基于侵蚀过程的喀斯特坡耕地土壤重金属迁移机制

为探索喀斯特坡耕地土壤重金属元素随径流迁移机制,通过人工模拟降雨试验方法,系统研究了不同降雨强度和坡度下Cu、Zn和Ni元素随地表径流迁移转化机制。结果表明:(1)不同处理条件下坡面产流量呈上升趋势,在产流10～20 min后达到峰值并趋于稳定,同时降雨强度越大,坡度越陡,产流量越高。(2)不同处理条件下产沙量均呈先迅速增加后缓慢减少的变化趋势,产沙量与降雨强度呈正比,且在相同降雨强度下存在临界坡度。(3)供试土壤中重金属均以残渣态为主,随着产流时间的延长,径流中溶解态Ni和Cu元素变化无明显规律,上下波动幅度不大,溶解态Zn在径流中含量低于检测下限,而颗粒态Cu、Zn和Ni含量基本呈现先快速上升又逐渐下降的变化趋势,与径流产沙量变化趋势一致。

Migration mechanism of heavy metals in karst slope farmland based on erosion process volume up content copy share

In order to explore the migration mechanism of soil heavy metal elements in karst sloping farmland with runoff, the migration and transformation mechanisms of Cu, Zn and Ni elements with surface runoff under different rainfall intensities and slopes were systematically studied through artificial rainfall simulation test methods. The results showed that: (1) The slope discharge under different treatment conditions showed an upward trend, reaching a peak value after 10-20 minutes and tending to stabilize. At the same time, the greater the rainfall intensity, the steeper the slope and the higher the discharge. (2) The sediment yield under different treatment conditions showed a rapid increase first and then a slow decrease trend. The sediment yield was proportional to the rainfall intensity, and there was a critical slope under the same rainfall intensity. (3) The heavy metals in the tested soil are mainly in the residue state. With the extension of the runoff time, the dissolved Ni and Cu elements in the runoff have no obvious changes, and the fluctuation range is small. The content of dissolved Zn in the runoff is low. At the lower limit of detection, the content of particulate Cu, Zn, and Ni basically showed a rapid increase and then gradually decrease, which was consistent with the change trend of runoff sediment yield.