We characterized the sulfur geochemistry and microbial community structure of seven circumneutral wastewaters from two Canadian nickel mines collected in summer, winter, and spring, in 2014 and 2015. We also established and characterized sulfur oxidizing enrichments for these wastewater samples in two pH corrals of 7–5 and 5–3. Mine 1 exhibited lower contents of total soluble sulfur compounds and reactive soluble sulfur compounds (oxidation state < + VI) relative to Mine 2. Mine 1 also exhibited greater wastewater microbial community diversity with more unique sequences than Mine 2, resulting in clear NMDS differentiation and Bray–Curtis dissimilarity between the two mines’ microbial communities. Proteobacteria dominated all wastewater samples and enrichment communities, ranging between 58–99% of the total of sequences retrieved from the corresponding samples. However, a shift in dominance occurred from primarily Alphaproteobacteria (28–77%) in the circumneutral wastewater communities to Gammaproteobacteria (> 80%) in the moderately acidic enrichment communities. A further pH dependent shift occurred from Halothiobacillus spp. dominating the pH 7–5 enrichments to Thiomonas spp. dominating the pH 5–3 enrichments. These results provide putative biological indicators for better prediction and management of sulfur processes and AMD onset in mining wastewaters.

中文翻译：

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微生物演替标志着采矿废水酸化的开始

我们对 2014 年和 2015 年夏季、冬季和春季收集的来自两个加拿大镍矿的七种环中性废水的硫地球化学和微生物群落结构进行了表征。我们还在两个 pH 值为 7 的畜栏中建立并表征了这些废水样品的硫氧化富集–5 和 5–3。与矿 2 相比，矿 1 的总可溶性硫化合物和反应性可溶性硫化合物（氧化态 < + VI）的含量较低。 与矿 2 相比，矿 1 还表现出更大的废水微生物群落多样性和更独特的序列，导致明显的 NMDS 分化和两个矿山微生物群落之间的布雷-柯蒂斯差异。变形菌在所有废水样本和富集群落中占主导地位，范围在从相应样本中检索到的序列总数的 58-99% 之间。然而，优势发生了从环绕中性废水群落中的主要 Alphaproteobacteria (28-77%) 到中等酸性富集群落中的 Gammaproteobacteria (> 80%) 的转变。Halothiobacillus spp 发生了进一步的 pH 依赖性变化。控制硫单胞菌属的 pH 7-5 富集。主导 pH 5-3 的富集。这些结果为更好地预测和管理采矿废水中的硫过程和 AMD 发生提供了推定的生物指标。Halothiobacillus spp 发生了进一步的 pH 依赖性变化。控制硫单胞菌属的 pH 7-5 富集。主导 pH 5-3 的富集。这些结果为更好地预测和管理采矿废水中的硫过程和 AMD 发生提供了推定的生物指标。Halothiobacillus spp 发生了进一步的 pH 依赖性变化。控制硫单胞菌属的 pH 7-5 富集。主导 pH 5-3 的富集。这些结果为更好地预测和管理采矿废水中的硫过程和 AMD 发生提供了推定的生物指标。