title: The associations of heavy metals with crystalline iron oxides in the polluted soils around the mining areas in Guangdong Province, China.
abstract: In current selective sequential extraction (SSE) methods, heavy metals associated well-crystallized iron oxyhydroxides are not well defined and considered, and usually fall into residual forms, which actually make their mobility and environmental risk underestimated. This study compared various fractions of heavy metals in samples of mining tailings and nearby soils under different land uses in Guangdong Province of China. Iron oxides in these soils were mainly Al-substituted goethites and/or hematites. Independent of the land uses, the percentages of various Cd fractions in the soils decrease in the order of well-crystallized iron oxyhydroxides-associated (27.2-91.2%) > residual (2.1-37.0%) > reducible FeMn oxides (3.2-45.7%) > exchangeable (1.0-28.2%) > organic-associated form (0-5.1%). Pb mainly existes in the residual fraction (25.9-74.5%), followed by crystalline iron oxyhydroxides-associated (0.4-69.0%) and reducible fractions (2.4-40.4%). Zn mainly exists in the residual fraction (25.4-85.9%), followed by the well-crystallized iron oxyhydroxides-associated fraction (6.4-55.0%). However, Cu mainly existes in the residual form and the fractionation of Cu varies obviously between samples. The association of these metals with crystalline iron oxyhydroxides in the soils decreases in the sequence of Cd > Pb > Zn > Cu. These results suggest that in heavy-metal-polluted weathered soils in tropical and subtropical areas enriched with iron oxides, it is essential to assess potential bioavailability and toxicity of heavy metals bound to well-crystallized iron oxyhydroxides with appropriate procedures in the fractionation measurement. The modified Tessier method present here can be used to quantify the fractions of heavy metals in such areas.
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yin
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Nianhao
authors.initials: N
authors.lastname: Tan
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environment and Soil Science, Guangzhou 510650, China.
authors.forename: Chuanping
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Juju
authors.initials: J
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Liang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 210008 Nanjing, China.
authors.forename: Mingkai
authors.initials: M
authors.lastname: Qu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xionghan
authors.initials: X
authors.lastname: Feng
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Guohong
authors.initials: G
authors.lastname: Qiu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Wenfeng
authors.initials: W
authors.lastname: Tan
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: liufan@mail.hzau.edu.cn.
authors.forename: Fan
authors.initials: F
authors.lastname: Liu
mesh_terms: D005591:Chemical Fractionation; D002681:China; D004784:Environmental Monitoring; D005290:Ferric Compounds / Q000032:analysis* / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis* / Q000737:chemistry; D008906:Mining; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D019216:Metals, Heavy; D012989:Soil Pollutants; C000499:ferric oxide
keywords: Iron oxyhydroxides; Metal fraction; Mobility; Selective sequential extraction procedures; Soil pollution