MX as an Index of Tocicity of Drinking Water in Distribution Systems

测定饮用水中的所有物质是不可能的。作为综合水质指标的生物检测结果有望用于水质管理。消毒副产物作为饮用水水质指标时，应在水处理工艺和配水中适当选择。在给水系统中，MX被认为是一个合适的指示剂。在本研究中，发现MX在水中不稳定，这是由于MX在水中的水解和氯化分解。此外，还发现MX在水相中的衰减速率强烈地依赖于pH。在碱性条件下，MX的衰减速度要快得多。此外，当存在较高的氯存在时，MX衰减得更快。MX诱发染色体畸变和转化的活性也表现出类似的趋势。琵琶湖非两阶段法测得的诱发染色体畸变率和诱发转化率在加氯后迅速增加，然后开始逐渐下降。MX在定性和定量上都能较好地反映氯化水在管网中的毒性。然而，有必要将剩余氯考虑在内。

It is impossible to determine and measure all substances in drinking water. The bioassay results used as comprehensive water quality indicators are expected to be utilized for water quality management. When disinfection by-products are used as indicators of drinking water quality, they should be chosen properly in water treatment process and water distribution. In the water distribution systems, MX was supposed to be a suitable indicator. In this study, MX was found to be unstable in water due to the hydrolysis and the decomposition by chlorination. Also, it was found that the decay rate of MX in aqueous phase strongly depends on pH. The decay rate of MX is much faster in alkali region. Furthermore, MX decayed faster when higher chlorine was present. The activities inducing chromosomal aberrations and transformations of MX showed similar tendency. The activity inducing chromosomal aberrations and the activity inducing transformations measured by non-two-stage assay in Lake Biwa increased rapidly after the addition of chlorine, and then began to decrease gradually. MX seemed to be an appropriate indicator qualitatively and quantitatively for the toxicity of chlorinated water in distribution system. However, it was necessary to take the residual chlorine into consideration.