増殖阻害試験に用いる供試藻類の栄養条件がモノクロラミンの毒性評価に及ぼす影響

Abstract

The toxicity of monochloramine (NH2Cl), which is the main by-product of sewage effluent chlorination, was evaluated from growth inhibition in different condition of nutrients by a green alga Selenastrum capricornutum. The effect of NH2C1 on algal growth was depended on the nutrients condition, and nutrients limited algal cells were more sensitive than the non-limited cells. When using the nutrient-limited algal cells for the test organisms, lowest-observed-effect concentration (LOEC) and 50% effective concentration (EC50) after 96 hours exposed period were 0.001 and 0.002 mg-Cl2·l-1, respectively.The obtained LOEC and EC50 were lower than the water quality criteria for residual oxidants and the detection limit of oxidant determination. It is clear that chemical analysis is insufficient to monitor the various effluents. From these results, an algal growth test using the nutrient-limited algal cells is very sensitive and useful for the toxicity evaluation of disinfected effluents.