Supported by the National Key Research and Development Program of China (No. 2017YFD0801503)
In China, heavy metal pollution in soils is very serious, especially cadmium(Cd)and arsenic(As)pollution. In Cd and As(Cd-As)co-contaminated soils, the two elements Cd and As act either antagonistically or synergically, and their effective concentrations are affected by soil pH, redox potential, and some other soil environmental factors, which makes it more difficult to remediate the Cd-As co-contaminated soil and seriously threatens food security in our country. In this paper, a review is presented to show the advantages and disadvantages of the passivation materials for Cd-As soil co-contamination, as well as their effects and mechanisms. Common passivating materials include biochar, phosphates, metals and their oxides, silicon-containing materials, clay minerals, organic fertilizers and some other new materials. Recently, a large amount of studies have demonstrated that biochar is a good adsorbent for Cd, but modified biochar is usually used in combination with other materials, like metals or their oxides, clay minerals, poultry manure, compound fertilizer, etc. to passivate Cd and As simultaneously. The mechanism of modified biochar to passivate Cd and As was ion exchange, coprecipitation and surface complexation. Phosphate is mainly applied together with iron salt or iron powder to passivate Cd by adsorption and isomorphic substitution, and to passivate As by site-competition; metals and their oxides are mostly combined with biochar, lime or clay minerals to passivate Cd through specific adsorption and coprecipitation, and to passivate As through redox and complexation. Iron silicon fertilizer, silicon calcium fertilizer or silicon potassium fertilizer is used to passivate Cd via coprecipitation, and to passivate As through specific adsorption and site competition mechanism. In clay minerals, sepiolite is widely used, mainly combined with metal oxide, calcium magnesium phosphate fertilizer, etc., to passivate Cd and As through ion exchange, precipitation and complexation. Sludge and animal manure, which contain organic matter with high degree of humification, are used to passivate Cd and As mainly through adsorption, redox, organic complex and microbial interaction. In addition, the materials rich in sulfhydryl-and amino-groups, glutamate, S and Se can also effectively immobilize Cd and As simultaneously. The passivation materials used in Cd-As co-contaminated soil are reviewed and characterized in this study to provide some guidance for the remediation of Cd and As co-contaminated soils.
李英,商建英,黄益宗,王农.镉砷复合污染土壤钝化材料研究进展[J].土壤学报,2021,58(4):837-850. DOI:10.11766/trxb201912170575 LI Ying, SHANG Jianying, HUANG Yizong, WANG Nong. Research Progress on Passivation Materials for Cadmium-Arsenic Co-Contamination in Soil[J]. Acta Pedologica Sinica,2021,58(4):837-850.复制