Mercury Monitoring on the Fond du Lac Reservation

Transcription

1 Mercury Monitoring on the Fond du Lac Reservation Joy Wiecks, Air Quality Technician Fond du Lac Band of Lake Superior Chippewa December 15, 2005 WRAP Board Meeting

2 FDL Mercury Monitoring Program Reservation Overview Environmental Mercury Mercury in Minnesota Mercury and FDL Natural Resources Site History Data FDL Advisories and Other Projects Future Studies

3 Fond du Lac Reservation Located in Northeastern Minnesota. Rural area about 20 miles from Duluth/Superior. Reservation has 108 water bodies, totaling 2850 acres lots of wetlands. Ceded Territories cover 8 million acres.

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5 About Environmental Mercury Silvery, liquid metal at room temperature. An element does not break down. When released, evaporates and circulates in the atmosphere until deposited in lakes and oceans. Bacteria and chemical reactions that take place in water cause mercury to change into a more toxic form called methylmercury. Methylmercury builds up in the bodies of plankton, fish, humans, and other animals and is a neurotoxin.

6 Mercury on the Reservation Mercury is a concern because the boreal forest/wetland ecoregion is very sensitive to mercury deposition. Methylation more likely to occur due to watershed characteristics. Higher risk for bioaccumulation and human exposure due to the presence of fish-eating species. Clean Air Mercury rule unlikely to lead to reductions in our region.

7 Mercury in Minnesota (Year 2005 Data) In 2005, about 3,341 lbs will be released in Minnesota (down from 3600 lb in 2000). 98% of this was discharged to the atmosphere. Only 10-30% of deposition comes from in-state sources. 58% of mercury emitted comes from energy production (up from 51%). 22% is from purposeful uses, including latex paint, fungicides, waste combustion, fluorescent lamp breakage, dental preparations, etc (down from 28%). 20% is from materials processing (taconite mining, pulp and paper) (down from 21%).

8 Mercury and Fish Consumption Consumption of large game-fish can lead to mercury poisoning in humans. Native populations at risk because of consumption of fish as a traditional food source. Mercury poisoning can cause damage to the nervous system and is especially harmful for small children and developing fetuses. Animals can suffer effects, too. Threshold for effects unknown!! Advisories just a starting point. Great Lakes Indian Fish and Wildlife Commission consumption study versus EPA s CAMR numbers.

9 Natural Resources at FDL Fish harvests (2002): From Mille Lacs, total tribal take was about 54,000 pounds of walleye. FDL harvest was about 7,142 pounds. Rice harvested: 20,000-25,000 lb/yr Moose harvested: 38 in 2001 Waterfowl harvested: est. <500/yr

10 Precipitation Deposition Site History Site established in 1997 in cooperation with Glass and Sorensen at University of Minnesota Duluth (UMD) and with Cloquet Forestry Center. Monitor principle of operation. Analytical method is cold vapor atomic absorption. Sample collected every Tuesday and delivered to UMD. Updates at site Replaced old M.I.C. monitor with NTN monitor (2002) although not using NTN analysis. Started analyzing for methyl mercury in Sept

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13 Data Total mercury data shows spring-thru-fall spikes. Total mercury concentration ranges from ng/l. Methylmercury data seems to show spikes in summer/fall. Methylmercury as a percentage of total mercury ranges from 0.2% (7/01) to 16.8% (4/03).

14 Total Mercury Data

15 Methyl Mercury Data

16 Sediment Assessment In 2000, GLNPO funded study of 12 reservation lakes: characterize sediments, assess contaminant levels in bioavailable portion (Hg, Pb, PCB s), toxicity tests. Sediment quality database developed; an additional indicator of reservation water quality. Found higher Hg values associated with organic sediments. 30 of 96 sites had dry wt Hg exceeding Level 1 Sediment Quality Threshold of 0.18 ug/g. Shallow lakes had consistently higher Hg levels. No PCB problems were found but some elevated Pb levels were observed, theorized to be from lead shot in the sediment.

17 Phase II Sediment Study Second GLNPO project (2002) included 12 St. Louis River sites; same parameters plus methyl mercury. Analyzed archived samples from Phase I for mehg. Added results to database. Correlated sediment quality and water quality parameters and watershed factors. Got a good handle on degree of Hg in water bodies.

18 StLR Big Joe Martin Lost Third West Twin Sophie Perch Pat Martin Rice Portage Dead Fish Simian Total Hg Concentration, ng/g dw

19 Average Across Sites for Each Water Body Average MeHg Conc. (dry wt), ng/g Pat Martin Lost Big Joe Martin StLR Perch West Twin Rice Portage Deadfish Sophie Third Simian

20 All Lakes MeHg Conc., ng/g dw R 2 = Total Hg Conc., ng/g dw

21 West Twin Total Hg, ng/g dw R 2 = 0.66 North Basin South basin Water Depth, m

22 Perch Lake 250 Total Hg Conc., ng/g dw R 2 = Water Depth, m North Basin South Basin

23 Lake Averages Total Hg Conc., ng/g R 2 = Total Watershed

24 Total Hg Conc., ng/g R 2 = Wetland / Water Area

25 Lake Averages Total Hg, ng/g R 2 = Color, Pt-Co

26 Lake Averages Total Hg, ng/g R 2 = TSS, mg/l

27 250.0 Total Hg, ng/g ANC

28 Fish Tissue Samples In 2000, FDL partnered with the MN Dept of Health to study fish contaminants, develop culturally sensitive consumption guide. Fish collected from St. Louis River and 7 Reservation lakes; targeted species that are commonly eaten. Also lists non-native species (tuna, shark). Mercury drives consumption restrictions (PCB s and other contaminants ruled out). Produced fish advisories and a guide for expectant mothers.

29 Wild Foods Study Comprehensive risks/benefits analysis funded by MN Sea Grant. Cultural and nutritional benefits of wild foods (vs. market alternatives) offset contaminant exposure. Wild rice, waterfowl, moose analyzed for Hg, Pb. Waterfowl and fish have comparable Hg. Moose livers found to be high in cadmium, no Hg uptake found in rice..

30 Future Studies Sampling more waterfowl. Continuing fish tissue analysis. Continuing atmospheric deposition monitoring (currently total Hg only). Investigate potential sediment mercury mitigation techniques.

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