Abstract
The problem of mercury input and its further distribution in the Arctic environment is actively debated, especially in recent times, due to the observed processes of permafrost thawing causing the enhanced release of mercury into the Arctic atmosphere and further distribution in the terrestrial and aquatic ecosystem. The atmospheric mercury deposition occurs via dry deposition and wet scavenging by precipitation events. Here we present a study of Hg in wet precipitation on the remote territory of the Russian Arctic; the data were obtained at the monitoring stations Nadym and Salekhard in 2016–2018. Mercury pollution of the Salekhard atmosphere in cold time is mainly determined by regional and local sources, while in Nadym, long-range transport of mercury and local fuel combustion are the main sources of pollutants in the cold season, while internal regional sources have a greater impact on the warm season. Total mercury concentrations in wet precipitation in Nadym varied from <0.5 to 63.3 ng/L. The highest Hg concentrations in the springtime were most likely attributed to atmospheric mercury depletion events (AMDE). The contributions of wet atmospheric precipitation during the AMDE period to the annual Hg deposition were 16.7% and 9.8% in 2016/2017 and 2017/2018, respectively. The average annual volume-weighted Hg concentration (VWC) in the atmospheric precipitation in Nadym is notably higher than the values reported for the remote regions in the Arctic and comparable with the values obtained for the other urbanized regions of the world. Annual Hg fluxes in Nadym are nevertheless close to the average annual fluxes for remote territories of the Arctic zone and significantly lower than the annual fluxes reported for unpolluted sites of continental-scale monitoring networks of the different parts of the world (USA, Europe, and China). The increase of Hg deposition flux with wet precipitation in Nadym in 2018 might be caused by regional emissions of gas and oil combustion, wildfires, and Hg re-emission from soils due to the rising air temperature. The 37 cm increase of the seasonally thawed layer (STL) in 2018 compared to the 10-year average reflects that the climatic changes in the Nadym region might increase Hg(0) evasion, considering a great pool of Hg is contained in permafrost.
Highlights
IntroductionMercury is a global pollutant that can be released into the environment both from natural sources and processes (emissions from the ocean, geothermal activities and volcanic eruptions, rock weathering, and biomass burning) [1] and anthropogenic activity (coal, oil, and natural gas combustion, mining and smelting activities, gold and silver mining, waste processing, chlor-alkali and cement industry, etc.) [2]
Mercury is a global pollutant that can be released into the environment both from natural sources and processes [1] and anthropogenic activity [2]
Available global emissions inventories are quite complete and accurate for some anthropogenic sources; there are still uncertainties in the development of mercury emission inventories for natural sources and the re-emission of Hg [3,4]
Summary
Mercury is a global pollutant that can be released into the environment both from natural sources and processes (emissions from the ocean, geothermal activities and volcanic eruptions, rock weathering, and biomass burning) [1] and anthropogenic activity (coal, oil, and natural gas combustion, mining and smelting activities, gold and silver mining, waste processing, chlor-alkali and cement industry, etc.) [2]. With the existing air circulation system, pollutants are transported from sources thousands of kilometers away from the Arctic region (from the industrially developed regions of Europe, Asia, and North America) in winter, while in the summer, the contribution of meridional transport from medium-distance and local sources of pollution increases [5]. Biomagnification (a cumulative increase in the Hg concentrations as it moves up the food chain) is observed, causing the highest concentrations in top predators, including humans [11,12]
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