Cable bacteria activity and impacts in Fe and Mn depleted carbonate sediments
Cable bacteria activity and impacts in Fe and Mn depleted carbonate sediments
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DOI：
10.1016/j.marchem.2022.104176
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发表时间：
2022-10-20
期刊：
影响因子：
3
通讯作者：
Zhu，Qingzhi
中科院分区：
文献类型：
--
作者：
Yin，Hang;Aller，Josephine Y.;Zhu，Qingzhi
电缆细菌的代谢活动使硫化物氧化为硫酸盐在缺氧沉积物中通过长距离电子传递耦合到表面沉积物中的O2和NO3−/NO2−的还原。氧化和还原半反应的空间分离需要修改成岩模型，假设电子供体和受体在沉积矿床内相互耦合。在这项研究中，我们表明，电缆细菌可以成为建立和保持代谢活性的硫化物，但铁，锰，和固相硫化物耗尽，碳酸盐泥浆从佛罗里达湾，美国。沉积物表面的pH值最大值反映产电代谢1和3周之间的沉积物培养在实验室的缩影与好氧上覆水。索丝细胞丰度随着时间的推移而变化，最初的增加集中在地下，但到实验结束时，地下和含氧表面沉积物中的细胞丰度都增加了。碳酸盐泥浆中电缆细菌活性的发展表明，长距离电子传输代谢可以利用地下溶解的硫化物（例如，H2S）作为唯一的还原剂源持续的时间没有过渡到Fe-硫化物，显然没有形成与Fe和Mn循环相关的中间亚氧化区域。H2S的消耗最初发生在富含O2-NO3−的好氧-亚氧区，并过渡到占主导地位的但不排他的地下电缆细菌阳极区。一旦建立，电缆细菌显着改变沉积物碳酸盐循环。热力学计算表明，文石和高镁方解石在表层沉积层（深度< 0.25 cm）为过饱和（Ω <$2.0 -3.2），在阳极区（深度1-2 cm）为欠饱和（Ω <$0.2）。高镁方解石和文石可能沉淀在表层沉积物中，溶解在阳极区，溶解证实了孔隙水Ca 2+，Mg 2+浓度升高。磷循环耦合到有机质的矿化，碳酸盐矿物循环，和明显的细胞内积累的多磷酸盐。因此，电缆细菌可能发挥了重要作用，在收购的P海草在碳酸盐矿床，P是有限的，否则不可逆的吸附和自生矿物沉淀。
The metabolic activities of cable bacteria enable the oxidation of sulfide to sulfate in anoxic sediment at depth through long distance electron transport coupled to the reductions of O2and NO3−/NO2−in surface sediment. The spatial separation of oxidation and reduction half reactions requires modification of diagenetic models that assume electron donors and acceptors are coupled with each other locally within sedimentary deposits. In this study, we show that cable bacteria can become established and remain metabolically active in sulfidic, but Fe, Mn, and solid phase sulfide-depleted, carbonate muds from Florida Bay, USA. Sediment surface pH maxima reflecting electrogenic metabolism developed between 1 and 3 weeks in sediment incubated in laboratory microcosms with oxic overlying water. Cable filament cell abundances varied over time, with the increase initially focused within the subsurface, but by the end of experiments, cell abundances increased both in subsurface and oxic surface sediment. The development of cable bacteria activity in carbonate muds demonstrates that long-distance electron transport metabolism can utilize subsurface dissolved sulfide (e.g., H2S) as a sole reductant source for sustained periods without transition to Fe-sulfide and apparently without formation of an intermediate suboxic region associated with Fe and Mn cycling. H2S consumption occurs initially within the O2-NO3−rich oxic – suboxic zone and transitions to a dominant, but not exclusive, subsurface cable bacteria anodic zone. Once established, cable bacteria significantly altered sediment carbonate cycling. Thermodynamic calculations demonstrated that aragonite and hi-Mg-calcites were supersaturated (Ω ∼2.0–3.2) in the surface sediment layer (< 0.25 cm depth) and were undersaturated (Ω ∼ 0.2) in the anodic zone (1–2 cm depth). Hi-Mg-calcites and aragonite likely precipitated in the surface sediment and dissolved in the anodic region, the dissolution confirmed by elevated porewater Ca2+, Mg2+concentrations. P cycling was coupled to remineralization of organic matter, carbonate mineral cycling, and apparently intracellular accumulation of polyphosphates. Thus, cable bacteria may play an important role in the acquisition of P by seagrasses in carbonate deposits where P is otherwise limited by irreversible adsorption and authigenic mineral precipitation.