Critical examination of trace element enrichments and depletions in soils: As, Cr, Cu, Ni, Pb, and Zn in Swiss forest soils
Critical examination of trace element enrichments and depletions in soils: As, Cr, Cu, Ni, Pb, and Zn in Swiss forest soils
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DOI：
10.1016/s0048-9697(99)00522-7
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发表时间：
2000-04-17
影响因子：
9.8
通讯作者：
Shotyk, W
中科院分区：
文献类型：
--
作者：
Blaser, P;Zimmermann, S;Shotyk, W
这项研究的目的是获得瑞士森林土壤中微量元素浓度的概述，并根据人为输入和成岩背景对测量值进行批判性评估。选择了23个地点，这些地点代表了瑞士广泛的天然森林地点、基岩材料和土壤类型。在每个地点，从所有成因土层到C或B/C层都收集了样本。用X射线荧光光谱仪测定所有样品中砷、铬、铜、镍、铅、锌的总含量。从最低土层的样品中测得的浓度估计的地质背景值有明显的差异。在花岗岩和片麻岩中，铬和镍的背景浓度最低，而在石灰岩和泥灰岩中，铅和锌的背景浓度最高。以锆为参照物，对微量元素的富集度或贫化率进行了评价。在同一剖面内，6种微量元素随深度的变化表现出完全不同的富/贫化模式。对可能导致这些模式的各种自然过程和人为输入进行了批判性的讨论。基于这一评价，调查的森林土壤中铅和锌的污染最严重，砷和铜的污染程度较小，而人为输入的铬和镍似乎不那么重要。这些数据表明，与使用表层土壤样品的最大允许浓度(MAC)相比，对富集系数的关键评估是评估土壤中微量元素污染的更好工具。按本文所述计算的富集度考虑了地质变化对金属丰度的影响，而MAC则没有。为了获得对土壤溶液浓度的估计，从10个土壤剖面的子集收集的水萃取物被分析了相同的微量元素。各元素的溶解度一般随土壤深度的增加而降低。但腐殖质层中的铬、铜、镍的溶解度低于下伏矿物层。对于所有元素，与富集元素的土壤样品相比，在该元素中枯竭的土壤样品集合的溶解度更高。(C)2000 Elsevier Science B.V.保留所有权利。
The aim of this study was to obtain an overview of trace element concentrations in Swiss forest soils and to critically assess the measured values with respect to anthropogenic input vs, lithogenic background. Twenty-three sites were selected which represent a broad range of natural forest sites, bedrock material and soil types of Switzerland. At each site, samples were collected from all genetic soil horizons down to a C or B/C horizon. Total concentrations of As, Cr, Cu, Ni, Pb, and Zn in all samples were determined by X-ray fluorescence spectrometry. There were distinct differences in the geological background values estimated from the concentrations measured in the samples from the lowest soil horizon. Background concentrations for Cr and Ni were lowest in granite and gneiss, whereas Pb and Zn were highest in limestone and mart. Enrichment or depletion of the trace elements was assessed using Zr as reference element. Within the same profile, the six trace elements showed completely different enrichment/depletion patterns with depth. The various natural processes and anthropogenic inputs that can lead to these patterns are critically discussed. Based on this critical assessment, pollution of the investigated forest soils was found to be most severe for Pb and Zn and to a somewhat lesser extent for As and Cu, whereas anthropogenic input of Cr and Ni seems to be less important. The data suggest that a critical evaluation of enrichment factors is a better tool to assess soil pollution with trace elements than the use of maximum allowable concentrations (MAC) for topsoil samples. The enrichment factors calculated as described here consider the effects of geological variation on metal abundances whereas the MAC does not. In order to obtain an estimate of soil solution concentrations, water extracts of the samples collected from a subset of 10 soil profiles were analyzed for the same trace elements. Solubility of all elements generally decreased with soil depth. An exception was Cr, Cu, and Ni solubility in the humus layer, which was lower than in the underlying mineral horizon. For all elements, solubility was higher for the collective of soil samples depleted in this element when compared to the samples, in which the element was enriched. (C) 2000 Elsevier Science B.V. All rights reserved.