| 硫酸盐还原菌介导的吸附态砷的迁移转化 |
| 摘要点击 1658 全文点击 583 投稿时间：2018-06-11 修订日期：2018-07-17 |
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| 中文关键词 Desulfovibrio vulgaris DP4 吸附态砷 迁移转化 针铁矿 原位还原 硫酸盐还原菌 |
| 英文关键词 Desulfovibrio vulgaris DP4 adsorbed arsenic transformation goethite in situ reduction sulfate reducing bacteria(SRB) |
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| 中文摘要 |
| 自然界中砷（As）主要被吸附在铁氧矿物上，吸附态砷从铁氧矿物释放至水体是水中砷污染的主要来源.在此过程中，微生物起着至关重要的作用.本研究的目的是探究加入硫酸盐还原菌Desulfovibrio vulgaris DP4对吸附态砷迁移转化的影响.结果表明，0 h两体系砷释放量均为0 μmol·L-1.与对照组相比，前84 h DP4促进了吸附态五价砷[As（Ⅴ）]的脱附，在13 h砷的释放量达到最大值12.6 μmol·L-1，占初始总吸附量（16 μmol·L-1）的79%，是对照组（1.5 μmol·L-1）的8.4倍.而在84 h之后，DP4体系的砷浓度低于非生物对照组，表明溶解态砷被再次固定.此过程中，砷的释放量与氧化还原电位（Eh）显著相关（P=0.001）.XRD结果表明，在DP4作用下针铁矿的结晶度降低了50%，且结晶度越低，吸附能力越强，这可能是后期砷被再次固定的原因之一.同时SEM-EDS表明DP4使得针铁矿发生团聚，部分被转化为硫铁矿.As的XANES结果表明固相中没有硫化砷生成，这进一步证明固相中生成的主要是硫铁矿，它对砷的再吸附导致了后期DP4体系中溶解态砷的浓度低于非生物对照组.此外，在固相中检测出了19%的As（Ⅲ），而液相中并未检测出溶解态的As（Ⅲ），据此推测硫酸盐还原菌原位还原了吸附态As（Ⅴ）. |
| 英文摘要 |
| In the natural environment, arsenic (As) is mainly adsorbed on iron oxide minerals. The release of adsorbed arsenic from iron oxide minerals to the water is the main source of arsenic pollution. Microbes play a crucial role for this process. The purpose of this study was to investigate the effect of the sulfate-reducing bacteria Desulfovibrio vulgaris DP4 on the transformation and mobilization of As. The experimental results show that the released As concentration of the two systems is 0 μmol·L-1 at 0 h. Compared with the control, DP4 promotes the desorption of As(Ⅴ) before the 84 h incubation process. The released As concentration reaches the maximum value of 12.6 μmol·L-1 at 13 h, accounting for~79% of the initial total adsorbed As (16 μmol·L-1). The maximum released As concentration is~8.4 times higher than that of the control (1.5 μmol·L-1). After 84 hours, the concentration of the released As in the DP4 system is lower than the abiotic control, which suggests that the released As is readsorbed on the solid surface. During the incubation process, the As mobility is significantly correlated with Eh. The XRD results show that the crystallinity of the solid samples in the DP4 system decreases by~50%. In general, a lower crystallinity of the adsorbent indicates a higher adsorption capacity. This may be one important reason for the As readsorption after 84 h. In addition, the SEM shows that goethite is agglomerated by DP4 and the EDS results indicate that goethite is partially transformed to an Fe-S mineral. Based on XANES, arsenic-sulfur minerals were not detected in the solid phase, which further confirms the SEM-EDS results, that is, that Fe-S minerals formed in the solid phase, rather than As2S3 (AsS). The released As was readsorbed on the secondary iron mineral, resulting in a lower dissolved As concentration in the DP4 system than in the abiotic control. Furthermore, 19% As(Ⅲ) was detected in the solid phase while dissolved As(Ⅲ) was not determined during the incubation process. The results suggest that sulfate-reducing bacteria may directly reduce adsorbed As(Ⅴ) to As(Ⅲ). |
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