EFFECT OF ORGANOTIN COMPOUNDS ON THE GROWTH OF THE FRESH-WATER ALGA SCENEDESMUS-QUADRICAUDA

Organotin compounds (OTCs) are extensively used in a variety of indust rial processes and their increasing discharge into the environment is a topic of current concern. Many OTCs are toxic to various organisms a nd they are used to a limited but significant extent as biocidal agent s in agriculture and technology. The concentration and form in which t in (Sn) is present in the environment determines its toxicological eff ects. The present study was conducted to determine the inhibitory effe ct of 12 OTCs [A, dibutyl tin bis-N,N-diethyldithiocarbamate; B, dimet hyltin bis(N,N-diethyldithiocarbamate); C, triphenyltin chloride; D, t riphenyltin acetate; E, triphenyltin N,N-diethyldithiocarbamate; F, tr ibenzyltin bis(N,N-diethyldithiocarbamate); G, tribenzyltin chloride; H, bis (tributyltin)-3,4,5,6-tetrachlor phthalate; I, tributyltin sulf aminate; J, tributyltin N,N-diethyldithiocarbamate; K, tributyltin nap hthenate; and L, tributyltin oxide (TBTO)] in four concentrations (0.0 01, 0.01, 0.1, and 1.0 mg/liter) on the growth of freshwater alga Scen edesmus quadricauda under standardized conditions. The inhibitory effe ct of OTCs after 12 days cultivation in percentages for each concentra tion used was determined and individual growth curves of S. quadricaud a for tested concentrations of OTCs and for control were plotted. On t he basis of the percentage of control growth the rank order of inhibit ion after 12 days application of OTCs in concentration 1.0 mg/liter wa s made: L = H = F = C > E > D > J = K > I > G > A > B. From this rank order, it is evident that the least inhibitive effects on algal growth were from the diorganotin compounds A and B, especially compound B wi th a methyl group in the n-alkyl chain. The most toxic was compound L (TBTO) with a butyl group in side chain. (C) 1996 Academic Press, Inc.