Overview of mercury measurements in the Antarctic troposphere

Abstract

Abstract. Polar ecosystems are considered to be the last pristine environments of the earth relatively uninfluenced by human activities.

Mercury in the Arctic tundra snowpack: temporal and spatial concentration patterns and trace gas exchanges

“…Concentrations in Hg diss of the five northernmost locations (< 100 km distance from the Arctic Ocean) were statistically significantly (p < 0.05, KruskalWallis test) higher compared to those measured at the four stations located in the interior tundra (> 100 km), which included the Toolik site where mean Hg diss concentrations were 0.33 ± 0.22 and 0.11 ± 0.07 ng L −1 for the same period, respectively. These patterns are consistent with previous observations in Alaska in springtime that suggested an ocean influence leading to higher Hg deposition, possibly linked to the presence of halogens (Douglas and Sturm, 2004;Landers et al, 1995;Snyder-Conn et al, 1997). We propose that low snowpack Hg concentrations (< 0.5 ng L −1 for Hg diss ) are common in inland northern Alaska areas and that the interior Arctic snowpacks exhibit lower levels compared to coastal locations that are subjected to more significant ocean influences and impacts by AMDEs.…”

“…Measurements performed at Toolik, with Hg diss concentrations averaging 0.17 ng L −1 and ranging between 0.08 and 1.15 ng L −1 , showed very low levels compared to many other high-latitude studies. This is generally lower than Hg concentrations in interior Arctic sites reported by Douglas and Sturm (2004) (i.e., Hg diss concen- trations between 0.5 and 1.7 ng L −1 ) and at the low end of concentrations found in Arctic studies along the coastal zone (0.14-820 ng L −1 , for both Hg diss and Hg tot ; Douglas et al, 2005;Douglas and Sturm, 2004;Ferrari et al, 2004Ferrari et al, , 2005Kirk et al, 2006;Nerentorp Mastromonaco et al, 2016;St. Louis et al, 2005;Steffen et al, 2002).…”

“…Most Arctic studies of snowpack Hg have been performed close to the coast (i.e., Alert and Barrow), and few studies include inland sites such as Toolik (Douglas and Sturm, 2004). …”

“…AMDEs have been mainly observed along the coasts, e.g., at Barrow in Alaska , Alert in Canada (Steffen et al, 2002), Ny-Ålesund in Svalbard , McMurdo in Antarctica , and directly over the sea ice Nerentorp Mastromonaco et al, 2016). The impact of AMDEs at inland sites is reduced with increasing distance from the coast (Douglas and Sturm, 2004;Obrist et al, 2017;Van Dam et al, 2013).…”

“…In the Arctic and Antarctic, Hg cycling is also affected by atmospheric Hg depletion events (AMDEs), which are observed primarily in the springtime along coastal locations (Angot et al, 2016a;Dommergue et al, 2010;Steffen et al, 2008). During AMDEs, atmospheric Hg 0 gas concentrations fluctuate strongly due to atmospheric conversion of Hg 0 gas to oxidized Hg II .…”