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Concentrations and loads of PCBs and OC pesticides in the urbanized Guadalupe River watershed

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

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Concentrations and loads of PCBs and OC pesticides in the 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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