PARENT SESSION

1L (2) - Exposure Modelling
Hall 13
8:30 AM - 10:15 AM, Thursday, 1 May 2003
Chair: Lammel, G.¹, ¹
Co-chair: Dachs, J.², ²

(TH13/2) Spatial and seasonal variability of biogeochemical processes affecting the oceanic occurrence and sink of persistent organic pollutants.

Dachs, Jordi¹, Del Vento, Sabino¹, Jurado, Elena¹, Lohmann, Rainer², Méjanelle, Laurence ³, Eisenreich, Steven⁴, Jones, Kevin², ¹ Dept. Environmental Chemistry, IIQAB-CSIC, Barcelona, Catalunya, Spain² Environmental Science Dept., Lancaster University, Lancaster, Lancaster, Spain³ University of Paris VI, Paris, Paris, France⁴ Institute for Environment and Sustainability, JRC, Ispra, Ispra, Italy

ABSTRACT- The understanding and quantification of the global dynamics, oceanic occurrence 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 as described by the global distillation theory. 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 measues of environmental biogeophysical variables and modeling of the transport of POPs from the atmosphere to the deep ocean. 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 primary productivity in surface waters. Settling fluxes, in addition are an effective removal process of POPs from surface waters lowering their concentrations. The effectiveness of the biological pump on controlling the exposure of organisms to POPs also shows an important seasonality.

Key words: biological pump, POPs, global dynamics, air-water exchange