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Mercury Strategy Outline. RMP CFWG September 14, 2007. CalFed Bay-Delta Mercury Strategy Core Components. Quantification and evaluation of mercury and methylmercury sources Remediation of mercury source areas Quantification of effects of ecosystem restoration on methylmercury exposure

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mercury strategy outline

Mercury Strategy Outline

RMP CFWG

September 14, 2007

calfed bay delta mercury strategy core components
CalFed Bay-Delta Mercury Strategy Core Components
  • Quantification and evaluation of mercury and methylmercury sources
  • Remediation of mercury source areas
  • Quantification of effects of ecosystem restoration on methylmercury exposure
  • Monitoring of mercury in fish, health-risk assessment, and risk communication
  • Assessment of ecological risk
  • Identification and testing of potential management approaches for reducing methylmercury contamination
mercury management questions delta tribs mercury council
Mercury Management Questions (Delta Tribs Mercury Council)
  • What is the nature and extent of the human health and ecological risks caused by mercury in the Sacramento River Watershed and downstream waters?
  • How well understood is the nature of mercury risk and the ability to reduce it?
  • What is a prudent course of action to reduce mercury risk in the SRW?
delta tribs mercury council knowledge gaps
Delta Tribs Mercury Council Knowledge Gaps

RMP likely to encounter similar gaps

  • Sources- loads from air, native soils, hot springs, mine tailings, bioavailability of diff source types
  • Transport/transformation- water quality effects on MeHg loads, uptake from various tribs, locations
  • Hg exposure various locations- food chain relationships, human consumption
  • Risk for given exposures- demonstrated effects of mercury in humans and wildlife
rmp mercury management questions
RMP Mercury Management Questions
  • Where is mercury entering the food web?
  • Which sources, processes, and pathways contribute disproportionately to food web accumulation?
  • Can we do anything about these high-leverage processes, sources, and pathways?
  • What effects can be expected from management actions?
  • Will total mercury reductions result in reduced food web accumulation?
where is mercury entering the food web
Where is mercury entering the food web?
  • Spatial and temporal dimensions to the question
    • General vs hotspot priority (target species, random vs fixed site)
    • Much of Bay above targets
    • Food web accumulation hotspots
    • Methylation hotspots
which sources processes and pathways contribute disproportionately to food web accumulation
Which sources, processes, and pathways contribute disproportionately to food web accumulation?
  • Sources- is all Hg ultimately bioavailable (for methylation, uptake)?
  • Processes- what (co)factors affect transport, transformation, uptake (what spatial and temporal scales of interest)?
  • Bioaccumulation- biggest jumps at lowest trophic levels (primary producer)
can we do anything about these high leverage sources processes and pathways
Can we do anything about these high-leverage sources, processes, and pathways?
  • Sources- Reduce totHg? Selected “reactive” souces?
  • Processes- Adjust (co)factors (aeration, flushing, nutrient loading)
  • Bioaccumulation- choose species, habitat design? (likely least flexibility?)
what effects can be expected from management actions
What effects can be expected from management actions?
  • Implies need to model questions 1 – 3?
    • Possible with conceptual or semi-quant models?
  • Interpret monitoring data?
    • Pre- post- action
    • Appropriate spatial and temporal scales (with associated variability) 
will total mercury reductions result in reduced food web accumulation
Will total mercury reductions result in reduced food web accumulation?
  • Currently tot Hg reductions the largest component of management strategy
  • A form of MQ 2 (which sources.. contribute to…)
  • Experimental or field approaches may be valuable
how to prioritize
How to prioritize?
  • RMP Q’s 2, 3, currently least known
  • Large factors, large uncertainties first
    • Portion of Hg convertible to MeHg
    • MeHg sources- in situ production, sed-water exchange, tributary loads,
    • Loss pathways- degradation, export
  • MeHg mass budget tool to ID gaps
    • Illustrating sensitivity to uncertainties
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