【作者】 谌芸； 何丙辉；

【Author】 CHEN Yun,HE Bing-hui (College of Resources and Environment,Key Laboratory of Eco-environments in Three Gorges Region (Ministry of Education),Southwest University,Chongqing 400715,China)

【机构】 西南大学资源环境学院三峡库区生态环境教育部重点实验室；

【摘要】 以小江流域为研究对象,通过径流小区试验测算出4类农地(水田、梯坪地、<25坡耕地、>25坡耕地)的土壤侵蚀强度、年土壤侵蚀量及年TN、TP流失量;此外,2008年在渠口、养鹿、高阳、黄石、双江等5个断面3次取样进行了水质调查,2008年6月8日又单独在高阳、黄石、双江取水样调查。所有的研究结果表明:①坡耕地是小江流域水土流失的主要策源地——49.80%的面积导致了92.80%土壤流失量;②水土流失对小江水体的富营养化贡献很大,因水土流失进入小江的TN、TP分别为62.81t·a-1、52.02t·a-1;③小江水体各时段的TN、TP浓度严重高于水体富营养化临界指标——TN为1.00mg·L-1,TP为0.20mg·L-1;④2008年"水华"现象发生在6月份,并非TN浓度最大的7月份,这与发生水体富营养化的适宜的水文、温度和光照条件密切相关;⑤小江水体TN、TP浓度变化受水土流失和当季氮、磷施用量的共同制约:TN浓度峰值与水土流失峰值具有同步性,出现在7月份;TP浓度峰值出现在4月份,施肥量起主导作用;⑥控制农地氮、磷流失,行之有效的措施有:坡改梯、退耕还林、优化土地利用和合理施肥等。更多还原

【Abstract】 Soil erosion and water loss is an important source of water eutrophication. Since June 2003 when the Three Gorges Reservoir began to storing water in the first phase,water bloom occurred repeatedly in some big bends and lower reaches in main Xiaojiang River,especially in summer. This water problem has become a serious threat to water quality in Three Gorges Reservoir. In this study,we calculated soil erosion intensity,the amount of soil erosion,and the amount of TN and TP losses for one year through monitoring experiments in runoff plots. Besides,in 2008,we collected water samples in 5 sections( Qukou,Yanglu,Gaoyang,Huangshi,Shuangjiang) for three times(April 18,July 16,November 28),and in June 8 we collected water samples singly in 3 sections(Gaoyang,Huangshi,Shuangjiang). The results of all experiments and studies demonstrate that (1) sloping land is the most important source of soil erosion and water loss in Xiaojiang River Basin. Its area proportion is 49.80%,but its amount of soil erosion proportion is 92.80% (2) soil erosion and water loss is a major contributor to eutrophication problems of Xiaojiang River. The losses of TN and TP are 62.81 t·a -1 、52.02 t·a -1 ,respectively,through soil erosion and water loss (3) in 4 samplings,concentrations of TN and TP seriously exceeded critical loads for eutrophication(TN is 1.00 mg·L -1 ,TP is 0.20 mg·L -1 ) (4)in 2008,water bloom occurred in June,but the peak concentration of TN occurred in July. This closely related to suitable conditions of eutrophication,such as hydrology,temperature and sunshine (5) concentrations of TN and TP in Xiaojiang River are controlled by soil erosion and water loss and quantities of N and P applied. The peak concentration of TN occurred in July which was consistent with the peak of soil erosion and water loss. The peak concentration of TP occurred in April because of leading role of applied fertilizer (6) there are many measures controlling N and P losses effectively in farmland,such as terracing sloping land,returning farmland to forest,optimizing land use,reasonable fertilization,and so on.更多还原