Hg0 trends in the North and South Atlantic Marine Boundary Layer

Abstract

It was recently found that atmospheric Hg had decreased with 20-38% worldwide since the mid 1990s. However, the decrease is not supported by emission inventories that show rising global anthropogenic emissions over the past decades. We analyzed atmospheric data from 22 ship cruises in the North Atlantic (defined as 2°N-65°N), and 15 in the South Atlantic (defined as 70°S-8°N) between 1977 and 2010, as well as surface water Hg0 from 10 cruises in the West Atlantic Ocean between 1998 and 2010. Linear regression analysis based on these cruise ensembles for each hemisphere will be discussed. We use the GEOS-Chem biogeochemical model to explore possible drivers of the Hg0 trends found in this study and at previous studies at land based stations. These findings will also be discussed.