Influence of reservoir water level fluctuations on sediment methylmercury concentrations downstream of the historical Black Butte mercury mine, OR

Eckley, Chris S.; Luxton, Todd P.; McKernan, John; Goetz, Jennifer; Goulet, J.

doi:10.1016/j.apgeochem.2015.06.011

Cited by 51 publications

(42 citation statements)

References 74 publications

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“…Although the vast majority of relationships (all Hg and DOC forms confounded) were positive, we unexpectedly found a few cases where relationships were negative. Negative relationships were not only found in studies conducted in systems impacted by anthropogenic activities such as urban areas (Brigham et al, 2009), intense industrialization (Fagnani et al, 2012), waste water (Guedron et al, 2014), artificial reservoirs (Noh et al, 2016), mining activities (Eckley et al, 2015), and near an old lithium industry but also in natural systems (Bravo et al, 2017;Brazeau et al, 2013;Porvari & Verta, 2003;Vidon et al, 2014). A possible explanation for these negative relationships is that anthropogenic or natural inputs of Hg that are not accompanied by DOC inputs alter the basic relationship.…”

Section: Discussionmentioning

confidence: 98%

“…In total, 108 studies were excluded through that screening process. A total of 44 studies were kept from this search (Bergman & Bump, 2014;Berndt et al, 2016;Berndt & Bavin, 2012;Braaten et al, 2014;Bravo et al, 2017;Brazeau et al, 2013;Burns et al, 2012Burns et al, , 2013Burns et al, , 2014Burton et al, 2013;Chaves-Ulloa et al, 2016;de Wit et al, 2014;Demers et al, 2013;Denkenberger et al, 2014;Dranguet et al, 2017;Eckley et al, 2015;Eklöf et al, 2013;Ekstrom et al, 2016;Fagnani et al, 2012;Gerson & Driscoll, 2016;Girard et al, 2016;Guedron et al, 2014;Hamelin et al, 2015;Haverstock et al, 2012;Houben et al, 2016;Jeremiason et al, 2016;Leopold et al, 2012;Loftin et al, 2012;Luo et al, 2014;MacMillan et al, 2015;Moreno et al, 2016;Navratil et al, 2015;Noh et al, 2016;Oswald & Branfireun, 2014;Painter et al, 2015;Picado & Bengtsson, 2012;Poste et al, 2015;Pyhtila et al, 2012;Riscassi et al, 2016;Sherman & Blum, 2013;…”

Section: Data Acquisitionmentioning

confidence: 99%

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Global Meta‐Analysis on the Relationship Between Mercury and Dissolved Organic Carbon in Freshwater Environments

2019

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In freshwater ecosystems, several studies have shown a strong linear relationship between total mercury (THg) or methylmercury (MeHg) and dissolved organic carbon (DOC) concentrations. Variations in this linear relationship have been reported, but the magnitude and causes of this variation are not well known. The objective of this study was to conduct a meta‐analysis to quantify and understand the global variation of this mercury (Hg)–DOC association. This meta‐analysis included 54 studies in lentic and lotic ecosystems for a total of 85 THg–DOC and 59 MeHg–DOC relationships. There was an increase in Hg with DOC concentrations in water with a global average slope of 0.25 (confidence interval (CI): 0.20–0.35) ng/mg for THg and 0.029 (CI: 0.014–0.044) ng/mg for MeHg. Relationships were stronger for (1) North American studies, (2) natural environments compared to those disturbed by anthropogenic activities, (3) spatial studies compared to temporal studies, (4) filtered samples (THg only), and (5) the aromatic fraction of DOC compared to the bulk DOC. Coupling with DOC was stronger for THg than for MeHg. Ecosystem type (lentic vs. lotic), geographical coordinates, and publication year did not influence the strength of relationships. Overall, we show that there is a strong but variable coupling between carbon and mercury cycles in freshwater ecosystems globally and that this link is modulated regionally by geographic location, temporal scale, and human activity, with implications for understanding these rapidly changing biogeochemical processes in response to global change.

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Section: Discussionmentioning

confidence: 98%

Section: Data Acquisitionmentioning

confidence: 99%

Global Meta‐Analysis on the Relationship Between Mercury and Dissolved Organic Carbon in Freshwater Environments

2019

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“…Specifically, we will test the hypothesis that water-level fluctuations result in an increase in MeHg production within a reservoir and that this is influenced by enhanced sulfate cycling and increased partitioning of inorganic Hg to porewater. A previous study conducted at this site (Cottage Grove Reservoir) identified a subtle, yet statistically significant, increase in sediment MeHg concentrations in the seasonally inundated mudflats of the reservoir compared to the permanently inundated sediments (Eckley et al, 2015). In our current study, we expand on these findings by including the areas along the reservoir shoreline that are seasonally inundated wetlands and by adding porewater measurements and isotopic Hg methylation assays to further explore the mechanisms driving MeHg production.…”

Section: Introductionmentioning

confidence: 86%

“…Newly created reservoirs have been shown to have higher MeHg production due to increased organic material available after flooding terrestrial landscapes (Hall et al, 2005;St Louis et al, 2004); however even decades after the initial impoundment reservoirs can continue to have elevated MeHg levels due to ongoing seasonal water-level fluctuations (Anderson et al, 1995;Bodaly et al, 2007) and/or changes in the foodweb structure (lotic to lentic). Water-level fluctuations are believed to promote the recycling of sulfide in sediment to sulfate when exposed to the air, which can enhance microbial methylation when sediments are re-wetted (Eckley et al, 2015;Evers et al, 2007). In addition, this process may enhance partitioning of sediment-bound Hg into the porewater/aqueous phase where it is more available for microbial uptake; however to our knowledge the influence of this mechanism has not been previously assessed in reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Water-level fluctuations influence sediment porewater chemistry and methylmercury production in a flood-control reservoir

Eckley

Luxton

Goetz

et al. 2017

Environmental Pollution

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Reservoirs typically have elevated fish mercury (Hg) levels compared to natural lakes and rivers. A unique feature of reservoirs is water-level management which can result in sediment exposure to the air. The objective of this study is to identify how reservoir water-level fluctuations impact Hg cycling, particularly the formation of the more toxic and bioaccumulative methylmercury (MeHg). Total-Hg (THg), MeHg, stable isotope methylation rates and several ancillary parameters were measured in reservoir sediments (including some in porewater and overlying water) that are seasonally and permanently inundated. The results showed that sediment and porewater MeHg concentrations were over 3-times higher in areas experiencing water-level fluctuations compared to permanently inundated sediments. Analysis of the data suggest that the enhanced breakdown of organic matter in sediments experiencing water-level fluctuations has a two-fold effect on stimulating Hg methylation: 1) it increases the partitioning of inorganic Hg from the solid phase into the porewater phase (lower log K values) where it is more bioavailable for methylation; and 2) it increases dissolved organic carbon (DOC) in the porewater which can stimulate the microbial community that can methylate Hg. Sulfate concentrations and cycling were enhanced in the seasonally inundated sediments and may have also contributed to increased MeHg production. Overall, our results suggest that reservoir management actions can have an impact on the sediment-porewater characteristics that affect MeHg production. Such findings are also relevant to natural water systems that experience wetting and drying cycles, such as floodplains and ombrotrophic wetlands.

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“…Wet-dry cycling is important for the methylation process as it reoxidizes sulfur for metabolism by sulfate reducing bacteria, and therefore, methylation of HgII, and subsequent bioaccumulation of MeHg in biota, may be influenced by the frequency of drying and flooding in wetlands (Sando et al 2007;Eckley et al 2015;Singer et al 2016). Consequently, intermittent wetlands will contain higher amounts of MeHg in the water and in residing fish (Ackerman and Eagles-Smith 2010;Coleman Wasik et al 2015).…”

Section: Differences In Thg In Tadpoles In Different Pondsmentioning

confidence: 99%

Survey of mercury in boreal chorus frog (Pseudacris maculata) and wood frog (Rana sylvatica) tadpoles from wetland ponds in the Prairie Pothole Region of Canada

Boczulak

Vanderwel

Hall

2017

FACETS

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Tadpoles are important prey items for many aquatic organisms and often represent the largest vertebrate biomass in many fishless wetland ecosystems. Neurotoxic mercury (Hg) can, at elevated levels, decrease growth, lower survival, and cause developmental instability in amphibians. We compared total Hg (THg) body burden and concentration in boreal chorus frog (Pseudacris maculata) and wood frog (Rana sylvatica) tadpoles. Overall, body burden and concentration were lower in boreal chorus frog tadpoles than wood frog tadpoles, as expected, because boreal chorus frog tadpoles consume at lower trophic levels. The variables species, stage, and mass explained 21% of total variation for body burden in our models but had negligible predictive ability for THg concentration. The vast majority of the remaining variation in both body burden and THg concentration was attributable to differences among ponds; tadpoles from ponds in three areas had considerably higher THg body burden and concentration. The pond-to-pond differences were not related to any water chemistry or physical parameter measured, and we assumed that differences in wetland geomorphology likely played an important role in determining Hg levels in tadpoles. This is the first report of Hg in frog tadpoles in the Prairie Pothole Region of North America.

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Influence of reservoir water level fluctuations on sediment methylmercury concentrations downstream of the historical Black Butte mercury mine, OR

Cited by 51 publications

References 74 publications

Global Meta‐Analysis on the Relationship Between Mercury and Dissolved Organic Carbon in Freshwater Environments

Global Meta‐Analysis on the Relationship Between Mercury and Dissolved Organic Carbon in Freshwater Environments

Water-level fluctuations influence sediment porewater chemistry and methylmercury production in a flood-control reservoir

Survey of mercury in boreal chorus frog (Pseudacris maculata) and wood frog (Rana sylvatica) tadpoles from wetland ponds in the Prairie Pothole Region of Canada

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