Research of Vertical Migration and Occurrence of Cd and As in Acid Paddy Soil under Simulated Irrigation

According to the research of vertical migration and occurrence of Cd and As in acid paddy soil, the conclusions are as follows. The longitudinal migration of Cd in TZ kb1 , TZ 1 , TZ 2 , TZ 3 and TZ 5 found that Cd in the upper and lower layers of soil columns all lost to varying degrees with the increase of water injection contents (irrigation years). With the longitudinal leaching of irrigation water, when the adsorption capacity of the soil was greater than the water injection and rinsing capacity, the trend of accumulation (TZ 4 -TZ 6 ) further appeared. The vertical migration results of As in TZ kb1 , TZ 1 , TZ 2 , TZ 3 and TZ 5 found that As mainly accumulated in the upper layer of soil columns. Without considering other output ways, it can be seen that the binding ability of As to acid paddy soil was stronger than Cd, and its cumulative efficiency in 20 years was higher than Cd. However Cd cumulative efficiency of TZ 3 and TZ 5 in acid paddy soil may be greater than As with time. In general, As was less affected by irrigation water on vertical leaching of soil columns compared with Cd.