乐清湾海域COD分布特征及对富营养化贡献分析

Temporal and Spatial Distributions of COD and Its Contribution to Eutrophication in Yueqing Bay

根据2013-2014年度四个航次乐清湾海域调查资料,对海水中COD的时空分布特征进行研究,评价其污染水平,分析对该海域富营养化的贡献。研究表明,乐清湾海域COD浓度范围为0.39~6.05 mg/L,平均浓度为1.68 mg/L,呈现西高东低的分布特征;研究海域COD污染水平夏季>秋季>冬季>春季。COD对富营养化的贡献范围为41.29%~59.50%,平均贡献率为47.85%。COD是影响乐清湾海域富营养化的重要因素,但并非决定性因子,富营养化程度加重时来自营养盐的贡献表现更为突出。

Based on the field data of the Yueqing Bay from 2013 to 2014, the distribution characteristics of chemicaloxygen demand （COD） were studied. The pollution level was evaluated, and its contribution to the eutrophication in thestudy area was analyzed. The results showed that the average concentration of COD was 1.68 mg/L, with a range from0. 39 mg/L to 6. 05 mg/L. The distribution of COD was characterized by a decreasing tendency from the west to the east.The pollution level of COD was summer〉autumn〉winter〉spring. The range of contribution to the eutrophication was from42.29% to 59.50% , and the mean value was 47.85%. The contribution decreased with the increase of eutrophicationindex. The temporal and spatial distributions of COD were affected by the land runoff, terrestrial input and hydrodynamicprocess. COD was an important factor contributing to eutrophication, but was not the decisive factor. When theeutrophication degree increased, the contribution of nutrient to the eutrophication became more dramatic.