The effect of microbial sulfidogenesis on the stability of As-Fe coprecipitate with low Fe/As molar ratio under anaerobic conditions
The effect of microbial sulfidogenesis on the stability of As-Fe coprecipitate with low Fe/As molar ratio under anaerobic conditions
复制标题
厌氧条件下微生物硫化作用对低Fe/As摩尔比As-Fe共沉淀物稳定性的影响
DOI：
10.1007/s11356-015-5927-z
复制
发表时间：
2016
影响因子：
5.8
通讯作者：
Jia Yongfeng
中科院分区：
文献类型：
--
作者：
Wang Shaofeng;He Xin Yu;Pan Rongrong;Xu Liying;Wang Xin;Jia Yongfeng
在低Fe/As比的固相中，微生物硫化作用对As转化和活化的影响还不清楚。本研究采用化学萃取法和K边XANES法研究了不同硫酸盐含量的砷铁共沉淀物中砷的微生物转化和活化。结果表明，约2.7%，24.4%，和83.7%的总砷释放到水相中，分别在低，中，高硫酸盐处理，表明大量硫酸盐的存在下，可以提高微生物砷动员在砷铁共沉淀。在低硫酸盐处理中，As的迁移主要是由于Fe（OH）2的还原溶解和As的还原解吸。在中、高浓度硫酸盐处理下，砷酸盐和三价铁的还原作用显著增强。在固相中观察到完全的三价铁还原，这意味着Fe（氧）氢氧化物转化为次生矿物，可能是增强As动员的主要原因之一。根据溶解的As（III）和S（−II）的浓度，热力学计算预测在孵育35天后会形成硫代亚砷酸盐。由于硫代砷物种是更移动的，它的形成可能是最重要的因素之一，提高在高硫酸盐系统中的砷释放。研究结果对全面预测缺氧条件下微生物硫化作用下As与Fe（OH）2的环境行为具有重要意义。
The effect of microbial sulfidogenesis on As transformation and mobilization in solid phase with low Fe/As ratio is still not well known. In this study, microbial transformation and mobilization of As in the As–Fe coprecipitate with different sulfate levels were investigated using chemical extraction and K-edge XANES of As and S. Results showed that approximately 2.7, 24.4, and 83.7 % of total As were released into the aqueous phase in the low-, mid-, and high-sulfate treatments, respectively, indicating that the presence of large amounts of sulfate could enhance microbial arsenic mobilization in the As–Fe coprecipitate. In the low-sulfate treatment, As mobilization was primarily attributed to the reductive dissolution of the Fe (oxy)hydroxides and the As reduction and desorption. In the mid- and high-sulfate treatments, the reduction of arsenate and ferric iron was significantly enhanced. Complete ferric iron reduction was observed in the solid phase, implying that Fe (oxy)hydroxide was transformed to secondary minerals and may be the one of the primary causes for the enhanced As mobilization. Thermodynamic calculations predicted the formation of thioarsenite species after 35 days of incubation based on the concentration of dissolved As(III) and S(−II). Since thioarsenic species is more mobile, its formation may be one of the most important factors enhancing the As release in the high-sulfate system. The result of this study is of significance to completely predict the environmental behavior of As associated with Fe (hydr)oxides in the presence of microbial sulfidogenesis under anoxic conditions.