5种钝化剂对镉砷污染稻田的田间修复效果对比

Comparative of the field remediation effect of cadmium and arsenic contaminated paddy by five passivators

为选取费效比高的镉砷复合污染稻田土壤修复材料,比较了黏土矿物和调理剂不同投加组合对稻田土壤中镉砷的田间修复效果,并且针对种植水稻进行了修复效果的验证;研究了修复前后稻田土壤镉砷的有效形态变化、镉砷的形态分布变化、土壤理化性质变化、成熟期水稻产量和水稻各部分镉砷的含量。结果表明,修复100 d后,不同修复材料的二乙烯三胺五乙酸提取态Cd浓度与空白对照组相比均有明显下降;各修复材料均能提高土壤中Cd的残余态(RS)和As的有机结合态(OM)。修复材料处理后,土壤pH均有所提升,其他理化性质初期虽有所变化,但最终会恢复到空白对照组的水平附近;除1 kg·m^-2的膨润土处理外,其他材料处理后水稻干谷产量均有所提升;农田调理剂处理后水稻的可食用部分Cd含量最低,修复率达到72.0%。水稻的可食用部分As含量无显著差异,籽粒中Cd和As平均含量符合食用标准。调理剂在田间修复镉砷复合污染稻田土壤中有明显优势,黏土矿物仅适用于镉污染农稻田土壤的修复。

In order to select high cost-effectiveness remediation materials for Cd-As combined contaminated paddy soil,the field remediation effects of Cd-As in paddy soil by the different combinations of clay minerals and conditioner(F)were compared,and their remediation effects were verified by rice planting.For the paddy soils before and after remediation,the available contents and the species distribution of Cd and As in them,their physical and chemical properties,the yield of rice at maturity and the content of cadmium and arsenic in various parts of rice were studied.The results showed that the extractable Cd concentration of diethylenetriamine pentaacetic acid from 100 d remediated paddy soils with different repair materials decreased significantly,which were compared with the blank control group.The actions of each remediation material could improve the residual state(RS)of Cd and the organic binding state(OM)of As in soil.The soil pH increased after the treatment of the remediation materials,and some changes occurred at first for other physical and chemical properties,while these properties could restored to the level of the blank control group at last.Except for bentonite treatment with 1 kg·m^-2,the dry grain yield per mu of rice increased when paddy was treated by other materials.After conditioner(F2)remediation,Cd content in edible part of rice was the lowest,and the recovery rate reached 72.0%.There was no significant difference in As content in edible parts of rice,and the average contents of Cd and As in grains met the food standard.Conditioner has obvious advantages in field remediation of Cd-As contaminated paddy soil,while clay minerals are only suitable for remediation of Cd contaminated paddy soil.