Microbial Engineering of Floc Fe and Trace Element Geochemistry in a Circumneutral, Remote Lake

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• 作者：Amy V. C. Elliott ; Lesley A. Warren
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 17, 2014
• 年：2014
• 卷：48
• 期：12
• 页码：6578-6587
• 全文大小：444K
• 年卷期：v.48,no.12(June 17, 2014)
• ISSN：1520-5851

文摘

Evaluation of lacustrine floc Fe, Pb, and Cd biogeochemistry over seasonal (summer, winter) and water column depth (metalimnetic, hypolimnetic) scales reveals depth-independent seasonally significant differences in floc Fe biominerals and trace element (TE: Pb, Cd) sequestration, driven by floc microbial community shifts. Winter floc [TE] were significantly lower than summer [TE], driven by declining abundance and reactivity of floc amorphous Fe^(III)-(oxy)hydroxide (FeOOH) phases under ice ([FeOOH]^summer = 37鈥?7 mgg^鈥? vs [FeOOH]^winter = 0.3鈥? mgg^鈥?). Further, while high summer floc [FeOOH] was observed at both water column depths, winter floc was dominated by Fe^(II) phases. However, the observed seasonal change in the nature and concentrations of floc Fe-phases was independent of water column [Fe], O₂, and pH and, instead, significantly correlated to floc bacterial community membership. Bioinformatic modeling (Unifrac, PCA analyses) of in situ and experimental microcosm results identified a temperature-driven seasonal turnover of floc microbial communities, shifting from dominantly putative Fe metabolisms within summer floc to wintertime ancillary Fe reducing and S metabolizing bacteria. This seasonal shift of floc microbial community functioning, significantly the wintertime loss of microbial Fe^(II)-oxidizing capability and concomitant increases of sulfur-reducing bacteria, alters dominant floc Fe minerals from Fe^(III) to Fe^(II) phases. This resulted in decreased winter floc [TE], not predicted by water column geochemistry.