Passive remediation systems (PRS) use both biotic and abiotic processes to precipitate contaminants from abandoned mine drainage (AMD) so that the contaminants do not spread into local watersheds. PRS are efficient at removing heavy metals but sulfate remediation frequently does not occur. To understand the reasons for the lack of sulfate remediation, we studied four PRS that treat circumneutral AMD and one raw mine drainage discharge. Using 16S sequencing analysis, microbial community composition revealed a high relative abundance of bacterial families with sulfur cycling genera. Anaerobic abiotic studies showed that sulfide was quickly geochemically oxidized in the presence of iron hydroxides, leading to a buildup of sulfur intermediates. Supplementation of laboratory grown microbes from the PRS with lactate demonstrated the ability of actively growing microbes to overcome this abiotic sulfide oxidation by increasing the rate of sulfate reduction. Thus, the lack of carbon sources in the PRS contributes to the lack of sulfate remediation. Bacterial community analysis of 16S rRNA gene revealed that while the microbial communities in different parts of the PRS were phylogenetically distinct, the contaminated environments selected for communities that shared similar metabolic capabilities.

中文翻译：

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有限的碳源阻止了周围废弃矿井排水中的硫酸盐修复

被动修复系统（PRS）使用生物过程和非生物过程来从废弃的矿井排水（AMD）中沉淀污染物，以使污染物不会扩散到本地集水区。PRS可以有效去除重金属，但经常不会进行硫酸盐修复。为了了解缺乏硫酸盐修复的原因，我们研究了四种治疗周围性AMD的PRS和一种未处理的矿山排水。使用16S测序分析，微生物群落组成显示具有硫循环属的细菌家族相对较高。厌氧性非生物研究表明，在氢氧化铁的存在下，硫化物迅速被地球化学氧化，从而导致了硫中间产物的积累。从PRS向实验室生长的微生物补充乳酸盐表明，能够通过增加硫酸盐的还原速率来积极生长的微生物克服这种非生物硫化物氧化的能力。因此，PRS中碳源的缺乏导致了硫酸盐修复的缺乏。对16S rRNA基因的细菌群落分析表明，尽管PRS不同部分的微生物群落在系统发育上是不同的，但为具有相似代谢功能的群落选择了受污染的环境。