In cooperation with the Texas Commission on Environmental Quality
Occurrence, Trends, and Sources in Particle-Associated Contaminants in Selected Streams and Lakes in Fort Worth, Texas
By Peter C. Van Metre, Jennifer T. Wilson, Glenn R. Harwell, Marcus O. Gary, Franklin T. Heitmuller, and Barbara J. Mahler
U.S. Geological Survey
Water-Resources Investigations Report 03–4169
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Contents
Abstract
Introduction
Purpose and Scope
Review of Existing Data
Acknowledgments
Methods
Study Design and Watershed Characteristics
Collection of Sediment Cores
Collection of Suspended-Sediment Samples in Streams
Analytical Methods
Age Dating Cores
Evaluating Trends in Cores
Estimating Contaminant Yields on the Basis of Cores
Development of Ratings for Suspended-Sediment Sampling Sites
Big Fossil Creek
Sycamore Creek
Lake Como Inflow
Echo Lake Inflow
Fosdic Lake Inflow
Estimating Contaminant Loads in Streams
Particle-Associated Contaminants in Cores and Suspended Sediments
Quality Assurance of Chemical Data
Lake Como
Age Dating and Sedimentation Rates
Sediment Properties, Contaminant Trends, and Relations to Inflows
Organochlorine Pesticides and Polychlorinated Biphenyls
Trace Elements
Polycyclic Aromatic Hydrocarbons
Contaminant Yields Based on Cores
Echo Lake
Age Dating and Sedimentation Rates
Sediment Properties, Contaminant Trends, and Relations to Inflows
Organochlorine Pesticides and Polychlorinated Biphenyls
Trace Elements
Polycyclic Aromatic Hydrocarbons
Contaminant Yields Based on Cores
Fosdic Lake
Age Dating and Sedimentation Rates
Sediment Properties, Contaminant Trends, and Relations to Inflows
Organochlorine Pesticides and Polychlorinated Biphenyls
Trace Elements
Polycyclic Aromatic Hydrocarbons
Contaminant Yields Based on Cores
Inflows to Clear Fork and West Fork Trinity River
Organochlorine Pesticides and Polychlorinated Biphenyls
Trace Elements and Polycyclic Aromatic Hydrocarbons
Event Loads and Yields in Streams
Interpretations and Implications of Contaminant Occurrence, Trends, and Sources
Contaminant Occurrence
Trends
Organochlorine Pesticides and Polychlorinated Biphenyls
Trace Elements
Polycyclic Aromatic Hydrocarbons
Sources and Transport: Relations Between Land Use and Contaminants
Source Strength: Contaminant Yields to Reservoirs
Transport and Fate: Relations Between Suspended Sediments and Sediment Cores
Fate: Sediments and Fish
Summary and Conclusions
References
Appendixes
1 |
Chemical Data | |
1.1 |
Cesium-137 concentrations in bottom sediments | |
1.2 |
Grain-size distribution in selected sediment core samples | |
1.3 |
Suspended-sediment concentrations and selected grain-size distributions in suspended sediment | |
1.4 |
Selected chlorinated hydrocarbon compound concentrations in bottom and suspended sediments | |
1.5 |
Selected major and trace element concentrations in bottom and suspended sediments | |
1.6 |
Selected polycyclic aromatic hydrocarbon compound concentrations in bottom and suspended sediments | |
2. |
Quality Assurance | |
2.1 |
Sample groups for organics analyses and duplicate sample relative percent differences | |
2.2 |
Chlorinated hydrocarbon quality control samples | |
2.3 |
Chlorinated hydrocarbon duplicate samples | |
2.4 |
Polycyclic aromatic hydrocarbon quality control samples | |
2.5 |
Polycyclic aromatic hydrocarbon duplicate samples | |
2.6 |
Sample groups for major and trace element analyses and duplicate and triplicate sample relative percent differences | |
2.7 |
Major and trace element quality control samples | |
2.8 |
Major and trace element duplicate and triplicate samples | |
2.9 |
Cesium-137 quality control and duplicate samples | |
3. |
Loads and Yields | |
| 3.1 |
Loads and yields of chlorinated hydrocarbons on suspended-sediment samples | |
| 3.2 |
Loads and yields of major and trace elements on suspended-sediment samples | |
| 3.3 |
Loads and yields of polycyclic aromatic hydrocarbons on suspended-sediment samples | |
4. |
Fish-Tissue Data | |
4.1 |
Trinity River fish samples | |
4.2 |
Lake Como fish samples | |
4.3 |
Echo Lake fish samples |
|
4.4 |
Fosdic Lake fish samples | |
Figures
| 1–2. |
Maps showing: |
|
| 1. |
Locations of suspended-sediment sampling sites and lakes where sediment cores collected, Fort Worth, Texas | |
| 2. |
Land use and sampling locations in Lake Como, Echo Lake, and Fosdic Lake watersheds, Fort Worth, Texas | |
| 3–7. |
Graphs showing: |
|
| 3. |
Cesium-137 and lead concentrations in Lake Como core sediment used for age dating samples | |
| 4. |
Grain size and organic carbon in Lake Como core sediment and Lake Como inflow suspended-sediment samples | |
| 5. |
Trends of chlorinated hydrocarbons in Lake Como core sediment and Lake Como inflow suspended sediment | |
| 6. |
Trends of trace elements in Lake Como core sediment and Lake Como inflow suspended sediment | |
| 7. |
Trends of polycyclic aromatic hydrocarbons (PAHs) in Lake Como core sediment and Lake Como inflow suspended sediment | |
| 8. |
Map showing sediment thickness and sampling
sites in Lake Como |
|
| 9–12. |
Graphs showing: |
|
| 9. |
Cesium-137 concentrations in Echo Lake core sediment used for age dating samples | |
| 10. |
Trends of chlorinated hydrocarbons in Echo Lake core sediment and Echo Lake inflow suspended sediment | |
| 11. |
Trends of trace elements in Echo Lake core sediment and Echo Lake inflow suspended sediment | |
| 12. |
Trends of polycyclic aromatic hydrocarbons (PAHs) in Echo Lake core sediment and Echo Lake inflow suspended sediment | |
| 13. |
Map showing sediment thickness and sampling
sites in Echo Lake |
|
| 14–18. |
Graphs showing: |
|
| 14. |
Cesium-137 and lead concentrations in Fosdic Lake core sediment used for age dating samples | |
| 15. |
Grain-size variations in Fosdic Lake core sediment | |
| 16. |
Trends of chlorinated hydrocarbons in Fosdic Lake core sediment and Fosdic Lake inflow suspended sediment | |
| 17. |
Trends of trace elements in Fosdic Lake core sediment and Fosdic Lake inflow suspended sediment | |
| 18. |
Trends of polycyclic aromatic hydrocarbons (PAHs) in Fosdic Lake core sediment and Fosdic Lake inflow suspended sediment | |
| 19. |
Map showing sediment thickness and sampling
sites in Fosdic Lake |
|
| 20–25. |
Graphs showing: |
|
| 20. |
Storm volume, sediment load, and zinc yield for storms at the three lake inflows and Big Fossil and Sycamore Creeks | |
| 21. |
Relations between selected contaminant concentrations in sediment and percent urban land use for all suspended-sediment samples and all core samples dated 1990 or later | |
| 22. |
Relations between selected contaminant concentrations in suspended sediment and percent urban land use for all suspended-sediment samples | |
| 23. |
Ratio of median suspended-sediment concentrations (n = 4) to median top-of-core sediment concentrations (n = 3) of selected organic contaminants and trace elements | |
| 24. |
Concentration of chlordane in fish tissues collected from Lake Como, Echo Lake, and Fosdic Lake | |
| 25. |
Concentrations of total PCBs in fish tissues collected from two sites in the Trinity River near and in Fort Worth, Texas | |
Tables
|
1. |
Listing of water-quality impairment in Fort Worth area streams and lakes |
|
2. |
Summary of historical fish-tissue data |
|
3. |
Land use/land cover for study watersheds in 2000 |
|
4. |
Selected characteristics of sediment cores and core sampling sites |
|
5. |
Constituents and laboratory reporting levels |
|
6. |
Trend testing results and variability of concentrations from 1965 to 2001 on primary sediment core from each lake |
|
7. |
Sediment mass accumulation rates (MAR) in lakes |
|
8. |
Watershed yields of selected constituents estimated using a mass-balance approach in reservoirs |
|
9. |
Storm volumes and sediment loads used to compute contaminant loads and yields |
|
10. |
Spearman’s rank order correlations between selected organochlorine compounds or trace elements in sediment and land use |
|
11. |
Selected contaminant concentrations and cultural enrichment factors (CEF) estimated using regression equations presented in figures 21 and 22 |
Abstract
Several lakes and stream segments in Fort Worth, Texas, have fish consumption bans because of elevated levels of chlordane, dieldrin, DDE, and polychlorinated biphenyls (PCBs). This study was undertaken to evaluate current loading, trends, and sources in these long-banned contaminants and other particle-associated contaminants commonly found in urban areas. Sampling included suspended sediments at 11 sites in streams and bottom-sediment cores in three lakes. Samples were analyzed for chlorinated hydrocarbons, major and trace elements, and polycyclic aromatic hydrocarbons (PAHs). All four legacy pollutants responsible for fish consumption bans were detected frequently. Concentrations of chlordane, lead, and PAHs most frequently exceeded sediment-quality guidelines. Trends in DDE and PCBs since the 1960s generally are decreasing; and trends in chlordane are mixed with a decreasing trend in Lake Como, no trend in Echo Lake, and an increasing trend in Fosdic Lake. All significant trends in trace elements are decreasing, and most significant trends in PAHs are increasing. Sedimentation surveys were conducted on each of the three lakes and used in combination with sediment core data to compute sediment mass balances for the lakes, to estimate long-term-average loads and yields of sediment, and to estimate recent loads and yields of selected contaminants.
Concentrations of most trace elements in suspended sediments were similar to those at the tops of cores, but concentrations of many hydrophobic organic contaminants were two to three times larger. As a result, for these fluvial systems, sediment cores probably provide a historical record of trace element contamination but could underestimate historical concentrations of organic contaminants. However, down-core profiles suggest that relative concentration histories are preserved in these sediment cores for many organic contaminants (such as chlordane and total DDT) but not for all (such as dieldrin).
Percent urban land use correlates strongly with selected contaminant concentrations in sediments. Organochlorine pesticides had significant correlations to residential land use, whereas PCBs, cadmium, lead, zinc, and PAHs more often correlate significantly with commercial and industrial land uses, which suggests different urban sources for different contaminants. The amount of enrichment in these contaminants associated with urban land use predicted from regression equations, expressed as the ratio of concentrations predicted for 100 percent urban to 30 percent urban, ranges from 3.6 to 6.9 for PCBs and heavy metals to about 15 for chlordane, total DDT, and PAHs. These data indicate that urbanization is having a substantial negative effect on sediment and water quality and that legacy pollutants are being actively transported to streams and lakes 13 to 30 years after their use was restricted or banned. They further suggest that fish in the lakes and these water bodies will continue to be exposed to legacy pollutants in sediment for many years to come.
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