Abstract
Mercury (Hg) is a naturally occurring element that bonds with organic matter and, when converted to methylmercury, is a potent neurotoxicant. Here we estimate potential future releases of Hg ...from thawing permafrost for low and high greenhouse gas emissions scenarios using a mechanistic model. By 2200, the high emissions scenario shows annual permafrost Hg emissions to the atmosphere comparable to current global anthropogenic emissions. By 2100, simulated Hg concentrations in the Yukon River increase by 14% for the low emissions scenario, but double for the high emissions scenario. Fish Hg concentrations do not exceed United States Environmental Protection Agency guidelines for the low emissions scenario by 2300, but for the high emissions scenario, fish in the Yukon River exceed EPA guidelines by 2050. Our results indicate minimal impacts to Hg concentrations in water and fish for the low emissions scenario and high impacts for the high emissions scenario.
The intentional use of mercury (Hg) in products and processes (“commercial Hg”) has contributed a large and previously unquantified anthropogenic source of Hg to the global environment over the ...industrial era, with major implications for Hg accumulation in environmental reservoirs. We present a global inventory of commercial Hg uses and releases to the atmosphere, water, soil, and landfills from 1850 to 2010. Previous inventories of anthropogenic Hg releases have focused almost exclusively on atmospheric emissions from “byproduct” sectors (e.g., fossil fuel combustion). Cumulative anthropogenic atmospheric Hg emissions since 1850 have recently been estimated at 215 Gg (only including commercial Hg releases from chlor-alkali production, waste incineration, and mining). We find that other commercial Hg uses and nonatmospheric releases from chlor-alkali and mining result in an additional 540 Gg of Hg released to the global environment since 1850 (air: 20%; water: 30%; soil: 30%; landfills: 20%). Some of this release has been sequestered in landfills and benthic sediments, but 310 Gg actively cycles among geochemical reservoirs and contributes to elevated present-day environmental Hg concentrations. Commercial Hg use peaked in 1970 and has declined sharply since. We use our inventory of historical environmental releases to force a global biogeochemical model that includes new estimates of the global burial in ocean margin sediments. Accounting for commercial Hg releases improves model consistency with observed atmospheric concentrations and associated historical trends.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Understanding the biogeochemical cycling of mercury is critical for explaining the presence of mercury in remote regions of the world, such as the Arctic and the Himalayas, as well as local ...concentrations. While we have good knowledge of present-day fluxes of mercury to the atmosphere, we have little knowledge of what emission levels were like in the past. Here we develop a trend of anthropogenic emissions of mercury to the atmosphere from 1850 to 2008for which relatively complete data are availableand supplement that trend with an estimate of anthropogenic emissions prior to 1850. Global mercury emissions peaked in 1890 at 2600 Mg yr–1, fell to 700–800 Mg yr–1 in the interwar years, then rose steadily after 1950 to present-day levels of 2000 Mg yr–1. Our estimate for total mercury emissions from human activities over all time is 350 Gg, of which 39% was emitted before 1850 and 61% after 1850. Using an eight-compartment global box-model of mercury biogeochemical cycling, we show that these emission trends successfully reproduce present-day atmospheric enrichment in mercury.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
More than three billion people rely on seafood for nutrition. However, fish are the predominant source of human exposure to methylmercury (MeHg), a potent neurotoxic substance. In the United States, ...82% of population-wide exposure to MeHg is from the consumption of marine seafood and almost 40% is from fresh and canned tuna alone
. Around 80% of the inorganic mercury (Hg) that is emitted to the atmosphere from natural and human sources is deposited in the ocean
, where some is converted by microorganisms to MeHg. In predatory fish, environmental MeHg concentrations are amplified by a million times or more. Human exposure to MeHg has been associated with long-term neurocognitive deficits in children that persist into adulthood, with global costs to society that exceed US$20 billion
. The first global treaty on reductions in anthropogenic Hg emissions (the Minamata Convention on Mercury) entered into force in 2017. However, effects of ongoing changes in marine ecosystems on bioaccumulation of MeHg in marine predators that are frequently consumed by humans (for example, tuna, cod and swordfish) have not been considered when setting global policy targets. Here we use more than 30 years of data and ecosystem modelling to show that MeHg concentrations in Atlantic cod (Gadus morhua) increased by up to 23% between the 1970s and 2000s as a result of dietary shifts initiated by overfishing. Our model also predicts an estimated 56% increase in tissue MeHg concentrations in Atlantic bluefin tuna (Thunnus thynnus) due to increases in seawater temperature between a low point in 1969 and recent peak levels-which is consistent with 2017 observations. This estimated increase in tissue MeHg exceeds the modelled 22% reduction that was achieved in the late 1990s and 2000s as a result of decreased seawater MeHg concentrations. The recently reported plateau in global anthropogenic Hg emissions
suggests that ocean warming and fisheries management programmes will be major drivers of future MeHg concentrations in marine predators.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The spatial distribution of 29 per- and polyfluoroalkyl substances (PFASs) in seawater was investigated along a sampling transect from Europe to the Arctic and two transects within Fram Strait, ...located between Greenland and Svalbard, in the summer of 2018. Hexafluoropropylene oxide-dimer acid (HFPO-DA), a replacement compound for perfluorooctanoic acid (PFOA), was detected in Arctic seawater for the first time. This provides evidence for its long-range transport to remote areas. The total PFAS concentration was significantly enriched in the cold, low-salinity surface water exiting the Arctic compared to warmer, higher-salinity water from the North Atlantic entering the Arctic (260 ± 20 pg/L versus 190 ± 10 pg/L). The higher ratio of perfluoroheptanoic acid (PFHpA) to perfluorononanoic acid (PFNA) in outflowing water from the Arctic suggests a higher contribution of atmospheric sources compared to ocean circulation. An east–west cross section of the Fram Strait, which included seven depth profiles, revealed higher PFAS concentrations in the surface water layer than in intermediate waters and a negligible intrusion into deep waters (>1000 m). Mass transport estimates indicated a net inflow of PFASs with ≥8 perfluorinated carbons via the boundary currents and a net outflow of shorter-chain homologues. We hypothesize that this reflects higher contributions from atmospheric sources to the Arctic outflow and a higher retention of the long-chain compounds in melting snow and ice.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
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 MeHg uptake and trophic transfer at the base of marine food webs. The model successfully reproduces measured concentrations in phytoplankton and zooplankton across diverse sites from the Northwest Atlantic Ocean. Highest MeHg concentrations in phytoplankton are simulated under low dissolved organic carbon (DOC) concentrations and ultraoligotrophic conditions typical of open ocean regions. This occurs because large organic complexes bound to MeHg inhibit cellular uptake and cell surface area to volume ratios are greatest under low productivity conditions. Modeled bioaccumulation factors for phytoplankton (102.4–105.9) are more variable than those for zooplankton (104.6–106.2) across ranges in DOC (40–500 μM) and productivities (ultraoligotrophic to hypereutrophic) typically found in marine ecosystems. Zooplankton growth dilutes their MeHg body burden, but they also consume greater quantities of MeHg enriched prey at larger sizes. These competing processes lead to lower variability in MeHg concentrations in zooplankton compared to phytoplankton. Even under hypereutrophic conditions, modeled growth dilution in marine zooplankton is insufficient to lower their MeHg concentrations, contrasting findings from freshwater ecosystems.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Anthropogenic activities have enriched mercury in the biosphere by at least a factor of three, leading to increases in total mercury (Hg) in the surface ocean. However, the impacts on ocean fish and ...associated trends in human exposure as a result of such changes are less clear. Here we review our understanding of global mass budgets for both inorganic and methylated Hg species in ocean seawater. We consider external inputs from atmospheric deposition and rivers as well as internal production of monomethylmercury (CH3Hg) and dimethylmercury ((CH3)2Hg). Impacts of large-scale ocean circulation and vertical transport processes on Hg distribution throughout the water column and how this influences bioaccumulation into ocean food chains are also discussed. Our analysis suggests that while atmospheric deposition is the main source of inorganic Hg to open ocean systems, most of the CH3Hg accumulating in ocean fish is derived from in situ production within the upper waters (<1000m). An analysis of the available data suggests that concentrations in the various ocean basins are changing at different rates due to differences in atmospheric loading and that the deeper waters of the oceans are responding slowly to changes in atmospheric Hg inputs. Most biological exposures occur in the upper ocean and therefore should respond over years to decades to changes in atmospheric mercury inputs achieved by regulatory control strategies. Migratory pelagic fish such as tuna and swordfish are an important component of CH3Hg exposure for many human populations and therefore any reduction in anthropogenic releases of Hg and associated deposition to the ocean will result in a decline in human exposure and risk.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Mercury (Hg) is a naturally occurring element in the Earth's crust. It can be harmful to human health when released in large quantities and/or converted to the neurotoxicant methyl mercury in aquatic ...ecosystems. This study analyzes global and regional trends in anthropogenic Hg releases to the atmosphere between 2010 and 2015, as well as the associated trends in modeled and measured Hg concentrations at sites around the world. In general, we find that global Hg emissions and concentrations have grown slightly in this period, as declines from the phase-out of commercial Hg use in the developed world have been more than matched by increases in Hg-related activities in the industrializing countries of the world. We estimate that global Hg emissions between 2010 and 2015 have grown at a rate of 1.8%/yr, from 2188 Mg (+44%/-20%, 80% C.I.) in 2010 to 2390 Mg (+42%/-19%, 80% C.I.) in 2015. Regionally, emissions declined over this period in the U.S. (−10%), OECD Europe (−5.8%), and Canada (−3.2%), while they increased in Central America (+5.4%), South Asia (+4.6%), and Eastern Africa (+4.0%). East Asia remained the largest emitting region at 1012 Mg in 2015, though growth there has slowed significantly in recent years. The production of Hg (+7.9%), caustic soda (+6.3%), and cement (+6.3%) showed the highest increases by source type, though artisanal and small-scale gold mining (ASGM) was the single largest source of emissions in 2015 (775 Mg). The commercial use of Hg in dental applications (−5.6%) and electrical equipment (−5.2%) continued to decline. These emission trends show a continuation of the regional and sectoral shifts that began in the 1970s, but with a resulting reversal in global trends, because the benefits from Hg phase-out in North America and Europe have been largely realized and industrial growth in developing countries has begun to dominate. The emission trends are in agreement with trends in modeled and measured concentrations, which show small declines in surface air total gaseous Hg concentrations in eastern North America and Western Europe between 2010 and 2015, but slight increases for much of the rest of the world, driven by the continued increases in emissions from Asia and from ASGM. Our results suggest that reductions of Hg in the North Atlantic region have been largely successful, and focus now needs to shift to Asia and to the continued practice of ASGM worldwide.
Display omitted
•Global trends in mercury emissions and concentrations are estimated for 2010–2015.•Declines since the 1970s in North America and Europe are now leveling out.•Emissions continue to grow in Asia, Africa, and other industrializing regions.•As a result, global emissions have grown slightly (1.8%/yr) during this period.•Mercury use, coal combustion, and small-scale gold mining need further controls.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
