High spatial resolution of distribution and interconnections between Fe- and N-redox processes in profundal lake sediments.
High spatial resolution of distribution and interconnections between Fe- and N-redox processes in profundal lake sediments.
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DOI：
10.1111/1462-2920.12566
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发表时间：
2014-10
影响因子：
5.1
通讯作者：
E. D. Melton;P. Stief;S. Behrens;A. Kappler;C. Schmidt
中科院分区：
文献类型：
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作者：
E. D. Melton;P. Stief;S. Behrens;A. Kappler;C. Schmidt
Fe和N的地球化学循环在淡水环境中起着关键作用。我们的目的是确定深湖沉积物中的N和Fe循环的空间定位和相互联系。测定了O2、NO3（-）、NH 4（+）、pH、Eh、Fe（II）和Fe（III）的浓度梯度，并采用最大概然数法和定量聚合酶链反应法对微生物的分布进行了评价。氧化还原区可分为好氧区（0-8 mm），其中微需氧菌（Gallionellaceae）最丰富的深度为7 mm。其次是反硝化区（6-12 mm），其中NO3（-）依赖的Fe（II）氧化剂和有机异养反硝化剂都还原硝酸盐。最后，在12.5-22.5 mm处确定了一个铁氧化还原过渡区。Fe（III）在该区域上方最丰富，而Fe（II）在该区域下方最丰富。结晶不良的铁的高丰度表明铁循环。Fe和N循环通过硝酸盐还原Fe（II）氧化剂生物连接，并且通过反硝化过程中形成的NOx（-）物质化学连接，NOx（-）物质可以化学氧化Fe（II）。这项研究结合了高分辨率的化学，分子和微生物数据，以查明沉积氧化还原带，其中Fe是循环之间的Fe（II）和Fe（III）和Fe和N-氧化还原过程相互作用。
The Fe and N biogeochemical cycles play key roles in freshwater environments. We aimed to determine the spatial positioning and interconnections of the N and Fe cycles in profundal lake sediments. The gradients of O2, NO3(-), NH4(+), pH, Eh, Fe(II) and Fe(III) were determined and the distribution of microorganisms was assessed by most probable numbers and quantitative polymerase chain reaction. The redox zones could be divided into an oxic zone (0-8 mm), where microaerophiles (Gallionellaceae) were most abundant at a depth of 7 mm. This was followed by a denitrification zone (6-12 mm), where NO3(-)-dependent Fe(II) oxidizers and organoheterotrophic denitrifiers both reduce nitrate. Lastly, an iron redox transition zone was identified at 12.5-22.5 mm. Fe(III) was most abundant above this zone while Fe(II) was most abundant beneath. The high abundance of poorly crystalline iron suggested iron cycling. The Fe and N cycles are biologically connected through nitrate-reducing Fe(II) oxidizers and chemically by NOx(-) species formed during denitrification, which can chemically oxidize Fe(II). This study combines high resolution chemical, molecular and microbiological data to pinpoint sedimentary redox zones in which Fe is cycled between Fe(II) and Fe(III) and where Fe and N-redox processes interact.