Abstract: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.