Arsenic fractionation in soils using an improved sequential extraction procedure
Arsenic fractionation in soils using an improved sequential extraction procedure
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DOI：
10.1016/s0003-2670(01)00924-2
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发表时间：
2001-06-12
影响因子：
6.2
通讯作者：
Adriano, DC
中科院分区：
文献类型：
--
作者：
Wenzel, WW;Kirchbaumer, N;Adriano, DC
污染物的风险评估需要简单且有意义的工具，以获取土壤中不同活性和生物可利用性的污染物库的信息。我们通过选择常用于金属、硒和磷顺序提取的提取试剂，开发并测试了一种砷的顺序提取程序（SEP）。对已用于磷和金属顺序提取程序中的替代提取剂（包括硝酸铵、醋酸钠、盐酸羟胺、乙二胺四乙酸、氢氧化铵和氟化铵）进行的测试表明，它们要么对砷的提取效率很低，要么对目标相的选择性或特异性不足。最终得到的顺序包括以下五个提取步骤：（1）0.05 M硫酸铵，20℃/4小时；（2）0.05 M磷酸二氢铵，20℃/16小时；（3）0.2 M草酸铵缓冲液（避光，pH 3.25），20℃/4小时；（4）0.2 M草酸铵缓冲液 + 抗坏血酸（pH 3.25），96℃/0.5小时；（5）硝酸/过氧化氢微波消解。在化学分馏的固有局限性内，这些砷的组分似乎主要与（1）非特异性吸附；（2）特异性吸附；（3）铁和铝的无定形和结晶不良的水合氧化物；（4）铁和铝的结晶良好的水合氧化物；以及（5）残余相相关。这种解释得到了对土壤和纯矿物相的选择性和特异性测试以及对选定土壤中砷的能量色散X射线微分析（EDXMA）的支持。在20种土壤中，砷在这五个组分中的分配情况（%，中位数和范围）为：（1）0.24（0.02 - 3.8）；（2）9.5（2.6 - 25）；（3）42.3（12 - 73）；（4）29.2（13 - 39）；以及（5）17.5（1.1 - 38）。改进后的顺序提取程序在常规土壤分析中易于应用，从重复性（w≥0.98）和回收率测试来看是可靠的。该顺序提取程序可用于预测由于土壤修复或环境因素改变而导致的各种固相砷活性的变化。（C）2001 Elsevier Science B.V.保留所有权利。
Risk assessment of contaminants requires simple, meaningful tools to obtain information on contaminant pools of differential lability and bioavailability in the soil. We developed and tested a sequential extraction procedure (SEP) for As by choosing extraction reagents commonly used for sequential extraction of metals, Se and P. Tests with alternative extractants that have been used in SEPs for P and metals, including NH4NO3, NaOAc, NH2OH . HCl, EDTA, NH4OH and NH4F were shown to either have only low extraction efficiency for As, or to be insufficiently selective or specific for the phases targeted. The final sequence obtained includes the following five extraction steps: (1) 0.05 M (NH4)(2)SO4, 20 degreesC/4 h; (2) 0.05 M NH4H2PO4, 20 degreesC/16 h; (3) 0.2 M NH4+-oxalate buffer in the dark, pH 3.25, 20 degreesC/4h; (4) 0.2 M NH4+-oxalate buffer + ascorbic acid, pH 3.25, 96 degreesC/0.5 h; (5) HNO3/H2O2 microwave digestion. Within the inherent limitations of chemical fractionation, these As fractions appear to be primarily associated with (1) non-specifically sorbed; (2) specifically-sorbed; (3) amorphous and poorly-crystalline hydrous oxides of Fe and Al; (4) well-crystallized hydrous oxides of Fe and Al; and (5) residual phases. This interpretation is supported by selectivity and specificity tests on soils and pure mineral phases, and by energy dispersive X-ray microanalysis (EDXMA) of As in selected soils. Partitioning of As among these five fractions in 20 soils was (%, medians and ranges): (1) 0.24 (0.02-3.8); (2) 9.5 (2.6-25); (3) 42.3 (12-73); (4) 29.2 (13-39); and(5) 17.5 (1.1-38). The modified SEP is easily adaptable in routine soil analysis, is dependable as indicated by repeatability (w greater than or equal to 0.98) and recovery tests. This SEP can be useful in predicting the changes in the lability of As in various solid phases as a result of soil remediation or alteration in environmental factors. (C) 2001 Elsevier Science B.V. All rights reserved.