Biogeochemistry of metalliferous peats:: Sulfur speciation and depth distributions of dsrAB genes and Cd, Fe, Mn, S, and Zn in soil cores
Biogeochemistry of metalliferous peats:: Sulfur speciation and depth distributions of dsrAB genes and Cd, Fe, Mn, S, and Zn in soil cores
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DOI：
10.1021/es070555v
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发表时间：
2007-08-01
影响因子：
11.4
通讯作者：
Bruns, Mary Ann
中科院分区：
文献类型：
--
作者：
Martinez, Carmen Enid;Yanez, Carolina;Bruns, Mary Ann
在纽约西部曼宁泥炭地地区的土壤中研究了镉、铁、锰、硫和锌浓度与异化硫酸盐还原细菌基因之间的空间关系。在表现出锌植物毒性的区域内收集泥炭核心，并根据深度确定 pH 值和元素浓度。使用 S-XANES 光谱估计 S 的氧化态。从泥炭土中提取土壤微生物群落 DNA，用于深度多样性谱的核糖体 RNA 基因间间隔区分析 (RISA)。为了评估硫酸盐还原微生物 (SRM) 的存在，还使用 DNA 提取物作为模板，对编码异化亚硫酸盐还原酶的 dsrAB 基因进行 PCR 检测。元素分布、S 氧化还原形态和 dsrAB 基因检测随深度和含水量的变化而变化。泥炭土的 pH 值随着深度的增加而增加。 Zn、Cd 和 S 的最高浓度出现在中间深度，而 Mn 的浓度最高出现在最上面的泥炭层。铁随深度呈现出相对均匀的分布。氧化还原敏感元素 S 和 Mn（而非 Fe）的浓度似乎对含水量的变化做出响应，并表明泥炭核心存在垂直氧化还原分层，其中最上面的泥炭通常呈酸性和氧化性，而较深的泥炭通常呈中性和还原性。即便如此，S-XANES 分析表明，表层泥炭含有 > 50% 的还原形式总硫，而深层泥炭通常含有 < 5% 的氧化形式总硫。虽然泥炭的细菌 RISA 谱多种多样，但 dsrAB 基因检测密切遵循氧化还原分层化学。大多数情况下，dsrAB 基因在较深的泥炭层中检测到，其中硫积累明显，而在最顶层的泥炭层中未检测到，其中锰积累表明有氧条件。综合化学、光谱和微生物分析表明，长期暴露于干湿循环导致曼宁泥炭地地区泥炭核心内形成两个具有不同化学和微生物特征的氧化还原分层区域。正如本研究所示，氧化还原条件的变化会影响细菌群落组成和有毒元素的向下流动，这对水污染和金属修复策略的设计具有影响。
Spatial relationships between concentrations of Cd, Fe, Mn, S, and Zn and bacterial genes for dissimilatory sulfate reduction were studied in soils of the Manning peatland region in western New York. Peat cores were collected within a field exhibiting areas of Zn phytotoxicity, and pH and elemental concentrations were determined with depth. The oxidation states of S were estimated using S-XANES spectroscopy. Soil microbial community DNA was extracted from peat soils for ribosomal RNA intergenic spacer analysis (RISA) of diversity profiles with depth. To assess the presence of sulfate-reducing microorganisms (SRM), DNA extracts were also used as templates for PCR detection of dsrAB genes coding for dissimilatory (bi)sulfite reductase. Elemental distributions, S redox speciation, and detection of dsrAB genes varied with depth and water content. The pH of peat soils increased with depth. The highest concentrations of Zn, Cd, and S occurred at intermediate depths, whereas Mn concentra tions were highest in the topmost peat layers. Iron showed a relatively uniform distribution with depth. Concentrations of redox sensitive elements, S and Mn, but not Fe, seemed to respond to variations in water content and indicated vertical redox stratification in peat cores where topmost peats were typically acidic and oxidizing and deeper peats were typically circumneutral and reducing. Even then, S-XANES analyses showed that surface peats contained > 50% of the total S in reduced forms while deep peats contained generally < 5% of the total S in oxidized forms. While bacterial RISA profiles of the peats were diverse, dsrAB gene detection followed redox stratification chemistry closely. For the most part, dsrAB genes were detected in deeper peats, where S accumulation was evident, while they were not detected in topmost peat layers where Mn accumulation indicated oxic conditions. Combined chemical, spectroscopic, and microbiological analyses indicated that prolonged exposure to dry-wet cycles resulted in the formation of two redox-stratified zones with distinct chemical and microbiological signatures within peat cores of the Manning peatland region. As illustrated in this study, changes in redox conditions affect bacterial community composition and downward mobility of toxic elements, which has implications for water contamination and the design of metal remediation strategies.