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Investigation on organotin coumpounds reactivity using enriched isotopic tracers in porewaters and polluted coastal sediments from the Eastern Adriatic, Croatia

Croatian Adriatic Coast is still widely polluted with organotin compounds as a consequence of its long-term use in antifouling paints (1, 2). Even more, distribution of butyltin compounds in mussels and seawater suggested that TBT-based antifouling paints may be still in use (2). As polluted sediments represent a permanent source of organotin compounds for the whole ecosystem, it is of great importance to estimate their persistence and mobility in sediment. The proposed work allowed studying the main environmental factors affecting the persistence and degradation of Sn organometallic contaminants in sediments sampled at three polluted locations (marinas and ports) characterized with different sediment types. A complete methodology combining field incubations with the addition of species-specific isotopically enriched tracers (117TBT, 119DBT, 116TPhT) and a mathematical approach based on the deconvolution of isotopic patterns was used (3). The methodology has been applied for the study of environmental reactivity of Sn compounds in the total sediment and in isolated porewater and to investigate their transformations mechanisms under controlled conditions (anoxic condition, temperature and light control). Oxic/suboxic surface layer and anoxic bottom layer were incubated in order to assess organotin transformation processes under different biogeochemical conditions (redox potential, organic matter reactivity, bacterial community). Such experimental in situ incubations have allowed to evaluate the reactivity of these compounds in highly polluted coastal sediments and to determine the half live of each compounds. References [1] M. Furdek, M. Vahčič, T. Zuliani, N. Mikac, J. Ščančar, Organotin contamination in the coastal zone of the eastern Adriatic coast (Šibenik area), Rapp. Comm. Int. Mer Medit. 39 (2010) 252. [2] M. Furdek, M. Vahčič, J. Ščančar, R. Milačič, G. Kniewald, N. Mikac, Organotin compounds in seawater and mussels Mytilus galloprovincialis along the Croatian Adriatic coast, Mar. Pollut. Bull. 64 (2012) 189-199. [3] P. Rodriguez-Gonzalez, S. Bouchet, M. Monperrus, E. Tessier, D. Amouroux, Environ. Sci. Pollut. Res. 20 (2013) 1269-1280.

Organotin compounds; tributyl tin; isotopically enriched tracers; degradation; sediment; porewater

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