象山港海域营养状况分析与富营养化水平评价

Status analysis of nutrients and eutrophication assessment in seawater of the Xiangshan Harbor

根据2010年4月份和7月份象山港海域水质调查资料,分析了该海域海水中N、P、Si营养盐的分布特征、时空变化及其结构,利用Si∶N∶P比、有机污染指数、富营养化状态指数和潜在富营养化对该海域进行了评价。结果表明,7月份DIN的分布由港底向港口逐渐降低,4月份无明显变化趋势;PO4-P4、7月份空间分布趋势相同,都是由港底向港口方向逐渐降低,4、7月SiO3-Si的浓度基本保持一致,高浓度区出现在港底附近海域。从营养结构看,与Redfield值和Justic等提出的营养盐化学计量限制标准比较符合P限制。富营养化评价表明,整个象山港海域水质一直处于严重污染水平和高富营养程度,且有机污染和富营养化程度均存在港底最高,越往港湾出口处污染越轻的趋势。由于港内水动力交换能力较弱,一旦水文气象条件适宜,随时有爆发赤潮的可能。

Based on the field data of the Xiangshan Harbor in April and July in 2010,the distribution characteristics and spatio-temporal variations of N、P、Si nutrients and the structure characteristics of them in Xiangshan Harbor were analyzed.Furthermore,the value of Si：N：P,eutrophication index（E）,organic index（A） and potential eutrophication were employed to assess the eutrophication degree of the whole sea water.The results of comprehensive analysis have shown that the distribution of DIN in July and PO4-P in April and July decreased gradually from the inner bay to the bay mouth.However,the content of inorganic nitrogen in April and silicate was relatively high in Xangshan Bay top.According to the nutrition structure,the inorganic phosphorus was the limit factor for growth of phytoplankton,and compared with Redfield ration and limit standard of chemical measure for the nutrient salts,it is accorded with the limit condition of inorganic phosphorus.According to eutrophication index（E） and organic index（A）,the whole waters in Xiangshan Bay was in the serious pollution condition.Furthermore,the level of organic pollution and eutrophication was highest in Xiangshan Bay,which has a decreasing trend from Xiangshan Bay top to exit.Because of Xiangshan Bay hydrodynamic situation feebleness,the red disaster would be happened at any moment in case of hydrometeorological conditions were suitable.