长江口夏季水体磷的形态分布特征及影响因素

The distribution characteristics and influence factors of some species phosphorus in waters of the Changjiang River Estuary in summer

根据2006年7月至9月"海监49号"科学考察船夏季航次的调查数据,分析了长江口及邻近海域水体中磷形态的平面分布特征及其影响因素,结果表明,调查海域水体各种形态磷平均浓度均为底层高于表层,并呈现出由河口向邻近海域降低的趋势。杭州湾及最大混浊带部分区域水体中以颗粒态磷为主,且颗粒态无机磷为磷的主要存在形态;长江口门及江苏东部近海区域水体中以溶解态磷为主,溶解态无机磷为磷的主要存在形态;舟山群岛东部外海区表层水体以溶解态磷为主,溶解态有机磷为磷的主要存在形态,而底层水体中溶解态磷浓度略高于颗粒态磷,以溶解态无机磷为磷的主要存在形态。水体中颗粒态无机磷与颗粒态有机磷、颗粒总磷与总磷、总磷与悬浮颗粒物均呈非常显著的正相关,说明悬浮颗粒物是颗粒态磷的主要影响因素。调查海域外海区域绝大部分站位水体中溶解态无机磷表层浓度接近或小于浮游植物生长限制的动力学最低阈值,是磷限制或潜在的磷限制区域。

Based on field observations from July to September in 2006, the distribution characteristics and influence factor of some species phosphorus in waters of the Changjiang Estuary were discussed in this paper. The results showed that the concentrations of some species phosphorus were slightly higher in the bottom than in the surface, and decreased greatly from the estuary to the adjacent waters. The average of TP was 3.93 μmol/dma in the surface water and 5. 09 μmol/dma in the bottom water. The average of TDP was 1.40 μmot/dina in the surface water and 1. 56 μmol/dma in the bottom water. The average of PP was 2. 53μmol/dma in the surface water and 3. 55μmol/dm3 in the bottom water. The average of DIP was 0. 71 μmol/dma in the surface water and 0.90 μmol/dma in the bottom water. The average of DOP was 0.69 μmol/dma in the surface water and 0.72 μmol/dma in the bottom water. The average of PIP was 1.60 μmol/dma in the surface water and 2.42 μmol/dma in the bottom water. The average of POP was 0.93 μmol/dma in the surface water and 1.12μmol/dma in the bottom water. In A, PP was the main factor which affect the distribution of TP and account for 76.6% in the surface water and 83.2% in the bottom water, and PIP was the main existing forms of the TP and accounted for 50.8% in the surface water and 57.9% in the bottom water. In B, TDP was the main factor which affect the distribution of TP and accounted for 62.7% in the surface water and 64.3% in the bottom water, and DIP which was the main existing forms of the TP accounted for 36.7% in the surface water and 37.50//oo in the bottom water. In C, TDP was the main factor which affect the distribution of TP and accounted for 68.7% in the surface water and 52.3% in the bottom water, DOP was the main existing forms of the TP and accounted for 46.3% in the surface water; TDP was slightly higher than PP （47.7%） in the bottom water, DIP （30. 2%） and PIP （31. 4%） was the main existing forms of the TP. The positive correlations between PIP and POP, between PP and TP, and between TP and SPM, suggested SPM was the main factor which affects the distribution of PP. Correlative analysis between environmental factors and different speciation of phosphorus in sea water shows that salinity has negative correlated with DIP and TDP. The negative relationships between the salinity and DIP and between the salinity and TDP suggested the phosphorus discharges. The positive correlation between DIP and DOP in the surface of A and in the bottom of B suggested that DIP and DOP maybe have the same source. The surface concentrations of DIP of most stations in C were approximative or less than 0. 1 μmol/dm3 , so this region was in the state of phosphorus limitation or potential phosphorus limitation and particle phosphorus was very important as potential phosphate.