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Contamination of PCBs and OC Pesticides in Urbanized Guadalupe River Watershed

This presentation discusses the concentrations and loads of PCBs and OC pesticides in the urbanized Guadalupe River watershed. It also explores the potential sources of contamination, monitoring approaches, and implications of the findings on water quality.

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Contamination of PCBs and OC Pesticides in Urbanized Guadalupe River Watershed

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  1. Item #2 Concentrations and loads of PCBs and OC pesticides in the urbanized Guadalupe River watershed Presented to:RMP Sources, Pathways, and Loadings WorkgroupMay 22, 2007 Jon LeatherbarrowSan Francisco Estuary Institute, Oakland, CAUC Davis, Civil & Environmental Engineering, Davis, CA

  2. Item #2 PCB and OCP use in urban areas

  3. Item #2 Legacy contamination in urban environment • Areas of heaviest use of PCBs; contaminated areas; continued use and accidental release; • Areas of most recent widespread use of many OCPs (e.g., chlordane, dieldrin, HCHs); direct application, release • Development and disturbance of former agricultural lands; post World War II and Silicon Valley “boom” in the 1960s • Persistence in watershed soils and aquatic sediments due to chemical and physical stability; • Continuing local, regional, and global impacts from cycling of contaminant residues through non-point source pollution pathways (i.e., runoff, atmospheric)

  4. Item #2 Guadalupe River monitoring approach • Sample collection: • PCBs (n=72, WY2003-06) • OCPs: DDT, HCHs (n=44 WY2003-04) dieldrin, chlordane • Grab samples (WY2003) • D-96 sampler (WY2004-06) • Sample analysis • Laboratory: Axys Analytical Services, Ltd. Sidney, BC • Method: HRGC/HRMS, EPA 1668A

  5. Item #2 Guadalupe River monitoring results

  6. Item #2 Δ Rising stage ● Falling stage Base flow ■ Regression: contaminants on SSC

  7. Item #2 Annual loading (***preliminary***)

  8. Item #2 Estimates from Fikslin and Suk (2003); Foster et al. (2000a,b); Ko and Baker (2004); Leatherbarrow et al. (2005) Watershed yields: Penta-PCBs

  9. Item #2 Rowe et al. (2007) estimate that highlighted watershed yields reported in Delaware River TMDL are atmospherically driven Watershed yields: Penta-PCBs

  10. Item #2 Sum of p,p’-isomers of DDE, DDD, DDT Sum of chlordane compounds Watershed yields*: Pesticides Dieldrin *All yields in ng/m2/day; Estimates from Foster et al. (2000); Foster et al. (2003); Leatherbarrow et al. (2005)

  11. Item #2 Potential sources: PCB congeners 12/16/02 19:55 (GR24) 10/26/04 5:50 (GR310) 10/26/04 7:50 (GR311) Aroclor 1260 Aroclor 1254

  12. Item #2 Potential sources: PCB congeners Ratio of GR311:GR310 Aroclor 1016 Aroclor 1242

  13. Item #2 Penta-PCBs ▼ Hepta-PCBs □ Watershed processing of PCBs

  14. Item #2 p,p’-DDT ▼ p,p’-DDD □ Watershed processing of DDT

  15. Item #2 Implications of findings: sources • Diffuse source distribution in the watershed: • Positive linear relationships of contaminants with SSC; • Relatively constant PCB congener profile; • Gradient in contamination from urban to non-urban areas: • Differences in rising and falling stage regressions indicates high SSC-based concentrations likely emanating from lower urban areas compared to upper non-urban areas; • Periodic inputs of PCBs from unique sources: • Anomalous profiles in some samples; • Atmospheric inputs likely discernable in evolving profile patterns; • Relatively unweathered sources of pesticides: • High percentage of parent DDT material at high flows; • Similar increase in technical mixture profiles in other OCPs;

  16. Item #2 Implications of findings: loadings • Watershed yields consistent with contaminated urban areas: • PCB yields above expected yields from atmospheric deposition; • Urban influence evident compared to other land uses: • Comparison of watershed yields indicates high potential source density in urban areas compared to non-urban areas; • Urban runoff contributes to impairment of SF Bay: • Mass budget models indicate loading of PCBs and OCPs on the order of 10 kg/yr could significantly delay water quality improvement; • PCB TMDL loading target for urban runoff = 2 kg/yr • Loads of 0.5-1 kg/yr from Guadalupe, combined with other tributaries, are expected to contribute to prolonged impairment of water quality.

  17. Item #2 Information needs • Modeling • Hydrologic routing: where is the water coming from? • Sediment transport: where is the sediment coming from? • Contaminant transport: link evolving contaminant profiles to sources of water and sediment. • Treatment options • Source reconnaissance • Structural treatment device placement and optimization • Information gathering on other tributaries • Monitoring other selected tributaries • Extrapolation/modeling methods

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