Management effects on greenhouse gas dynamics in fen ditches.
Management effects on greenhouse gas dynamics in fen ditches.
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DOI：
10.1016/j.scitotenv.2016.11.005
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
M. Peacock;L. Ridley;C. Evans;V. Gauci
中科院分区：
文献类型：
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作者：
M. Peacock;L. Ridley;C. Evans;V. Gauci
在全球范围内，大面积的泥炭地已经通过挖沟排干，通常是为了增加农业产量。通过降低地下水位，人们通常认为排水将甲烷（CH 4）排放到大气中的规模减少到可以忽略不计的水平。然而，排水沟本身是已知的CH 4和其他温室气体（GHG）的来源，但排放量的数据很少，特别是二氧化碳（CO2）和一氧化二氮（N2 O），并显示出很高的空间和时间变异性。在这里，我们报告溶解的温室气体和扩散通量的CH 4和CO2从沟渠在英国低地沼泽不同的管理下，半自然沼泽，农田，农田恢复到低强度的草地。沟渠在所有三个沼泽排放温室气体到大气中，但通量和溶解的温室气体表现出广泛的季节性和站点内的变化。甲烷通量特别大，所有三个地点的平均值在8月达到峰值，为120-230 mg m− 2d− 1。农田和其他两个站点之间的CO2通量和所有三个溶解的温室气体的显着差异，这表明集约化农业对沟渠土壤地球化学有重大影响。使用环境和水化学数据的多元回归模型能够解释29-59%的溶解温室气体观测变化。半自然、草地和农田沟渠的CH 4年通量分别为37.8、18.3和27.2 g CH 4 m − 2 yr − 1，各站点的CO2年通量相似（1100至1440 g CO2 m − 2 yr − 1）。我们认为，分沟渠是重要的贡献者，以规模的温室气体排放量，特别是甲烷。沟渠排放量应列入人为改造的沼泽地的温室气体预算，特别是在排水已经消除了最初的陆地CH 4源的情况下，例如农业泥炭地。
Globally, large areas of peatland have been drained through the digging of ditches, generally to increase agricultural production. By lowering the water table it is often assumed that drainage reduces landscape-scale emissions of methane (CH4) into the atmosphere to negligible levels. However, drainage ditches themselves are known to be sources of CH4and other greenhouse gases (GHGs), but emissions data are scarce, particularly for carbon dioxide (CO2) and nitrous oxide (N2O), and show high spatial and temporal variability. Here, we report dissolved GHGs and diffusive fluxes of CH4and CO2from ditches at three UK lowland fens under different management; semi-natural fen, cropland, and cropland restored to low-intensity grassland. Ditches at all three fens emitted GHGs to the atmosphere, but both fluxes and dissolved GHGs showed extensive variation both seasonally and within-site. CH4fluxes were particularly large, with medians peaking at all three sites in August at 120–230 mg m− 2d− 1. Significant between site differences were detected between the cropland and the other two sites for CO2flux and all three dissolved GHGs, suggesting that intensive agriculture has major effects on ditch biogeochemistry. Multiple regression models using environmental and water chemistry data were able to explain 29–59% of observed variation in dissolved GHGs. Annual CH4fluxes from the ditches were 37.8, 18.3 and 27.2 g CH4m− 2yr− 1for the semi-natural, grassland and cropland, and annual CO2fluxes were similar (1100 to 1440 g CO2m− 2yr− 1) among sites. We suggest that fen ditches are important contributors to landscape-scale GHG emissions, particularly for CH4. Ditch emissions should be included in GHG budgets of human modified fens, particularly where drainage has removed the original terrestrial CH4source, e.g. agricultural peatlands.