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(15-11) Oceanic controls on global dynamics of persistent organic pollutants. Dachs, Jordi*,1, Lohmann, Rainer2, Ockenden, Wendy3, Méjanelle, Laurence4, Eisenreich, Steven5, Jones, Kevin3, 1 Dept. Environmental Chemistry, IIQAB-CSIC, Barcelona, Spain2 Department of Civil and Environmental Engineering, Cambridge, MA, USA3 Dept. of Environmental Sciences, Lancaster, UK4 Laboratory of Biogeochemistry and Marine Chemistry, Paris, France5 Dept. of Environmental Sciences, New Brunswick, NJ, USA ABSTRACT- The understanding and quantification of the global dynamics and sinks of persistent organic pollutants (POPs) are important in order to assess their environmental impact and fate. So far, global dynamics of POPs has been thought to be driven by air-surface exchange processes where temperature would play a central role controlling volatilization and deposition processes at the global scale. The present study is an assessment of the role of biogeochemical processes such as phytoplankton uptake and oceanic vertical fluxes of particles on the global dynamics of POPs. This study is based on field measurements of polychlorinated biphenyls (PCBs), polychlorinated dibenzo furans (PCDFs) and dioxins (PCDDs), remote sensing estimation of oceanic temperature, wind speed and chlorophyll and modeling of the interactions between air-water exchange, phytoplankton uptake and export of organic matter and POPs out of the mixed layer. It is shown that the biological pump, and thus the sinking of marine particulate matter plays a major role enhancing deposition at mid-high latitudes and thus driving the global distribution of POPs. However, the relative importance of the biological pump depends on the POP physical-chemical properties and the primary productivity in surface waters. Furthermore, the atmospheric occurrence of hydrophobic POPs (log Kow > 6) is driven by enhanced air-water exchange due to phytoplankton uptake and subsequent sinking of particles. It is concluded that the oceans play a critical role controlling the global dynamics and the final sink of POPs. Key words: persistent organic pollutants, global dynamics, sinking fluxes, atmospheric deposition |
