Selective adsorption of dissolved organic matter to mineral soils
Selective adsorption of dissolved organic matter to mineral soils
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DOI：
10.1016/j.geoderma.2012.07.001
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发表时间：
2012-11-01
期刊：
影响因子：
6.1
通讯作者：
Moore, T. R.
中科院分区：
文献类型：
--
作者：
Kothawala, D. N.;Roehm, C.;Moore, T. R.
当土壤溶液通过森林矿物土壤时，溶解有机碳（DOC）的化学和结构组成会由于与土壤颗粒表面的相互作用而发生实质性变化。通常，吸附过程在矿质土壤中占主导地位，DOC的浓度大幅降低。我们研究了DOC的分子和结构组成的变化，在平衡过程中与加拿大各地收集的矿质土壤（n = 43），发现DOC的整体芳香族含量下降，几乎在所有情况下，从使用特定的吸光度（苏瓦）和荧光指数的平衡。荧光指数显示，灰化B层，具有典型的大吸附容量（Qmax），具有最大的芳香性，这是部分解释了低得多的芳香含量的DOC解吸从土壤表面的减少。与此相反，DOC芳香性火山B层，也具有高Qmax的减少，主要是由于吸附。一个意想不到的发现是，在使用高效体积排阻色谱法（HPLC）平衡过程中，淋溶土和灰壤分别释放出极高（2.6 × 10（6）Da）和极低（420 Da）分子量（MW）的有机物质。在一般情况下，DOC的平均数均MW（M-N）下降的所有土壤类型，但在M-N的最大降幅观察到的矿物土壤具有大的Qmax，包括灰化和火山B层。FUR光谱的变化分析表明，DOC官能团的最突出的变化是羧基的减少，这甚至大于芳香族DOC的去除。本研究的结果强调，虽然DOC浓度可能会大幅下降，通过矿质土壤的通道，它是有价值的，考虑DOC的贡献，从解吸预先存在的土壤C。这项研究的结果至关重要的是包括多种分析技术来跟踪DOC特性的变化，并包括广泛的矿质土壤。(C)2012爱思唯尔有限公司版权所有。
As soil solutions pass through forested mineral soils, the chemical and structural compositions of dissolved organic carbon (DOC) can alter substantially due to interactions with soil particle surfaces. Typically, adsorption processes dominate in mineral soils and the resulting concentration of DOC is reduced substantially. We studied changes in the molecular and structural compositions of DOC during equilibration with mineral soils collected across Canada (n = 43) and found that the overall aromatic content of DOC decreased with equilibration in almost all cases from using specific absorbance (SUVA) and the fluorescence index. The fluorescence index revealed that podzolic B horizons, with typically large adsorption capacity (Qmax), had the greatest reduction in aromaticity, which was partially explained by the much lower aromatic content of DOC desorbed from soils surfaces. In contrast, a decrease in DOC aromaticity for volcanic B horizons, also with high Qmax, was primarily due to adsorption. An unexpected finding was the release of extremely high (2.6 x 10(6) Da) and low (420 Da) molecular weight (MW) organic materials during equilibration using high performance size exclusion chromatography (HPLC), for luvisols and podzols, respectively. In general, the average number-average MW (M-n) of DOC decreased for all soil types, but the greatest decrease in M-n was observed for mineral soils with large Qmax, including the podzolic and volcanic B horizons. Analysis of changes in FUR spectra revealed that the most prominent change to DOC functional groups was a reduction in carboxyl groups, which was even greater than the removal of aromatic DOC. The findings of this study emphasize that while DOC concentrations may decrease substantially during passage through mineral soils, it is valuable to consider the contribution of DOC from desorption of pre-existing soil C. Essential to the findings of this study was the inclusion of multiple analytical techniques to track changes to DOC character, and the inclusion of a wide range of mineral soils. (C) 2012 Elsevier B.V. All rights reserved.