摘要
利用镁基膨润土(MB)和水泥(SN)作为钝化剂修复化工厂砷(As)、铅(Pb)复合污染土壤,探索了两种钝化剂对土壤pH值、有机碳含量(OC)、阳离子交换量(CEC)、浸出毒性及重金属形态分布的影响,结合钝化前后土壤形貌的变化,初步揭示了钝化机理.结果表明,两种钝化剂均可使土壤pH值显著升高,有机碳含量增加,阳离子交换能力增强.钝化30 d后,MB-5对As、Pb的钝化率分别达到67.09%和65.93%;SN-5对As、Pb的钝化率分别达到65.76%和65.04%.经两种钝化剂处理后,Pb的弱酸提取态和可还原态向更加稳定的可氧化态和残渣态转化.MB处理使土壤As由可交换态、可氧化态向无定形铁结合态、结晶性铁结合态转化,SN处理使土壤As向残渣态转化.两种钝化剂均可使土壤的微观形态从片状转变为碎屑状、增加团聚颗粒.与SN相比,MB更能促使土壤As(III)向As(V)转化,从而显著降低土壤毒性.
Magnesium bentonite(MB)and cement(SN)were used as passivators to remediate the As/Pb contaminated soil.The soil pH,organic carbon content(OC),cation exchange capacity(CEC),leaching toxicity and heavy metal speciation distribution,as well as the passivation mechanism were explored after the addition of both passivators.Combined with the changes in soil morphology before and after passivation,initially revealed the passivation mechanism.The results showed that both passivators increased soil pH significantly,increased OC and enhanced CEC.After 30 days′passivation,the passivation rates of MB-5 on As and Pb reached 67.09%and 65.93%respectively.The soil As and Pb reduced 65.76%and 65.04%by SN-5 addition,respectively.At the same time,the soil acid extraction state and reducible state of Pb had transformed into more stable oxidable state and residual state when treated by both passivators.Soil As was transformed from exchangeable state and oxidizable state to amorphous iron binding state and crystalline iron binding state as for MB treatment.And soil As was transformed to residual state while treated by SN.The soil microscopic morphology had changed from flake to clastic together with the increasing of soil aggregate particles after passivators′addition.Compared with SN,MB could promote the soil As(III)to converting into As(V),which could significantly reduce the soil toxicity.
作者
温小情
林亲铁
肖荣波
黄润林
陈怡君
李晓燕
王玉鹏
刘楚藩
WEN Xiaoqing;LIN Qintie;XIAO Rongbo;HUANG Runlin;CHEN Yijun;LI Xiaoyan;WANG Yupeng;LIU Chufan(Guangdong Industrial Contaminated Site Remediation Technology and Equipment Engineering Research Center,School of Environmental Science and Engineering,Guangdong University of Technology,Guangzhou 510006)
出处
《环境科学学报》
CAS
CSCD
北大核心
2020年第9期3397-3404,共8页
Acta Scientiae Circumstantiae
基金
国家重大科技研发专项(No.2018YFC1802803,2017YFD0801302)。
关键词
As
PB
复合污染
土壤修复
钝化剂
As
Pb
compound pollution
soil remediation
passivator
