Mercury Sources in Local Watersheds: Speciation, Release to Stormwater, and Remaining Questions Lester McKee RMP Sources Pathways and Loadings Work Group Chair San Francisco Estuary Institute lester@sfei.org Feb 19th 2008 8

RMP Hg Strategy “…it may be possible to identify specific fractions of total mercury entering the Bay…that contribute disproportionately to accumulation in species of concern…” Q2. Which processes, sources, and pathways contribute disproportionately to food web accumulation? Implies we need to understand: Mass loads – essential for TMDLs Speciation (availability) of different inputs Temporal dynamics (within years and between years) Spatial patterns (Local impacts) 8

Outline Review sources, loads, speciation, and temporal dynamics in Bay Area: Mining runoff Urban runoff Non-urban runoff First order estimate of methyl-Hg entering the Bay from watersheds. Not ready to do reactive-Hg loads. 8

Mining Sources - “True Sources” draining to SF Bay CEP report (Abu-Saba, 2003) High Priority (documented discharges, high connectivity to the Bay, obvious habitat threats): Marsh Creek, Mt Diablo La Joya, Napa R. Bella Oaks, Napa R. Borges, American Canyon Ck. New Almaden Mines, Guadalupe R. 8

Mining Sources (New Almaden, Guadalupe R.) Total Hg Loads Estimated Long Term Average (1975-2006) = 129 kg * Year-to-date Estimated * 8

Mining Sources (New Almaden, Guadalupe R.) Wet Season Speciation Hg-T (ng/L) HgD (%) MeHgT Hg-R Guadalupe River at Hwy 101 MDL -18,700 3* 0.4* Alamitos Creek at Graystone Lane 1,243 - 19,800 1.4* 0.07* Alamitos Creek at Hacienda 58 – 110,000 McAbee Ck at Little Stone Bridge 470 - 2,800 Literature Review McKee et al., 2003 200 - >100,000 Mason and Dean, 2007 0.3 - 13,000 0.02 - 3.1 (<1) (<5) * Weighted concentration () = authors preference 8

Mining Sources (New Almaden, Guadalupe R Mining Sources (New Almaden, Guadalupe R.) Temporal dynamics (within years) HgD(%) 15% MeHgT(%) 2% 8

Urban Sources 8 Industrial, railway lines and auto wreckers Land fills, recycling facilities and transport of recyclable goods Ongoing uses (dental, batteries, laboratory, PDAs, other) Watershed surface and channel sediment erosion (natural background) Gasoline and diesel Paint Watershed surface and channel sediment erosion (atmospherically derived) Atmospheric deposition (on going) 8

Urban Sources Estimate 45% of the urban Hg budget is either derived from historic atmospheric loading or ongoing atmospheric loading Watershed surface and channel sediment erosion (atmospherically derived) Atmospheric deposition (on going) 8

Urban Loads (estimates) Method Author HgT (kg) Range “SIMPLE MODEL” (Davis et al., 2000) and BASMAA bed sediment data KLI, 2002 96 52 - 226 Reorganization of the Urban Hg Mass Balance (SFEI and GeoSyntec, 2006) GeoSyntec and SFEI, 2006 103 None and literature concentrations (McKee et al., 2004) McKee unpublished 150 10 - 1,028 Estimated urban sediment load (410 M kg) and urban sediment concentration (0.38 mg/kg) San Francisco Bay TMDL 160 8

Urban Speciation 8 Hg-T (ng/L) HgD (%) MeHgT Hg-R Zone 4 Line A, Hayward (Dry year) 1.9 - 55 15* 1.6* San Pedro Stormdrain, San Jose 2.1 - 499 2.3* 0.4* Airport Pkwy, San Jose 70 9.8 1.4 Coyote Creek, Hwy 237 (rising) 11 - 39 Literature Review McKee et al., 2003 13 - 1,370 (30-90) Mason and Dean, 2007 5 - 35.2 0.8 Wet - 4 Dry 4.8 Wet - 11 Dry * Weighted concentration () = authors preference 8

Urban Temporal dynamics (within years) (San Pedro, Storm Drain (San Jose) HgD(%) 65% MeHgT(%) 1% 8

Urban Temporal dynamics (within years) (Z4LA, Storm Drain (Hayward) 36% HgD(%) MeHgT(%) 4% 8

Non-urban Sources Natural Background (0.08 mg/kg) Atmospheric Deposition (downwind of urban) Agriculture uses (pesticides and dairy) Rural home uses Watershed surface and channel sediment erosion (natural background) Watershed surface and channel sediment erosion (atmospherically derived) 8

Non-urban Sources Atmospheric Deposition (downwind of urban) 8 Watershed surface and channel sediment erosion (atmospherically derived) 8

Non-urban Loads 8 Method Author HgT (kg) Range Estimated urban sediment load (410 M kg) and urban sediment concentration (0.38 mg/kg) San Francisco Bay TMDL 25 None “SIMPLE MODEL” (Davis et al., 2000) and BASMAA bed sediment data KLI, 2002 27 7 - 37 and literature concentrations (McKee et al., 2004) McKee unpublished 32 5 – 57 Reorganization of the Urban Hg Mass Balance (SFEI and GeoSyntec, 2006) GeoSyntec and SFEI, 2006 52 8

Non-urban Speciation 8 Hg-T (ng/L) HgD (%) MeHgT Hg-R Coyote Creek, Hwy 237, San Jose (falling stage) 18 - 59 Literature Review McKee et al., 2003 1 - 90 Mason and Dean, 2007 0 - 88 <10 - 87 0.05 – 56 (1-10)* (15) * Dependant on amount of wetland () = authors preference 8

Non-urban Temporal dynamics (within years) No information locally Review by Mason and Dean (2007) summarizes much of the recent literature: Higher % HgD associated with low SSC streams and summer base flow Seasonality of % MeHgT less clear but can correlate with flow, SSC, and HgT in some systems. Influenced by %wetland and DOC in some systems 8

First Order Estimate of MeHgT loads Land Use Method Reference MeHg (kg) Range Mine Field data collected over four years in the Guadalupe River at Hwy 101 McKee et al., 2006 0.5 0.2 - 0.8 Urb “SIMPLE MODEL”, local and literature concentrations (Mason and Dean, 2007) McKee unpublished 0.4 0.02 - 2.3 Applying a ratio of MeHg to the urban loads estimates for the Bay Area 1.5 0.4 - 2.6 Non- urb 0.004 - 0.3 Applying a ratio of MeHg to the non-urban loads estimates for the Bay Area 1.25 0.001 – 29* *Biggest uncertainty 8

Summary New A picture of total and methyl mercury variation in Bay Area watersheds is emerging Loads Speciation Seasonality Q2 Non-urban runoff is potentially a large source of MeHg and Hg-R in both wet and dry weather flow No local data (Suggest Napa, Walnut, Alameda, or Coyote) Urban dry weather flows high in MeHg and Hg-R as a % of HgT, but no loads data to determine impact Will sample Z4LA this early summer (n = 9 samples) Bay Hg Basin Plan Amendment and MRP call for monitoring 8

References Mason R., and Dean, D., 2007. WERF’s bioavailability project: Research update. The Claremont Resort & Spa, Berkeley, California, December 4-5, 2007. McKee, L., Leatherbarrow, J., Eads, R., and Freeman, L., 2004. Concentrations and loads of PCBs, OC pesticides, and mercury associated with suspended sediments in the lower Guadalupe River, San Jose, California. A Technical Report of the Regional Watershed Program: SFEI Contribution #86. San Francisco Estuary Institute, Oakland, CA. 79pp. 8

Acknowledgements SFEI field and data management staff Sources Pathways and Loading Work Group Funding from: RMP CEP SCVWD, SCVURPPP, USACE Water Board Moss Landing Marine Laboratories 8