Low and Declining Mercury in Arctic Russian Rivers

Abstract

Mercury (Hg) dynamics in the Arctic is receiving increasing attention, but further understanding is limited by a lack of studies in Russia, which encompasses the majority of the pan-Arctic watershed. This study reports Hg concentrations and trends in burbot (Lota lota) from the Lena and Mezen Rivers in the Russian Arctic, and assesses the extent to which they differ from those found in burbot in arctic rivers elsewhere. Mercury concentrations in burbot in the Lena and Mezen Rivers were found to be generally lower than in 23 other locations, most of which are in the Mackenzie River Basin (Canada). Mercury concentrations in burbot in the Lena and Mezen Rivers also were found to have been declining at an annual rate of 2.3% while they have been increasing in the Mackenzie River Basin at annual rates between 2.2 and 5.1% during roughly the same time period. These contrasting patterns in Hg in burbot across the pan-Arctic may be explained by geographic heterogeneity in controlling processes, including riverine particulate material loads, historically changing atmospheric inputs, postdepositional processes, and climate change impacts.

High variability of atmospheric mercury in the summertime boundary layer through the central Arctic Ocean

“…TGM concentrations displayed an inhomogeneous distribution over the oceans, similar to the results obtained during the expedition of Galathea 3 cruise16, which covered the North Atlantic Ocean etc. The spatial distribution of TGM over the Arctic Ocean is notably in agreement with the recent observation of higher Hg in biota in the western Arctic than in the east1718. The frequency distribution of TGM concentrations is given in Figure 2a, and the Kolmogorov-Smirnov test suggested a normal distribution (P < 0.001).…”

Mercury Export from Arctic Great Rivers

“…27,28 In large major Russian rivers in recent decades, decreasing Hg concentrations in burbot (Lota lota) tissues are thought to reflect more recent historical declines in atmospheric Hg from decreased industrial activity and also an offset in bioaccumulation from increasing growth rates driven by warming river temperatures. 27,28 In contrast, Hg in burbot is increasing in the Mackenzie River watershed, 27 where the weathering of sulfide minerals, erosion of coal deposits, and Hg release from thawing permafrost are among the primary sources of Hg in regional freshwaters. 26,29 At this time, it remains difficult to predict how these complex, interacting factors will reshape aquatic Hg cycling in northern environments.…”

“…Continuing to make direct and frequent measurements of Hg in Arctic rivers is thus critical for establishing long-term trends and resolving the effects of changing northern environments on the Arctic Hg cycle. [27][28][29]54 ■ ASSOCIATED CONTENT * sı Supporting Information…”

Females Exceed Males in Mercury Concentrations of Burbot Lota lota

“…Muscle tissue of burbot caught in the Western Basin and East Arm of Great Slave Lake (Northwest Territories, Canada) during 1992 to 2012 averaged approximately 140 ng/g Hg (Evans et al 2013). Similarly, muscle tissue of burbot caught in the Lena and Menzen Rivers, located in the Russian Arctic, during 1980 to 2001 averaged between 100 and 200 ng/g Hg (Castello et al 2014). Substantially greater Hg concentrations have been recorded for muscle tissue of burbot from the Mackenzie River Basin, located in the Canadian Arctic, where mean Hg concentrations ranged between 220 and 440 ng/g during 1985 to 2009 (Carrie et al 2010).…”