中文摘要：

研究河流向河口及沿海海域输送的物质通量是一项国际性前沿课题.基于人类活动影响流域营养盐输移的定量分析,应用G lobal NEW S模型模拟1970-2003年长江输出溶解态无机磷（D IP）的通量,对其不同来源的贡献率进行了分析,并基于千年生态系统评估对未来社会经济发展规划的情景,对2050年长江输出D IP的通量进行预测.结果表明,从1970-2003年,长江输出的D IP通量呈逐年增加的趋势,2003年达到了14.05kg/km2,比1970年（2.45kg/km2）增加了近5倍.模拟值与对应年份的实测值之间无显著性差异,平均模拟误差为12.29%.1993年之前,长江输出D IP的主要来源是污水,贡献率达到了50%以上;1993年以后,以来自非点源的磷输入为主,其中以磷肥施用的贡献率最高,且呈逐年增加的趋势,2003年增加到了50.30%;畜禽粪便磷的贡献率变化平稳,大约在22.87%.污水来源的磷的贡献率自1993年之后呈逐年递减的趋势,到2003年减少为24.81%.情景预测表明,2050年无论何种情景下,长江输出的D IP通量都将超过2000年的2倍多,但是不同情景下D IP输出通量增加的幅度及不同来源的贡献率有较大差别.在日益增强的人类活动影响下,如何控制非点源的磷输入仍将是一项长期而紧迫的任务.

英文摘要：

Riverine transport is the principal pathway of dissolved elements from land to the sea.Based on the quantitative analysis of human effects on the phosphorus cycling within the Yangtze River basin,we estimated the exports of dissolved inorganic phosphorous（DIP） from the Yangtze River to the estuary for the period 19702003,by using the Global NEWS-DIP model.Modeled DIP export increased from 2.45kg/km2 in 1970 to 14.05kg/km2 in 2003 under the enhancing anthropogenic activities.No significant difference between the modeled and measured values at the level of P=0.05 is observed,and the average model error is 12.29%.Diffuse sources（including chemical fertilizer application and animal manure P input） had contributed the most in DIP export since 1993.The contribution varied between 58.60% and 75.48%.Sewage discharge was the major source of river DIP export before 1993,with the contribution varying between 99.98% and 45.21%,while the contribution decreased rapidly since then until to 24.81% in 2003.We also discussed possible future trajectories of DIP export based on the MEA scenarios.How to control the diffuse nutrient inputs under enhancing human pressures will be a long-term and urgent task.