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Multi‐decadal decline of mercury in the North Atlantic atmosphere explained by changing subsurface seawater concentrations
Author(s) -
Soerensen Anne L.,
Jacob Daniel J.,
Streets David G.,
Witt Melanie L. I.,
Ebinghaus Ralf,
Mason Robert P.,
Andersson Maria,
Sunderland Elsie M.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053736
Subject(s) - seawater , mercury (programming language) , atmosphere (unit) , oceanography , environmental science , surface water , atmospheric sciences , geology , meteorology , geography , environmental engineering , computer science , programming language
We analyze 1977–2010 trends in atmospheric mercury (Hg) from 21 ship cruises over the North Atlantic (NA) and 15 over the South Atlantic (SA). We find a steep 1990–2009 decline of −0.046 ± 0.010 ng m −3 a −1 (−2.5% a −1 ) over the NA (steeper than at Northern Hemispheric land sites) but no significant decline over the SA. Surface water Hg 0 measurements in the NA show a decline of −5.7% a −1 since 1999, and limited subsurface ocean data show an ∼80% decline from 1980 to present. We use a coupled global atmosphere‐ocean model to show that the decline in NA atmospheric concentrations can be explained by decreasing oceanic evasion from the NA driven by declining subsurface water Hg concentrations. We speculate that this large historical decline of Hg in the NA Ocean could have been caused by decreasing Hg inputs from rivers and wastewater and by changes in the oxidant chemistry of the atmospheric marine boundary layer.