不同土地类型下重金属随暴雨径流迁移过程及速率对比

Transportation processes and rates of heavy metals in an artificial rainstorm runoff under different land use types

选择太湖上游西苕溪流域最具代表性的5种土地类型,利用野外人工降雨装置,研究了不同形态重金属(Cu,Cr,Pb,Zn)随暴雨径流水相及沉积物相的迁移过程,对比了流域内不同土地利用/土地覆被条件下重金属的迁移特征,并估算了流失速率.结果表明,在相同的降雨条件下,桑林Cu、Zn和Pb随地表径流水相的迁移量最大,分别达0.21、0.45和0.15 mg·m-2·min-1;水田Cr迁移量最大,达0.06 mg·m-2·min-1;松林重金属迁移量都很小,而且重金属随地表径流水相的迁移主要是通过悬浮细颗粒态。地表径流沉积物相的重金属流失量远高于水相,水相迁移速率仅占沉积物相迁移率的0.1％～4.9％;从地表径流水相重金属迁移量占沉积物相迁移量的比例来看,Cu较高,Cr、Pb、Zn较低.

Studies on the transportation and flux of various kinds of heavy metals in runoff and sediment of five typical land-use types in West Tiaoxi catchment showed that the losses of Cu (0.21 mg·m-2·min-1), Zn (0.45 mg·m-2· min-1), and Pb (0.15 mg·m-2 f3min-1) in mulberry and that of Cr (0.06 mg·m-2·min-1) in paddy field were larger in surface runoff, while their losses in pinery were very small. Suspended thin particles played the main role on transporting heavy metals in surface runoff under all kinds of land uses. The losses from runoff were much lower than that from sediment, which only occupied 0.1 % ~ 4.9 % , and the loss rate of Cu from runoff and sediment was higher than that of Cr, Pb and Zn.