オオミジンコによる河川水中の化学物質の有害性モニタリング Monitoring the Biological Effects of Chemicals in River Water using Daphnia magna
A biomonitoring test was used to assess whether rivers and streams maintained sufficient water quality to support aquatic life. <i>Daphnia magna</i> were exposed to the water samples collected from 17 sites of 13 rivers and streams in Tokyo and its suburbs and the acute response of <i>D. magna</i> was monitored.<br>The mobility of the organism was acutely inhibited in the water of six rivers and streams tested. Discharge to these sites was from paddy field, and was a significant proportion of the total flow of the streams and rivers. Gas chromatography-mass spectroscopy of the samples revealed the presence of some pesticides in the water samples. Determination of the toxicity of organophosphate insecticides such as fenitrothion and diazinon to <i>D. magna</i> showed 50% inhibition concentration of mobility at 48-hr exposure (48 h-EC<sub>50</sub>) of 0.10 to 1.0 μg/<i>l</i>. The concentrations of these insecticides in the water samples correlated well with the toxicity measurements of each sample. These insecticide concentrations accounted for most of the toxicity.<br>This biomonitoring test using <i>D. magna</i> was highly sensitive and simple. The significance of detecting these insecticides at acutely toxic concentrations to <i>D. magna</i> in some waters of the streams and rivers indicates that they have an adverse effect on some aquatic lives such as crustacean and benthic insects.
日本水産学会誌 63(4), 627-633, 1997-07-15