Fan Chun-hui, Zhang Ying-chao, Wang Jia-hong
Guang Pu Xue Yu Guang Pu Fen Xi. 2015 Feb;35(2):534-8.
The soil contamination of heavy metals, from the areas of mine, highway, industrial area, agricultural land and so on, is nowadays a serious issue all over the world. The contamination of heavy metals in large agricultural area might lead to the decrease of products quality and economic value. Actually, the accumulation amount of heavy metals by crops is much more related to the activated speciation, which is exchangeable and able to transform to the forms of carbonates, Fe-Mn oxides, organic matter and residual. Thus, the investigation to reveal the transformation mechanism of heavy metals caused by soil conditions might be appropriate to reduce the contaminated risk to crops. The vermicular red soil from the agricultural area of central China was used as sample in the paper, and the Tessier Sequential Extraction Procedure-atomic absorption spectroscopy (AAS) was applied to discuss the chemical speciation and non-biological transformation mechanism of Pb at different conditions. The results showed: the total amount of Pb is 32.56 mg x kg(-1), lower than the first level of the State Environmental Quality Standard for Soils. The Pb content of different speciation, with decreased concentration, is residual (54.55% of total Pb content), bound to Fe-Mn oxides, bound to organic matter, bound to carbonates and exchangeable. The pH value of red soil is related to the charge amount on surface of inorganic colloids and organic matter, and the water content of red soil would change the redox potential, effective for the variation of chemical speciation of Pb. The environmental factors of straw dosage and aging time could change Pb speciation, with Pb concentration of residual form the highest. The Muller index of Igeo is 0.3025, indicating the contribution of human activities. The Tessier Sequential Extraction Procedure-AAS is effective for the non-biological transformation mechanism identification of Pb speciation in red soil.
来自矿区、公路、工业区、农田等区域的重金属土壤污染，如今是全球范围内的一个严峻问题。大面积农业区域的重金属污染可能导致农产品质量和经济价值下降。实际上，作物对重金属的累积量与活性形态密切相关，活性形态即可交换态，且能够转化为碳酸盐、铁锰氧化物、有机质和残渣态。因此，开展调查以揭示土壤条件导致的重金属转化机制，可能有助于降低作物受污染风险。本文以华中农业区域的蠕虫状红壤为样本，采用Tessier连续提取法 - 原子吸收光谱法（AAS）来探讨不同条件下铅的化学形态及非生物转化机制。结果表明：铅的总量为32.56 mg x kg(-1)，低于国家土壤环境质量标准一级标准。不同形态铅的含量，按浓度递减依次为残渣态（占总铅含量的54.55%）、铁锰氧化物结合态、有机质结合态、碳酸盐结合态和可交换态。红壤的pH值与无机胶体和有机质表面的电荷量有关，红壤的含水量会改变氧化还原电位，对铅化学形态的变化有影响。秸秆用量和老化时间等环境因素能够改变铅的形态，其中残渣态铅的浓度最高。地积累指数Igeo为0.3025，表明存在人类活动的影响。Tessier连续提取法 - AAS对于红壤中铅形态的非生物转化机制识别是有效的。
