根据2004年4个季度的调查数据,以化学需氧量(COD)、溶解无机氮(DIN)、磷酸盐(PO4-P)、叶绿素a(Chl-a)和溶解氧(DO)作为评价指标,运用模糊综合评价模型对长江口海域海水富营养化水平进行评价。结果表明,约有一半的调查站点呈现富营养化,长江口门及冲淡水区(122.5°E以西)富营养化程度较高,外海(122.5°E以东)富营养化程度较低,富营养程度从外海向近岸增加。富营养化区域全年大部分都分布于盐度小于20的一侧,呈明显的季节分布和区域分布,表明长江口海域的富营养化水平主要受到长江冲淡水的控制。
Based on seasonal data for 2004, COD, DIN, phosphate,Chl-a, and DO were chosen to be the assessment parameters, and fuzzy synthesis evaluation is applied to assessing the eutrophication levels in the Changjiang estuary. The result showed that about half the sampling sites are at the stage of eutrophication.The outlets and the dilution zone of the Changjiang river(on the west of 122.5°E) are characterized as eutrophication. The off-sea of the Changjiang estuary(on the east of 122.5°E) is at the oligotrophic stage. The eutrophication levels are gradually increasing from off-sea to offshore. Most of all the areas charactered as eutrophication are located at the areas below salinity 20. The obvious seasonal and regional variabilities showed that, the eutrophication levels of this area are dominated by the diluted water in the Changjiang River.