Transcript Possible Guidance for the assessment of impacted sediments

Framework for the Ecological
Assessment of Impacted
Sediments at Mining Sites in
Region 7
By
Jason Gunter (R7 Life Scientist)
[email protected]
and
Venessa Madden (R7 Ecological Risk Assessor)
[email protected]
Purpose
Provide background information on
previous activities and potential future
activities.
Present options that could be used as
guidance to assess mining-impacted
sediments in R6 and R7.
EPA Region 7’s Historical Approach
Sediment Chemistry
– Provides information that is directly relevant
for the assessment of contamination within
the sediments.
– Does not, by itself, provide a basis for
determining if the ecosystem goals and
objectives are being achieved.
– Many of the stresses put on the environment
are too diverse for chemical control
approaches to assess alone.
Sediment Quality Guidelines (SQGs)
– McDonald Numbers (EPA SQGs)
Chemical benchmarks developed from sediment toxicity
tests.
Intended to define the concentration of contaminants
associated with high or low effects on biota (MacDonald
and Ingersoll 2002).
Help determine whether contaminants are present in
amounts that could cause or contribute adverse effects.
Site conditions could be unique, reducing the predictive
ability of SQGs.
Whenever possible, decisions regarding the management
of contaminated sediments should be made using a
weight of evidence approach, which includes sediment
chemistry and other relevant data.
What needs to be done?
Data compilation
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–
–
–
Interpretation of data
Mapping of data
Determination of data gaps
Identifying and mapping the magnitude of
exceedance
Develop a Work Plan/Sampling Analysis Plan for
bulk sediment/pore water toxicity testing.
Develop a Work Plan/Sampling Analysis Plan for
aquatic community assessment
Develop site-specific sediment cleanup goals.
Data Compilation
Why?
– To discover what research has been done in
the past.
– To discover the data gaps in the existing data.
– Compiling the existing data could reduce the
amount of future work.
– Could improve the communication among the
organizations involved.
Development of a Work Plan/Sampling
Analysis Plan for bulk sediment/pore water
toxicity testing.
Prioritize sampling areas using historical and
current data.
Use conventional toxicity testing.
In addition, use a sensitive native species for
toxicity tests.
– Using a sensitive native species such as unionid
mussels not only represents an actual environmental
receptor, but it could also provide us with cleanup
goals that are more protective of aquatic life.
Native species could be more sensitive than conventional
species.
Sediment Quality Triad Approach
Integration of multiple tools using a weightof-evidence approach.
Sediment Chemistry, Sediment Toxicity,
Aquatic Community Data, and possibly
Tissue Data.
Sediment Toxicity Tests
Advantages
– Provide quantitative information on sediment toxicity.
– Standard methods have been established to minimize
the effects of the physical characteristics of the
sediments.
– Ecologically and socially relevant.
Disadvantages
– Some tests may not be sensitive enough to detect
sub-lethal effects.
– Field-collected sediments can be manipulated before
testing.
– Certain sediment phases may be less relevant for
evaluating the in situ effects of contaminants.
Sediment Toxicity cont.
Utilize USGS and Southwest Missouri
State University for sediment toxicity
support.
Use native fauna for toxicity tests
– E.G., Unionid Mussels, macroinvertebrates.
Development of a Work
Plan/Sampling Analysis Plan for
aquatic community assessment
Focus on population (abundance of
keystone species; age and size structure)
and community structure (benthic index,
multivariate analysis).
Reference condition, baseline conditions,
evaluate effects of natural and
anthropogenic disturbances.
Benthic Population and Structure
Benthic Community Assessment
– B-IBI (overall assessment including aquatic
arthropods, mollusks, and annelids).
Multimetric index used to measure aquatic health.
Compares study area to what is expected using a
regional baseline condition.
– EPT Index-Ephemeroptera (Mayflies), Plecoptera
(Stoneflies), Tricoptera (Caddisflies).
Organisms often associated with high quality habitats.
EPT index normally increases with increasing water
quality.
Fish Community and Structure
Exposure can result in decreased survival,
reduced growth, or impaired reproduction.
Advantages
– Easy to identify;
– Reflect the effects of degraded watersheds;
– Species representing different trophic levels;
– Easily understood by public.
Fish population and Structure
Index of Biotic Integrity (IBI)
– Metrics are used to measure species richness
and composition, trophic and reproductive
function, and fish abundance and
composition.
A less intense, benthic fish assessment
could be accomplished.
Table 1. Contingency table for assessing impacts of contaminated sediments on
aquatic life based on four separate indicators of sediment quality (Ingersoll et al., 2001)
S.C.
T.T
B.C.
T.C.
Possible Conclusions
+
+
+
+
Impact highly likely: contaminant induced degradation of sediment-dwelling
organisms in the field and bioaccumulation evident.
-
-
-
+
Impact unlikely: contaminant induced degradation of sediment-dwelling
organisms in the field not evident, tissue residues due to exposure to
water or diet, possibly from other sites.
+
-
-
+
Impact on higher trophic levels likely: contaminants not toxic to sedimentdwelling organisms; bioaccumulation evident.
-
+
-
+
Impact likely: unmeasured factors contributing to toxicity and
bioaccumulation evident.
-
-
+
+
Impact likely: effect to organisms in the field probably due to sediment
contamination and bioaccumulation evident.
+
+
-
+
Impact likely: toxic chemicals probably stressing sediment-dwelling
organisms; bioaccumulation evident
-
+
+
+
Impact likely: unmeasured contaminants contributing to toxicity and
bioaccumulation is evident.
+
-
+
+
Impact likely: toxicity tests not sensitive enough and bioaccumulation is
evident.
+
+
+
-
Impact highly likely: contaminant-induced degradation of sediment dwelling
organisms evident, limited bioaccumulation.
S.C. = Sediment Chemistry
T.T. = Toxicity Test
B.C. = Benthic Community
T.C. = Tissue Chemistry
Final Goal
Ultimately, we would like to develop site
specific sediment cleanup goals using the
Weight-of-Evidence Approach.
– Develop site-specific SQGs using the
resources available (historical and current
data, reference concentrations, toxicity tests,
aquatic community assessments, etc.).