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1 PCB and PBDE Loads in Coyote Creek: Conceptual models and Estimates of Regional Small Tributaries Loads Lester McKee, John Oram and, Jon Leatherbarrow.

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Presentation on theme: "1 PCB and PBDE Loads in Coyote Creek: Conceptual models and Estimates of Regional Small Tributaries Loads Lester McKee, John Oram and, Jon Leatherbarrow."— Presentation transcript:

1 1 PCB and PBDE Loads in Coyote Creek: Conceptual models and Estimates of Regional Small Tributaries Loads Lester McKee, John Oram and, Jon Leatherbarrow Sources Pathways and Loadings Workgroup November 13 th 2006 San Francisco Estuary Institute Item #3

2 2 History USGS discharge USGS discharge WY 1999 – 2006 (ongoing) WY 1999 – 2006 (ongoing) USGS suspended sediment data USGS suspended sediment data WY 2005 WY 2005 WY 2006 WY 2006 Regional Board TMDL laboratory funding ($10k) Regional Board TMDL laboratory funding ($10k) WY 2005 PCB, PBDE, HgT, SSC, organic carbon WY 2005 PCB, PBDE, HgT, SSC, organic carbon SFEI field team able to grab 7 samples during wading stage only during breaks from Guadalupe R. sampling SFEI field team able to grab 7 samples during wading stage only during breaks from Guadalupe R. sampling Item #3 San Francisco Estuary Institute

3 3 Field Location Item #3 San Francisco Estuary Institute Coyote Ck. at Hwy 237 USGS Guadalupe R. at Hwy 101 USGS

4 4 Methods Sampling Location USGS Gage Shelter Item #3

5 5 Methods Grab samples from mid depth at wading stages Grab samples from mid depth at wading stages Regression between instantaneous SSC and PCB/PBDE concentrations Regression between instantaneous SSC and PCB/PBDE concentrations USGS 15 minute discharge USGS 15 minute discharge USGS 15 minute SSC estimates from GCLASS USGS 15 minute SSC estimates from GCLASS Item #3 San Francisco Estuary Institute

6 6 Results - Concentrations Item #3 San Francisco Estuary Institute SampleSSC (mg/L)PCB (pg/L)PBDE (pg/L) CC40-3,34914,889 CC70512,75812,896 CC802283,4999,386 CC90775,59915,949 CC ,35336,623 CC921962,6607,138 CC ,12412,831 min-2,6607,138 max-10,35336,623 mean-4,90615,673 FWMC*-9,30529,852 * Based on annual load

7 7 Regression Estimators PCBs Item #3 San Francisco Estuary Institute

8 8 Regression Estimators PBDEs Item #3 San Francisco Estuary Institute

9 9 Problem How to we apply the two populations of data (regression estimators) to published USGS daily sediment records? How to we apply the two populations of data (regression estimators) to published USGS daily sediment records? Solution: Obtain 15 minute records Solution: Obtain 15 minute records Errors Errors USGS accurately measures 15-minute discharge USGS accurately measures 15-minute discharge USGS only estimates 15 minute SSC based on rating relationships between flow and about 100 real measurements of SSC USGS only estimates 15 minute SSC based on rating relationships between flow and about 100 real measurements of SSC San Francisco Estuary Institute

10 10 Results - Loads Item #3 San Francisco Estuary Institute OctNovDecJanFebMarAprTotal Flow (Mm 3 ) PCB (g) PBDE (g) ,409

11 11 Historic Flow Item #3 Average = 41 Mm 3 Measured Estimated San Francisco Estuary Institute

12 12 Average Load Estimate – Method PCB Item #3 San Francisco Estuary Institute

13 13 Average Load Estimate – Method PBDE Item #3 San Francisco Estuary Institute

14 14 Estimated Average Loads Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following: Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following: Item #3 San Francisco Estuary Institute Flow (Mm 3 ) PCB (kg) PBDE (kg) Minimum~2~0 Maximum~174~12~40 Average~41~1.5~5~5

15 15 Guadalupe R. Estimate of Average Loads Item #3 San Francisco Estuary Institute

16 16 Methods Develop a regression estimator using monthly flow and monthly load Develop a regression estimator using monthly flow and monthly load Obtain historic monthly flow records for the period 1971 – 2006 Obtain historic monthly flow records for the period 1971 – 2006 Estimate monthly loads Estimate monthly loads Calculate average Calculate average Item #3 San Francisco Estuary Institute

17 17 Guadalupe Regression Estimators Item #3 San Francisco Estuary Institute

18 18 Estimated Average Loads Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following: Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following: Item #3 Flow (Mm 3 ) PCB (kg) PBDE (kg) Minimum2.8~0 Maximum247.8~5~13 Average58.2~1~1~2.5 San Francisco Estuary Institute

19 19 Coyote – Guadalupe Comparison Are the estimates reasonable? PBDE (kg) PCB (kg)Ratio Coyote Ck Guadalupe R.2.51 Item #3 Area (below Dams)IndComRes Open/ Ag PCB Average PCB Maximum Coyote Ck. (km2) Percentage (%) Guadalupe R. (km2) Percentage (%) (mg/kg) San Francisco Estuary Institute

20 20 Estuary Interface Pilot Study Item #3 Leatherbarrow et al., 2002 Coyote Creek Guadalupe River Water (pg/L)Wet7,0006,100 Dry4,0007,169 Sediment (ug/kg)Wet4543 Dry4631 San Francisco Estuary Institute

21 21 Estimating Total Regional Small Tributaries Loads: Extrapolation methods in the absence of hydrologic models Item #3 San Francisco Estuary Institute

22 22 Methods (PCBs and PBDEs) 1.Add Guadalupe and Coyote estimated average annual loads together and scale by area a)Total area b)Excluding area above reservoirs 2.Assume most load is associated with urban area and scale the sum of Guadalupe and Coyote estimated average annual loads by an urban land use factor. Item #3 San Francisco Estuary Institute

23 23 Methods (PCBs only) 3. Use the sum of Coyote+Guadalupe average loads to scale (calibrate) land use specific estimates of PCB export derived by an extensive literature review and mass balance model (SFEI Prop 13). Apply these to land use statistics below reservoirs for the Bay Area (Davis et al., 2000). Item #3 San Francisco Estuary Institute

24 24 Methods (PBDEs only) 4. Scale PBDE loads to PCB loads using a ratio of 3:1 Item #3 San Francisco Estuary Institute

25 25 Statistics for Calculations Item #3 Area (km 2 ) Ind (km 2 ) Com (km 2 ) Res (km 2 ) Open/Ag (km 2 ) Guadalupe R Coyote Ck Bay Area Small Tributaries6, ,7264,147 Area Excluding Reservoirs (km 2 ) Ind (km 2 ) Com (km 2 ) Res (km 2 ) Open/Ag (km 2 ) Guadalupe R Coyote Ck Bay Area Small Tributaries5, ,7262,547 San Francisco Estuary Institute

26 26 Prop 13 export estimates (Ref: Mangarella et al., 2006) Item #3 San Francisco Estuary Institute

27 27 Scaled (Calibrated) Unit Exports Item #3 Land Use Unit Loading (g/km2/yr) Unit Loading Normalized to Open Space Industrial Commercial9.67 Residential2.92 Open/Agriculture1.41 San Francisco Estuary Institute

28 28 Results Annual Average Loads Estimates for Total Bay Area Small Tributaries Item #3 Method PCB (kg) Range* (kg) PBDE (kg) Range* (kg) 1a Area Ratio b Area Ratio (excl. reservoirs) Area Ratio (urban only) Calibrated unit export21 63 Best estimate** * Assumed - 50% error + 100% error based authors hypothesis that Coyote and Guadalupe are not representative of other Bay Area urban watersheds due to large size and relatively low connectivity / drainage density ** Authors judgment San Francisco Estuary Institute


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