Department of Soil & Environmental Sciences, National Chung Hsing University, Taichung, TW 40227, Taiwan, ROC.
Chemosphere. 2012 May;87(6):587-94. doi: 10.1016/j.chemosphere.2012.01.010. Epub 2012 Feb 4.
Humic substances are a major component of soil organic matter that influence the behavior and fate of heavy metals such as Cr(VI), a toxic and carcinogenic element. In the study, a repetitive extraction technique was used to fractionate humic acids (HAs) from a peat soil into three fractions (denoted as F1, F2, and F3), and the relative importance of O-containing aromatic and aliphatic domains in humic substances for scavenging Cr(VI) was addressed at pH 1. Spectroscopic analyses indicated that the concentrations of aromatic C and O-containing functional groups decreased with a progressive extraction as follows: F1>F2>F3. Cr(VI) removal by HA proceeded slowly, but it was enhanced when light was applied due to the production of efficient reductants, such as superoxide radical and H(2)O(2), for Cr(VI). Higher aromatic- and O-containing F1 fraction exhibited a greater efficiency for Cr(VI) reduction (with a removal rate of ca. 2.89 mmol g(-1) HA under illumination for 3 h). (13)C NMR and FTIR spectra further demonstrated that the carboxyl groups were primarily responsible for Cr(VI) reduction. This study implied the mobility and fate of Cr(VI) would be greatly inhibited in the environments containing such organic groups.
腐殖质是土壤有机质的主要组成部分，会影响 Cr(VI) 等重金属的行为和归宿，Cr(VI) 是一种有毒和致癌元素。在研究中，采用重复提取技术将泥炭土中的腐殖酸（HA）分为三个部分（分别表示为 F1、F2 和 F3），并在 pH 值为 1 时探讨了腐殖质中含 O 的芳族和脂肪族结构域对 Cr(VI) 的清除作用。光谱分析表明，随着提取的进行，芳族 C 和含 O 官能团的浓度逐渐降低，如下所示：F1>F2>F3。HA 对 Cr(VI) 的去除过程缓慢，但由于产生了有效的还原剂，如超氧自由基和 H(2)O(2)，光照会增强 Cr(VI) 的去除。具有较高芳族和含 O 的 F1 部分对 Cr(VI)的还原效率更高（在光照 3 小时下，约有 2.89 mmol g(-1) HA 的去除率）。(13)C NMR 和 FTIR 光谱进一步表明，羧基主要负责 Cr(VI)的还原。这项研究表明，在含有此类有机基团的环境中，Cr(VI)的迁移和归宿将受到极大抑制。
