福建南日群岛秋季海洋生态环境诊断与评价

Marine environment of Nanri Archipelago,Fujian Province in summer: Diagnosis and assessment

根据2007年9月和10月福建南日岛生态调查资料,从海水水质、海水营养结构与营养水平、生物多样性等3个方面诊断与评价了南日群岛海域环境现状,利用综合质量指数法对海洋生态环境质量进行综合评价,并探讨了不同评价指数的关系及合理性.结果表明:海域的pH、溶解氧(DO)、化学需氧量(COD)、Pb、Cd、Hg、As含量均符合第二类海水水质标准.71%站位的磷酸盐、14%站位的无机氮和7%站位的石油类污染物超第二类海水水质标准.海水水质总体属于较好等级,营养结构表现为氮限制,大部分海域处于富营养化状态,依据浮游生物的多样性指数评价结果为"轻污染-清洁"水平.生态环境综合质量指数评价结果表明南日群岛海域生态环境总体处于良好水平.利用不同的评价指数对海域环境健康状况进行诊断的结果存在一定差异.在实际评价中应综合运用化学指标和生物指标,才能得到相对客观的结论.

Based on the ecological investigation data in September and October 2007,the status of the marine ecological environment of Nanri Archipelago,Fujian Province in summer was diagnosed and assessed from the aspects of sea water quality,nutrient structure and levels,and biodiversity.The comprehensive quality index method was used for the assessment of the marine ecological environment,and the rationality of the assessment obtained from different indices was also discussed.The sea water pH,dissolved oxygen（DO）,chemical oxygen demand（COD）,and Pb,Cd,Hg,and As concentrations were all within the limit values of the GradeⅡstandard of Sea Water Quality Standard（GB 3097-1997）,while the phosphate concentration at 71% stations,inorganic nitrogen at 14% stations,and oil concentration at 7% stations were all above the GradeⅡstandard of Sea Water Quality Standard.Overall,the seawater quality was of better grade,nutrient structure was characterized by N-limited,most of the sea water was at a state of eutrophication,and the diversity index of plankton was at mildly polluted or unpolluted level.The comprehensive quality index indicated that the seawater quality of the Nanri Archipelago was relatively fine.There existed definite differences in the assessment results by using different diagnosis methods,and hence,a relatively objective assessment about marine environmental quality and health status could only be made when the chemical and biological indicators were comprehensively used.