Presentation on theme: "Framework for the Ecological Assessment of Impacted Sediments at Mining Sites in Region 7 By Jason Gunter (R7 Life Scientist) and."— Presentation transcript:
Framework for the Ecological Assessment of Impacted Sediments at Mining Sites in Region 7 By Jason Gunter (R7 Life Scientist) and Venessa Madden (R7 Ecological Risk Assessor)
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 7s 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 –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 weight- of-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.
++++ 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 sediment- dwelling 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. 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 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.).