东海赤潮高发区营养盐时空分布特征及其与赤潮的关系

Seasonal Variation and Spatial Distribution of Nutrients and Their Relationships with Harmful Algal Blooms in Coastal Area of the East China Sea

根据2002-04～2003-02期间在长江口及其邻近海域进行的4个综合航次的调查资料,分析了该海区营养盐季节变化及分布特征,并初步探讨了海区营养盐状况与赤潮的关系.结果表明,各项营养盐的平均浓度分别为：溶解无机氮（DIN）（17.93±2.46）μmol·L^-1,磷酸盐（PO4^3- -P）（0.59±0.11）μmol·L^-1和硅酸盐（SiO3^2- -Si）（15.34±3.23）μmol·L^-1,调查海区处于富营养化状态;海区营养盐含量存在明显的季节变化,表现为秋冬季节高于春夏季节,其平面分布特征呈现近岸高、外海低,沿岸方向向离岸方向逐渐降低的特点;调查海区DIN和SiO32--S主要来源于长江冲淡水等陆源输入,PO43--P主要来源于长江冲淡水和台湾暖流;调查海区的赤潮发生区域主要集中在营养盐浓度相对较高,而总悬浮颗粒物（TSP）含量相对较低的区域.

Based on the data from four cruises that carried out in the Changjiang River estuary and its adjacent areas from 2002-04 to 2003-02, the seasonal variation and spatial distribution of nutrients were analyzed, and the relationship between nutrients condition and the harmful algal blooms （HABs） was also discussed. Results showed that the annual average concentration of nutrient was （17.93 ± 2.46） μmol·L^-1 for DIN, （0.59 ± 0.11 ）μmol·L^-1 for PO4^3- -P, （15.34 ± 3.23） μmol·L^-1 for SiO3^2- -Si, and the study area was in the state of eutrophication. The average concentration of nutrient showed a remarkable seasonal fluctuation with the higher value in autumn and winter and lower value in spring and summer. The spatial distribution of the nutrients was typically such that the concentrations of DIN, PO4^3- -P and SiO3^2- -Si decreased from inshore to offshore area, and the contours generally decreased rapidly in down-coast directions. DIN and SiO3^2- -Si of the study area were largely contributed by Changjiang River diluted water and other terrigenous inputs, while PO4^3- -P mainly by Changjiang River diluted water and the Taiwan Warm Current. The following HABs showed that its occurrences were usually laid in the areas with higher nutrients and lower total suspended particles （TSP）.