ORGANOTIN COMPOUNDS AND THEIR ADSORPTION BEHAVIOR ON SEDIMENTS

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This paper present a brief overview of the occurrence and degradation of organotin compounds in water and sediments, and their sorption behavior on natural sediment particles and pure clay minerals.Organotins change in their form from cation to hydroxides in accordance with an increase of pH values, and they would exist as simple neutral hydroxides in aqueous solution under natural environment pH.The concentrations of organotins in water and sediments vary in a wide range according to the degree of contamination of aquatic environment.The concentration of triorganotins in aquatic sediments are generally orders of magnitude higher than the aqueous concentrations.Hence, sorption is a key process determining the transport and fate of triorganotins in aquatic environment.Published sorption coefficients (K) for aqueous tributyltin (TBT) in sediment or particulate matter range from 3.4×10^2 to 1.9×10^6(Lkg^<-1>), but the majority of reported K values have benn in the order of 10^3.It was suggested that the K value increases with increasing the amount of fine particles and expandable minerals in sediment.The effects of salinity on the K value were different depending on the sorbent-to-solution mass ratios used in an experiment.The K values for homo-ionic clay minerals were affected by the type of exchangeable cations and pH.An example of the biological degradation of Bu_3Sn^+ in water and sediment was also presented.
日本粘土学会の論文