长江河口近岸水体自然净化作用及其初步评价

按照水体的净化机理，结合长江口和上海滨岸带近岸水体的物理、化学和生物等因素的实际特征，对近岸水体的自然净化作用进行了阐述和分析。并在历史资料和实测资料基础上，就近岸水体的自然净化作用进行了评价。评价结果表明，因长江河口近岸水体存在较强的自然净化作用机制，近岸水体体的自然净化能力较强，环境容量较大，但由于污染物输入量的不断增加，部分岸段近岸水体的环境质量有逐渐下降的趋势；近岸水体的自然净化作用具有明显的季节性变化，长江口南岸水域洪水季节水体的自然净化作用比估水季节强，而杭州湾北岸水域的自然净化作用表现为相反的变化趋势，因此建议在近岸污水排放过程中应考虑近岸水体的净化能力，遵循水体的自然净化作用规律。

PRIMARY ASSESSMENT OF THE SELF-PURIFICATION IN COSATAL WATERS ALONG CHANGJIANG ESTUARY

Based on the mechanisms of water self purification, together with characteristics of its physical, chemical and biological factors, the self purification of coastal waters along Changjiang Estuary and Shanghai coast lines has been analyzed in this study. Meanwhile, according to historic and measured data, the assessment of self purification of coastal waters has showed that they have better self purification,although aquatic environmental quality in some parts of coast lines gets worse with the increasing of pollutants input ,and that there is obvious seasonal variation on self purification of waters. This phenomenon indicates that the self purification of waters along the south bank of Changjiang Estuary is better in the flood season than in the dry season,while there exists some inverse trend of seasonal variations in north bank of Hangzhou Bay. Therefore, it has been proposed that self purification of coastal waters should be taken into account during sewage discharging.