长江流域沿江镉异常示踪与追源的战略与战术

STRATEGY AND TACTICS FOR TRACING AND SOURCE TRACKING OF Cd ANOMALIES ALONG THE CHANGJIANG RIVER BASIN

正在进行的多目标地球化学调查成果显示,长江流域存在全流域的Cd异常。长江流域Cd异常示踪与追源研究的长期目标是查明长江流域沿江各主要支流(汇水面积大于5000km2)Cd等重金属元素的物质来源、迁移形式和输入/输出通量、分辨自然源与人为源各自所占份额,建立沿江各支流Cd时空演化模型,监测它的未来发展趋势,对潜在生态效应进行预警预测;短期目标是针对Cd异常的重点地区,如长江源头、三峡库区、湘江流域、江淮流域、长江三角洲及流域内的4大淡水湖泊,查明Cd异常的来源,重建Cd异常形成的地球化学记录,评估可预见的将来(如10～50年)Cd异常的生态效应。

The results of the multi-purpose regional geochemical investigation show that there exist Cd anomalies spreading along the whole Changjiang River basin. The long-term objective of the study on tracing and source tracking of the anomalies is to understand the material sources, emigrational modes and input/output flux, as well as percentages for natural and man-made material sources of Cd and other heavy metal elements along main tributaries of the Changjiang River (with collecting area of more than 5 000km 2), so as to establish time-spatial evolutionary pattern of Cd anomalies along every main tributary, monitor the developing trend, and to predict potential ecological effects and give corresponding early warning. While its immediate objective is to investigate sources of Cd anomalies in key areas, such as the headwater of the Changjiang River, the Xiangjiang River basin, the Jianghuai basin, delta of the Changjiang River, as well as four major freshwater lakes in the Changjiang River basin, so as to reconstruct geochemical records of anomaly forming, and so to predict ecological effects in near future ( in 10~50 years for example).