Labile Cd and Pb in vegetable-growing soils estimated with isotope dilution and chemical extractants
Labile Cd and Pb in vegetable-growing soils estimated with isotope dilution and chemical extractants
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DOI：
10.1016/j.geoderma.2010.10.010
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发表时间：
2011-01-15
期刊：
影响因子：
6.1
通讯作者：
Huang, Yun-Feng
中科院分区：
文献类型：
--
作者：
Huang, Zhi-Yong;Chen, Ting;Huang, Yun-Feng
与化学提取法相比，基于同位素稀释法的E值是评价土壤中易变性重金属的一个明确指标。采用稳定同位素稀释法测定了污染土壤（QZDH和PTHJ）和非污染蔬菜土壤（XMTA）中Cd和Pb的E值，并对E-1（min）进行了分区。基于两种同位素交换动力学（IEK）模型（包括迭代非线性回归和对数-对数线性回归）计算E-1（min-24）（h）和E->24 h值。此外，还采用四种单一化学提取剂和改进的BCR法连续提取法对土壤中活性Cd和Pb库进行了估算。结果表明，除QZDH土壤外，土壤有效态Cd（E-1 min和E1 min-24 h）含量普遍高于EDTA提取态，也高于Sigma（BCR）形态（包括酸提取态、还原态和氧化态）。对于Pb。3种土壤中E-有效值仅高于EDTA提取的各组分（QZDH），而低于Sigma（BCR）。与EDTA提取剂相比，由于Cd、Pb同位素在土壤悬浮液中的固定作用和同位素交换金属的提取不完全，使得用于快速评价土壤中Cd、Pb的生物有效性和植物效应的有效态E可能被高估。(c)2010爱思唯尔有限公司版权所有。
E value, based on isotope dilution method, is considered as an unambiguous index to assess the labile heavy metals in soils compared with the methods of chemical extraction. In the present study, the E values of Cd and Pb in polluted soils (QZDH and PTHJ soils) and non-polluted vegetable-growing soils (XMTA soils) were determined using stable isotope dilution method, and the compartments of E-1 (min). E-1 (min-24) (h) and E->24 h values were calculated based on the two models of isotopic exchange kinetics (IEK) including an iterative nonlinear regression and a log-log linear regression. In addition, the pools of labile Cd and Pb in soils were also estimated with four single chemical extractants and a modified sequential extraction procedure of BCR approach. Results showed that the amounts of Cd in E-available including E-1 min and E1 min-24 h pools were generally higher than those extracted with EDTA, and were also higher than the amounts in Sigma(BCR) fractions (including acid-extractable, reducible and oxidizable fractions) except for QZDH soils. But for Pb. E-available value was only higher than that extracted with EDTA in polluted soils (QZDH), but lower than Sigma(BCR) fractions in the three soils. Compared with the extractant of EDTA, E-available pools of Cd and Pb, which are usually used to rapidly assess the metals' bioavailability and impact on plants in soils, might be overestimated due to the possible fixation of the spiked isotopes in soil suspensions and the incompletely extraction of isotopically exchanged metals in E measurement. (c) 2010 Elsevier B.V. All rights reserved.