USGS

Water Resources of Colorado

Distribution and Concentrations of Selected Organochlorine Pesticides and PCB’s in Streambed Sediment and Whole-Body Fish in the Upper Colorado River Basin, 1995–96

Fact Sheet 167–97

by Verlin C. Stephens and Jeffrey R. Deacon


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Table of Contents

Description of Sampling Unit and Study Approach
Established Guidelines
Major Organochlorine Compounds Detected in Relation to Established Guidelines
     Dichloro diphenyl trichloroethane (DDT)
     Dichloro diphenyl dichloroethylene (p,p'-DDE)
     Chlordane
     Polychlorinated Biphenyls (PCB’s)
     Dieldrin
     Dacthal (DCPA)
     Toxaphene
Water-Quality Implications
References Cited


Typical high-elevation stream in the UCOL study unit.

As a part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program, hydrologic and water-quality assessment of the Upper Colorado River Basin (UCOL) study unit began in 1994. Prior to the design of the integrated studies of water quality in the basin, a retrospective investigation was conducted to determine the availability of historical water-quality data and the location of previous research that occurred in the UCOL. The findings indicated that minimal data had been collected regarding the occurrence and distribution of organochlorine pesticides and polychlorinated biphenyls (PCB’s) in streambed sediment and whole-body fish in the UCOL study unit (Deacon and Stephens, 1996).

Organochlorine pesticides and PCB’s, all of which are organochlorine compounds, have been specifically targeted by standards and guidelines that exist to protect water quality for human and wildlife health. In 1995–96, a survey of selected organochlorine pesticides and PCB’s was conducted in the UCOL to (1) determine their distribution and concentrations in streambed sediment and whole-body fish, and (2) compare these concentrations to established water-quality guidelines.

Organochlorine compounds are unique because their presence can result only from human activities. These compounds disperse from their original point of application, typically agricultural fields and urban areas, to the hydrologic system through soil erosion, runoff, and precipitation. Due to the persistence, bioaccumulation, and hazards of these compounds, the use of many organochlorine pesticides has been banned or severely restricted in the United States. Organochlorine compounds are extremely persistent in the environment and have the unique property of concentrating in sediment and in the fatty tissue of aquatic life (Ware, 1989).

This fact sheet presents data for detections of selected organochlorine compounds in streambed sediment and whole-body fish. Data for all the compounds detected in samples collected for this study are in the U.S. Geological Survey National Water Information System (NWIS) data base.

DESCRIPTION OF SAMPLING UNIT AND STUDY APPROACH

Figure 1. Land use and sampling site locations in the Upper Colorado River Basin Study Unit.

The UCOL study unit (fig. 1) encompasses about 17,800 square miles and has varied climate, geology, hydrology, soils, topography, and land uses. Water quality throughout the basin is directly affected by these natural (physiography, altitude, geology, climate, soils) and human (population, land use, water allocation and use) factors (Apodaca and others, 1996). Sampling sites were selected to characterize differences among these environmental settings and various land uses and to acquire additional data regarding the occurrence and distribution of organochlorine compounds. Sampling sites in the eastern part of the study unit represent a high-altitude environment of small, clear, cool streams dominated by forest and rangeland. Adverse human effects on water quality in these areas predominantly are mining, increasing urban development, recreational use, and hydrologic modifications (dams and diversions). Sampling sites in the western part of the study unit are representative of a more arid climate dominated by larger, warmer, sediment-laden streams. Human effects on water quality in these areas are predominantly agriculture, water development, and increasing urban development and recreational use.

Streambed-sediment and whole-body-fish samples were collected in fall 1995 and 1996 (fig. 1, table 1) for analysis of concentrations of organochlorine pesticides and PCB’s. Nineteen sites were sampled for streambed sediment and analyzed for 33 organochlorine pesticides and PCB’s. Whole-body-fish samples were collected by electroshocking at 14 of the sampling sites and were analyzed for 28 organochlorine pesticides and PCB’s. Five of the sites sampled for streambed sediment did not contain, or were not sampled, for fish (table 1). Samples of streambed sediment and whole-body fish were collected, processed, and analyzed in accordance with NAWQA protocols (Crawford and Luoma, 1993; Shelton and Capel, 1994). Sample collection was limited to stream reaches that averaged 150–200 meters (m) in length for each of the wadeable sampling sites and 500–750 m in length for the non-wadeable sites. Twenty to 25 individual subsamples of streambed sediment from the upper 2 centimeters were collected from a variety of undisturbed, continuously wetted depositional zones. The subsamples were composited into a glass container, homogenized, and sieved to <2 millimeters. The samples were then frozen and shipped to a laboratory for analysis. Each of the whole-body-fish samples collected consisted of a composite of seven similarly sized fish of the same species. The predominant species collected in the eastern higher altitudes was brown trout and the predominant species collected in the western lower reaches of the basin was the sucker. Each fish collected was weighed, measured, sexed, and aged. Fish also were closely scrutinized for signs of disease, parasites, or other abnormal features. Samples were prepared for the organochlorine and PCB analyses by wrapping the individual whole fish in aluminum foil, freezing the sample, and shipping to the laboratory for analysis.

 

Table 1. Sampling-site information

[Sites listed indicate collection of streambed-sediment samples and type of whole-body-fish samples as noted; na, not available; mi2, square miles]

Site
number
(fig. 1)
Site
name
Site
identifier
Site
type
Sample
collection
date,
streambed
sediment
Sample
collection
date,
whole-fish
tissue
Drainage
area
(mi2)
Type of
whole-
body-fish
sample used
for analysis
1
Colorado River below Baker Gulch
09010500
Reference
10/10/95
08/17/95
53
Brown trout
2
French Gulch near Breckenridge
09046530
Mining
10/05/95
na
11
No fish found
3
Blue River below French Gulch
392944106024400
Mining
10/05/95
08/25/95
69
Brown trout
4
Gore Creek at mouth near Minturn
09066510
Urban/
Recreation
10/10/95
08/15/95
102
Brown trout
5
East River below Cement Creek
09112200
Urban/
Recreation
10/13/95
10/16/95
238
Brown trout
6
Gunnison River at County Road 32
383103106594200
Mixed
10/13/95
08/16/95
2,128
Brown trout
7
Gunnison River below Gunnison Tunnel
09128000
Reference
10/13/95
09/21/95
3,965
Brown trout
8
Uncompahgre River near Ridgway
09146200
Mining
10/12/95
10/17/95
149
White sucker
9
Colorado River at Dotsero
09070500
Mixed
10/10/95
08/23/95
4,394
Brown trout
10
Dry Fork at upper station near De Beque
09095300
Reference
10/11/95
na
97
No fish found
11
Colorado River near Cameo
09095500
Mixed
10/11/95
08/23/95
8,050
Bluehead sucker
12
Dry Creek near Begonia Road
09149480
Agriculture
10/12/95
08/18/95
175
White sucker
13
Tongue Creek near Cory, CO
09144200
Agriculture
10/12/95
08/24/95
200
White sucker
14
Gunnison River near Grand Junction
09152500
Mixed
10/12/95
08/16/95
7,928
Bluehead sucker
15
33 Road drain near mouth
390347108265800
Agricultural drain
09/17/96
na
na
No fish collected
16
Appleton drain near mouth
390624108374900
Agricultural drain
09/17/96
na
na
No fish collected
17
Copeco drain near mouth
390723108400500
Agricultural drain
09/17/96
na
na
No fish collected
18
Reed Wash near Mack
09153290
Agriculture
11/20/95
11/21/95
16
Flannelmouth sucker
19
Colorado River near Colorado-Utah State line
09163500
Mixed
10/11/95
08/17/95
17,843
Bluehead sucker

 

Bed-sediment sample collection.
Electroshocking from a boat at a non-wadeable site.

ESTABLISHED GUIDELINES

The Provincial Sediment Quality Guidelines (PSQG) (Environment Canada, 1995) were used to compare concentrations of organochlorine pesticides and PCB’s in streambed-sediment samples collected in this study. These guidelines are based on chronic and long-term effects of contaminant concentrations on benthic organisms. The PSQG establish two assessment values for some of the organochlorine and PCB contaminants analyzed in this study: the lower threshold effect level (TEL) and the higher probable effect level (PEL). The TEL represents the guideline concentration of sediment contamination below which adverse effects are expected to rarely occur. The PEL represents the guideline concentration above which adverse effects are expected to frequently occur. Concentrations that fall between the TEL and PEL are levels at which adverse effects are expected to occasionally occur (Environment Canada, 1995). The only national guidelines available for evaluating organochlorine-compound concentrations in whole-body fish have been established by the National Academy of Sciences and National Academy of Engineering (NAS/NAE). These guidelines apply to the protection of wildlife that consume fish (National Academy of Sciences and National Academy of Engineering, 1973).

MAJOR ORGANOCHLORINE COMPOUNDS DETECTED IN RELATION TO ESTABLISHED GUIDELINES

Dichloro diphenyl trichloroethane (DDT): DDT is a well-documented, persistent organochlorine compound that has been banned from use in the United States since 1972. The six degradation products of DDT were analyzed for, and the sum of the individual concentrations are denoted as total DDT in this fact sheet. Total DDT was detected in streambed-sediment samples at 7 of 19 sites and in whole-body-fish samples at 12 of 14 sites (fig. 2). DDT was the most frequently detected organochlorine compound, with the highest concentrations found in the UCOL study unit. The highest concentrations detected in streambed-sediment samples were collected from sites 15, 16, and 17, which are agricultural drains. Concentrations of the samples collected at these sites exceeded the PSQG TEL of 6.98 µg/kg (micrograms per kilogram) for total DDT. None of the sites exceeded the PEL of 4,450 µg/kg.

Figure 2. Concentrations of total DDT and total chlordane in streambed sediment and whole-body fish.
Figure 3. Concentrations of p,p'-DDE in streambed sediment and whole-body fish.

Samples collected at sites 3 and 7 had no detections of total DDT in whole-body fish. Samples collected at site 1, a reference site (a reference site is one that is used to determine background or naturally occurring water-quality conditions) had a total DDT concentration of 11 µg/kg in whole-body fish. This concentration was higher than other samples collected in the eastern, higher altitude sampling sites and might be attributed to residues from applications of DDT to forested areas for the control of spruce budworm in the 1950’s (L.F. Carter, U.S. Geological Survey, written commun., 1997). Total DDT concentrations in whole-body fish were highest at agricultural and mixed land-use sites. The concentration of total DDT in whole-body-fish samples collected at site 12 (983 µg/kg), an agricultural site, approached the NAS/NAE guideline of 1,000 µg/kg for the protection of wildlife that consume fish.

Dichloro diphenyl dichloroethylene (p,p'-DDE): P,p'-DDE is a degradation by-product of DDT and has separate PSQG guidelines established for concentrations of this individual isomer in streambed sediment. Of the seven samples collected that had detections in streambed sediment, all concentrations exceeded the TEL (1.42 µg/kg). Sample concentrations at two agricultural drain sites (site 15, 56 µg/kg; site 17, 19 µg/kg) greatly exceeded the PEL (6.75 µg/kg) (fig. 3). All seven of these samples were collected from agricultural and mixed land-use sites in the western part of the study unit. P,p'-DDE also was detected in 12 of 14 samples collected for whole-body fish; however, none of the concentrations exceeded NAS/NAE guidelines.

Figure 4. Concentrations of PCB’s and dieldrin in streambed sediment and whole-body fish.
Figure 5. Concentrations of DCPA and toxaphene in streambed sediment and whole-body fish.

Chlordane: Chlordane is highly toxic to fish and historically was used as a contact insecticide until 1980 when it was banned except for termite control and wood treatment. In this fact sheet, the sum of the chlordane isomers (cis-chlordane, trans-chlordane, cis-nonachlor, trans-nonachlor, oxychlordane, and heptachlor epoxide) is referred to as “total chlordane.” None of the chlordane isomers were detected in streambed-sediment samples, but some were detected in whole-body-fish samples collected at some agricultural and mixed land-use sites (fig. 2). Total chlordane concentrations for whole-body-fish samples ranged from 25.2 to 86.4 µg/kg. Whole-body-fish samples collected at site 18, an agricultural land-use site, had the highest total chlordane concentration (86.4 µg/kg) and approached the NAS/NAE guideline for whole-body fish of 100 µg/kg.

Polychlorinated Biphenyls (PCB’s): PCB’s are well-documented, persistent organochlorine compounds that have been banned since 1979. Historically, these compounds primarily were used as industrial heat-exchange and dielectric fluids used in capacitors and transformers. PCB’s were detected only in whole-body-fish samples at site 8 (fig. 4), a mining land-use site, with a concentration of 180 µg/kg. The NAS/NAE guideline for whole-body fish is 500 µg/kg.

Dieldrin: Dieldrin also has been banned from use in the United States. The PSQG guidelines for dieldrin are a TEL of 2.85 and PEL of 6.67 µg/kg. Dieldrin was detected in streambed sediment at two agricultural drain sites (15 and 16); however, only site 15 exceeded the TEL guideline with a concentration of 3.5 µg/kg (fig. 4). Dieldrin was the second most frequently detected organochlorine compound (5 of 14 sites) in whole-body-fish samples. Concentrations of dieldrin in whole-body-fish samples occurred predominantly at agricultural land-use sites, and concentrations at all sites ranged from 6.0 to 71 µg/kg. The highest concentration of 71 µg/kg from site 12 was less than the NAS/NAE guideline of 100 µg/kg.

Weighing and measuring of individual fish.

Dacthal (DCPA): Dacthal, more commonly known as DCPA, is used as a selective preemergent herbicide. It is considered a general hazard to fish and is the only compound analyzed for and detected in this study that has not been banned from use. DCPA was detected in trace amounts in streambed-sediment samples collected at agricultural sites. The streambed-sediment sample collected from site 17 had the highest concentration at 10 µg/kg (fig. 5). DCPA was detected in whole-body-fish samples at three sites (12, 14, and 19) with concentrations ranging from 32 to 52 µg/kg. There are no established guidelines for concentrations of DCPA in streambed sediment or whole-body fish.

Toxaphene: Toxaphene (Camphechlor) was widely used as a preharvest insecticide for cotton, grains, vegetables, and fruit. Toxaphene was banned in 1982 after it was used to replace DDT as an agricultural insecticide. Toxaphene was only detected in whole-body-fish samples (fig. 5) at site 18 (300 µg/kg), an intensive agricultural land-use site. Concentration at this site exceeded the NAS/NAE guideline (100 µg/kg) for toxaphene concentrations in whole-body fish.

WATER-QUALITY IMPLICATIONS

Whole-body-fish sample processing.

Organochlorine pesticides and PCB’s were more frequently detected and were at much higher concentrations in whole-body-fish samples than in streambed-sediment samples. Six of 33 individual organochlorine compounds analyzed for were detected in streambed-sediment samples. Eighteen of the 28 individual organochlorine compounds analyzed for were detected in whole-body-fish samples. Although the use of organochlorine compounds such as DDT, chlordane, and PCB’s was discontinued in the early 1970’s, all of these compounds were detected in whole-body-fish samples and, to a much lesser extent, in streambed-sediment samples collected in the UCOL study unit. The sites with the most detections and highest concentrations of organochlorine compounds in streambed-sediment and whole-body-fish samples generally were located in the western, lower reaches of the basin, which includes some mixed land use but which generally is agricultural.

Site 12 had the most detections of organochlorine compounds in streambed-sediment and whole-body-fish samples. Site 15 was sampled only for streambed sediment but had concentrations of a degradational form of DDT (p,p'-DDE) that exceeded PSQG guidelines by more than eight times the PEL. In addition, all other organochlorine compounds detected in streambed sediment at this site exceeded the TEL, and some exceeded the PEL. Concentrations of toxaphene in whole-body-fish samples collected from site 12 exceeded levels established for the protection of wildlife that consume fish.

Assessing the implications of organochlorine pesticide and PCB concentrations in fish and wildlife is becoming increasingly important because of recent evidence suggesting that some organochlorine compounds may disrupt endocrine systems, even at low concentrations (Colburn and others, 1993). Also, the cumulative or synergistic effects associated with multiple occurrences of toxic compounds are not well understood or documented. Although most of the organochlorine compounds detected in the samples from the study have been banned, the environmental degradation of these compounds is slow; therefore, organochlorine compounds such as DDT, chlordane, and PCB’s remain in the UCOL study unit long after use has been restricted.

REFERENCES CITED

Apodaca, L.E., Driver, N.E., Stephens, V.C., and Spahr, N.E., 1996, Environmental setting and implications on water quality, Upper Colorado River Basin, Colorado and Utah: U.S. Geological Survey Water-Resources Investigations Report 95–4263, 34 p.

Colburn, T., van Saal, F.S., and Soto, A.M., 1993, Developmental effects of endocrine-disrupting chemicals in wildlife and humans: Environmental Health Perspectives, v. 101; p. 378–384.

Crawford, J.K., and Luoma, S.N., 1993, Guidelines for studies of contaminants in biological tissues for the National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 92–494, 69 p.

Deacon, J.R., and Stephens, V.C., 1996, Summary of biological and contaminant investigations related to stream water quality and environmental setting in the Upper Colorado River Basin, 1938–95: U.S. Geological Survey Water-Resources Investigations Report 96–4172, 37 p.

Environment Canada, 1995, Interim sediment quality guidelines: Ottawa, Ontario, Ecosystem Conservation Directorate Evaluation and Interpretation Branch, 63 p.

National Academy of Sciences and National Academy of Engineering, 1973, Water quality criteria, 1972: U.S. Environmental Protection Agency, EPA R3–73–033, 594 p.

Shelton, L.R., and Capel, P.D., 1994, Guidelines for collecting and processing samples of streambed sediment for analysis of trace elements and organic contaminants for the National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 94–458, 20 p.

Ware, G.W., 1989, The pesticide book: Fresno, Calif., Thomson Publications, 3d ed., 340 p.

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