A5036184756- Mercury impact and mitigation studies
- Heavy Metal Exposure and Toxicity
- Toxic Organic Pollutants Impact
- Isotope Analysis in Ecology
- Heavy metals in environment
- Marine animal studies overview
- Atmospheric and Environmental Gas Dynamics
- Water Treatment and Disinfection
- Water Quality and Resources Studies
- Microplastics and Plastic Pollution
- Fish Ecology and Management Studies
- Analytical chemistry methods development
- Microbial Community Ecology and Physiology
- Conservation Techniques and Studies
- Mine drainage and remediation techniques
- Marine Bivalve and Aquaculture Studies
- Economic, financial, and policy analysis
- Hydrology and Sediment Transport Processes
- Biosensors and Analytical Detection
- Advanced biosensing and bioanalysis techniques
- Aquatic Invertebrate Ecology and Behavior
- Laser-induced spectroscopy and plasma
- Mining and Resource Management
- Marine and environmental studies
- Fire effects on ecosystems
United States Geological Survey
2018-2025
Upper Midwest Water Science Center
2018-2025
Pacific Island Ecosystems Research Center
2023
University of Wisconsin System
2018
Rutgers, The State University of New Jersey
2014-2016
Rutgers Sexual and Reproductive Health and Rights
2014
Rütgers (Germany)
2014
The biological production of monomethylmercury (MeHg) in soils and sediments is an important factor controlling mercury (Hg) accumulation aquatic terrestrial food webs. In this study we examined the fractionation Hg stable isotopes during methylation nongrowing cultures anaerobic bacteria Geobacter sulfurreducens PCA Desulfovibrio desulfuricans ND132. Both organisms showed mass-dependent, but no mass-independent methylation. Despite differences rates, two had similar factors (αr/p = 1.0009...
Mercury (Hg) methylation is a microbially mediated process that converts inorganic Hg into bioaccumulative, neurotoxic methylmercury (MeHg). The metabolic activity of methylating organisms highly dependent on biogeochemical conditions, which subsequently influences MeHg production. However, our understanding the ecophysiology methylators in natural ecosystems still limited. Here, we identified potential locations production anoxic, sulfidic hypolimnion freshwater lake. At these sites, used...
Identifying the sources of methylmercury (MeHg) and tracing transformations mercury (Hg) in aquatic food web are important components effective strategies for managing current legacy Hg sources. In our previous work, we measured stable isotopes (δ202Hg, Δ199Hg, Δ200Hg) Laurentian Great Lakes estimated source contributions to bottom sediment. Here, identify isotopically distinct signatures trout (Salvelinus namaycush) walleye (Sander vitreus), driven by both food-web water-quality...
Mercury (Hg) contamination of aquatic food webs is controlled in part by the formation and accumulation toxic bioaccumulative methylmercury (MeHg). MeHg production mediated metabolically diverse microorganisms carrying hgcAB gene pair, while demethylation reaction several biotic abiotic processes. However, relative importance these two processes on environmental factors that influence them are poorly characterized, especially eutrophic environments. In this study, both Hg methylation a...
Significance Elevated mercury in fish poses risks to fish-consuming wildlife and humans. Tracing sources of by analyzing stable isotope ratios leads improved source-receptor understanding natural resource management. This work utilizes sediment archives trace the response recent domestic mitigation actions. Fish sediments rapidly responded a source perturbation contemporaneous with reduction late 1980s. Subsequently, energetic pathways were altered due dreissenid invasions, which dampened...
The strongest evidence for anthropogenic alterations to the global mercury (Hg) cycle comes from historical records of deposition preserved in lake sediments. Hg isotopes have added a new dimension these sedimentary archives, promising additional insights into source apportionment and biogeochemical processing. Presently, most interpretations changes are constrained small number locally contaminated ecosystems. Here, we describe natural isotope suite dated sediment cores collected various...
Industrial chemical contamination within coastal regions of the Great Lakes can pose serious risks to wetland habitat and offshore fisheries, often resulting in fish consumption advisories that directly affect human wildlife health. Mercury (Hg) is a contaminant concern many these highly urbanized industrialized regions, one which Saint Louis River estuary (SLRE), second largest tributary Lake Superior. The SLRE has legacy Hg drives high concentrations sediments, but it unclear whether...
A prerequisite for environmental and toxicological applications of mercury (Hg) stable isotopes in wildlife humans is quantifying the isotopic fractionation biological reactions. Here, we measured Hg isotope values relevant tissues giant petrels (Macronectes spp.). Isotopic data were interpreted with published HR-XANES spectroscopic that document a stepwise transformation methylmercury (MeHg) to Hg-tetraselenolate (Hg(Sec)4) selenide (HgSe) (Sec = selenocysteine). By mathematical inversion...
Streams in the northeastern U.S. receive mercury (Hg) varying proportions from atmospheric deposition and legacy point sources, making it difficult to attribute shifts fish concentrations directly back changes Hg source management. Mercury stable isotope tracers were utilized relate sources of co-located bed sediments 23 streams across a forested urban-industrial land-use gradient within this region. Mass-dependent isotopes (δ202Hg) prey game at sites depleted (medians −0.95 −0.83 ‰,...
The robust application of stable mercury (Hg) isotopes for source apportionment and risk assessment necessitates the understanding mass-dependent fractionation (MDF) as a result internal transformations within organisms. Here, we used high energy-resolution X-ray absorption near edge structure spectroscopy isotope ratios total (δ202THg) methylmercury (δ202MeHg) to elucidate chemical speciation Hg resultant MDF MeHg demethylation in waterbirds. In three waterbirds (Clark's grebe, Forster's...
Mercury (Hg) contamination has been a persistent concern in the Florida Everglades for over three decades due to elevated atmospheric deposition and system's propensity methylation rapid bioaccumulation. Given declines Hg concentrations conterminous United States efforts mitigate nutrient release greater ecosystem, it was vital assess how dynamics responded on temporal spatial scales. This study used multimedia approach (water biota) examine methylmercury (MeHg) across 76-site network within...
The transfer of aquatic contaminants, including mercury (Hg), to terrestrial food webs is an often-overlooked exposure pathway animals. While research has implemented the use shoreline spiders assess Hg transfer, it unclear whether sources, estimated from isotope ratios, can be successfully resolved inform site assessments and remedy effectiveness. To examine we collected (Tetragnatha spp.) insect larvae (suborder Anisoptera) across a mosaic habitats in St. Louis River Bad River, tributaries...
Increased lake eutrophication, influenced by changing climate and land use, alters aquatic cycling bioaccumulation of mercury (Hg). Additionally, seasonally dynamic circulation plankton community composition can confound our ability to predict changes in biological Hg concentrations sources. To assess temporal variation, we examined seasonal total (THg) methylmercury (MeHg) stable isotope values seston, waters, sediments, fish from two adjacent urban eutrophic lakes Madison, Wisconsin. In...
Abstract Wetlands play a vital role in contaminant cycling and uptake. Understanding how sulfate (SO 4 2‒ ) influences the conversion of inorganic mercury (Hg(II)) to toxic methylmercury (MeHg) is critical for predicting wetland responses land use climate change. Here, we sampled surface pore waters across SO gradients three freshwater Everglades wetlands assess linkages between , MeHg, dissolved organic matter (DOM), sulfide (S(‒II)). Increasing concentrations increase S(‒II) DOM...
Abstract Climate change is increasing sulfate export and changing wetland extent in mountain regions. These changes may increase microbially mediated production of the neurotoxic substance methylmercury due to enhanced metabolism environments. Here, we assess concentrations formation rates across high-elevation wetlands Colorado Rocky Mountains. We also investigate controls on within subalpine peatlands by amending soils with mimic increased stream from alpine zone measuring for different...
Through stable isotope measurements of total mercury (HgT), identification crucial processes and transformations affecting different sources (Hg) has become possible. However, attempting to use HgT isotopes track bioaccumulation Hg among food web compartments can be challenging, if not impossible, when tissues have varying methylmercury (MeHg) contents. We measured MeHg ratios within the lower Fox River examine how these values differed across in biota were influenced by legacy...
Ecosystems downstream of mercury (Hg) contaminated sites can be impacted by both localized releases as well Hg deposited to the watershed from atmospheric transport. Identifying source in water, sediment, and fish is important for determining effectiveness source-control remediation actions. This study uses measurements stable isotopes soil, differentiate between an abandoned mine non-mine-related sources. The site located within Willamette River (Oregon, United States), which includes...
Abstract With the 2011 promulgation of Mercury and Air Toxics Standards by U.S. Environmental Protection Agency, successful negotiation United Nations Environment Program Minamata Convention, emissions mercury (Hg) have declined in States. While declines atmospheric Hg concentrations North America are encouraging, linking to changing domestic global source portfolios remains challenging. To address these research gaps, Geological Survey initiated first national‐scale effort establish a...