Atlantic mercury emission determined from continuous analysis of the elemental mercury sea-air concentration difference within transects between 50°N and 50°S

• Published in: Global biogeochemical cycles Vol. 25; no. 3
• Main Authors: Kuss, J., Zülicke, C., Pohl, C., Schneider, B.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01.09.2011
• Subjects: air-sea exchange; Atlantic Ocean; Atmospheric sciences; Biological oceanography; Chemical oceanography; elemental mercury; oceanic Hg source; seasonality
• ISSN: 0886-6236; 1944-9224
• DOI: 10.1029/2010GB003998

Mercury in the environment deserves serious concern because of the mobility of volatile elemental mercury (Hg0) in the atmosphere, in combination with the harmful effect of Hg compounds on human health and the ecosystem. A major source of global atmospheric mercury is presumed to be oceanic Hg0 emission. However, available Hg0 surface water data to reliably estimate the ocean's mercury emissions are sparse. In this study, high‐resolution surface water and air measurements of Hg0 were carried out between Europe and South Africa in November 2008 and between South America and Europe in April–May 2009. On each cruise a strong enrichment of Hg0 in tropical surface water was determined that apparently followed the seasonal shift of the Intertropical Convergence Zone (ITCZ). A combination of a high Hg0 production rate constant and the actual low wind speeds, which prevented emission, probably caused the accumulation of Hg0 in surface waters of the ITCZ. Hg0 emissions in the tropics were significant only if wind speed variability on a monthly scale was considered, in which case the observed significant decline of total Hg in tropical surface waters during the northern winter could be explained. In the midlatitudes, increased autumn Hg0 emissions were calculated for November in the Northern Hemisphere and for May in the Southern Hemisphere; conversely, emissions were low during both the northern and the southern spring. Mercury removal from surface waters by Hg0 emission and sinking particles was comparable to its supply through wet and dry deposition. Key Points New data describing Atlantic elemental mercury distribution Calculated Atlantic Hg(0) sea‐air fluxes based on a large data set Estimated fluxes seem in balance with supply and other removal processes