Biological sulfate reduction in an epigene karst aquifer and its impact on cave environment
Biological sulfate reduction in an epigene karst aquifer and its impact on cave environment
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DOI：
10.1016/j.jhydrol.2021.126804
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发表时间：
2021-11
影响因子：
6.4
通讯作者：
F. Guo;G. Jiang;Fan Liu
中科院分区：
文献类型：
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作者：
F. Guo;G. Jiang;Fan Liu
岩溶含水层中人为活动产生的外源硫酸盐不仅对地下水造成污染，硫酸盐的还原产物还可能酸化洞穴环境。然而，研究还没有探索在低温下纯石灰岩含水层中是否会发生硫酸盐还原。在本研究中，观察到地下水硫酸盐浓度高（高达131 mg/L），并不规则地分布在洞外，而它下降到较低的值，平均为3.96 mg/L的洞穴内。受岩溶发育的非均质性和水文条件的影响，地下水环境呈氧化或还原状态，在溶洞饱和带具有较强的还原性，氧化还原电位（ORP）介于−99 mV ~ −344 mV之间。微生物群落分析表明，厌氧细菌的存在，特别是硫酸盐还原菌（SRB）是普遍存在于地下水。一般来说，H2S可以在洞穴内的地下水位检测到，可能的值范围为0.056至0.444 mg/m3。本研究结果表明，硫酸盐还原发生在表生岩溶含水层中的SRB的存在下，具体。岩溶发育和水文条件的差异，以及洞穴环境中污染物的日益富集，是研究地点水化学和硫酸盐还原强度差异的原因。H2S挥发进入洞壁水分中，促使H2S氧化成H2SO 4，进而参与碳酸盐的溶解，对洞穴遗址文物造成破坏。本研究的结果有助于提高认识的H2S生产在表生岩溶含水层和洞穴遗址的管理策略提供科学支持。
Exogenous sulfate (produced by anthropogenic activities) in karst aquifer does not only induce groundwater pollution, reduction products of sulfate may also acid cave environment. However, studies have not explored whether sulfate reduction can occur in pure limestone aquifer under low temperature. In this study, it was observed that sulfate concentrations of groundwater were high (up to 131 mg/L) and irregularly distributed outside the cave, while it dropped to low values of 3.96 mg/L on average inside the cave. Influenced by the heterogeneity of karst development and hydrological conditions, the groundwater environment exhibited oxidation or reduction, and had a strong reducing condition in the saturation zone of the cave, with the oxidation–reduction potential (ORP) ranging from −99 mV to −344 mV. Microbial community analysis revealed the presence of anaerobic bacteria; in particular, sulfate reducing bacteria (SRB) was prevalent in the groundwater. Generally, H2S could be detected at the groundwater table inside the cave, with possible values ranging from 0.056 to 0.444 mg/m3. The findings of this study revealed that sulfate reduction occurred specifically in the epigene karst aquifer in the presence of SRB. The difference in karst development and hydrological conditions, as well as the increasing contaminant enrichment of the cave environment, are the adduced reasons for the difference in water chemistry and the strength of sulfate reduction in the study site. The volatilization of H2S into the moisture on the cave wall precipitated the oxidation of H2S to H2SO4, which then participated in carbonate dissolution, inducing damage to cultural relics from the cave site. The results of this study have contributed to enhancement of knowledge on H2S production in epigene karst aquifers and provided scientific support to management strategies in cave sites.