• 关键词：丘陵  汇水区  林-稻系统  铅  迁移

• 基金项目：湖南省教育厅科学研究创新平台开放基金项目（No.16K105）；湖南省重点研发计划项目（农业支撑领域）（No.2015NK3025）

• 王小丽
• 1. 中南林业科技大学生命科学与技术学院, 长沙 410004;2. 南方林业生态应用技术国家工程实验室, 长沙 410004

• 陈建国
• 1. 中南林业科技大学生命科学与技术学院, 长沙 410004;2. 南方林业生态应用技术国家工程实验室, 长沙 410004;3. 会同杉木生态系统国家野外科学研究站, 会同 418307

• 杨爱爱
• 1. 中南林业科技大学生命科学与技术学院, 长沙 410004;2. 南方林业生态应用技术国家工程实验室, 长沙 410004

• 郭卉
• 1. 中南林业科技大学生命科学与技术学院, 长沙 410004;2. 南方林业生态应用技术国家工程实验室, 长沙 410004

• 摘要：铅通过食物链的迁移和积累对人类健康的毒害作用日益为社会所重视，而水稻是人类铅摄入的主要途径之一，因此，对稻田土壤铅的迁入途径及其过程特征的研究十分必要.为了探明湖南地区远离城镇、工矿区的丘陵稻区铅的输入、迁移、滞留机制，选择位于湘东北地域的汩罗市桃林林场的林地-山塘-稻田汇水区系统作为研究对象，在水稻大田生长期间，原位研究其大气沉降、岗地径流、山塘水、稻田水、水稻生长等过程的铅通量.结果表明：①输入系统的铅源是大气沉降，其中，在水稻生育前期通过东南季风输入的区域外源铅占90%；②山塘是大气沉降铅的主要集纳地貌单元，存留了大气沉降输入岗地和山塘总铅的66%；③林-稻汇水区系统岗地铅净留存28.8~57.7 g·hm^-2，山塘铅净留存604.3~961.9 g·hm^-2，稻田铅净留存89.6~90.9 g·hm^-2；而对照系统岗地铅净输出173.3 g·hm^-2，山塘净留存3427.6 g·hm^-2，稻田净留存87.1 g·hm^-2；④岗地和山塘对铅的截留量能够互补；⑤从岗地通过径流-山塘水过程迁移到稻田的大分子有机物能够增强稻田对铅的截留.综上所述，丘陵林-稻汇水区系统中铅的循环与大气沉降有关，系统内岗地森林类型、郁闭度、降水产流及泥沙、有机物的输出都会影响铅在系统中的迁移和分配.

• Abstract：The toxic effect of lead(Pb) on the migration and accumulation of Pb in human health are increasingly coming to societal attention, more especially as rice is one of the main source of human Pb in southern China. Therefore, it is necessary to study the pathway of Pb and its process characteristics in the paddy soil. Our objective is to study the mechanism of Pb input, migration, and retention in hilly rice-cropping areas, which are far from towns and industrial and mining enterprises in Hunan Province. In situ studies were conducted on three experimental fields located in the forest-pond-paddy field catchment system in Taolin Forest Farm in Miluo City, northeastern Hunan. The Pb migration-retention fluxes for the selected system were measured during rice growth and recorded for the process of atmospheric sedimentation, hilly runoff, mountain pond water, and paddy field water. The main results are shown as follows:① the Pb input into the catchment system comes from atmospheric sedimentation, and 90% of the Pb was imported through the southeast monsoon in the early stage of rice growth; ② the pond is the main geomorphic unit for atmospheric Pb deposition, as 66% of the atmospheric Pb input was being retained from the upper land and the atmospheric sedimentation over the ponds;③the net Pb retention was between 28.8~57.7 g·hm^-2 in hilly land, 604.3~961.9 g·hm^-2 in hilly pond, and 89.6~90.9 g·hm^-2 in paddy field; in the control system, the net output of Pb in hilly land was 173.3 g·hm^-2, whereas that of the mountain pond was 3427.6 g·hm^-2, and that of paddy field was 87.1 g·hm^-2; ④Pb interception can complement each other in hills and ponds; ⑤macro-molecular organic matter migrated from hilly land to paddy field through runoff-pond water process can enhance Pb interception in paddy field. In summary, the flux of Pb is related to atmospheric deposition in the hilly forest-rice catchment system, while forest types, canopy density, precipitation runoff, sediment, and organic matter output can affect the migration and distribution of Pb in the system.

• Key words：hilly  catchment area  forest-rice agroforestry systems  Pb  migration

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