A decline in Arctic Ocean mercury suggested by differences in decadal trends of atmospheric mercury between the Arctic and northern midlatitudes

• Published in: Geophysical Research Letters
• Main Authors: Chen, Long, Zhang, Yanxu, Jacob, Daniel J., Soerensen, Anne L., Fisher, Jenny A., Horowitz, Hannah M., Corbitt, Elizabeth S., Wang, Xuejun
• Other Authors: Chen, L (reprint author), Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 USA., Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 USA., Peking Univ, Coll Urban & Environm Sci, Minist Educ, Lab Earth Surface Proc, Beijing 100871, Peoples R China., Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA., Stockholm Univ, Dept Environm Sci & Analyt Chem, S-10691 Stockholm, Sweden., Harvard Univ, TH Chan Sch Publ Hlth, Dept Environm Hlth, Boston, MA USA., Univ Wollongong, Sch Chem, Wollongong, NSW, Australia.
• Format: Journal/Newspaper
• Language: English
• Published: GEOPHYSICAL RESEARCH LETTERS 2015
• Subjects: mercury; Arctic; trend; climatological variables; AIR-SEA EXCHANGE; METHYLATED MERCURY; GASEOUS MERCURY; SURFACE WATERS; 10-YEAR TRENDS; TEMPERATURE; DEPOSITION; ATLANTIC; MODEL; ICE; Arctic Ocean; North Atlantic; Sea ice
• Online Access: https://hdl.handle.net/20.500.11897/418071; https://doi.org/10.1002/2015GL064051

Atmospheric mercury (Hg) in the Arctic shows much weaker or insignificant annual declines relative to northern midlatitudes over the past decade (2000-2009) but with strong seasonality in trends. We use a global ocean-atmosphere model of Hg (GEOS-Chem) to simulate these observed trends and determine the driving environmental variables. The atmospheric decline at northern midlatitudes can largely be explained by decreasing North Atlantic oceanic evasion. The midlatitude atmospheric signal propagates to the Arctic but is countered by rapid Arctic warming and declining sea ice, which suppresses deposition and promotes oceanic evasion over the Arctic Ocean. The resulting simulation implies a decline of Hg in the Arctic surface ocean that we estimate to be -0.67%yr(-1) over the study period. Rapid Arctic warming and declining sea ice are projected for future decades and would drive a sustained decline in Arctic Ocean Hg, potentially alleviating the methylmercury exposure risk for northern populations. U.S. National Science Foundation; China Scholarship Council [201306010173]; National Natural Science Foundation of China [41130535] SCI(E) EI ARTICLE [e-mail]; [e-mail] 14 6076-6083 42