Development of a SiteSpecific Standard for Selenium in Open Waters of Great Salt Lake, Utah - PowerPoint PPT Presentation

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Development of a SiteSpecific Standard for Selenium in Open Waters of Great Salt Lake, Utah

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Title: Development of a SiteSpecific Standard for Selenium in Open Waters of Great Salt Lake, Utah


1
Development of a Site-Specific Standard for
Selenium in Open Waters of Great Salt Lake, Utah
2
Central Question
  • What is the acceptable waterborne concentration
    of selenium (Se) that prevents impairment of the
    beneficial uses of the open waters of the Great
    Salt Lake?
  • Two parts to answering
  • the question
  • Understanding Se in Great Salt Lake
  • Philosophical decision about protectiveness

Research Program
Steering Committee, Water Quality Board
3
Outline
  • Research Program Overview
  • Preliminary steps
  • GSL Studies
  • Observations
  • Recommendations

4
Research Program Overview
  • Began with formation of the Science Panel in 2004
  • Science Panel initially
  • commissioned two studies
  • Development of analytical
  • techniques
  • Conceptual model of Se
  • cycling in GSL

5
What effects are of most concern?
  • Panel agreed that birds were likely the
    beneficial users of Great Salt Lake that are most
    sensitive to Se
  • Exposure of birds to Se is through their diet
  • Water quality standard will be developed to be
    protective of birds that feed primarily on open
    waters of Great Salt Lake

6
Study Area Open waters of GSL
7
What effects are of most concern?
Best-documented and most readily monitored effect
of Se on birds is reproductive success. More
information is required to understand effect of
Se on body weight/condition of migrating or
over-wintering birds.
8
What effects are of most concern?
  • How is reproductive success defined?
  • Practically measured by egg
  • hatchability
  • Hatchability (or hatching
  • success) is the percentage of eggs
  • that hatch from those that are incubated full
    term
  • Hatchability is a more sensitive endpoint than
    teratogenesis endpoint (deformities)

9
How much Se in eggs is too much?
  • Subject of debate for many years
  • Science Panel members submitted all information
    they deemed pertinent to answering this question
  • 29 publications
  • offered their own opinions
  • Science Panel, by consensus, identified the
    analysis in Ohlendorf 2003 as the analysis to be
    used, and the range defined by its EC10 as
    protective of beneficial uses

10
How much Se in eggs is too much?
  • The range of values that will prevent impairment
    of beneficial uses on GSL was determined to be
  • 6.4 16 mg Se/kg
  • each value within this range has
  • its own estimated level of effect
  • ranging from 2 21 reduction
  • in hatchability
  • Range is based upon mallard
  • studies to incorporate safety factor
  • Since November 2006, new analyses have been
    discussed. Each discussion resulted in
    confirmation of the initial range of values.

11
  • Great Salt Lake Studies

12
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13
Great Salt Lake Studies
  • Project 1
  • Mike Conover, John Cavitt
  • Looked at breeding, migrating and over-wintering
    birds
  • Project 2 5
  • Wayne Wurtsbaugh, Brad Marden, Martin Grosell
  • Looked at uptake from water/sediment to brine
    shrimp and brine flies

14
Great Salt Lake Studies
  • Project 3
  • Dave Naftz, Bill Johnson
  • Looked at sources of Se to Great Salt Lake
  • Project 4
  • Bill Johnson, Dave Naftz
  • Looked at Se cycling and Se loss mechanisms

15
Key Observations
  • Question No. 1 Any effects from Se observed?
  • Reproductive effects
  • No egg hatchability effects or deformities were
    observed in eggs or chicks of gulls, avocets, or
    stilts associated with the open waters of Great
    Salt Lake.
  • Hatching rates consistent with non-contaminated
    sites
  • Egg Se in gulls 2.89 mg/kg shorebirds 2.72
    mg/kg below the 85 percentile of background
    levels.
  • 3 eggs out of 133 eggs in lower half of Panel
    guidelines all from near KUCC outfall

16
Key Observations
  • Non-reproductive effects
  • A determination cannot be made at this time
  • due to confounding variables and insufficient
  • data however, elevated concentrations of
  • selenium and mercury were found in bird blood
    and livers.
  • This may indicate that some of these birds are
    using selenium to detoxify mercury.

17
Key Observations
  • Question Nos. 2 3 How is Se taken up into the
    food chain?
  • Summarized in individual final reports
  • Data and observations integrated into a
    GSL-specific Bioaccumulation Model

18
Projects 2 5
Project 1
19
Key Observations
  • Questions 4 5 Where does Se come from and go?
  • Most Se went to atmosphere, followed by to the
    North Arm and sediment
  • Identified more Se loss from than loads to GSL
  • Observed Se in GSL increase slightly
  • Mass balance requires more research

Selenium Loads
20
Recommendations
  • The water quality standard should be a
    tissue-based standard, based upon the selenium
    concentration found in bird eggs.
  • A selenium water quality standard that prevents
    impairment for aquatic dependent wildlife of
    Great Salt Lake lies within the range of 6.4 to
    16 mg Se/kg for bird eggs.

21
Recommendations
  • For implementation, the water column
    concentration of selenium associated with the
    standard will be derived from the Bioaccumulation
    Model.

22
Recommendations
  • The State should adopt a tiered approach for
    monitoring, assessment, and management options to
    ensure the selenium water quality standard is not
    exceeded.

23
Recommendations
  • The State should conduct further research on a
    number of topics to validate and assess the
    current model and standard
  • Levels of protectiveness will be recommended by
    Steering Committee and determined by Water
    Quality Board
  • Individual position statements were prepared by
    each Science Panel member

24
Recommendations
  • Six Science Panel members recommended 12-13
    mg/kg, the mean EC10 for mallard eggs
  • One member recommended 5.0 mg/kg
  • One member abstained (USGS policy did not allow
    for recommendation)
  • All recommended that assessment framework be
    included as part of standard

25
  • Questions/Comments?
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