Author(s): Xiaoli Liu; Zhaoxia Zeng; Baiqing Tie; Qiuwen Chen; Zhe Chen; Ruilun Zheng
Linked Author(s): Qiuwen Chen
Keywords: Paddy rice; Biochar; Lime; Heavy metal non-point load; Hunan province mining are
Abstract: Biochar and lime has attracted tremendous research interests due to its ability of increasing some toxic heavy metal irons immobilization in soil. However, few studies focus on the effects of biochar and lime application on soluble heavy metal release from historically heavy metal contaminated soil to waterlogged paddy water and non-point loads with in situ field experiment. Two years study was conducted to evaluate Cd, Pb, As metal irons immobilization and non-point loads reduction effectiveness after rice, bean derived biochars and lime application into a historically multi-metal contaminated soil by in situ field experiment, in central Hunan province mining area. Results showed that, additions of biochar derived from rice and bean straw (20 t·hm-2) significantly increased soil pH by 0. 6-1. 1 units, while lime application (50kg·hm-2) has no obvious effect on pH. Rice biochar addition reduced soluble Cd, Pb concentration of paddy waterlogged water by 56-80% , 60-85% respectively, and bean biochar addition also caused soluble Cd, Pb reduction by 61-83% , 51-86% respectively, compared to control treatment. No obvious reduction efficiency of soluble Cd, Pb, As of paddy waterlogged water was observed after lime application comparing to control. However, rice and bean biochar addition obviously increased the soluble As concentration of paddy waterlogged water by30-84% and 19-84% respectively, but not for lime. Both rice and bean biochar application can significantly decreased non-point loads of Cd and Pb during natural rainfall runoff events, but significantly increased As non-point load than control and lime application, which maybe will cause potential water environment risk due to much soluble As irons release into aqueous phase.