改良剂对土壤As钝化作用及生物可给性的影响

Influence of amendments on inactivation and bio-accessibility of arsenic in soils

采用室内土壤培养法研究不同改良剂(硫酸亚铁、骨炭、生物调理剂、磷酸二氢钙和堆肥)对土壤As化学形态转化和生物可给性的影响.结果表明,除堆肥和磷酸二氢钙处理外,其他3种改良剂均显著地提高土壤的p H值.BCR分级提取表明,土壤As主要以残渣态形式存在.添加磷酸二氢钙显著地提高了土壤As的移动性,而添加硫酸亚铁、骨炭、生物调理剂和堆肥却显著地降低了土壤As的移动性.培养1个月后,添加硫酸亚铁、骨炭和生物调理剂导致土壤酸可提取态As含量分别比对照处理降低86.65%、76.88%和34.19%.添加不同的改良剂对土壤As的生物可给性也有影响,除磷酸二氢钙处理外,硫酸亚铁、骨炭、生物调理剂和堆肥均显著性地降低了土壤As的生物可给性,其中硫酸亚铁处理对As的固定效果最好.培养2个月后,添加硫酸亚铁处理导致土壤As的生物可给性含量分别比对照降低90.76%,而添加磷酸二氢钙处理导致土壤As的生物可给性含量分别比对照提高1.81倍.硫酸亚铁、骨炭和生物调理剂可作为钝化As污染土壤的潜力材料.

A batch soil column incubation experiment was conducted to investigate the inactivation and bio-accessibility of arsenic（As） affected by five amendments（ferrous sulfate, bone char, modifying agent, monocalcium phosphate and compost）. The amendments increased soil pH except monocalcium phosphate and compost. BCR sequential extraction showed that As was mainly in the residual fraction form. The treatment with monocalcium phosphate significantly（P〈0.05） increased mobility of As. However, addition of ferrous sulfate, modifying agent, bone char and compost decreased mobility of As significantly. After one month incubation, addition of ferrous sulfate, bone char and modifying agent decreased the content of HOAC-soluble As by 86.65%, 76.88% and 34.19% respectively comparing with the control. Different amendments had different effects on the bio-accessibility of As. All amendments reduced the bio-accessibility of As except monocalcium phosphate. Compared with the control treatment, addition of ferrous sulfatethe decreased bio-accessible As content by 90.76% after 2 months incubation, while bio-accessible As content increased by 1.81-fold with monocalcium phosphate addition. The results suggest that ferrous sulfate, bone char and modifying agent are the potential materials to remediate As contaminated soils.