Abstract :
The inhibitory and toxic effects of five tributyltin compounds and one dibutyltin compound were determined under standardized conditions on the freshwater plankton algaScenedesmus quadricaudaand the benthic organismsTubifex tubifexandChironomus plumosus. Observed were the mortality of benthos after 96 h and the inhibition of growth, photosynthesis, and chlorophyllacontent of the alga after 12 days of cultivation. The effects of the compounds were expressed as LC50values for mortality and EC50values for inhibition. Attention was focused on the influence of the bound X anion on the toxicological effects of the test compounds [dibutyltin bis(N,N-diethyldithiocarbamate (DBTC); bis(tributyltin 3,4,5,6-tetrachlorophthalate (TBTP); tributyltin sulfaminate (TBTS); tributyltinN,N-diethyldithiocarbamate (TBTC); tributyltin naphthenate (TBTN); bis(tributyltin) oxide) (TBTO)]. From the results obtained the following conclusions can be made: For benthic organisms the anionic groupN,N-diethyldithiocarbamate as well as the anionic inorganic group oxide had a very large toxic effect. The lowest efficiency was indicated for the 3,4,5,6-tetrachlorophthalate anion. When the positions of the tested compounds with respect to dependence of the bound anion were evaluated for the alga, it was concluded that the position of the anionic group in inhibitory rank orders depended on the parameter. The efficiency of the organic anionN,N-diethyldithiocarbamate was low in all divisions tested (especially for photosynthesis inhibition). Strong effects for all parameters tested were noted for the compound with organic anion 3,4,5,6-tetrachlorophthalate as well as the compound with the inorganic anion oxide, except for photosynthesis inhibition. From the results obtained the following rank orders of toxicity and/or inhibition are established:T. tubifex—TBTO>TBTC>TBTN>DBTC>TBTS>TBTP;Ch. plumosus—TBTS≥TBTC>TBTO>TBTN>DBTC>TBTP;S. quadricauda, growth inhibition—TBTO>TBTP>TBTN>TBTC>DBTC=TBTS;S. quadricauda, chlorophyllacontent—TBTO≥DBTC>TBTP=TBTC>TBTN=TBTS;S. quadricauda, photosynthesis inhibition—TBTP>TBTS≥TBTN>DBTC>TBTO>TBTC.
