Co-regulation of redox processes in freshwater wetlands as a function of organic matter availability?
Co-regulation of redox processes in freshwater wetlands as a function of organic matter availability?
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DOI：
10.1016/j.scitotenv.2007.11.001
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发表时间：
2008-10-15
影响因子：
9.8
通讯作者：
Storck, F. R.
中科院分区：
文献类型：
--
作者：
Alewell, C.;Paul, S.;Storck, F. R.
湿地在景观中具有重要的过滤功能，但被认为是全球气候变化下其要素动态的最大未知数。关于湿地中硫、氮、有机物和酸度的汇和源功能的信息对于淡水再生至关重要。最近的研究结果表明，氧化还原过程并不完全控制的顺序还原链（即电子受体的可用性），但电子供体的可用性可能是一个重要的调节器。我们的假设是，只有在其电子供体的可用性有限的网站（低浓度的溶解有机碳（DOC））遵循顺序还原链的概念。我们比较了两个淡水湿地系统的结果：1）德国南部低山脉北方云杉集水区内的三个森林沼泽（高DOC制度）和2）在瑞士西北部莱茵河谷地下水富集区的三个洪泛平原土壤（低DOC制度）。（几厘米），以及森林沼泽地的土壤溶液和地下水浓度（高DOC制度）表明同时消耗硝酸盐和硫酸盐与铁的释放，锰和甲烷（CH 4）以及稳定硫同位素的富集，表明归因于不同氧化还原梯度的过程的共存。土壤和含水层的气体测量下降到4.6米的地下水富集网站（低DOC制度和碳限制）显示极高的代谢率与二氧化碳（CO2），一氧化二氮（N2 O）和甲烷浓度分别达到50，30和3倍的大气浓度。同时，地下水氧（O-2）饱和度为50%至95%之间。我们的结论是，独立的DOC制度的顺序还原链是不是一个合适的概念，在我们的系统。而不是电子受体或供体的可用性微网站的变化可能会解释我们的网站内的氧化还原过程的共存。(C)2007 Elsevier B. V.保留所有权利。
Wetlands have important filter functions in landscapes but are considered to be the biggest unknowns regarding their element dynamics under global climate change. Information on sink and source function of sulphur, nitrogen, organic matter and acidity in wetlands is crucial for freshwater regeneration. Recent results indicate that redox processes are not completely controlled by the sequential reduction chain (that is electron acceptor availability) but that electron donor availability may be an important regulator. Our hypothesis was that only sites which are limited in their electron donor availability low concentrations of dissolved organic carbon (DOC)) follow the concept of the sequential reduction chain.We compared the results of two freshwater wetland systems: 1) three forested fens within a boreal spruce catchment in a low mountain range in southern Germany (high DOC regime) and 2) three floodplain soils within a groundwater enrichment area in the Rhein valley in northwest Switzerland (low DOC regime).Micro scale investigations (a few cm) with dialyse chambers as well as soil solution and groundwater concentrations at the forested fens (high DOC regime) indicated simultaneous consumption of nitrate and sulphate with release of iron, manganese and methane (CH4) as well as an enrichment in stable sulphur isotopes indicating a co-existence of processes attributed to different redox gradients. Soil and aquifer gas measurements down to 4.6 m at the groundwater enrichment site (low DOC regime and carbon limitation) showed extreme high rates of metabolism with carbon dioxide (CO2), dinitrous oxide (N2O) and CH4 concentrations reaching fifty, thirty and three times atmospheric concentrations, respectively. Simultaneously, groundwater oxygen (O-2) saturation was between 50 and 95%. We concluded that independent of DOC regime the sequential reduction chain was not a suitable concept in our systems. Instead of electron acceptor or donor availability micro site variability might explain the co-existence of redox processes within our sites. (C) 2007 Elsevier B.V. All rights reserved.