Sediment genotoxicity and its relationship to the frequency of chironomid labial plate deformities

Sediment samples were taken from seven locations in the WeIland River in December 1986 and April 1987. The DMSO extracts of these sediment samples showed a significant (ptoxic effect for one location situated dir ectly below a polyvinyl chloride plant's discharge pipe (station D-l) . It was concluded that genotoxic contaminants were associated with the sediments from this l ocation. Analysis of sediment samples from the nearby station D-2 resulted in a significant (p <0 . 05) positive genotoxic response in December but not in April. Chironomids (midge larvae) taken from each of seven study locations were analyzed for the frequency of chironomid labial plate deformities (over 1000 individual specimens were observed) . The samples from station D-l showed the highest frequency of chironomid labial plate deformities (10 . 9% ± 3.2%), while samples from the upstream control (station A) displayed t,he lowest frequency of deformities (3.8% ± 1.3%). All samples were coded to avoid unconscious biases . The results of the genotoxicity study indicated that station D-l in the WeIland River was contaminated with genotoxic materials. The genotoxic materials may have induced the observed increased frequency in chironomid labial plate deformities . Samples from stations C and D-l, located in a downstream portion of the river bounded by an industrialized area were slightly toxic according to -the alkaline phosphatase inhib_ii~ion component of the 50S chromotest analyses. The toxicity of these samples was only evident once they had been activated by the 59 (liver extract) mixture.

ARCR 011

Dark brown sediment with clasts ranging from small to large in size. Clast shape ranges from angular to sub-rounded. Rotation structures are common throughout the sample. They can mainly be seen surrounding clasts of all sizes. Lineations and comet structures are also abundant. Minor amounts of grain stacking/crushing can also be seen.