Mercury Export from Arctic Great Rivers

Zolkos, Scott; Krabbenhoft, David P.; Suslova, Anya; Tank, Suzanne E.; McClelland, J. W.; Spencer, Robert G. M.; Shiklomanov, A. I.; Zhulidov, Alexander V.; Gurtovaya, Tatiana Yu.; Zimov, N.; Zimov, S. A.; Mutter, E. A.; Kutny, Les; Amos, Edwin; Holmes, Robert M.

doi:10.1021/acs.est.9b07145

Cited by 62 publications

(60 citation statements)

References 56 publications

(176 reference statements)

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“…Total Hg concentration in Slims River water was quite low (total [Hg] in unfiltered water: 3.86 ng L −1 ), and similar to concentrations found in other subarctic and arctic rivers (Søndergaard et al 2015;Vermilyea et al 2017;Zolkos et al 2020). Interestingly, most of the Hg in the Slims River was found in the particulate phase (dissolved [Hg]: <0.05 ng L −1 , <1.3 percent of total Hg) and was likely sorbed to fine, glacial, suspended sediments carried by the river (Vermilyea et al 2017) to downstream Kluane Lake.…”

Section: The Slims River Periodsupporting

confidence: 74%

Mercury accumulation in sediments of Lhù’ààn Mânʼ (Kluane Lake, YT): Response to past hydrological change

Zabel

Hall

Branfireun

et al. 2021

Arctic, Antarctic, and Alpine Research

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Northern lakes provide many ecosystem services, including the provision of traditional foods and clean water. These systems are vulnerable to climate-driven changes in hydrology and contaminant accumulation, but the direction and magnitude of projected changes are poorly constrained. One contaminant of concern is mercury; currently, we cannot accurately predict how mercury accumulation in lakes will respond to climate-induced changes, especially in lakes with glacial inflows and complex hydrology. Sediment cores collected from two regions of a glacially fed lake (Lhù'ààn Mân'; Kluane Lake, Yukon, Canada) were analyzed to investigate controls on sediment mercury accumulation in the context of previously described hydrological changes. Differences in catchment contributions drove differences in sediment mercury accumulation between lake regions during the Duke River hydrological period (ca. 750-1650). During the more recent Slims River hydrological period (ca. 1650-2015), mercury accumulation did not differ between regions, and mercury was delivered to the lake primarily via catchment organic matter and carbonate-rich sediments from the largest, glacially derived inflow (Slims River). Recent climate-induced geomorphic change caused loss of the main lake inflow (Slims River) in 2016, making Kluane Lake an ideal system for future investigations of how loss of glacial inflow will affect mercury accumulation in northern lakes.

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Section: The Slims River Periodsupporting

confidence: 74%

Mercury accumulation in sediments of Lhù’ààn Mânʼ (Kluane Lake, YT): Response to past hydrological change

Zabel

Hall

Branfireun

et al. 2021

Arctic, Antarctic, and Alpine Research

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“…The Arctic is particularly vulnerable to anthropogenic Hg perturbations because it may be a global Hg sink as prevailing atmospheric circulation carries Hg to northern latitudes 5 . Although anthropogenic pollution is a major contributor to the elevated Hg concentrations in Arctic biota, inputs from climatically vulnerable naturally occurring pools have also received more recognition during the last decade [6][7][8][9][10] . For example, Arctic rivers are a significant Hg source to the Arctic Ocean and are climatically sensitive due to their intensifying hydrological cycles (variability and magnitude), widespread catchment permafrost cover and disproportionate warming in the Arctic 9,11 .…”

mentioning

confidence: 99%

Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

et al. 2021

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The Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521–3,300 mmol km−2 year−1) are two orders of magnitude higher than from Arctic rivers (4–20 mmol km−2 year−1). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4–212 kmol year−1), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31–1.97 kmol year−1). High dissolved mercury concentrations (~20 pM inorganic mercury and ~2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (~51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.

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“…Under‐ice samples were collected from the midchannel surface station through a hole in the ice. Sampling locations were Salekhard (Ob'), Dudinka (Yenisey), Zhigansk (Lena), Cherskiy (Kolyma), Pilot Station (Yukon), and Tsiigehtchic (Mackenzie) (Holmes et al., 2012; McClelland et al., 2008; Raymond et al., 2007; Zolkos et al., 2020).…”

Section: Methodsmentioning

confidence: 99%

Pan‐Arctic Riverine Dissolved Organic Matter: Synchronous Molecular Stability, Shifting Sources and Subsidies

Behnke

McClelland²,

Tank

et al. 2021

Global Biogeochemical Cycles

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Climate change is dramatically altering Arctic ecosystems, leading to shifts in the sources, composition, and eventual fate of riverine dissolved organic matter (DOM) in the Arctic Ocean. Here we examine a 6-year DOM compositional record from the six major Arctic rivers using Fourier-transform ion cyclotron resonance mass spectrometry paired with dissolved organic carbon isotope data (Δ 14 C, δ 13 C) to investigate how seasonality and permafrost influence DOM, and how DOM export may change with warming. Across the pan-Arctic, DOM molecular composition demonstrates synchrony and stability. Spring freshet brings recently leached terrestrial DOM with a latent high-energy and potentially bioavailable subsidy, reconciling the historical paradox between freshet DOM's terrestrial bulk signatures and high biolability. Winter features undiluted baseflow DOM sourced from old, microbially degraded groundwater DOM. A stable core Arctic riverine fingerprint (CARF) is present in all samples and may contribute to the potential carbon sink of persistent, aged DOM in the global ocean. Future warming may lead to shifting sources of DOM and export through: (1) flattening Arctic hydrographs and earlier melt modifying the timing and role of the spring high-energy subsidy; (2) increasing groundwater discharge resulting in a greater fraction of DOM export to the ocean occurring as stable and aged molecules; and(3) increasing contribution of nitrogen/sulfur-containing DOM from microbial degradation caused by increased connectivity between groundwater and surface waters due to permafrost thaw. Our findings suggest the ubiquitous CARF (which may contribute to oceanic carbon sequestration) underlies predictable variations in riverine DOM composition caused by seasonality and permafrost extent.

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Mercury Export from Arctic Great Rivers

Cited by 62 publications

References 56 publications

Mercury accumulation in sediments of Lhù’ààn Mânʼ (Kluane Lake, YT): Response to past hydrological change

Mercury accumulation in sediments of Lhù’ààn Mânʼ (Kluane Lake, YT): Response to past hydrological change

Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

Pan‐Arctic Riverine Dissolved Organic Matter: Synchronous Molecular Stability, Shifting Sources and Subsidies

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