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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• 作者：Carmen Enid Martí ; nez ; Carolina Yá ; ñ ; ez ; Soh-joung Yoon ; Mary Ann Bruns
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：August 1, 2007
• 年：2007
• 卷：41
• 期：15
• 页码：5323 - 5329
• 全文大小：376K
• 年卷期：v.41,no.15(August 1, 2007)
• ISSN：1520-5851

文摘

Spatial relationships between concentrations of Cd, Fe,Mn, S, and Zn and bacterial genes for dissimilatorysulfate reduction were studied in soils of the Manningpeatland region in western New York. Peat cores werecollected within a field exhibiting areas of Zn phytotoxicity,and pH and elemental concentrations were determinedwith depth. The oxidation states of S were estimated usingS-XANES spectroscopy. Soil microbial community DNAwas extracted from peat soils for ribosomal RNA intergenicspacer analysis (RISA) of diversity profiles with depth.To assess the presence of sulfate-reducing microorganisms(SRM), DNA extracts were also used as templates forPCR detection of dsrAB genes coding for dissimilatory (bi)sulfite reductase. Elemental distributions, S redoxspeciation, and detection of dsrAB genes varied withdepth and water content. The pH of peat soils increasedwith depth. The highest concentrations of Zn, Cd, andS occurred at intermediate depths, whereas Mn concentrations were highest in the topmost peat layers. Ironshowed a relatively uniform distribution with depth.Concentrations of redox sensitive elements, S and Mn,but not Fe, seemed to respond to variations in water contentand indicated vertical redox stratification in peat coreswhere topmost peats were typically acidic and oxidizingand deeper peats were typically circumneutral and reducing.Even then, S-XANES analyses showed that surfacepeats contained >50% of the total S in reduced formswhile deep peats contained generally <5% of the total Sin oxidized forms. While bacterial RISA profiles of the peatswere diverse, dsrAB gene detection followed redoxstratification chemistry closely. For the most part, dsrABgenes were detected in deeper peats, where S accumulationwas evident, while they were not detected in topmostpeat layers where Mn accumulation indicated oxic conditions.Combined chemical, spectroscopic, and microbiologicalanalyses indicated that prolonged exposure to dry-wetcycles resulted in the formation of two redox-stratified zoneswith distinct chemical and microbiological signatureswithin peat cores of the Manning peatland region. Asillustrated in this study, changes in redox conditions affectbacterial community composition and downward mobilityof toxic elements, which has implications for watercontamination and the design of metal remediation strategies.