Castro Valley Atmospheric Deposition Monitoring Brake Pad Partnership Stakeholder Conference June 2005 Donald Yee, Amy Franz San Francisco Estuary Institute, Oakland, CA

Copper Source Loading Estimates (Process Profiles) Physical & Chemical Characterization of Wear Debris (Clemson University) Water Quality Monitoring (ACCWP) Steering Committee, Scientific Advisory Team, and Stakeholder Involvement Process (Sustainable Conservation) Air Deposition Modeling (AER) Watershed Modeling (U.S. EPA) Bay Modeling (URS) Final Report Data Assessment Conclusions Air Deposition Monitoring (SFEI) Representative Sample of Brake Pad Wear Debris (BMC/Link Test Labs) BPP Technical Studies

Study Objectives Measure copper atmospheric deposition rates at monitoring sites in Castro Valley Creek watershed Determine if there are significant spatial and temporal differences in deposition at the monitored sites. Measure other trace elements and benzene to allow potential evaluation of the contributions of vehicle and other sources to copper emissions and deposition to the watershed.

Deposition Sampling Locations  wet dry  wet dry gas  bulk dry gas

CV Aerial Photo  Madison  CVCC  CVE  Redwood

CV Community Center 

CV Elementary 



Redwood Professional Building 

Redwood

Madison Reservoir 

Sampling Methods  Wet (only) deposition (2 week duration)  Modified Aerochem Metrics automatic precipitation collector (110VAC required)  Bulk (=wet+dry) deposition (2 week)  Similar to wet, continuous (no power, funnel+bottle)  Dry deposition (2 day)  Greased plate collector (no power),  Benzene Gas (added Nov 2004, 2 day)  6L Summa stainless canister under vacuum, 48 hr flow controller

Aerochem Metrics Collector

Greased Surrogate Surface Plate

Summa Canister & Flow Controller

Conceptual Focus  Maximum spatial difference in deposition  High traffic vs low traffic areas  Temporal differences  Wet vs dry season  Weekday vs weekend (dry only)

Wet & Bulk Samples Collected NR = no rain MF = malfunction

Dry & Gaseous Samples Collected

Previous Wet & Dry Cu Deposition RMP air deposition pilot study Sites intentionally away from roads in North (Martinez), Central (Treasure Island), & South Bay (NASA Ames) Dry deposition 3.0 ± 2.0 µg/m 2 day Treasure Island) Wet deposition 1.7 ± 1.6 µg/m 2 day Treasure Island) Total (not measured) = sum of wet+dry = 4.7 µg/m 2 day

CV Dry Deposition Cu dry deposition average 18 µg/m 2 day (all sites & events)

Dry Deposition Copper Cu dry deposition > previous SF Bay measurements (average ~6x higher) Spatial differences significant (p < 0.05) Redwood > CVCC~CVE (most elements) Madison < CVCC~CVE (most elements) Redwood > Madison (nearly all elements) Temporal differences not significant Weekday & weekend not significantly different Wet & dry season not significantly different

Wet Deposition (CVCC & CVE) Cu wet deposition average 2.3 µg/m 2 day

Wet Deposition Copper deposition Cu wet deposition slightly > previous SF Bay measurements (average +30% but not statistically) Spatial differences not significant (p > 0.05) CVCC~CVE similar deposition rates (most elements)

CV Bulk Deposition Cu bulk avg 7.2 µg/m 2 day (all sites & events) & CVE = 8.2 < total (wet+dry) = 18.1 µg/m 2 day

Bulk Deposition Wet < Bulk < Wet+Dry Generally dry deposition (alone) > bulk for any site Spatial differences often significant Madison < another site (Al Si Fe Cu Zn Sr Sb Ba Pb) Redwood > Madison (Fe Cu Zn Sr Sb Ba Pb)

Benzene Concentrations  Madison  Redwood  CVE

Benzene Redwood > Madison (significant ~2x difference) Weekday (Wed to Fri~5pm) vs weekend (Fri to Sun~5pm) not significantly different Moderate correlation to Cu deposition (R )

Issues for Interpretation Comparability wet vs bulk deposition sites Bulk vs total (wet+dry) deposition Differences in site geometry Relationship of benzene and copper

Wet vs Bulk Deposition Sites Wet < bulk for any given site & event (CVCC & CVE) Redwood (bulk) vs CVE & CVCC (wet) significance unclear, maybe be methodology driven, but Redwood bulk > Madison bulk Same collection method, thus real intersite differences

Bulk vs Wet + Dry Bulk < Wet+Dry Bulk = Wet + “Net” Dry Net dry = + deposition – resuspension Greased plate resuspension = 0 Any air deposition models need resuspension term Likely to differ among surfaces – funnel vs road vs rooftop vs tree vs lawn

Site Geometry Issues Lateral distance from road CVCC, Madison ~35m from nearest roadway, Redwood ~25m from Redwood Road, ~45m from Hwy 580 CVE slightly closer (~25m) Elevation relative to road CVCC +5m, CVE +12m, Madison +10m, Redwood +8m over Redwood Rd but –5m from 580 Influence of elevation can be modeled Orientation relative to road Madison, CVE west of nearest road

Benzene & Copper Vehicle sources, but different processes Benzene generation & emissions during vehicle operation Copper particle generation from braking Copper resuspension from many surfaces Different phases & transport Copper on large particles drops rapidly Only gaseous benzene measured Useful for evaluating different aspects of air model

Conclusions Cu CV sites > SF Bay sites (wet & dry) Redwood > CVCC~CVE > Madison Cu and other elements, benzene Sampler position vs roadway may be important Wet+dry vs bulk indicates resuspension Different monitoring elements (e.g. benzene & Cu) will be useful for evaluating different modeling components

Acknowledgements Support : BPP via ABAG for SWRCB Prop. 13 grant Sites : CV Unified School District, Alameda County, Hayward RPD, EBMUD Sampling : Amy Franz, Sarah Pearce, Seth Schonkoff, Chuck Striplen, Jennifer Lin Labs : Clarkson Univ (Holsen group), Caltest, Air Toxics Ltd. Review : BPP SAT, SC, and external reviewers