Air‐sea exchange in the global mercury cycle

Abstract

[1] We present results from a new global atmospheric mercury model coupled with a mixed layer slab ocean. The ocean model describes the interactions of the mixed layer with the atmosphere and deep ocean, as well as conversion between elemental, divalent, and nonreactive mercury species. Our global mean aqueous concentrations of 0.07 pM elemental, 0.80 pM reactive, and 1.51 pM total mercury agree with observations. The ocean provides a 14.1 Mmol yr À1 source of mercury to the atmosphere, at the upper end of previous estimates. Re-emission of previously deposited mercury constitutes 89% of this flux. Ocean emissions are largest in the tropics and downwind of industrial regions. Midlatitude ocean emissions display a large seasonal cycle induced by biological productivity. Oceans contribute 54% (36%) of surface atmospheric mercury in the Southern (Northern) Hemisphere. We find a large net loss of mercury to the deep ocean (8.7 Mmol yr À1 ), implying a $0.7%/year increase in deep ocean concentrations.

Effect of climate change on air quality

“…Increased volatilization of mercury from ocean and land reservoirs as a result of climate change would transfer mercury between ecosystems via atmospheric transport, re-depositing it in a more mobile and presumably more toxic form. Volatilization of mercury from the ocean is directly affected by warming (lower solubility of elemental mercury) and would also be affected by changes in ocean biology and circulation (Strode et al, 2007;Sunderland and Mason, 2007). Increased volatilization of soil mercury could potentially be of considerable importance, as the amount of mercury stocked in soil (1.2 Â 10 6 Mg) dwarfs that in the atmosphere (6 Â 10 3 Mg) and in the ocean (4 Â 10 4 Mg) (Selin et al, 2008).…”

Elemental mercury (Hg(0)) in air and surface waters of the Yellow Sea during late spring and late fall 2012: Concentration, spatial-temporal distribution and air/sea flux

“…These observations also highlight that an assumed constant DGM concentrations in the modeling study may lead to substantial uncertainties of air/sea Hg(0) flux since the measurements presented the high temporal and spatial variation of DGM in surface waters. More reliable parameterization to describe the aquatic DGM production and consumption will significantly improve the modeling result (Strode et al, 2007;Soerensen et al, 2013).…”

“…In seawater Hg can reduce to Hg(0) via photochemistry and microbial activities (Amyot et al, 1997;Rolfhus and Fitzgerald, 2004;Fantozzi et al, 2009;Qureshi et al, 2010;Whalin et al, 2007;Monperrus et al, 2007) from sea surface to atmosphere (Fitzgerald et al, 1984;Kuss and Schneider, 2007;Fu et al, 2010;Andersson et al, 2011;Ci et al, 2011a;Qureshi et al, 2012). Modeling studies showed that more than 80% of Hg deposited to oceans is reemitted to atmosphere as Hg(0) (e.g., Strode et al, 2007).…”

“…Oceanic Hg cycle is one of the most important fractions of global Hg biogeochemical cycle (Fitzgerald et al, 2007;Strode et al, 2007;Soerensen et al, 2010b;Mason et al, 2012). Globally, atmospheric deposition is the dominant Hg input to the ocean (Mason and Sheu, 2002;Selin, 2009).…”

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

“…gaseous elemental Hg and monomethyl Hg) or to operationally defined species based on laboratory analytical measurements such as total Hg (THg) and reactive Hg (Hg R ). [1][2][3] Table 1 summarises the abbreviations we use in this paper and their descriptions. This paper discusses the results from research conducted throughout the Arctic.…”