|Abstract Title:||Pan-Arctic Mapping of Mercury in Arctic Ocean Sediments|
|Presenter Name:||Alyssa Azaroff|
|Session:||Special Session - Climate-Driven Perturbations of Arctic Mercury Cycling|
|Co-Authors:||Alyssa Azaroff,Jannik Martens,Amanda Poste,Lars-Eric Heimbuerger-Boavida,Henning Jensen,Stephen Kohler,Anna Pie?kowski,rjan Gustafsson,Sofi Jonsson|
Abstract Information :
Marine sediments play a key role in the global cycling of mercury (Hg) by acting as an ultimate sink for this toxic trace element. The distribution and burial rates of Hg in marine sediments are, however, poorly characterized. This is especially true for the Arctic Ocean, which in comparison to other marine systems, receives a large fraction of the Hg from the terrestrial compartment (e.i. river discharge, permafrost, coastal erosion, ice complex deposit). Here, we present the first pan-Arctic map of Hg in Arctic Ocean surface sediments (0-5 cm). We have compiled data on total mercury (THg) concentrations from 677 stations in the Arctic Ocean covering all major basins. Based on the affinity of Hg for organic carbon (OC), and basin-specific relationships between THg and OC from this study, we have interpolated THg concentrations using the OC-CASCADE database (4250 stations, Martens et al. 2021) and Empirical Bayesian Kriging. In line with previous studies, we have estimated an average THg concentration of 50 ñ 23 ng g-1 d.w. in surface sediment. THg was higher in the Central Arctic Basin, East Siberian Sea, Laptev Sea, and the Beaufort Sea than the other shelf seas. Based on the dry bulk density and sediment flux, THg stock and flux were estimated from this new THg map. While the THg stock is in the same order as previously estimated, the THg flux is higher than previously thought, thus suggesting that burial rates of Hg in Arctic Ocean sediments may previously have been underestimated.