Title: Development of a SiteSpecific Standard for Selenium in Open Waters of Great Salt Lake, Utah
1Development of a Site-Specific Standard for
Selenium in Open Waters of Great Salt Lake, Utah
2Central 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
3Outline
- Research Program Overview
- Preliminary steps
- GSL Studies
- Observations
- Recommendations
4Research 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
5What 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
6Study Area Open waters of GSL
7What 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.
8What 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)
9How 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
10How 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 12(No Transcript)
13Great 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
14Great 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
15Key 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
16Key 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.
17Key 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
18Projects 2 5
Project 1
19Key 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
20Recommendations
- 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.
21Recommendations
- For implementation, the water column
concentration of selenium associated with the
standard will be derived from the Bioaccumulation
Model.
22Recommendations
- The State should adopt a tiered approach for
monitoring, assessment, and management options to
ensure the selenium water quality standard is not
exceeded.
23Recommendations
- 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
24Recommendations
- 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
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