engleski

Butyltin and total tin contamination in sediments from the eastern Adriatic coast (Croatia)

Butyltins (BuTs) have been introduced into the marine environment by the use of tributyltin (TBT) as biocide in antifouling paints since 1960s. However, after it was established that TBT has various toxic effects on the non target organisms, like the appearance of imposex in gastropods at very low levels (1-2 ng L-1), the use of TBT-based antifouling paints has been banned in many countries worldwide, including all of Europe, while in Croatia they are banned since 2006. However, the ban cannot solve the problem immediately, since contaminated sediments represent a long term source of TBT pollution to the marine environment. Due to resuspension of contaminated surface sediments, TBT desorption beck into the water column occurs. This paper provides a comprehensive study of the persistence of BuTs in contaminated marine sediments and presents the data on their degradation potentials in porewaters, both in oxic and anoxic conditions. The BuTs transformation processes were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Furthermore, organic carbon content was determined to elucidate its influence on the degradation processes. The study suggests that a limiting step in BuTs degradation in marine sediments is their desorption into porewaters, where their degradation occurs rather fast with half-lives of 2.9 to 9.2 days, while the degradation in oxic condition is faster than in anoxic. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter In addition to BuTs distribution in sediments, the concentrations of total tin were also determined in order to test a hypothesis that anthrophogenic inorganic tin present in marine sediments originates primarily from TBT and its application in antifouling paints. Strong and statistically significant correlations between BuTs and total Sn confirmed this assumption.

tributytin (TBT) ; pollution ; sediments ; degradation kinetic ; total tin

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