Abstract
Method for eliminating lethal action substances in river sediments was investigated as a part of the study to establish a routine method for monitoring mutagenicity of river sediments. Mutagenicity test was carried out by the pre-incubation method using Salmonella typhimurium TA 98 and TA 100 with and without S9 mix. River sediments were collected at each estuary of four rivers, the Tama river, the Tsurumi river, the Sagami river and the Sakawa river, in Kanagawa prefecture.
All crude extracts from the sediments showed the lethal action on the tester strains. The lethal action was stronger in the extracts from heavily polluted rivers than slightly polluted rivers. Mutagenicity was only observed in the extract from the Sagami river, a slightly polluted river, suggesting the elimination of the lethal action substances is essential for the mutagenicity assay of river sediments.
Treatment of the crude extracts with the activated copper column was effective in reducing the lethal action. However, it was not enough for the complete elimination of the lethal action substances.
Most of the lethal action substances were in the neutral fraction of the crude extract. Then, the neutral fraction was separated by a high performance liquid chromatography (HPLC), and each separated fraction was served for mutagenicity test and survivor test. HPLC was effective for the separation of the lethal action substances and mutagenic substances in the neutral fraction. These results suggest strongly that HPLC is useful for the preparation of test samples for mutagenicity assay of river sediments.
