水稻全生育期内零价铁与生物炭钝化土壤镉砷的协同效应与机制  

Synergistic Passivating Effects and Mechanisms of Zero Valent Iron and Biochar on Cadmium and Arsenic in Paddy Soil over A Whole Growth Period of Rice

作　　者：张晓峰 方利平 李芳柏 于焕云 刘传平 杜衍红 ZHANG Xiaofeng;FANG Liping;LI Fangbai;YU Huanyun;LIU Chuanping;DU Yanhong(Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management/Guangdong Institute of Eco-environmental Science&Technology/Guangdong Academy of Sciences,Guangzhou 510650,China;National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China,Guangzhou 510650,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]广东省科学院/广东省生态环境技术研究所/广东省农业环境综合治理重点实验室,广东广州510650 [3]华南土壤污染控制与修复国家地方联合工程研究中心,广东广州510650 [4]中国科学院大学,北京100049

出　　处：《生态环境学报》2020年第7期1455-1465,共11页Ecology and Environmental Sciences

基　　金：国家重点研发计划课题(2018YFF0213403);国家自然科学基金项目(41807143);广东省自然科学基金项目(2018A030313696)。

摘　　要：镉(Cd)和砷(As)在土壤中地球化学行为相反,因而难以实现对它们的同步钝化。为了同时降低稻米中Cd和As的积累以达到提高粮食安全的目的,选择了零价铁(ZVI)和生物炭(BC)的组合材料来修复稻田土壤中的Cd/As复合污染。通过盆栽实验,在水稻全生育期内,密集采取了孔隙水、根际土壤、水稻植株和根表铁膜等样品,分析了其中Cd/As含量与存在形式的动态变化过程,并以此探究了水稻整个生命周期内ZVI或/和BC对稻田土壤中Cd/As生物有效性的钝化效果与机制。结果表明,相比于对照组,生物炭仅降低稻米中Cd,降低率为15.4%;ZVI能同时降低稻米中Cd和As质量分数,其降低率分别达17.0%和24.5%;而ZVI+BC组合对稻米中Cd和As降低量最强,分别高达50.2%和35.6%,表现出明显的协同钝化效应。土壤孔隙水与重金属连续提取结果表明,ZVI能使水溶态、吸附态与可交换态Cd和As转化为铁氧矿物结合态,而BC主要导致水溶态与可交换态Cd转为碳酸盐结合态。相对而言,ZVI+BC组合通过共同促进铁氧矿物的形成与分散,从而导致大部分的水溶态、吸附态与可交换态Cd和As与铁氧矿物形成结合态,是抑制稻米积累Cd和As的主要作用机制。因此,ZVI和BC的组合材料可以同步高效修复稻田土壤中的Cd/As的复合污染,这将有利于实现中轻度Cd/As污染稻田的安全利用。The geochemical behaviors of cadmium(Cd)and arsenic(As)in soil are opposite,so it is difficult to achieve their simultaneous passivation.In order to reduce the accumulation of Cd and As in rice grains synchronously and improve food security,the combination of zero valent iron(ZVI)and biochar(BC)was selected to remedy the Cd/As co-contaminated paddy soils.By pot experiment,the samples of pore water,rhizosphere soils,rice plants and iron plaques on the surface of roots were intensively collected over the whole growth period of rice,subsequently the dynamics of Cd/As contents and existing forms in thus samples were analyzed,and thereby the passivating effects and mechanisms of ZVI or/and BC on Cd/As bioavailabilities in paddy soils were investigated during a whole lifecycle of rice.The results demonstrated that compared with the control,BC just reduced the content of Cd in rice by 15.4%;ZVI could reduce the content of both Cd and As in rice by 17.0%and 24.5%,respectively;while the ZVI+BC combination led to the largest reduction of Cd and As in rice(50.2%and 35.6%),and thus showed the synergistic effects on passivating Cd and As in paddy soil.The results of soil pore water and sequential extraction of soil analyses indicated that ZVI can transform water-soluble,adsorbed and exchangeable Cd and As into the iron oxides bound state;BC should mainly cause the water-soluble and exchangeable Cd to enter carbonate bound state.In comparison,the ZVI+BC combination should promote the formation and dispersion of iron oxide minerals and immobilize the most water-soluble,adsorbed and exchangeable Cd and As.Therefore,the combination of ZVI and BC can simultaneously and efficiently remedy the paddy soil co-contaminated with Cd and As,which would be conducive to realize the safe utilization of the moderately and lightly Cd/As-polluted paddy fields.

关 键 词：镉 砷 零价铁 生物炭 同步钝化 

分 类 号：Q145.2[生物学—生态学] X173[生物学—普通生物学]