A5059951789- Mercury impact and mitigation studies
- Toxic Organic Pollutants Impact
- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Per- and polyfluoroalkyl substances research
- Marine animal studies overview
- Atmospheric aerosols and clouds
- Heavy Metal Exposure and Toxicity
- Marine and coastal ecosystems
- Arctic and Antarctic ice dynamics
- Environmental Justice and Health Disparities
- Methane Hydrates and Related Phenomena
- Heavy metals in environment
- Climate change and permafrost
- Atmospheric Ozone and Climate
- Ecology and biodiversity studies
- Wildlife-Road Interactions and Conservation
- Geochemistry and Geologic Mapping
- Climate variability and models
- Environmental Toxicology and Ecotoxicology
- Rangeland and Wildlife Management
- Indigenous Studies and Ecology
- Marine Bivalve and Aquaculture Studies
- Marine and fisheries research
Harvard University Press
2023-2025
Harvard University
2017-2024
Massachusetts Institute of Technology
2015-2019
Dalhousie University
2011-2017
We present a new chemical mechanism for Hg0/HgI/HgII atmospheric cycling, including recent laboratory and computational data, implement it in the GEOS-Chem global chemistry model comparison to observations. Our includes oxidation of Hg0 by Br OH, subsequent HgI ozone radicals, respeciation HgII aerosols cloud droplets, speciated photolysis gas aqueous phases. The tropospheric Hg lifetime against deposition is 5.5 months, consistent with observational constraints. reproduces observed surface...
Per- and polyfluoroalkyl substances (PFAS) are a diverse class of fluorinated anthropogenic chemicals that include perfluoroalkyl acids (PFAA), which widely used in modern commerce. Many products environmental samples contain abundant precursors can degrade into terminal PFAA associated with adverse health effects. Fish consumption is an important dietary exposure source for PFAS bioaccumulate food webs. However, little known about bioaccumulation precursors. Here, we identify quantify...
Drinking water contamination by per- and polyfluoroalkyl substances (PFAS) is widespread near more than 300 United States (U.S.) military bases that used aqueous film-forming foams (AFFF) for fire training firefighting activities. Much of the PFAS at these sites consist precursors can transform into terminal compounds known health concern but are omitted from standard analytical methods. Here, we estimate expected duration contribution precursor biotransformation to groundwater an...
Per- and polyfluoroalkyl substances (PFAS) are a diverse class of highly persistent anthropogenic chemicals that detectable in the serum most humans. PFAS exposure has been associated with many adverse effects on human health including immunotoxicity, increased risk certain cancers, metabolic disruption. binding to abundant blood proteins (human albumin [HSA] globulins) is thought affect transport active sites, toxicity, elimination half-lives. However, few studies have investigated...
Abstract Anthropogenic mercury (Hg(0)) emissions oxidize to gaseous Hg(II) compounds, before deposition Earth surface ecosystems. Atmospheric reduction of competes with deposition, thereby modifying the magnitude and pattern Hg deposition. Global models have postulated that in atmosphere occurs through aqueous-phase photoreduction may take place clouds. Here we report experimental rainfall rates are much slower than modelled rates. We compute absorption cross sections compounds show fast...
Abstract When released to the biosphere, mercury (Hg) is very mobile and can take millennia be returned a secure, long-term repository. Understanding where when Hg was as result of human activities allows better quantification present-day reemissions future trajectories environmental concentrations. In this work, we estimate time-varying releases in seven world regions over 500 year period, 1510–2010. By our estimation, comprises 95% all-time anthropogenic releases. Globally, 1.47 Tg were...
Methylmercury (MeHg) concentrations can increase by 100 000 times between seawater and marine phytoplankton, but levels vary across sites. To better understand how ecosystem properties affect variability in planktonic MeHg concentrations, we develop a model for uptake trophic transfer at the base of food webs. The successfully reproduces measured phytoplankton zooplankton diverse sites from Northwest Atlantic Ocean. Highest are simulated under low dissolved organic carbon (DOC)...
Significance Elevated levels of mercury in Arctic marine wildlife have been linked to midlatitude anthropogenic emissions which are transported the Ocean by air. Modeling studies, however, suggest that rivers contribute equal amounts Ocean. In this study, we provide comprehensive data on large Eurasian rivers. We find spring flood flux from is indeed large, confirms a new cycling paradigm: Mid-latitude reach terrestrial air, whereby vegetation uptake transfers atmospheric tundra and boreal...
Water supplies for millions of U.S. individuals exceed maximum contaminant levels per- and polyfluoroalkyl substances (PFAS). Contemporary legacy use aqueous film forming foams (AFFF) is a major contamination source. However, diverse PFAS sources are present within watersheds, making it difficult to isolate their predominant origins. Here we examine source signatures among six adjacent coastal watersheds on Cape Cod, MA, U.S.A. using multivariate clustering techniques. A distinct signature...
Hundreds of public water systems across the United States have been contaminated by use aqueous film-forming foams (AFFF) containing per- and polyfluoroalkyl substances (PFAS) during firefighting training activities. Prior work shows AFFF contain hundreds precursors missed standard methods. However, most abundant in remain uncertain, mixture contents are confidential business information, hindering proactive management PFAS exposure risks. Here, we develop apply a novel method (Bayesian...
Significance The atmospheric chemistry of mercury, a global priority pollutant, is key to its transport and deposition the surface environment. Assessments risks humans ecosystems rely on an accurate understanding mercury cycling. This work shows that chemical reactions rates currently employed interpret Hg in atmosphere fails explain observed concentrations deposition. We report model simulations incorporating recent developments photoreduction mechanisms oxidized forms (Hg I II ) lead...
[1] The meridional transport of water vapor into the High Arctic, accompanied by dry enthalpy and clouds, impacts surface radiative forcing. evolution one such moist intrusion over 9–11 February 2010 is presented. event analyzed using a unique blend measurements including new pan-Arctic retrieval column from Microwave Humidity Sounders, profiles Raman lidar ground-based microwave radiometer at Polar Environment Atmospheric Research Laboratory (PEARL), in Eureka (80°N, 86°W), on Ellesmere...
SignificanceRussian rivers are the predominant source of riverine mercury to Arctic Ocean, where methylmercury biomagnifies high levels in food webs. Pollution controls thought have decreased late-20th-century loading watersheds, but there no published long-term observations on Russian rivers. Here, we present a unique hydrochemistry dataset determine trends river particulate concentrations and fluxes recent decades. Using hydrologic deposition modeling together with multivariate time series...
In 2005, Calvert and Lindberg (Calvert, J. G.; Lindberg, S. E. Atmos. Environ.2005,39, 3355-3367) wrote that the use of laboratory-derived rate constants for OH + Hg(0) "...to determine extent Hg removal by in troposphere will greatly overestimate importance this reaction." The HOHg• intermediate formed from mostly fall apart atmosphere before it can react. By contrast, laboratory experiments, expected to react with radicals (whose concentrations are much higher than atmosphere). Yet, almost...
Perfluorocarboxylic acids (PFCAs) are environmental contaminants that highly persistent, and many bio-accumulative have been detected along with their atmospheric precursors far from emission sources. The overall importance of precursor emissions as an indirect source PFCAs to the environment is uncertain. Previous studies estimated using models degradation pathways differing complexities, leading quantitatively different results. We present results simulations PFCA formation fate chemical...
Abstract Human activities have released large quantities of neutral persistent organic pollutants (POPs) that may be biomagnified in food webs and pose health risks to wildlife, particularly top predators. Here we develop a global 3‐D ocean simulation for four polychlorinated biphenyls (PCBs) spanning range molecular weights volatilities better understand effects climate‐driven changes biogeochemistry on the lifetime distribution POPs. Observations are most abundant Arctic Ocean. There,...
Global pollution has exacerbated accumulation of toxicants like methylmercury (MeHg) in seafood. Human exposure to MeHg been associated with long-term neurodevelopmental delays and impaired cardiovascular health, while many micronutrients seafood are beneficial health. The largest source for general populations originates from marine fish that harvested the global ocean sold commercial market. Here, we use high-resolution catch data fisheries an empirically constrained spatial model examine...
National commitments under the Paris Agreement on climate change interact with other global environmental objectives, such as those of Minamata Convention Mercury. We assess how mercury emissions and deposition reductions from national policy in China could contribute to country's Convention. examine scenarios developed using a computable general equilibrium model China's economy, end-of-pipe control that meet Convention, these policies combination, evaluate atmospheric transport model. find...
Abstract Soils account for the largest global mercury reservoirs, but observations are sparse in many regions. The accumulation and turnover of soils determines whether they act as an atmospheric source or sink. Here, we present a spatial analysis soil from large survey (three horizons, ∼4800 sites) across conterminous United States conducted by U.S. Geological Survey. Soil pools were calculated 11 layers, cumulatively representing top 1 m soil, totaling 158 ± 2 Gg (±SD) (20.3 0.2 mg −2 )....
Abstract Volcanism is the largest natural source of mercury (Hg) to biosphere. However, past Hg emission estimates have varied by three orders magnitude. Here, we present an updated central estimate and interquartile range (232 Mg a −1 ; IQR: 170–336 ) for modern volcanic emissions based on advances in satellite remote sensing sulfur dioxide (SO 2 improved method considering uncertainty Hg:SO ratios. Atmospheric modeling shows influence surface atmospheric concentrations extratropical...
Mercury (Hg) is emitted to air by natural and anthropogenic sources, transports deposits globally, bioaccumulates toxic levels in food webs. It addressed under the global 2017 Minamata Convention, for which periodic effectiveness evaluation required. Previous analyses have estimated impact of different regulatory strategies future mercury deposition. However, using atmospheric models traditionally hold legacy emissions (recycling previously deposited Hg) constant, do not account their...
We quantitatively examine the relative importance of uncertainty in emissions and physicochemical properties (including reaction rate constants) to Northern Hemisphere (NH) Arctic polycyclic aromatic hydrocarbon (PAH) concentrations, using a computationally efficient numerical technique applied global-scale chemical transport model GEOS-Chem. Using polynomial chaos (PC) methods, we propagate uncertainties for PAHs benzo[a]pyrene, pyrene phenanthrene simulated spatially resolved concentration...
Abstract Mercury (Hg) is a naturally occurring element that has been greatly enriched in the environment by human activities like mining and fossil fuel combustion. Despite commonalities some carbon dioxide (CO 2 ) Hg emission sources, implications of long‐range climate scenarios for anthropogenic emissions have yet to be explored. Here, we present comprehensive projections extending year 2300 evaluate impacts on global atmospheric deposition. Projections are based four Shared Socioeconomic...