春、夏季长江口邻近海域COD分布特征、影响因素及对富营养化的贡献

根据2009年春季(5月)和夏季(8月)对长江口海域的调查监测资料,研究了海水中COD的时空分布特征,并对其污染水平进行了评价,同时分析了COD对海域富营养化的贡献,探讨了化学耗氧有机物的主要来源及与环境因子的关系。结果表明,长江口海域春夏季表层、春夏季底层之间COD均存在显著的差异,春季表层与底层、夏季表层与底层之间COD则无显著差异,春季表、底层COD的平均浓度、最高浓度均小于夏季,平面分布呈由近岸向远海逐渐递减的趋势;夏季研究海域COD污染高于春季;COD对富营养化的贡献范围为39.69%~63.58%,平均贡献为(46.53±4.49)%,贡献随着富营养化指数的增加而减小;陆地径流输入以及陆源排放是COD的主要来源;COD与环境因子均存在一定的相关关系;COD时空分布主要受制于长江冲淡水,对富营养化的贡献主要受营养盐影响,与海底沉积物再悬浮也有一定的联系。

Distribution characteristics of COD, its influencing factors and its contribution to the eutrophication in waters near the Changjiang River Estuary in spring and summer

Based on the data from the surveys in the Changjiang River Estuary in spring (May) and summer (August) of 2009, the distribution characteristics of COD and its influencing mechanism were studied and the level of pollution was evaluated. Meanwhile, its contribution to the eutrophication in the study area was analyzed, and the main source of COD, the relationship between environmental factors and COD and the seasonal variation of COD were discussed. The results showed that the concentration of COD was significantly different at the surface in spring and summer, as well as in the bottom in spring and summer, and there was no significant difference at the surface and in the bottom in spring, as well as at the surface and in the bottom in summer. The average concentration and the maximum concentration of COD at the surface and in the bottom in spring were lower than those in summer. The distribution was characterized by the tendency of decreasing from the alongshore to the open sea. The pollution level of COD in summer was lower than that in spring. The range of contribution to the eutrophication was from 39.69% to 63.58%, and the average was (46.53±4.49)%. The contribution decreased with the increase of eutrophication index. The runoff and emission from land-based sources were the main sources of COD. There was a certain relationship between environmental factors and COD. The spatial and temporal distributions of COD were regulated by the diluted water of Changjiang River, and the contribution of COD to the eutrophication was influenced by nutrients and sediment resuspension.