Advances in Understanding Pollutant Mass Loadings

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Advances in Understanding Pollutant Mass Loadings

• Lester McKee
• Jon Konnan, Richard Looker, Nicole David, Jay
  Davis

Article on Page 77 of the Pulse
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Why Measure Loadings?

• Fish consumption advisories since 1993
• San Francisco Bay is listed as impaired for a
  range of contaminants
• Initially loadings information was generated to
  develop TMDL project reports written by the Water
  Board
• More loadings information
• Measurement of progress towards targets

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What are the priority contaminants?
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What are the Main Sources and Pathways?
Urban Stormwater
In-Bay contaminated sites
Guadalupe River
Focus is on the larger pathways that are deemed
potentially controllable
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What Stormwater Loading Studies are ongoing?

• Sacramento River
• Guadalupe River
• Zone 4 Line A

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Sacramento River at Mallard Island near
Pittsburg
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Sacramento River at Mallard Island near
Pittsburg
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Sacramento River at Mallard Island near
Pittsburg
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Sacramento River at Mallard Island near
Pittsburg
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Concentration on particles(Low moderate flow)
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Concentration on particles(Large storms)
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Loadings per year - Sediment
Journal of Hydrology McKee et al., 2006
Mean 1 million metric t
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Loadings per year Mercury
ETC David et al., in review
Mean 210 kg
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Loadings per year - PCBs
Mean 9.6 kg
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Guadalupe River at Hwy 101 in San Jose
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Guadalupe River at Hwy 101 in San Jose
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Guadalupe River at Hwy 101 in San Jose
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Mercury on Particles
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PCBs on Particles
Urban stormwater
Non-urban stormwater
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Loadings per year - Sediment
Mean 14,000 metric t
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Loadings per year - Mercury
Mean 130 kg Methylmercury ltlt1
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Loadings per year - PCBs
Mean 0.9 kg PBDEs 2.5x greater
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Zone 4 Line A Tributary at Cabot Blvd. in Hayward
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Zone 4 Line A Tributary at Cabot Blvd. in Hayward
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Zone 4 Line A Tributary at Cabot Blvd. in Hayward
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Loadings normalized per unit area per year
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What have we learned?Mercury
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What have we learned?PCBs
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Remaining Questions and Progress

• Mercury
• Which watersheds are most contaminated?
• What are the loadings from specific watersheds
  and the region as a whole
• Currently based on sediment Hg concentrations and
  out-dated estimates of regional sediment loads
• Little information on mercury speciation
• Methylmercury
• Reactive mercury

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Remaining Questions and Progress

• PCBs
• Little information on loadings from small heavily
  industrialized watersheds
• Mainly near the Bay margin
• Focus on old industrial
• Which watersheds are most contaminated?
• What are the sources and processes of release?

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Remaining Questions and Progress

• PBDEs and OC pesticides
• One box model paper published in Environment
  International (Oram et al 2008)
• Penta and Octa banned when will the loads go
  down - will the Bay recover?
• Dioxins and pyrethroid pesticides
• No information on urban loadings
• Little to no information on other pathways
• Selenium, Copper, Nickel, PAHs
• Not recently discussed

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What are the remaining questions?

• All contaminants
• Are there high leverage areas or processes on
  the Bay margin where contaminants impact the base
  of the food web
• What is the linkage between watershed loadings
  and hotspots or high leverage areas on the
  Bay margin

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Planning efforts to prioritize and address data
gaps

• Small Tributaries Loadings Strategy
• Being developed now
• Mercury Strategy (page 4 of the Pulse)
• First strategy to be developed
• Dioxin Strategy
• Priorities vary by stakeholder very expensive
  so still debate over funding
• Modeling Strategy
• Being developed now

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Small Tributaries Loading Strategy

• 1) Impairment
• Which are the high-leverage small tributaries
  that contribute most to Bay impairment?
• 2) Loading
• What are the concentrations and average annual
  loads of pollutants of concern from small
  tributaries?
• 3) Trends
• How are concentrations or loads of pollutants of
  concern from small tributaries changing on a
  decadal scale?
• 4) Support for Management Actions
• What are the projected impacts of management
  actions and where should management actions be
  implemented?

• A three page document that includes
• Key questions and priorities
• Guiding principles
• A timeline
• Recommended methods

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Summary

• Our understanding of pollutant mass loads has
  changed considerably
• We now have accurate measurements of loads in
  three watersheds
• But there are still many questions
• Through time the needs for information are
  becoming more explicit and the RMP is adapting to
  new needs
• Constant re-evaluation of the management
  questions
• 5-year plans for the workgroups and the program
  as a whole
• Focus strategy documents (contaminant or issue
  specific)

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Acknowledgements

• Mercury labs
• MLML
• UCSC
• Brooks Rand
• Trace organics lab AXYS

• Sediment studies
• USGS
• USDA
• RiverMetrics
• Field staff
• SFEI
• UCSC
• Water Board