淹水条件下蚕沙复配材料对酸性水稻土中镉铅钝化的影响

Effect of silkworm excrement composites on passivation of cadmium and lead in acid paddy soil under flooded condition

通过室内淹水土培实验,研究蚕沙配施蚕沙炭、膨润土、腐殖质钾和泥炭对酸性水稻土中镉(Cd)、铅(Pb)的钝化效果,从土壤pH、有机质、有效态Fe、Mn含量变化初步探析蚕沙复配材料对镉、铅的钝化机制。结果表明,蚕沙复配材料均不同程度地提高了土壤pH和有机质含量,有效态Cd、Pb的含量随着淹水时间的延长都有不同程度的降低。培养28d后,与对照相比,添加了蚕沙+蚕沙炭(CB)、蚕沙+腐殖质钾(CF)、蚕沙+蚕沙炭+腐殖质钾(CBF)、蚕沙+泥炭(CN)处理的土壤有效态Cd分别降低了16.07%、15.51%、11.08%、7.76%,有效态Pb则降低了32.54%、27.12%、37.72%、42.31%。其中蚕沙+蚕沙炭(CB)对镉的钝化效果最好,蚕沙+泥炭(CN)处理对铅的钝化效果最好,综合来看,CB和CN处理同时对镉铅有很好的钝化效果,可以作为镉铅复合污染土壤的修复材料。相关分析结果显示,土壤的pH、有机质与有效态Cd、Pb含量均呈显著负相关关系,表明蚕沙复配材料对土壤中镉、铅的钝化作用可以通过提高土壤的pH、有机质含量来实现。

The impacts of amendments（silkworm excrement compounded with biochar, bentonite, humic potassium and peat） on availability of cadmium（Cd） and lead（Pb） in acid paddy soil under flooded condition were studied.Soil culture experiments were carried out to reveal the mechanism of immobilization of Cd and Pb according to the alterations in soil pH, organic matter, available Fe and available Mn contents. Results showed that soil pH and organic matter contents were increased, while the available Cd and Pb contents were both decreased after addition of silkworm excrement composites. After the 28 d soil cultivation, compared with the control experiment, the contents of available Cd in the treatments of silkworm excrement compounded with biochar（CB）, silkworm excrement compounded with humic potassium（CF）, silkworm excrement compounded with biochar and humic potassium（CBF）,and silkworm excrement compounded with peat（CN） decreased by 16.07%, 15.51%, 11.08% and 7.76%, while Pb availability decreased by 32.54%, 27.12%, 37.72% and 42.31%, respectively. Among various silkworm excrement composites, the CB exhibited the best Cd passivation effect, while CN showed the best Pb passivation result. The CB and CN had better performance for decreasing Cd and Pb availability. The significant negative correlations between Cd and Pb availability and the soil pH, organic matter contents indicated that the increase of soil pH and organic matter contents were the important mechanism of decreasing the soil Cd and Pb availability by adding silkworm excrement composites.