A survey was conducted of water and sediment from across Canada in 1993-94 to assess the effectiveness of the 1989 regulation of antifouling uses of tributyltin (TBT) under the Canadian Pest Control Products Act. The survey was also designed to assess concentrations of 13 other organotin species in water and sediment, and in sewage treatment plant influents, effluents and sludges. The main conclusion is that the 1989 regulation has only been partially effective. It has had some effect in the reduction of TBT concentrations in fresh water, but not in sea water. It has had less effect in the reduction of TBT concentrations in sediment, probably because of the longer persistence of TBT in sediment than in water. In many locations the TBT concentration was high enough to cause acute and chronic toxicity to aquatic and benthic organisms. In some areas there may be potential for recycling TBT from contaminated sediments back into the water column. In addition, it appears that large harbours that handle ships legally painted with TBT-containing antifouling paints continued to experience ecotoxicologically significant TBT contamination. Other organotin species found appear to pose no acute or chronic hazards to fresh water or marine organisms, but nothing is known of their hazards to benthic organisms. The presence of monooctyltin and dioctyltin in sediments and sewage treatment plant influents, effluents and sludges is reported for the first time, and tripropyltin is quantified in sediments for the first time.

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Conversion of inorganic and organic selenium compounds to volatile selenium compounds (dimethyl selenide, dimethyl disetenide, and an unknown compound) by microorganisms in lake sediment has been observed. This conversion could also be effected by pure cultures of bacteria and fungi. Such transformations are significant in the transportation and cycling of elements in the environment.

The effects of a number of inorganic and organic tin compounds on pure cultures of green and blue-green algae and natural phytoplankton in lake water were tested. Organic tin compounds were generally more inhibitory to primary production and reproduction of the algae than inorganic tin compounds. The toxicity of organotin compounds varied considerably with the number and nature of the organic groups attached to tin, with trialkyl tin compounds being the most toxic forms. Within a given alkyl tin compound series, the longer the carbon chain, the higher the toxicity. A direct relationship between toxicity and partition coefficients of trialkyl tin compounds was observed. Other tin compounds had no such direct relationship.Key words: algae, tin, toxicity, partition coefficients

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A sensitive and accurate method is described for the measurement of the apparent complexing capacity of lake waters. It is based on the measurement of labile copper by differential pulse anodic stripping voltammetry after a number of ionic copper spikes have been allowed to equilibrate with the complexing materials in a water sample. Coefficients of variation for the determination of EDTA at a level of 0.50 μmole/liter in Hamilton Harbor water were 6 and 8%. Analysis of seven replicates of a Hamilton Harbor water sample gave an apparent complexing capacity of 0.52 μmole/liter Cu equivalent with a relative standard deviation of 7.7%. Analyses of a number of samples from Lake Erie and from lakes near Sudbury, Ontario gave a range from nondetectable to 0.70 μmole/liter Cu equivalent of complexing capacity.

The relationship between bioaccumulation and toxicity of tributyltin in Hyalella azteca was determined for future use in identifying freshwater sites of TBT induced toxicity in the field. Hyalella accumulated waterborne TBT rapidly, reaching equilibrium within 1 week. Short exposure times are, therefore, sufficient to measure TBT availability in laboratory or field exposures. Accumulation was not affected significantly by body size for animals between 0.1 and 0.6 mg dry weight, eliminating the need for a body size correction factor. Young amphipods were more sensitive to TBT than adults when both were exposed for 1 week. The 4-wk LC50 initiated with 0-1-week-old young was 4.8 nM. TBT accumulation was approximately proportional to TBT in water, and the 4-week LC50 expressed on a body concentration basis was 110 nmole/g dry weight. Accumulation of TBT by adult Hyalella to concentrations of about 100 nmole/g or more during short term (1-wk) exposures to environmental samples would suggest chronic TBT-induced toxicity is present at those sites.

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