Thallium speciation and extractability in a thallium- and arsenic-rich soil developed from mineralized carbonate rock.
Thallium speciation and extractability in a thallium- and arsenic-rich soil developed from mineralized carbonate rock.
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DOI：
10.1021/acs.est.5b00629
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发表时间：
2015-04
影响因子：
11.4
通讯作者：
A. Voegelin;Numa Pfenninger;Julia Petrikis;J. Majzlan;M. Plötze;A. Senn;S. Mangold;R. Steininger
中科院分区：
文献类型：
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作者：
A. Voegelin;Numa Pfenninger;Julia Petrikis;J. Majzlan;M. Plötze;A. Senn;S. Mangold;R. Steininger
研究了矿化碳酸盐岩发育的土壤中铊的形态和可提取性。在受影响最严重的地区，观察到表土（0-20厘米）中铊的总浓度为100-1000毫克/千克，在含有风化矿石碎片的土层中，底土中铊的浓度高达6000毫克/千克。利用同步加速器微聚焦X射线荧光光谱（μ-XRF）和X射线吸收光谱（μ-XAS）在T1 L3-边缘，部分T1（I）取代的黄钾铁矾和铁钒镁矾（Tl 2 O3）被鉴定为含T1次生矿物，由Tl-As-Fe-硫化物矿化风化形成，该矿化位于土壤发育的碳酸盐岩中。进一步的证据被发现为螯合的Tl（III）到锰氧化物和伊利石的Tl（I）的吸收。基于XAS的大量样品中Tl（III）、Tl（I）-黄钾铁矾和Tl（I）-伊利石的组分的定量表明，伊利石对Tl（I）的吸收是表土材料中主要的保留机制。氧化铊（III）吸收到锰氧化物是不太相关的，可能是因为铊负荷的土壤超过了这种吸收机制的能力。在10 mM的氯化钙提取物中的Tl的浓度增加，增加土壤Tl含量和降低土壤pH值，但没有表现出激烈的变化作为一个功能的Tl形态。对于污染土壤中的铊，本研究提供了第一个直接的光谱证据的伊利石吸收的铊（I），并指出需要进一步研究的吸附铊的粘土矿物和锰氧化物及其对铊在土壤中的溶解度的影响。
We investigated the speciation and extractability of Tl in soil developed from mineralized carbonate rock. Total Tl concentrations in topsoil (0-20 cm) of 100-1000 mg/kg are observed in the most affected area, subsoil concentrations of up to 6000 mg/kg Tl in soil horizons containing weathered ore fragments. Using synchrotron-based microfocused X-ray fluorescence spectrometry (μ-XRF) and X-ray absorption spectroscopy (μ-XAS) at the Tl L3-edge, partly Tl(I)-substituted jarosite and avicennite (Tl2O3) were identified as Tl-bearing secondary minerals formed by the weathering of a Tl-As-Fe-sulfide mineralization hosted in the carbonate rock from which the soil developed. Further evidence was found for the sequestration of Tl(III) into Mn-oxides and the uptake of Tl(I) by illite. Quantification of the fractions of Tl(III), Tl(I)-jarosite and Tl(I)-illite in bulk samples based on XAS indicated that Tl(I) uptake by illite was the dominant retention mechanism in topsoil materials. Oxidative Tl(III)uptake into Mn-oxides was less relevant, probably because the Tl loadings of the soil exceeded the capacity of this uptake mechanism. The concentrations of Tl in 10 mM CaCl2-extracts increased with increasing soil Tl contents and decreasing soil pH, but did not exhibit drastic variations as a function of Tl speciation. With respect to Tl in contaminated soils, this study provides first direct spectroscopic evidence for Tl(I) uptake by illite and indicates the need for further studies on the sorption of Tl to clay minerals and Mn-oxides and its impact on Tl solubility in soils.