Contaminated Sediment in the St. Clair River: Ecological Implications and the Path Forward ENVIRON International Corporation Public Consultation
Presentation Topics 1. Background 2. COA Framework Overview 3. Lines of Evidence 4. Prioritization of Zones for Sediment Management 5. Questions/Discussion
St. Clair Area of Concern (AOC) � International Joint Commission identified 43 AOCs under the Great Lakes Water Quality Agreement � St. Clair River named an AOC in 1985 – Contaminated sediment in the upper St. Clair River defined as high priority issue – Portions of upper St. Clair River remediated in 2004 � This study was done to – Evaluate risks posed by key chemicals in the remainder of the AOC – Help prioritize sediment management solutions
St. Clair River Interest (AOI) Area of
Key Questions Evaluated in this Study 1. Will fish or wildlife be harmed by chemicals in the sediment, invertebrates and fish? 2. Does the sediment need to be cleaned up to prevent harm to fish or wildlife? 3. If so, which areas are most important for cleanup? 4. What areas need to be studied more before decisions can be made? These questions are answered by applying the COA Framework
What is Sediment? � Mud at the bottom of the river = minerals + water + decaying plants & animals (“organic matter”) + insects, clams and worms (“invertebrates”) � Home to invertebrates, which Sediment sampling are the base of the food chain – Food for fish
What Are Chemicals? � Everything is made of chemicals – Caffeine is a chemical – Organic chemicals contain carbon – Inorganic chemicals are everything else � Pollution occurs when people add Caffeine harmful chemicals to the environment – Dose ose determines the effect � Many sources of pollution to the St. Clair River – Mercury and octachlorostyrene pollution are of primary concern Octachlorostyrene – There are natural sources of mercury and other chemicals
What are Mercury and Octachlorosytrene? � Mercury – Occurs naturally and as pollution – Converted in sediment from mercury (like in a thermometer) to methylmercury (methylation) – Methylmercury is biologically available � Octachlorosytrene – Byproduct of chlorination of organic chemicals – From industrial discharges � Both are persistent, bioaccumulative and toxic – Don’t break down much over time (persistent) – Build up in fish and animals that eat fish (bioaccumulative) – Potential to cause injury or harm (toxic) – Goal is to eliminate such chemicals from the natural environment, including sediment
How are Levels of Chemicals Described? � “parts per million” or ppm � In a jar of 1,000,000 jelly beans, 20 are green � Concentration of green jelly beans = 20 ppm
Are Chemicals in Sediment Causing Harm? The answer depends on: � Which chemicals are found in the sediments, where, and at what level? � Which chemicals may move in the environment, how, and where? � What levels of chemicals are safe for fish and wildlife?
Summary of Key Messages Risk from Biomagnification � Risk to some fish species � No risk to fish-eating wildlife Sediment Chemistry � All samples exceed Lowest Effect Level for Hg � 61% of samples exceed Severe Effect Level for Hg � Deep sediment 4 – 5 x surface sediment concentrations for Hg � No exceedances for octachlorostyrene (OCS) Benthic Alteration � No clear evidence of differences compared to reference sites due to Hg or OCS Sediment Toxicity � No strong evidence of toxicity
Methylmercury in Surface Sediment of the AOI Blue = lowest levels Brown = highest levels
Octachlorostyrene in Surface Sediment of the AOI Blue = lowest levels Brown = highest levels
What is the COA Framework? • Tool for making decisions about how to manage the contaminated sediment • Helps prioritize future sediment management actions
COA Framework Uses Four Main Lines of Evidence 1. Risk from Biomagnification 2. Sediment Chemistry 3. Benthos* Alteration 4. Sediment Toxicity * insects, worms, clams etc. that live in sediment
How are the Lines of Evidence Evaluated? � Rules for when – Adverse effects likely – Adverse effects uncertain – Adverse effects unlikely � Results for each LOE are combined to decide whether – No further action necessary – Further study necessary – Sediment management necessary
Which Species Were Studied? � Invertebrates (insects, Mayfly clams, and worms) Zebra mussels � Fish (sportfish such as Redhorse sucker northern pike and pickerel, and forage fish such as Emerald shiner shiners) � Birds (herring gull, double- Double- Herring gull crested cormorant) crested cormorant � Mammal (raccoon) Raccoon
Why Do Invertebrates Matter? � Important food for fish Mayfly – No invertebrates → no fish � They recycle nutrients – One species' waste is another’s Midge food � They live in the sediment with Amphipod the mercury and octachlorostyrene – Pass chemicals to fish when eaten
Why Do Fish Matter? � Central to aquatic ecosystems � Fish eat invertebrates Northern pike � People and wildlife eat fish � People enjoy fishing � Fish are key indicator of water and sediment quality Pickerel
Why Do These Wildlife Matter? � Top of this food chain – Eat the big fish that eat the little fish that eat the bugs that live in the sediment � Their biology is well known, so Raccoon studying them is possible � Sensitive to mercury and organic chemicals � Indicators of sediment quality Double-crested Herring gull cormorant and ecosystem health
Lines of Evidence 1. Risk from Biomagnification For each species, depends on a. Exposure b. Toxicity 2. Sediment Chemistry 3. Benthos Alteration 4. Sediment Toxicity
1a. How Is Exposure Measured in Invertebrates and Fish? � For invertebrates – Levels of mercury and octachlorostyrene in sediment Sediment Sampling � For fish – Levels of mercury and octachlorostyrene in fish and their prey Fish Tissue Sampling
1a. How Is Exposure Estimated for Wildlife? � What do the wildlife living in/near the AOI eat? � How much food do they eat? How often? � What levels of chemicals are in their food? � This information in used in mathematical equations to estimate “exposure”
1b. How Is Toxicity Measured in Fish? � Field data – Are they “fit”? – Are there equal numbers of males Fish Sampling and females? – How do they compare to fish in other waterbodies? – Are differences linked to mercury and octachlorostyrene levels? � Safe fish tissue levels from scientific literature – Mercury: 0.2 ppm – Octachlorostyrene: 0.015 to 0.18 ppm
1b. How Do We Measure Toxicity in Wildlife? � We reviewed and summarized published studies that report safe levels of mercury and octachorostyrene in birds and mammals � Calculate safe levels in their prey
2. How Is Sediment Chemistry Measured? � Chemicals settle out of the water and build up � Sediment samples collected as core or grab Sediment Core Sampling Sediment Grab Sampling � Laboratory analyzes sediment samples for chemical concentrations � Physical properties of sediment provides information on how chemicals move
3. How Is Benthos Alteration Measured? � Community survey – Collect sediment from the AOI and from “reference” areas – Count the types and numbers of invertebrates that live in the Benthic Sampling sediment – Compare the AOI community to reference area communities Sorting and Identifying Benthic Invertebrates
4. How Is Sediment Toxicity Measured? Toxicity Testing � Divide AOI sediment into jars � Add lab-reared invertebrates � Over time, record growth, reproduction, and survival � Compare the AOI results to reference area results Toxicity Testing
Results 1. Risk from Biomagnification 2. Sediment Chemistry 3. Benthos Alteration 4. Sediment Toxicity
1. Are AOI Fish at Risk from Biomagnification? � Compared levels in fish tissue to safe Species Risk levels Rock bass low – Categorized risk based on % of samples exceeding safe levels Yellow medium � Evaluated sex ratios and fitness of fish perch sampled for SFCMP Carp medium – No evidence of decreased fitness Freshwater medium – SMB & YP appear female-biased in St. Clair drum River, compared to other regional waterbodies – Female bias correlated with mercury White Medium concentrations in fish tissue in FWD, SMB, NP sucker & YP – But correlation ≠ causation and there are Redhorse High potential confounding factors sucker Conclusion: Some Fish Northern high Species May Be Harmed pike
1. Are AOI Wildlife at Risk from Biomagnification? Safe Prey Levels � Wildlife not at risk from mercury or octachlorostyrene because prey levels below safe levels Conclusion: Wildlife Not Likely To Be Harmed
2. Are Surface Sediment Chemistry Levels Elevated? � All mercury concentrations above the LEL [But sediment chemistry not necessarily related to biological effects] � No locations exceed calculated benchmark for octachlorostyrene
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