Mercury. Toxic trace element Occurs naturally Anthropogenic sources Methyl form of most concern

Transcription

1 Mercury Toxic trace element Occurs naturally Anthropogenic sources Methyl form of most concern

2 Natural sources Hg 0

3 Anthropogenic Sources Hg 2+ Hg 0 Hg p

4 Mercury in the Environment Inorganic Hg is now the predominant source of methylated mercury Fossil fuel burning

5 Chemical Pollution Inorganic form and methyl form both toxic Becomes methylated through natural transformations Biomagnification and bioaccumulation Top piscivorous wildlife have some of the highest levels Source: USGS modified from Cleckner et al

6 Wetlands and Mercury Methylmercury production. Source of methylmercury for freshwaters. Sink and source

7 Hg 0 Hg Hg p Hg 2+

8 Mercury concentrations in wetlands associated with coal-fired power plants (CFPPs) Richard Halbrook and Scott Weir Cooperative Wildlife Research Laboratory, Department of Zoology Southern Illinois University, Carbondale, Illinois

9 Objectives Preliminary information on total mercury (THg) in wetlands associated with coal-fired generating plants in Illinois H1: Sediment and tadpole THg will be higher downwind than upwind, and that concentrations will increase with increasing distance downwind H2: Sediment and tadpole THg concentrations will be positively correlated Specific protocols for monitoring mercury concentrations in wetland habitats

10 Selection of Power Plants Plants were selected on the following factors: Mercury emissions Prevailing wind data Suitable wetlands The plants selected are: Joppa, Baldwin, Newton, and Southern Illinois Power Cooperative (SIPC)

11 Sample Collections 45 total wetlands in May and June wetlands sampled from Baldwin and SIPC, 11 from Joppa, and 10 from Newton 3 upwind and between 3-5km 9 downwind Range: 3-5km, 8-10km, and 13-15km

12 Map of Wetlands, IL counties, CFPPs

13 Collection Methods Sediment sampled with core augers 3 samples from each wetland Temperature (ºC) Tadpoles sampled with dip nets Species, stage, mass, length

14 Sediment Variables Oxidation-reduction potential ph Texture

15 Total Hg in tadpoles determined using a Hydra AF cold vapor mercury analyzer. Tadpole digested by EPA method Mercury Analysis Sediment digested by EPA method 3051A. Analyzed at ISTC.

16 Statistics SAS (v 9.1) Normality, Shapiro-Wilks Analysis of covariance ANOVA Pearson Correlation (Bonferroni Correction)

17 Sediment Results log Sediment THg (ng/g dry weight) Baldwin Joppa SIPC Newton Range

18 Upwind vs Downwind log Sediment THg (ng/g dry weight) * Downwind Upwind Baldwin Joppa SIPC Newton

19 Tadpole Results (29 ponds)* Bullfrog Green Frog n Homogenized (35) a (36) ab 71 Whole (13) a (16) b 29 n *Mean + SE (n)

20 Tadpole Results 2.0 log Tadpole THg (ng/g wet weight) Baldwin Joppa SIPC Newton Range

21 Tadpole upwind vs downwind log Tadpole THg (ng/g wet weight) Downwind Upwind Baldwin Joppa SIPC Newton

22 Concentrations of importance Background conc Current Study Concentrations of concern Sediment THg ng/g (dw) A 8-82 ng/g (dw) 180 ng/g (dw) C Aquatic Vertebrates THg <80 ng/g (ww) B ng/g (ww) 500 ng/g (ww) D A Eisler 1987 B Terhivuo et al C MacDonald et al D Health Canada 2007

23 Correlations of Tadpole Variables THg Gosner Stage Total Length (mm) Weight (g) THg 1 Gosner Stage -0.25* 1 Total Length (mm) -0.47*** 0.71*** 1 Weight (g) -0.39*** 0.59*** 0.81*** 1 * = p < 0.10, *** = p < 0.01 (Bonferroni correction)

24 Tadpoles in the field Author Location Species Tissue Mercury conc Current study Burger and Snodgrass 2001 Bank et al Unrine et al Byrne et al Illinois Savannah River, SW Carolina Acadia National Park, Maine Savannah River, W Carolina Bullfrog Green frog Southern leopard frog Bullfrog Green frog Southern leopard frog Whole body Body, Tail, Digestive tract Whole body composite Carcass Gut 63.2 ng/g 45.1 ng/g < ng/g DL 19.1 ng/g 25.1 ng/g 184 ng/g (dw) 1275 ng/g (dw) Yugoslavia Unspecified Whole body 410, 490 ng/g

25 Other CFPP studies Author Place Biological Unit Distance from CFPP Species Conclusions Anderson and Smith Wangen and Williams Illinois 1 Lake, Terrestrial soil < 15 km Many fish species New Mexico Terrestrial Soil km N/A Soil sig. > downwind, Lake sed > after ops began, Fish conc very low Concentration as a function of distance were not significant for 9 elements Crockett and Kinnison 1979 Arizona Terrestrial Soil < 30 km N/A No pattern in concentric rings Pinkney et al Maryland Ponds 3-15 km Current Study Illinois Ponds/Wetlands 3-15 km Fish (bluegill, green sunfish, largemouth bass) Bullfrog, green frog larvae No pattern in concentric rings.field results did not match model No pattern for 3 of the CFPPs, Slight pattern downwind of Newton CFPP

26 Using tadpoles as bioindicators log pond mean sediment THg (ng/g dry weight) log pond mean tadpole THg (ng/g wet weight)

27 Conclusions Preliminary information on total mercury (THg) in wetlands associated with coal-fired generating plants in Illinois H1: Sediment and tadpole THg will be higher downwind than upwind, and that concentrations will increase with increasing distance downwind (Newton CFPP Only) H2: Sediment and tadpole THg concentrations will be positively correlated (Rejected) Develop Specific protocols for monitoring mercury concentrations in wetland habitats

28 Management Implications Concentrations of THg measured in sediment and tadpoles in wetlands surrounding Newton, Baldwin, Joppa, and SIPC CFPPs were are below levels of concern

29 Acknowledgements Illinois Sustainable Technology Center Gary Bordson and the metals group at ISTC Marvin Piwoni Cooperative Wildlife Research Lab Department of Zoology and Graduate School

30 Questions?

31 Conclusions With the exception of Newton, CFPPs did not have a significant pattern of THg concentrations in ponds 3-15 km downwind Tadpole THg was negatively correlated with length

32 Sediment THg and distance log Sediment THg (ng/g dry weight) Range

33 Sediment Variables Sediment THg Temperature ( C) ph Redox potential Pond area (m 2 ) A Tadpole THg A Sediment THg 1 Temperature ( C) ph Redox potential Pond area (m 2 ) A Tadpole THg A A = Pond means were used in these correlations *** = p < 0.01 (Bonferroni correction)

34 Texture 1.8 log sediment THg (ng/g dry weight) clay loam loam loamy sand sand sandy clay sandy clay loam sandy loam silt loam

35 Mercury across taxa Mammals Birds Amphibians Mechanism MeHg causes central nervous system damage Central nervous system damage Neurotoxicity (?) Physiological effects Behavioral impairment: anorexia, lethargy Weight loss, muscular incoordination Adults:? Tadpoles: swimming behavior Reproduction Readily crosses placental barrier Reduced hatchability and clutch size, eggshell thinning Effects on embryos (?)

36 Mercury and Amphibians MeHg Hg ng/g THg body burden Concentrations similar to fish

37 Local vs Regional vs Global Contradicting results regarding the local effects of coal-fired power plants Studies have reported local impacts Some have stated that local impacts are overestimated Atmospheric lifespan of mercury species

38 Quality Assurance/Quality Control Laboratory Blanks Laboratory Reagent Spikes Replicates Sediment Only: Matrix Spike Reference Material Tadpole Only: Matrix Quad Study

39 Tadpoles are kind of a pain Feeding behavior Predation escape Metamorphosis /Physiology

40 Newton Power Plant Sediment Tadpole log THg (ng/g) Range