Toxic Properties of Metals and Organotin Compounds and Their Interactions on Daphnia magna and Vibrio fischeri

In the present study toxicity tests were performed in order to determine the toxic properties of four organotin compounds and three heavy metals and to examine the interactive effects of binary metal mixtures on two different test species: the freshwater crustacean Daphnia magna and the marine bacterium Vibrio fischeri. D. magna proved to be more sensitive to metals than V. fischeri. Tributyltin chloride and copper were found to be the most toxic substances on both test organisms. The interactive effects between trimethyltin chloride/copper and trimethyltin/chromium on both test species were investigated and synergistic, additive and antagonistic actions were observed.     

Correlation of the methylating capacity of river and marine sediments to their organic sediment index

Methylation experiments of the metals Sn, Pb and Hg were carried out using representative terrestrial and marine sediment samples from the Axios river and Thermaikos Gulf in northern Greece. GC-FID, GC-TCD and GC-MS were used. The experiments were carried out on sterilised and bioactive samples by adding pure metals and metal salts (chloride, nitrate, oxalate, acetic, penicillaminic, methioninic and cysteinic). Except for sterilised HgCl2, methylated derivatives of Sn, Pb and Hg were produced only from bioactive sediments, and therefore higher yields were measured when nutrients were added to the sediments. Volatile products (CH4, CO2, H2S) of biological activity range between 35 and 250 mg l-. The correlation of methylation yield with organic sediment index (OSI), determined as the wt% product of [organic carbon] × [organic nitrogen], is positive for all the metals and metal salts added in the sediments. Methylation yields for Hg are found to be four orders of magnitude higher than those of Pb and Sn. In low OSI (terrestrial) sediments, the rate of Hg-methylation is higher than those of Pb and Sn. In high OSI (marine) sediments, where methylation of most of the contained Hg has taken place, methylation of Pb is slightly faster than Sn.