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MP7 Global Fate of POPs
(145) Observations on the role of soils in global POPs cycling.
Dalla Valle, M1, Dachs, J2, Jurado, E2, Jones, K1, 1 Lancaster University, Lancaster, UK2 IIQAB-CSIC, Barcelona, Catalunya, Spain
ABSTRACT- Surface oceans have recently been proved to be an important reservoir of persistent organic pollutants (POP), influencing their global distribution and seasonal trends. Because of the lipophilicity of POPs, soils are considered to have an even greater storage capacity. They may have an important role in the global fractionation phenomenon. A new approach to study the short and long term influence of soils in the global circulation of POPs has been developed by using global maps of temperature and organic carbon distribution and then applied to several congeners of PCB. The soil skin layer (1 mm) has been considered in order to assess the short term trends. As a result the maximum reservoir capacity of soil (MRC) seems to depend only on KOA and organic carbon fraction of the soil. Since the KOA of a chemical is temperature dependant, its daily and seasonal fluctuations can determine variations of the MRC of several orders of magnitude. The highest values of MRC are observed where low temperatures and high OC content in soil are found, like in Siberia, Canada and Scandinavia. Higher values are associated to the heavier congeners of PCBs. In general the MRC of soil is at least two orders of magnitude higher than the ocean one and its daily and seasonal variations are far greater. The influence of soil is expected to be greater where the daily and seasonal thermal excursion are higher.
Key words: POPs , global cycling, soil
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