钦州湾海域COD时空分布及对富营养化贡献分析

摘要

根据2010年4月(春季)和9月(秋季)钦州湾海域现场调查资料,对表层海水中化学需氧量(COD)的时空分布特征进行研究,评价其污染水平,分析COD对该海域富营养化的贡献,并探讨了COD的主要来源及与环境因子之间的关系。研究结果表明,钦州湾海域表层COD的平均浓度为(1.21±0.55) mg/L,浓度范围为0.57~2.38 mg/L,水平分布呈现由湾内向湾外逐渐递减的趋势；秋季研究海域COD污染水平高于春季；COD对富营养化的贡献范围为42.1%~64.7%,平均贡献为(50.3±6.7)%,贡献随着富营养化指数的增加而减小；COD与盐度、pH存在显著负相关,而与DIN、2SiO3-Si存在显著正相关。COD时空分布主要受陆地径流、陆源输入和水动力过程的影响, COD是影响钦州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 investigation data in the Qinzhou Bay in April (spring) and September (autumn) of 2010, the dis-tribution characteristics of chemical oxygen demand (COD) and its influencing factors were studied. The pollution level was evaluated, and its contribution to the eutrophication in the study area was analyzed. Meanwhile, the main source of COD, the relationship between COD and environmental factors were also discussed. The results showed that the average concen-tration of COD was (1.21 ± 0.55) mg/L, with a range from 0.57 mg/L to 2.38 mg/L . The distribution of COD was charac-terized by a decreasing tendency from the upper bay to the outside bay in spring and autumn. The pollution level of COD in autumn was higher than that in spring. The range of contribution to the eutrophication was from 42.1%to 64.7%, and the mean value was (50.3 ± 6.7)%. The contribution decreased with the increase of eutrophication index. During the survey pe-riod, the content of COD showed a negative correlation with salinity and pH, while a positive correlation with DIN and 23SiO -Si. The temporal and spatial distributions of COD were affected by the land runoff, terrestrial input and hydrody-namic process. COD was an important factor contributing to eutrophication, but was not the decisive factor., When the eu-trophication degree increased, the contribution of nutrient to the eutrophication became more dramatic.