Pedosphere 27(2): 193--204, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Remediation of heavy metal-polluted agricultural soils using clay minerals: A review
XU Yi1, LIANG Xuefeng2,3, XU Yingming2,3, QIN Xu2,3, HUANG Qingqing2,3, WANG Lin2,3,SUN Yuebing2,3
1College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China)
2 Innovation Team of Remediation of Heavy Metal-Contaminated Farmlands, Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191 (China)
3 Key Laboratory of Original Environmental Quality of MOA/Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Tianjin 300191 (China)
Corresponding Author:liangxuefeng@aepi.org.cn.
ABSTRACT
      Heavy metal contamination of agricultural soils poses risks and hazards to humans.The remediation of heavy metal-polluted soils has become a hot topic in environmental science and engineering.In this review, the application of clay minerals for the remediation of heavy metal-polluted agricultural soils is summarized, in terms of their remediation effects and mechanisms, influencing factors, and future focus.Typical clay minerals, natural sepiolite, palygorskite, and bentonite, have been widely utilized for the in-situ immobilization of heavy metals in soils, especially Cd-polluted paddy soils and wastewater-irrigated farmland soils.Clay minerals are able to increase soil pH, decrease the chemical-extractable fractions and bioavailability of heavy metals in soils, and reduce the heavy metal contents in edible parts of plants.The immobilization effects have been confirmed in field-scale demonstrations and pot trials.Clay minerals can improve the environmental quality of soils and alleviate the hazards of heavy metals to plants. As main factors affecting the immobilization effects, the pH and water condition of soils have drawn academic attention.The remediation mechanisms mainly include liming, precipitation, and sorption effects. However, the molecular mechanisms of microscopic immobilization are unclear.Future studies should focus on the long-term stability and improvement of clay minerals in order to obtain a better remediation effect.
Key Words:  bentonite, bioavailability, immobilization, liming effect, palygorskite, sepiolite, soil pH
Citation: Xu, Y., Liang, X., Xu, Y., Qin, X., Huang, Q., Wang, L. and Sun, Y. 2017. Remediation of heavy metal-polluted agricultural soils using clay minerals: A review. Pedosphere. 27(2): 193-204.
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