近23a来长江口及其邻近海域营养盐结构的变化趋势和影响因素分析

Analysis of trend of nutrient structure and influencing factors in Changjiang Estuary and its adjacent sea during 23 years

根据1984—2006年的调查资料，对长江口及其邻近海域溶解态无机氮（DIN）与磷酸盐（PO4-P）浓度及其比值变化趋势进行研究。结果表明近23a来长江口及其邻近海域中的DIN与磷酸盐浓度呈现增长趋势，氮磷比（N／P）呈现降低趋势。长江口的DIN、PO4-P、N／P变化范围分别为2．13—140．0μmol／L，0．0211—1．6955μmol／L和51．24580．56，其邻近海域变化范围分别为1．94～95．69μmol／L，0．0226～1．3806μmol／L和64．38～339．73。长江口目前营养盐限制因子仍是P。营养盐结构的变化可能与输沙量的减少和流域农田化肥使用结构变化有关。

According to monitoring data from 1984 to 2006, the trend of disolved inorganic nitrogen （ DIN）, phosphate （ PO4-P） and their ratio in Changjiang Estuary and its adjacent sea were analyzed. The results showed that the concentrations of DIN and PO4-P had been increasing,while the ratio of which has been decreasing during 23 years. The concentrations of DIN and PO4-P range from 2.13 - 140.0 μmol/L and 0. 0211 - 1. 6955 μmol/L in Changjiang Estuary, respectively,while 1.94 - 95.69 μmol/L and 0. 0226 - 1. 380 6 μmol/L in its adjacent sea,respectively. The N/P ranges from 51.24 - 580.56 and 64.38 - 339.73 in the study area, respectively. And currently the nutrient limiting factor was still phosphorus. The change in nutrient structure may result from the decrease of sendiment load in river and N/P in chemical fertilizer in farmland.