 453 ± 21 E692 117 E590

Benzo[e]pyrene, micrograms per kilogram 325 ± 25 347 114 304

Benzo[ghi]perylene, micrograms per kilogram 307 ± 45 E135 109 E124

Benzo[k]fluoranthene, micrograms per kilogram 225 ± 18 E250 111 E225

Chrysene, micrograms per kilogram 291 ± 31 450 102 439

Dibenzo[a,h]anthracene, micrograms per kilogram 53 ± 10 <117.25 -- --

Fluoranthene, micrograms per kilogram 651 ± 50 780 95 818

Indenopyrene, micrograms per kilogram 341 ± 57 E131 106 E123

Naphthalene, micrograms per kilogram 848 ± 95 1,020 77.0 1,325

Perylene, micrograms per kilogram 397 ± 45 498 99.2 502

Phenanthrene, micrograms per kilogram 406 ± 44 525 87.5 600

Pyrene, micrograms per kilogram 581 ± 39 629 93.7 671

Thorium, milligrams per kilogram 9.07 ± 0.16 10.9 -- --

Uranium, milligrams per kilogram 3.09 ± 0.13 3.37 -- --
Table 6. Relative percent differences between environmental samples and duplicate samples for halogenated organic compounds measured in strecollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. [μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated; DDD, dichlorodidichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ether]

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

alphaEndosulfan 

(μg/kg)

Benfluralin 

(μg/kg)

betaEndosulfan 

(μg/kg)

Chlorpyrifos 

(μg/kg)

cisChlordane 

(μg/kg)

ci

a

(μ

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV <0.2 <0.2 <0.2 <0.2 4.58 DUP <0.2 <0.2 <0.2 0.48 4.26 

RPD -- -- -- -- 1.81 

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV <0.2 <0.2 <0.2 <0.2 1.01 

DUP <0.2 <0.2 <0.2 0.28 2.10 

RPD -- -- -- -- 17.5 1

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <0.2 <0.2 <0.2 <0.2 1.76 

DUP <0.2 <0.2 <0.2 <0.2 1.60 

RPD -- -- -- -- 2.38 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV <0.2 <0.2 <0.2 E0.23 9.08 

DUP <0.2 <0.2 <0.2 E0.19 6.43 

RPD -- -- -- 4.76 8.54 

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

Desulfinylfipronil 

(μg/kg)

Dieldrin 

(μg/kg)

Endosulfan 

sulfate 

(μg/kg)

Fipronil 

sulfide 

(μg/kg)

Fipronil 

(μg/kg)

lam

Cyh

th

(μg

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV 0.317 <0.1 <0.4 0.336 <0.1 1

DUP <0.288 2.81 <0.4 <0.27 <0.1 1

RPD -- -- -- -- -- 1

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV <0.125 <0.1 <0.4 <0.1 <0.1 1

DUP <0.1 0.573 <0.4 <0.1 <0.1 1

RPD -- -- -- -- -- 4

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <0.1 E0.662 <0.4 <0.1 <0.1 <0

DUP <0.1 E0.608 <0.4 <0.1 <0.1 <0RPD -- 2.13 -- -- -- -

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 0.189 E2.72 <0.4 0.261 <0.435 <0DUP 0.229 E2.78 <0.4 0.352 <0.469 <0RPD 4.78 0.55 -- 7.42 -- -
Table 6. Relative percent differences between environmental samples and duplicate samples for halogenated organic compounds measured in strecollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Co[μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated; DDD, dichlorodidichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ether]

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

DDD 

(μg/kg)

DDE 

(μg/kg)

DDT 

(μg/kg)

Pendimethalin 

(μg/kg)

Tefluthrin 

(μg/kg)

Tetradifon 

(μg/kg)

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV <2 <1 <4 <1 <0.5 <0.2 DUP <2 <1 <4 <1 <0.5 <0.2 RPD -- -- -- -- -- -- 

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV <2 22.1 <4 <1 <0.5 <0.2 DUP <8.18 17.3 E11.7 <1 <0.5 <0.2 RPD -- 6.09 -- -- -- -- 

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV 2.96 6.72 0.829 <1 <0.5 <0.2 DUP <2.12 5.41 0.852 <1 <0.5 <0.2 RPD -- 5.40 0.68 -- -- -- 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV E30.3 41.5 <4 <1 <0.5 <0.2 DUP E22.1 28.2 <4 <1 <0.5 <0.2 RPD 7.82 9.54 -- -- -- -- 

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

PCB 

49 

(μg/kg)

PCB 

52 

(μg/kg)

PCB 

70 

(μg/kg)

PCB 

101 

(μg/kg)

PCB 

110 

(μg/kg)

PCB 

118 

(μg/kg)

PCB 

138 

(μg/kg

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV <2 <1 <2 <1 <1 <0.1 <0.1 DUP <2 <1 <2 <1 <1 <0.1 <0.1 RPD -- -- -- -- -- -- -- 

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV <2 <1 2.94 <1 <1 <0.1 <0.1 DUP E6.42 <1 <2 <1 <2.63 0.646 <0.1 RPD -- -- -- -- -- -- -- 

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <2 <1 <2 <1 <1 0.19 0.75 DUP <2 <1 <2 <1 0.548 0.19 0.63 RPD -- -- -- -- -- 0.26 4.28 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV <2 <1 <2 2.93 <10.7 3.20 6.06 DUP <2 <1 <2 2.06 <10.3 2.89 5.10 RPD -- -- -- 8.72 -- 2.55 4.30 
Table 6. Relative percent differences between environmental samples and duplicate samples for halogenated organic compounds measured in strecollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Co[μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated; DDD, dichlorodidichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ether] U.S. Geological Survey station number U.S. Geological Survey station name Short name for sampling site Map identifier (fig. 1) Sample date Sample type PCB 170 (μg/kg) PCB 174 (μg/kg) PCB 177 (μg/kg) PCB 180 (μg/kg) PCB 183 (μg/kg) PC

18

(μg/

08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Tex. Upstream Martínez MTZ-US 1/27/2014 ENV 0.432 0.416 0.250 0.859 0.126 0.4

DUP 0.478 0.305 0.199 0.682 <0.1 0.3RPD 2.53 7.70 5.68 5.74 -- 6.9

08178460 Apache Creek at South Brazos Street, San Antonio, Tex. Downstream Apache APC-DS 1/29/2014 ENV 0.684 0.412 0.28 1.04 0.159 0.5

DUP 0.963 0.429 0.30 1.09 0.244 0.5RPD 8.47 1.01 1.72 1.17 10.5 1.5

08178410 Alazán Creek at Tampico Street, San Antonio, Tex. Downstream Alazán ALZ-DS 5/29/2014 ENV 0.566 0.363 0.242 0.896 0.197 0.4

DUP 0.491 0.299 0.203 0.756 0.170 0.3RPD 3.55 4.83 4.38 4.24 3.68 5.1

08178100 San Pedro Creek at Santa Rosa Street, San Antonio, Tex. Upstream San Pedro SPD-US 5/28/2014 ENV 4.24 2.73 1.89 6.82 1.340 3.4

DUP 3.07 1.96 1.40 4.91 0.944 2.4RPD 8.00 8.21 7.45 8.14 8.67 8.2

U.S. Geological Survey station number U.S. Geological Survey station name Short name for sampling site Map identifier (fig. 1) Sample date Sample type 1,2-bis(2,4,6- tribromophenoxy) ethane (TBE) (μg/kg) PBDE 47 (μg/kg) PBDE 66 (μg/kg) PBDE 71 (μg/kg) PBDE 85 (μg/kg) 

08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Tex. Upstream Martínez MTZ-US 1/27/2014 ENV 0.36 14.2 0.474 <0.1 0.856 

DUP 1.43 12.5 0.346 <0.1 0.608 RPD 29.9 3.18 7.80 -- 8.47 

08178460 Apache Creek at South Brazos Street, San Antonio, Tex. Downstream Apache APC-DS 1/29/2014 ENV 0.502 13.4 0.423 <0.1 0.624 

DUP <0.32 10.0 0.275 <0.1 0.546 RPD -- 7.26 10.6 -- 3.33 

08178410 Alazán Creek at Tampico Street, San Antonio, Tex. Downstream Alazán ALZ-DS 5/29/2014 ENV E0.0865 0.813 0.0462 <0.1 E0.0796 

DUP E0.0826 <0.734 0.0438 <0.1 E0.0651 RPD 1.15 -- 1.33 -- 5.01 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV E0.384 E5.02 E0.231 <0.152 E0.412 DUP <0.1 E5.48 E0.218 E0.513 E0.393 RPD -- 2.19 1.45 -- 1.18 
Table 6. Relative percent differences between environmental samples and duplicate samples for halogenated organic compounds measured in strecollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Co[μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated; DDD, dichlorodidichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ether]

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

PBDE 

153 

(μg/kg)

PBDE 

154 

(μg/kg)

PBDE 

183 

(μg/kg)

Methyl 

triclosan 

(μg/kg)

Octachlorostyrene 

(μg/kg)

Pe

bro

tol

(μg

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV 1.96 1.73 <0.1 <6 <1 <DUP 1.63 1.28 <0.62 <6 <1 <RPD 4.60 7.48 -- -- -- 

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV 2.00 1.29 <0.1 <6 <1 <DUP 1.65 1.33 <0.266 <6 <1 <RPD 4.79 0.76 -- -- -- 

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV 0.115 0.1100 <0.1 <6 <1 <DUP 0.121 0.0995 E0.0695 <6 <1 <RPD 1.27 2.51 -- -- -- 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV E0.729 0.598 0.226 <6 <1 <DUP E0.671 0.608 <0.152 <6 <1 <RPD 2.07 0.415 -- -- -- 
Table 7. Relative percent differences between environmental samples and duplicate samples for polycyclic aromatic hydrocarbons measured in strcollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.[μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated]

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

2,6-Dimethlnaphthalene 

(μg/kg)

Anthracene 

(μg/kg)

9,10-

Anthraquinone 

(μg/kg)

Benzo[a]

pyrene 

(μg/kg)

Bis(2-

ethylhexyl)

phthalate 

(μg/kg)

Ca

z

(μ

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV 68.3 68.0 343 678 1,420 15

DUP 70.6 80.3 347 799 1,650 15

RPD 0.83 4.15 0.29 4.10 3.75 

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV 83.2 82.7 286 786 1,350 14

DUP 54.9 50.7 188 421 726 8

RPD 10.25 12.0 10.3 15.1 15.0 1

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <25 25.2 E59.6 223 142 2DUP <25 15.3 E102 187 <90 4RPD -- 12.2 13.1 4.39 -- 1

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 95.7 494 910 2,790 E779 E6DUP 81.6 437 864 2,650 E791 E5

RPD 3.98 3.06 1.30 1.29 0.38 

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

Naphthalene 

(μg/kg)

Phenanthrene 

(μg/kg)

Pyrene 

(μg/kg)

Benzo[a]

anthracene 

(μg/kg)

Hexachlorobenzene 

(μg/kg)

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV 35.6 453 1,280 442 <31.75 DUP 32.4 474 1,320 486 <28 RPD 2.35 1.13 0.77 2.37 -- 

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV 37.0 501 1,390 598 <32 DUP <32.5 306 722 288 <32.5 RPD -- 12.1 15.8 17.5 -- 

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <25 129 380 186 <25 DUP <25 188 448 140 <25 RPD -- 9.31 4.11 7.06 -- 

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 161 2,690 E6,190 2,800 <25 DUP 215 2,470 E5,840 2,540 <25 RPD 7.18 2.13 1.45 2.43 -- 
Table 7. Relative percent differences between environmental samples and duplicate samples for polycyclic aromatic hydrocarbons measured in strcollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Co[μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated]

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

1,2-Dimethylnaphthalene 

(μg/kg)

1,6-

Dimethylnaphthalene 

(μg/kg)

1-Methyl9Hfluorene 

(μg/kg)

1-Methylphenanthrene 

(μg/kg)

1-Met

pyren

(μg/k

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV <31.75 <31.75 <31.75 35.7 44.DUP <28 <28 <28 38.7 53.0 RPD -- -- -- 2.02 4.5

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV <32 <32 4.92 39.7 54.4 DUP <32.5 <32.5 <32.5 25.2 30.6 RPD -- -- -- 11.2 14.0 

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <25 <25 1.42 11.1 21.7 DUP <25 <25 <25 10.8 19.3 RPD -- -- -- 0.68 2.9

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 21.6 32.5 37.0 208 218 DUP 13.8 31.1 26.6 203 210 RPD 11.0 1.10 8.18 0.61 0.9

U.S. Geological 

Survey station 

number

U.S. Geological Survey 

station name

Short name 

for sampling 

site

Map 

identifier 

(fig. 1)

Sample 

date

Sample 

type

2-Methylanthracene 

(μg/kg)

Benzo[def]

fluorene 

(μg/kg)

9HFluorene 

(μg/kg)

Acenaphthene 

(μg/kg)

Acenaphthylene 

(μg/kg)

Benzo[

fluoran

thene 

(μg/kg

08178345

Martínez Creek at West 

Hildebrand Avenue, San Antonio, Tex.

Upstream 

Martínez MTZ-US 1/27/2014

ENV <31.75 75.9 23.1 14.4 <31.75 E1,660 DUP <28 79.9 27.8 16.7 <28 E1,370 RPD -- 1.28 4.62 3.70 -- 4

08178460

Apache Creek at South 

Brazos Street, San Antonio, Tex.

Downstream 

Apache APC-DS 1/29/2014

ENV <32 77.0 24.2 17.3 <32 E1,610 DUP <32.5 43.4 18.1 11.7 11.8 E908 RPD -- 14.0 7.21 9.66 -- 13

08178410

Alazán Creek at 

Tampico Street, San Antonio, Tex.

Downstream 

Alazán ALZ-DS 5/29/2014

ENV <25 23.0 6.64 3.78 4.18 368 DUP <25 15.8 6.29 4.35 6.01 352 RPD -- 9.28 1.34 3.55 9.02 1

08178100

San Pedro Creek at 

Santa Rosa Street, San Antonio, Tex.

Upstream 

San Pedro SPD-US 5/28/2014

ENV 110 432 197 178 65.5 E4,680 DUP 100 396 165 154 66.0 E4,340 RPD 2.43 2.17 4.42 3.61 0.19 1
Table 7. Relative percent differences between environmental samples and duplicate samples for polycyclic aromatic hydrocarbons measured in strcollected from sites on the Westside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Co[μg/kg, micrograms per kilogram; ENV, environmental sample; <, less than; DUP, duplicate sample; RPD, relative percent difference; --, no data; E, estimated] U.S. Geological Survey station number U.S. Geological Survey station name Short name for sampling site Map identifier (fig. 1) Sample date Sample type Benzo[k] fluoran- thene (μg/kg) Chrysene (μg/kg) Dibenzo [a,h] anthracene (μg/kg) Diben- zothio- phene (μg/kg) Indeno- pyrene (μg/kg) 

08178345 Martínez Creek at West Hildebrand Avenue, San Antonio, Tex. Upstream Martínez MTZ-US 1/27/2014 ENV E636 1,010 <70.5 <31.75 E276 

DUP E544 1,100 <69.4 <29 E261 RPD 3.90 2.13 -- -- 1.40 

08178460 Apache Creek at South Brazos Street, San Antonio, Tex. Downstream Apache APC-DS 1/29/2014 ENV E506 983 E84.3 <32 E360 

DUP E336 604 53.0 <32.5 E202 RPD 10.1 11.9 11.4 -- 14.1 

08178410 Alazán Creek at Tampico Street, San Antonio, Tex. Downstream Alazán ALZ-DS 5/29/2014 ENV 134 308 E44.2 6.32 E142 

DUP 128 306 E38.4 8.55 E126 RPD 1.15 0.16 3.51 7.50 2.99 

08178100 San Pedro Creek at Santa Rosa Street, San Antonio, Tex. Upstream San Pedro SPD-US 5/28/2014 ENV E1,640 4,180 E313 137 E1,080 

DUP E1,560 3,820 E324 136 E1,050 RPD 1.25 2.25 0.86 0.18 0.70 
Table 8. Analytical results for halogenated organic compounds found in laboratory set blank samples, and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014. [PBDE, polybrominated diphenyl ether; μg/kg, micrograms per kilogram; <, less than; E, estimated; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethy

chloroethane; PCB, polychlorinated biphenyls]

Set number Sample identifier, units

1,2-Bis

(2,4,6-

tribromophenoxy)

ethane

PBDE 

183

PBDE 

138

PBDE 

85

PBDE 

153

PBDE 

154

PBDE 

99

PBDE 

100

PBDE 

47

PBD

71

201407007

Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.30 0.086 0.80 <0

Spike, percent recovery 83 73 78 93 97 96 110 90 150 70 

Spike acceptable range lower limit, percent recovery 49 36 28 36 38 47 27 27 24 37 

Spike acceptable range upper limit, percent recovery 157 162 166 168 158 143 183 159 192 16

201417415

Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.11 0.036 0.26 <0

Spike, percent recovery 140 95 100 110 95 93 110 96 140 93 

Spike acceptable range lower limit, percent recovery 49 36 28 36 38 47 27 27 24 37 

Spike acceptable range upper limit, percent recovery 157 162 166 168 158 143 183 159 192 16

201416702

Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.11 0.035 0.22 <0

Spike, percent recovery 140 88 110 99 94 85 120 92 140 87 

Spike acceptable range lower limit, percent recovery 49 36 28 36 38 47 27 27 24 37 

Spike acceptable range upper limit, percent recovery 157 162 166 168 158 143 183 159 192 16

201424008

Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.059 <0.1 0.14 <0

Spike, percent recovery 100 100 110 120 110 110 130 120 160 11

Spike acceptable range lower limit, percent recovery 49 36 28 36 38 47 27 27 24 37 

Spike acceptable range upper limit, percent recovery 157 162 166 168 158 143 183 159 192 16

201408409

Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.23 0.055 0.50 <0

Spike, percent recovery 80 65 75 91 94 88 150 110 250 78 

Spike acceptable range lower limit, percent recovery 49 36 28 36 38 47 27 27 24 37 

Spike acceptable range upper limit, percent recovery 157 162 166 168 158 143 183 159 192 16

201425501

Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.16 0.051 0.25 <0

Spike, percent recovery 110 110 120 130 130 130 160 120 190 12

Spike acceptable range lower limit, percent recovery 49 36 28 36 38 47 27 27 24 37 

Spike acceptable range upper limit, percent recovery 157 162 166 168 158 143 183 159 192 16
Table 8. Analytical results for halogenated organic compounds found in laboratory set blank samples, and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued [PBDE, polybrominated diphenyl ether; μg/kg, micrograms per kilogram; <, less than; E, estimated; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethychloroethane; PCB, polychlorinated biphenyls] Set number Sample identifier, units Cyfluthrin Dacthal Desulfinyl- fipronil Dieldrin Endo- sulfan sulfate Fipronil Fipronil sulfide 

c

b

201407007 Blank, μg/kg <0.2 <0.2 <0.1 <0.1 <0.4 <0.1 <0.1 

Spike, percent recovery E86 84 62 110 83 <0.1 48 Spike acceptable range lower limit, percent recovery 15 52 16 47 21 33 28 Spike acceptable range upper limit, percent recovery 123 136 148 161 165 123 148 1

201417415 Blank, μg/kg <0.2 <0.2 <0.1 <0.1 <0.4 E0.90 <0.1 

Spike, percent recovery E130 76 61 82 84 E56 56 Spike acceptable range lower limit, percent recovery 15 52 16 47 21 33 28 Spike acceptable range upper limit, percent recovery 123 136 148 161 165 123 148 1

201416702 Blank, μg/kg <0.2 <0.2 <0.1 <0.1 <0.4 <0.1 <0.1 

Spike, percent recovery E110 93 85 90 97 E62 71 Spike acceptable range lower limit, percent recovery 15 52 16 47 21 33 28 Spike acceptable range upper limit, percent recovery 123 136 148 161 165 123 148 1

201424008 Blank, μg/kg <0.2 <0.2 <0.1 <0.1 <0.4 E0.42 <0.1 

Spike, percent recovery E110 110 91 120 130 E84 86 Spike acceptable range lower limit, percent recovery 15 52 16 47 21 33 28 Spike acceptable range upper limit, percent recovery 123 136 148 161 165 123 148 1

201408409 Blank, μg/kg <0.2 <0.2 <0.1 <0.1 <0.4 E0.015 <0.1 

Spike, percent recovery E99 88 90 91 110 E0.007 65 Spike acceptable range lower limit, percent recovery 15 52 16 47 21 33 28 Spike acceptable range upper limit, percent recovery 123 136 148 161 165 123 148 1

201425501 Blank, μg/kg <0.2 <0.2 <0.1 <0.1 <0.4 <0.1 <0.1 

Spike, percent recovery E120 93 94 130 130 E130 98 Spike acceptable range lower limit, percent recovery 15 52 16 47 21 33 28 Spike acceptable range upper limit, percent recovery 123 136 148 161 165 123 148 1
Table 8. Analytical results for halogenated organic compounds found in laboratory set blank samples, and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued[PBDE, polybrominated diphenyl ether; μg/kg, micrograms per kilogram; <, less than; E, estimated; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethychloroethane; PCB, polychlorinated biphenyls]

Set number Sample identifier, units Oxychlor- dane Oxyfluor- fen Pendi- methalin Penta- bromo- toluene Penta- chloro- anisole Penta- chloro- nitro- benzene Teflu- thrin 

201407007

Blank, μg/kg <1 <4 <1 <1 <0.1 <0.1 <0.5 Spike, percent recovery 39 74 74 83 60 74 75 Spike acceptable range lower limit, percent recovery 32 33 50 69 35 48 43 Spike acceptable range upper limit, percent recovery 164 153 146 141 155 162 127 

201417415

Blank, μg/kg <1 <4 <1 <1 <0.1 <0.1 <0.5 Spike, percent recovery 65 89 69 82 75 57 93 Spike acceptable range lower limit, percent recovery 32 33 50 69 35 48 43 Spike acceptable range upper limit, percent recovery 164 153 146 141 155 162 127 

201416702

Blank, μg/kg <1 <4 <1 <1 <0.1 <0.1 <0.5 Spike, percent recovery 77 94 78 88 86 74 95 Spike acceptable range lower limit, percent recovery 32 33 50 69 35 48 43 Spike acceptable range upper limit, percent recovery 164 153 146 141 155 162 127 

201424008

Blank, μg/kg <1 <4 <1 <1 0.014 <0.1 <0.5 Spike, percent recovery 100 110 100 110 99 110 97 Spike acceptable range lower limit, percent recovery 32 33 50 69 35 48 43 Spike acceptable range upper limit, percent recovery 164 153 146 141 155 162 127 

201408409

Blank, μg/kg <1 <4 <1 <1 <0.1 <0.1 <0.5 Spike, percent recovery 82 91 91 82 82 81 79 Spike acceptable range lower limit, percent recovery 32 33 50 69 35 48 43 Spike acceptable range upper limit, percent recovery 164 153 146 141 155 162 127 

201425501

Blank, μg/kg <1 <4 <1 <1 <0.1 <0.1 <0.5 Spike, percent recovery 110 110 87 110 74 71 100 Spike acceptable range lower limit, percent recovery 32 33 50 69 35 48 43 Spike acceptable range upper limit, percent recovery 164 153 146 141 155 162 127 
Table 8. Analytical results for halogenated organic compounds found in laboratory set blank samples, and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued [PBDE, polybrominated diphenyl ether; μg/kg, micrograms per kilogram; <, less than; E, estimated; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethychloroethane; PCB, polychlorinated biphenyls] Set number Sample identifier, units alpha- Endo- sulfan beta- Endo- sulfan bis(Hexachloro- cyclopentadieno) cyclooctane [dechlorane plus] cis- Chlordane cis- Nonachlor lambda

Cyhalothr

201407007 Blank, μg/kg <0.2 <0.2 <1 <0.2 <0.1 <0.2 

Spike, percent recovery 83 89 66 92 70 50 Spike acceptable range lower limit, percent recovery 21 21 44 32 42 8 Spike acceptable range upper limit, percent recovery 165 165 170 170 156 156 

201417415 Blank, μg/kg <0.2 <0.2 <1 <0.2 <0.1 <0.2 

Spike, percent recovery 82 87 86 79 78 110 Spike acceptable range lower limit, percent recovery 21 21 44 32 42 8 Spike acceptable range upper limit, percent recovery 165 165 170 170 156 156 

201416702 Blank, μg/kg <0.2 <0.2 <1 <0.2 <0.1 <0.2 

Spike, percent recovery 83 91 91 82 89 86 Spike acceptable range lower limit, percent recovery 21 21 44 32 42 8 Spike acceptable range upper limit, percent recovery 165 165 170 170 156 156 

201424008 Blank, μg/kg <0.2 <0.2 <1 <0.2 <0.1 <0.2 

Spike, percent recovery 110 130 110 100 110 100 Spike acceptable range lower limit, percent recovery 21 21 44 32 42 8 Spike acceptable range upper limit, percent recovery 165 165 170 170 156 156 

201408409 Blank, μg/kg <0.2 <0.2 <1 <0.2 <0.1 <0.2 

Spike, percent recovery 84 98 86 77 83 72 Spike acceptable range lower limit, percent recovery 21 21 44 32 42 8 Spike acceptable range upper limit, percent recovery 165 165 170 170 156 156 

201425501 Blank, μg/kg <0.2 <0.2 <1 <0.2 <0.1 <0.2 

Spike, percent recovery 110 140 110 110 110 75 Spike acceptable range lower limit, percent recovery 21 21 44 32 42 8 Spike acceptable range upper limit, percent recovery 165 165 170 170 156 156 
Table 8. Analytical results for halogenated organic compounds found in laboratory set blank samples, and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued[PBDE, polybrominated diphenyl ether; μg/kg, micrograms per kilogram; <, less than; E, estimated; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethychloroethane; PCB, polychlorinated biphenyls]

Set number Sample identifier, units

PCB 

congener 

49

PCB 

congener 

52

PCB 

congener 

70

PCB 

congener 

101

PCB 

congener 

110

PCB 

congener 

118

PCB 

congener 

138

PC

cong

14

201407007

Blank, μg/kg <2 <1 <2 <1 <1 <0.1 <0.1 <Spike, percent recovery E55 E57 59 82 87 74 76 6Spike acceptable range lower limit, percent recovery 9 4 9 10 16 35 27 3Spike acceptable range upper limit, percent recovery 113 112 115 130 130 155 155 14

201417415

Blank, μg/kg <2 <1 <2 <1 <1 <0.1 <0.1 <Spike, percent recovery E110 E89 95 84 87 84 80 8Spike acceptable range lower limit, percent recovery 9 4 9 10 16 35 27 3Spike acceptable range upper limit, percent recovery 113 112 115 130 130 155 155 14

201416702

Blank, μg/kg <2 <1 <2 <1 <1 <0.1 <0.1 <Spike, percent recovery E92 E90 96 89 95 93 88 8Spike acceptable range lower limit, percent recovery 9 4 9 10 16 35 27 3Spike acceptable range upper limit, percent recovery 113 112 115 130 130 155 155 14

201424008

Blank, μg/kg <2 <1 <2 <1 <1 <0.1 <0.1 <Spike, percent recovery E85 E95 110 110 110 100 110 10Spike acceptable range lower limit, percent recovery 9 4 9 10 16 35 27 3Spike acceptable range upper limit, percent recovery 113 112 115 130 130 155 155 14

201408409

Blank, μg/kg <2 <1 <2 <1 <1 <0.1 <0.1 <Spike, percent recovery E75 E69 79 79 80 75 76 7Spike acceptable range lower limit, percent recovery 9 4 9 10 16 35 27 3Spike acceptable range upper limit, percent recovery 113 112 115 130 130 155 155 14

201425501

Blank, μg/kg <2 <1 <2 <1 <1 <0.1 <0.1 <Spike, percent recovery E110 E92 110 97 100 100 100 10Spike acceptable range lower limit, percent recovery 9 4 9 10 16 35 27 3Spike acceptable range upper limit, percent recovery 113 112 115 130 130 155 155 14
Table 8. Analytical results for halogenated organic compounds found in laboratory set blank samples, and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued [PBDE, polybrominated diphenyl ether; μg/kg, micrograms per kilogram; <, less than; E, estimated; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethychloroethane; PCB, polychlorinated biphenyls] Set number Sample identifier, units PCB congener 170 PCB congener 174 PCB congener 177 PCB congener 180 PCB congener 183 PCB congener 187 PCB congener 194 

201407007 Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.013 

Spike, percent recovery 76 70 67 62 62 61 68 Spike acceptable range lower limit, percent recovery 28 51 38 40 34 33 57 Spike acceptable range upper limit, percent recovery 154 135 140 142 142 153 135 

201417415 Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Spike, percent recovery 81 80 79 82 82 81 81 Spike acceptable range lower limit, percent recovery 28 51 38 40 34 33 57 Spike acceptable range upper limit, percent recovery 154 135 140 142 142 153 135 

201416702 Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Spike, percent recovery 90 89 88 93 90 89 89 Spike acceptable range lower limit, percent recovery 28 51 38 40 34 33 57 Spike acceptable range upper limit, percent recovery 154 135 140 142 142 153 135 

201424008 Blank, μg/kg 0.011 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Spike, percent recovery 99 98 97 99 100 99 99 Spike acceptable range lower limit, percent recovery 28 51 38 40 34 33 57 Spike acceptable range upper limit, percent recovery 154 135 140 142 142 153 135 

201408409 Blank, μg/kg <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Spike, percent recovery 74 72 72 75 72 72 75 Spike acceptable range lower limit, percent recovery 28 51 38 40 34 33 57 Spike acceptable range upper limit, percent recovery 154 135 140 142 142 153 135 

201425501 Blank, μg/kg <0.1 <0.1 <0.1 0.009 <0.1 <0.1 <0.1 

Spike, percent recovery 98 98 97 100 98 96 99 Spike acceptable range lower limit, percent recovery 28 51 38 40 34 33 57 Spike acceptable range upper limit, percent recovery 154 135 140 142 142 153 135 
Table 9. Analytical results for polycyclic aromatic hydrocarbons found in laboratory set blank samples and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.[<, less than; E, estimated; μg/kg, micrograms per kilogram; --, no data]

Set number Sample identifier, units

1,2,4-Trichlorobenzene 1,2-Di- methylnaph- thalene 1,6-Di- methylnaph- thalene 1-Methyl- 9H-fluorene 1-Methyl- phenan- threne 1-Methyl- pyrene 2,3,6

met

na

tha

201414703

Blank, μg/kg <25 <25 <25 <25 <25 <25 <25 Spike, percent recovery 90.2 110 107 113 115 111 106 

Spike acceptable range lower limit, percent recovery 22.68 25.76 22.01 32.51 14.84 23.71 23Spike acceptable range upper limit, percent recovery 89.25 114.15 113.96 123.22 139.30 133.72 114

201423004

Blank, μg/kg <25 <25 <25 <25 <25 <25 <25 

Spike, percent recovery 83.7 109 108 106 131 E138 105 

Spike acceptable range lower limit, percent recovery 22.68 25.76 22.01 32.51 14.84 23.71 23

Spike acceptable range upper limit, percent recovery 89.25 114.15 113.96 123.22 139.30 133.72 114

201415405

Blank, μg/kg <25 <25 <25 <25 <25 <25 <25 

Spike, percent recovery 70.1 77.8 77.5 82.7 88.9 97.1 77

Spike acceptable range lower limit, percent recovery 22.68 25.76 22.01 32.51 14.84 23.71 23

Spike acceptable range upper limit, percent recovery 89.25 114.15 113.96 123.22 139.30 133.72 114

201424503

Blank, μg/kg <25 <25 <25 <25 <25 <25 <25 

Spike, percent recovery -- -- -- -- -- -- -

Spike acceptable range lower limit, percent recovery 22.68 25.76 22.01 32.51 14.84 23.71 23

Spike acceptable range upper limit, percent recovery 89.25 114.15 113.96 123.22 139.30 133.72 114

Set number Sample identifier, units 2-Methyl- anthracene 4H-Cyclopenta[def] phenanthrene Acenaph- thene Acenaph- thylene Anthra- cene Ant

quin

201414703

Blank, μg/kg <25 <25 <25 <25 <25 <2

Spike, percent recovery 106 115 110 101 107 10

Spike acceptable range lower limit, percent recovery 29.69 18.79 21.84 30.01 27.77 2Spike acceptable range upper limit, percent recovery 119.93 136.23 120.78 106.12 117.84 13

201423004

Blank, μg/kg <25 <25 <25 <25 <25 Spike, percent recovery E122 137 106 95.5 122 E11

Spike acceptable range lower limit, percent recovery 29.69 18.79 21.84 30.01 27.77 2

Spike acceptable range upper limit, percent recovery 119.93 136.23 120.78 106.12 117.84 13

201415405

Blank, μg/kg <25 <25 <25 <25 <25 <2

Spike, percent recovery 86.4 88.2 79.6 75.1 85.2 9Spike acceptable range lower limit, percent recovery 29.69 18.79 21.84 30.01 27.77 2Spike acceptable range upper limit, percent recovery 119.93 136.23 120.78 106.12 117.84 13

201424503

Blank, μg/kg <25 <25 <25 <25 <25 <2

Spike, percent recovery -- -- -- -- -- -

Spike acceptable range lower limit, percent recovery 29.69 18.79 21.84 30.01 27.77 2Spike acceptable range upper limit, percent recovery 119.93 136.23 120.78 106.12 117.84 13
Table 9. Analytical results for polycyclic aromatic hydrocarbons found in laboratory set blank samples and set spike data associated with samples cWestside Creeks (Alazán, Apache, Martínez, and San Pedro Creeks) and San Antonio River, San Antonio, Texas, 2014.—Continued [<, less than; E, estimated; μg/kg, micrograms per kilogram; --, no data] Set number Sample identifier, units Benzo[b] fluoran- thene Benzo[e] pyrene Benzo [ghi] perylene Benzo[k] fluoran- thene Bis(2- ethyl- hexyl) phthalate Carba- zole Chry- sene Dibenz [a,h] anthra- cene 

201414703 Blank, μg/kg <25 <25 <25 <25 13.8 <25 <25 <25 

Spike, percent recovery 120 127 113 114 113 117 104 108 Spike acceptable range lower limit, percent recovery 22.66 24.06 20.31 25.76 17.11 31.46 18.98 24.38 Spike acceptable range upper limit, percent recovery 146.34 147.20 135.58 138.24 143.51 136.25 139.01 134.99 

201423004 Blank, μg/kg 9.4 5.1 10.2 5.9 43.2 1.9 6.0 E8.9 

Spike, percent recovery 141 145 139 133 150 147 129 133 Spike acceptable range lower limit, percent recovery 22.66 24.06 20.31 25.76 17.11 31.46 18.98 24.38 Spike acceptable range upper limit, percent recovery 146.34 147.20 135.58 138.24 143.51 136.25 139.01 134.99 

201415405 Blank, μg/kg <25 <25 <25 <25 13.8 <25 <25 <25 

Spike, percent recovery 117 114 109 111 87.4 103 102 109 Spike acceptable range lower limit, percent recovery 22.66 24.06 20.31 25.76 17.11 31.46 18.98 24.38 Spike acceptable range upper limit, percent recovery 146.34 147.20 135.58 138.24 143.51 136.25 139.01 134.99 

201424503 Blank, μg/kg <25 <25 <25 <25 <51.0 <25 1.3 <25 

Spike, percent recovery -- -- -- -- -- -- -- -- Spike acceptable range lower limit, percent recovery 22.66 24.06 20.31 25.76 17.11 31.46 18.98 24.38 Spike acceptable range upper limit, percent recovery 146.34 147.20 135.58 138.24 143.51 136.25 139.01 134.99 

Set number Sample identifier, units Fluorene Hexachloro- benzene Indeno [1,2,3-cd] pyrene Naph- thalene Penta- chloro- anisole Penta- chloro- nitro- benzene Pery- lene Ph

t

201414703 Blank, μg/kg <25 <25 <25 7.2 <25 <25 <25 

Spike, percent recovery 111 105 111 105 111 81.7 99.4 1Spike acceptable range lower limit, percent recovery 27.87 24.22 23.10 15.74 24.24 10.94 16.00 Spike acceptable range upper limit, percent recovery 123.53 119.08 134.54 114.18 123.78 102.39 130.79 1

201423004 Blank, μg/kg <25 <25 E10.4 2.4 <25 <25 2.3 

Spike, percent recovery 105 96.3 138 98.4 100 69.5 122 1Spike acceptable range lower limit, percent recovery 27.87 24.22 23.10 15.74 24.24 10.94 16.00 Spike acceptable range upper limit, percent recovery 123.53 119.08 134.54 114.18 123.78 102.39 130.79 1

201415405 Blank, μg/kg <25 <25 <25 2.0 <25 <25 <25 <

Spike, percent recovery 80.4 76.4 106 77.0 79.3 59.0 99.2 Spike acceptable range lower limit, percent recovery 27.87 24.22 23.10 15.74 24.24 10.94 16.00 Spike acceptable range upper limit, percent recovery 123.53 119.08 134.54 114.18 123.78 102.39 130.79 1

201424503

Blank, μg/kg <25 <25 <25 6.7 <25 <25 <25 Spike, percent recovery -- -- -- -- -- -- -- Spike acceptable range lower limit, percent recovery 27.87 24.22 23.10 15.74 24.24 10.94 16.00 Spike acceptable range upper limit, percent recovery 123.53 119.08 134.54 114.18 123.78 102.39 130.79 1
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Crow and others—Occurrence and Concentrations of Selected Trace Elements, Halogenated Organic Compounds, and PAHs—SIR 2016–5136

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ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20165136 Printed on recycled paper

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