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A two-year study of mercury deposition in the Arctic finds that the main source of mercury is gaseous elemental mercury, which is deposited throughout the year and leads to very high soil mercury levels. Sinking mercury in the Arctic tundra Anthropogenic activities have led to large-scale mercury pollution in the Arctic, but it remains uncertain whether wet deposition of oxidized mercury via precipitation and sea-salt-induced chemical cycling of mercury are responsible for the high Arctic mercury load. This paper presents a mass-balance study of mercury deposition and stable isotope data from the Arctic tundra, and finds that the main source of mercury is in fact derived from gaseous elemental mercury, with only minor contributions from the other two suggested sources. Consistently high soil mercury concentrations derived from gaseous elemental mercury along an inland-to-coastal transect suggest that the Arctic tundra might be a globally important mercury sink and might explain why Arctic rivers annually transport large amounts of mercury to the Arctic Ocean. Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic 1 , 2 , 3 , 4 , 5 , 6 . It has been suggested that sea-salt-induced chemical cycling of Hg (through ‘atmospheric mercury depletion events’, or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg( ii )). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned 2 , 7 . Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide 8 , raising questions as to the sources of high Arctic Hg loading. Here we present a comprehensive Hg-deposition mass-balance study, and show that most of the Hg (about 70%) in the interior Arctic tundra is derived from gaseous elemental Hg (Hg(0)) deposition, with only minor contributions from the deposition of Hg( ii ) via precipitation or AMDEs. We find that deposition of Hg(0)—the form ubiquitously present in the global atmosphere—occurs throughout the year, and that it is enhanced in summer through the uptake of Hg(0) by vegetation. Tundra uptake of gaseous Hg(0) leads to high soil Hg concentrations, with Hg masses greatly exceeding the levels found in temperate soils. Our concurrent Hg stable isotope measurements in the atmosphere, snowpack, vegetation and soils support our finding that Hg(0) dominates as a source to the tundra. Hg concentration and stable isotope data from an inland-to-coastal transect show high soil Hg concentrations consistently derived from Hg(0), suggesting that the Arctic tundra might be a globally important Hg sink. We suggest that the high tundra soil Hg concentrations might also explain why Arctic rivers annually transport large amounts of Hg to the Arctic Ocean 9 , 10 , 11 .

The latest Permian mass extinction, the most devastating biocrisis of the Phanerozoic, has been widely attributed to eruptions of the Siberian Traps Large Igneous Province, although evidence of a direct link has been scant to date. Here, we measure mercury (Hg), assumed to reflect shifts in volcanic activity, across the Permian-Triassic boundary in ten marine sections across the Northern Hemisphere. Hg concentration peaks close to the Permian-Triassic boundary suggest coupling of biotic extinction and increased volcanic activity. Additionally, Hg isotopic data for a subset of these sections provide evidence for largely atmospheric rather than terrestrial Hg sources, further linking Hg enrichment to increased volcanic activity. Hg peaks in shallow-water sections were nearly synchronous with the end-Permian extinction horizon, while those in deep-water sections occurred tens of thousands of years before the main extinction, possibly supporting a globally diachronous biotic turnover and protracted mass extinction event. Previously, little direct evidence has been found to link large volcanic eruption events with the end-Permian mass extinction. Here, the authors find that mercury enrichment and isotope records in marine sections across the globe can be linked to increased volcanic activity, which resulted in the protracted Permian-Triassic biocrisis

Mercury (Hg) can enter the human body through the respiratory tract and digestive system, but also through the skin. Sources of Hg in the environment can be natural processes, but also human activities, including agriculture, chemical, and pharmaceutical industries. Hg can also enter the body through food, but also with cosmetics that are used for a long time. Therefore, the aim of this study was to evaluate the Hg content in 268 randomly selected cosmetics: Natural and conventional, for face and body. Hg content was determined using an atomic absorption spectrometer (AMA 254, Leco, Prague, Czech Republic). It was shown that the face preparations were characterized by a significantly higher Hg content than the body preparations. No differences in the content of the tested element were found between natural and conventional preparations. Hg could be detected in all samples with concentrations measured from 0.348 to 37.768 µg/kg.

The sources of isotopically light carbon released during the end-Triassic mass extinction remain in debate. Here, we use mercury (Hg) concentrations and isotopes from a pelagic Triassic–Jurassic boundary section (Katsuyama, Japan) to track changes in Hg cycling. Because of its location in the central Panthalassa, far from terrigenous runoff, Hg enrichments at Katsuyama record atmospheric Hg deposition. These enrichments are characterized by negative mass independent fractionation (MIF) of odd Hg isotopes, providing evidence of their derivation from terrestrial organic-rich sediments (Δ 199 Hg < 0‰) rather than from deep-Earth volcanic gases (Δ 199 Hg ~ 0‰). Our data thus provide evidence that combustion of sedimentary organic matter by igneous intrusions and/or wildfires played a significant role in the environmental perturbations accompanying the event. This process has a modern analog in anthropogenic combustion of fossil fuels from crustal reservoirs. Mercury (Hg) concentrations and isotopes from a deep-ocean Triassic–Jurassic (~201 Ma) boundary section provide evidence of large inputs from terrestrial organic-rich sources through combustion by magmatic sills and wildfires.

Anthropogenic activities have caused large-scale mercury (Hg) pollution in the Arctic reaching toxic levels, but knowledge of sources and pathways is sparse. Here, we present Hg stable isotope data in peat and key aquatic predatory species collected across Greenland. We observe distinct regional differences with significantly lower total Hg and higher δ 202 Hg in central-western versus northern-eastern Greenland influenced by different ocean currents. While Δ 200 Hg shows that atmospheric Hg deposition occurs predominantly (60–97%) as Hg(0), Δ 199 Hg reveals marked photochemical demethylation in especially freshwater habitats. We find δ 202 Hg in muscle tissue to increase with trophic level linked to internal metabolic transformation. Finally, we observe significant increases in total Hg and δ 202 Hg for several species/sites during the past 40 years, suggesting an increase in anthropogenic Hg sources and/or change in environmental processes. These findings show that ocean currents carrying large inventories of legacy Hg may be the dominant pathway driving present Hg uptake in Arctic marine and coastal areas. This explains the discrepancy between decreasing atmospheric Hg deposition in the Arctic in recent decades due to reduced global anthropogenic emissions, and the lack of response or increases in Hg-loads in many Arctic species, with implications for effectiveness evaluation of the Minamata Convention. Mercury pollution in the Arctic has reached toxic levels. Here, the authors compile mercury isotope data from peat and aquatic predator species collected across Greenland over the past 40 years, observing both regional differences and temporal trends.

Monomethylmercury (MMHg) is a potent toxin that bioaccumulates and magnifies in marine food webs. Recent studies show abundant methylated Hg in deep oceans (>1000 m), yet its origin remains uncertain. Here we measured Hg isotope compositions in fauna and surface sediments from the Mariana Trench. The trench fauna at 7000–11000 m depth all have substantially positive mass-independent fractionation of odd Hg isotopes (odd-MIF), which can be generated only in the photic zone via MMHg photo-degradation. Given the identical odd-MIF in trench fauna and North Pacific upper ocean (<1000 m) biota MMHg, we suggest that the accumulated Hg in trench fauna originates exclusively from MMHg produced in upper oceans, which penetrates to depth by sorption to sinking particles. Our findings reveal little in-situ MMHg production in deep oceans and imply that anthropogenic Hg released at the Earth’s surface is much more pervasive across deep oceans than was previously thought. Monomethylmercury is a toxin that humans can be exposed to after consumption of seafood in which it has bioaccumulated. Here the authors show that amphipods in the deepest point of the global ocean contain monomethylmercury with surface origins, suggesting rapid sinking of this toxin on particles.

Geochemical methods can identify the long-distance exchange of resources in the archaeological record. Cinnabar is a mineral with a limited number of geological sources; however, methods for determining the geological origin of cinnabar are constricted by the limited availability of comparative geological source materials. This study applies a multi-method approach to compare isotopic ratios of mercury and sulfur in archaeological specimens of cinnabar from museum collections and scientifically excavated materials from the Andes region of South America. We demonstrate that the δ 202 Hg to Δ 199 Hg relationship, assessed through Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS), falls along a predictive slope, while Isotope Ratio Mass Spectrometry (IR-MS) for sulfur (S) was not a reliable proxy for determining ore source. Furthermore, Hg isotope ratios from similar sites and contexts tended to cluster, suggesting that most sites exploited cinnabar from the same ore source. Statistical analyses support the idea that the Huancavelica deposit served as the primary source of cinnabar pigment for pre-Hispanic societies, while also revealing some intriguing divergences that suggest alternate sources were exploited during certain periods on the North and South Coasts of Peru. These results demonstrate that MC-ICP-MS analyses of mercury can be used to geochemically trace cinnabar ore in the Andes and beyond.

Mercury (Hg) and stable carbon and nitrogen isotope ratios were analysed in body feathers from nestlings of white-tailed eagles ( Haliaeetus albicilla) (WTE; n = 13) and Northern goshawks ( Accipiter gentilis ) (NG; n = 8) and in red blood cells (RBC) from NG (n = 11) from Norway. According to linear mixed model, species factor was significant in explaining the Hg concentration in feathers (LMM; p  < 0.001, estimate (WTE) = 2.51, 95% CI = 1.26, 3.76), with concentrations higher in WTE (3.01 ± 1.34 µg g −1 dry weight) than in NG (0.51 ± 0.34 µg g −1 dry weight). This difference and the isotopic patterns for each species, likely reflect their diet, as WTE predominantly feed on a marine and higher trophic-chain diet compared to the terrestrial NG. In addition, Hg concentrations in RBCs of NG nestlings were positively correlated with feather Hg concentrations ( Rho  = 0.77, p  = 0.03), supporting the potential usefulness of nestling body feathers to biomonitor and estimate Hg exposure. Hg levels in both species were generally below the commonly applied toxicity threshold of 5 µg g −1 in feathers, although exceeded in two WTE (6.08 and 5.19 µg g −1 dry weight).

The origin of methylmercury in pelagic fish remains unclear, with many unanswered questions regarding the production and degradation of this neurotoxin in the water column. We used mercury (Hg) stable isotope ratios of marine particles and biota to elucidate the cycling of methylmercury prior to incorporation into the marine food web. The Hg isotopic composition of particles, zooplankton, and fish reveals preferential methylation of Hg within small (< 53 μm) marine particles in the upper 400 m of the North Pacific Ocean. Mass-dependent Hg isotope ratios (δ202Hg) recorded in small particles overlap with previously estimated δ202Hg values for methylmercury sources to Pacific and Atlantic Ocean food webs. Particulate compound specific isotope analysis of amino acids (CSIA-AA) yield δ15N values that indicate more-significant microbial decomposition in small particles compared to larger particles. CSIA-AA and Hg isotope data also suggest that large particles (> 53 μm) collected in the equatorial ocean are distinct from small particles and resemble fecal pellets. Additional evidence for Hg methylation within small particles is provided by a statistical mixing model of even mass–independent (Δ200Hg and Δ204Hg) isotope values, which demonstrates that Hg within near-surface marine organisms (0–150 m) originates from a combination of rainfall and marine particles. In contrast, in meso- and upper bathypelagic organisms (200–1,400 m), the majority of Hg originates from marine particles with little input from wet deposition. The occurrence of methylation within marine particles is supported further by a correlation between Δ200Hg and Δ199Hg values, demonstrating greater overlap in the Hg isotopic composition of marine organisms with marine particles than with total gaseous Hg or wet deposition.

Hg isotope analysis in samples from background regions is constrained by the presence of low Hg concentration and therefore requires a pre-concentration method. Existing Hg pre-concentration methods are constrained by long sample processing time and limited sample loading capacity. Using foliar samples as a test case, an optimized Hg pre-concentration method is presented that involves the microwave-assisted digestion of samples for Hg isotope analysis with the addition of a pre-digestion step. Microwave-digested foliar samples and CRMs were transferred to an impinger, reduced with SnCl2, and collected in a 2.25 mL concentrated inverse aqua regia (3:1 HNO3:HCl, v/v). This resulted in an optimal acid concentration in the solution ideal for analysis on MC-ICP-MS. The time for purging with Hg-free N2 was optimized to 30 min and the efficiency of the pre-concentration method was tested using a combination of approaches. Tests performed on pure reagents and matrix of foliar samples spiked with 197Hg radiotracer showed recoveries averaging 99 ± 1.7% and 100 ± 3.0%, respectively. Mercury at concentrations as low as 1.83 ng g−1 was pre-concentrated by digesting aliquots of foliage samples in individual digestion vessels. Recoveries following their pre-concentration averaged 99 ± 6.0%, whereas recoveries of 95 ± 4.7% and 95 ± 2.5% were achieved for NIST SRM 1575a (pine needle) and reagents spiked with NIST SRM 3133, respectively. Analysis using multicollector-ICP-MS showed low fractionation of δ202Hg during sample pre-concentration with no significant mass-independent fractionation. The proposed method is a relatively simple and robust way to prepare Hg samples for Hg isotopic analysis and is suitable even for complex biological matrices.