Burrowing fauna mediate alternative stable states in the redox cycling of salt marsh sediments
Burrowing fauna mediate alternative stable states in the redox cycling of salt marsh sediments
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穴居动物介导盐沼沉积物氧化还原循环中的替代稳定状态
DOI：
10.1016/j.gca.2020.02.021
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发表时间：
2020
影响因子：
5
通讯作者：
F. Meysman
中科院分区：
文献类型：
--
作者：
S. J. van de Velde;Silvia Hidalgo;Ine Callebaut;G. Antler;R. James;M. Leermakers;F. Meysman
东盎格鲁盐沼系统（英国）最近产生了有趣的数据方面的沉积物地球化学。在这些盐沼相邻的池塘显示两个不同的制度的氧化还原循环：沉积物要么富含铁和bioturbated，或者他们是硫化物丰富和unbioturbated。对于这种显著的空间共现现象，目前还没有结论性的解释。在这里，我们量化的地球化学循环在这两个池塘类型，使用孔隙水分析和固相形态。我们的研究结果表明，在固相碳和铁输入的差异可能是小池塘类型之间，所以这些不能作为所观察到的氧化还原二分法的直接驱动程序。相反，我们的研究结果表明，生物扰动的存在起着关键作用，在过渡到以硫为主的铁为主的沉积物。海洋沉积物中穴居动物的存在刺激了有机物的矿化，增加了铁的循环，并限制了游离硫化物的积累。总体而言，我们建议，在池塘地球化学观察到的二分法是由于替代的稳定状态，这是由于非线性的相互作用，在沉积铁和硫的循环，被放大的生物扰动。这样，由于正反馈，固相输入的微小差异可以导致非常不同的氧化还原循环状态。铁和硫循环中的这种非线性可能是海洋沉积物的固有特征，因此，其他系统中可能存在其他稳定状态。
The East Anglian salt marsh system (UK) has recently generated intriguing data with respect to sediment biogeochemistry. Neighbouring ponds in these salt marshes show two distinct regimes of redox cycling: the sediments are either iron-rich and bioturbated, or they are sulphide-rich and unbioturbated. No conclusive explanation has yet been given for this remarkable spatial co-occurrence. Here, we quantify the geochemical cycling in both pond types, using pore-water analyses and solid-phase speciation. Our results demonstrate that differences in solid-phase carbon and iron inputs are likely small between pond types, and so these cannot act as the direct driver of the observed redox dichotomy. Instead, our results suggest that the presence of bioturbation plays a key role in the transition from sulphur-dominated to iron-dominated sediments. The presence of burrowing fauna in marine sediments stimulates the mineralisation of organic matter, increases the iron cycling and limits the build-up of free sulphide. Overall, we propose that the observed dichotomy in pond geochemistry is due to alternative stable states, which result from non-linear interactions in the sedimentary iron and sulphur cycles that are amplified by bioturbation. This way, small differences in solid phase input can result in very different regimes of redox cycling due to positive feedbacks. This non-linearity in the iron and sulphur cycling could be an inherent feature of marine sediments, and hence, alternative stable states could be present in other systems.
影响因子：
5.3
作者：
J. Mills;G. Antler;A. Turchyn
通讯作者：
J. Mills;G. Antler;A. Turchyn