Dodla Syam K, Wang Jim J, Delaune Ronald D, Breitenbeck Gary
School of Plant, Environmental and Soil Sciences, Louisiana State Univ. Agricultural Center, 104 Sturgis Hall-LSU, Baton Rouge, LA 70803, United States.
Chemosphere. 2009 Jul;76(4):517-22. doi: 10.1016/j.chemosphere.2009.03.013. Epub 2009 Apr 5.
Dynamics of carbon (C) gas emission from wetlands influence global C cycling. In many freshwater systems such as Louisiana freshwater marsh, soil contents of NO3(-) and SO4(2-) have increased due to nutrient loading and saltwater intrusion. This could affect C mineralization and the emission of the major greenhouse gases carbon dioxide (CO2) and methane (CH4). In this investigation, a laboratory microcosm study was carried out to elucidate the effects of NO(3)(-) and SO4(2-) on CO2 and CH4 production from a freshwater marsh soil located in the Barataria Basin of Louisiana coast, which has been subjected to the Mississippi River diversion and seawater intrusion. Composite soil samples were collected from top 50 cm marsh profile, treated with different levels of NO3(-) (0, 3.2 and 5mM) or SO4(2-) (0, 2, and 5mM) concentrations, and incubated for 214d under anaerobic conditions. The results showed that the presence of NO3(-) (especially at 3.2mM) significantly decreased CO2 productions whereas SO4(2-) did not. On the other hand, both NO(3)(-) and SO4(2-) treatments decreased CH4 production but the NO3(-) almost completely inhibited CH4 production (>99%) whereas the SO4(2-) treatments reduced CH4 production by 78-90%. The overall C mineralization rate constant under the NO3(-) presence was also low. In addition, the results revealed that a large proportion (95%) of anaerobic carbon mineralization in the untreated freshwater soil was unexplained by the reduction of any of the measured major electron acceptors.
湿地碳（C）气体排放动态影响全球碳循环。在许多淡水系统中，如路易斯安那州淡水沼泽，由于养分负荷和海水入侵，土壤中硝酸根离子（NO3(-)）和硫酸根离子（SO4(2-)）含量增加。这可能会影响碳矿化以及主要温室气体二氧化碳（CO2）和甲烷（CH4）的排放。在本研究中，开展了一项实验室微观模拟研究，以阐明硝酸根离子（NO3(-)）和硫酸根离子（SO4(2-)）对路易斯安那州海岸巴拉塔里亚盆地淡水沼泽土壤中二氧化碳（CO2）和甲烷（CH4）产生的影响，该地区已遭受密西西比河改道和海水入侵。从顶部50厘米的沼泽剖面采集复合土壤样本，用不同浓度水平的硝酸根离子（NO3(-)）（0、3.2和5毫摩尔）或硫酸根离子（SO4(2-)）（0、2和5毫摩尔）进行处理，并在厌氧条件下培养214天。结果表明，硝酸根离子（NO3(-)）（尤其是3.2毫摩尔时）的存在显著降低了二氧化碳的产生，而硫酸根离子（SO4(2-)）则没有。另一方面，硝酸根离子（NO3(-)）和硫酸根离子（SO4(2-)）处理均降低了甲烷的产生，但硝酸根离子（NO3(-)）几乎完全抑制了甲烷的产生（>99%），而硫酸根离子（SO4(2-)）处理使甲烷产生量减少了78 - 90%。硝酸根离子（NO3(-)）存在下的总碳矿化速率常数也较低。此外，结果表明，未经处理的淡水土壤中很大一部分（95%）厌氧碳矿化无法通过任何测得的主要电子受体的还原作用来解释。
