Controlling the process of denitrification in flooded rice soils by using microbial fuel cell applications
Controlling the process of denitrification in flooded rice soils by using microbial fuel cell applications
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DOI：
10.1016/j.agwat.2018.04.041
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发表时间：
2018-07
影响因子：
6.7
通讯作者：
T. Ranatunga;K. Hiramatsu;T. Onishi
中科院分区：
文献类型：
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作者：
T. Ranatunga;K. Hiramatsu;T. Onishi
控制反硝化速率有助于减少田间施用氮肥的损失。基于微生物燃料电池（MFC）理论与氧化还原变化相结合，研究了微生物燃料电池（MFC）在控制淹水水稻土壤反硝化方面的适用性。由于水下约10-20cm的土壤和靠近水面的土壤分别是厌氧和好氧的，通过绝缘线连接它们之间会产生电位梯度。这种装置可以利用微生物代谢过程中有机物氧化释放的电子来发电。这可以减少硝酸盐还原半反应的电子可用性，从而抑制反硝化。我们使用带有气室实验的种植盆在三种条件下研究了土壤中的氮损失：MFC系统、具有外部施加电压的MFC系统和作为对照的非MFC系统。每个系统设置一式三份，提供相同的氮肥量，并通过自动灌溉进行淹没。定期监测土壤氧化还原电位、N2O通量和土壤孔隙水中无机氮浓度。 MFC系统和外部施加电压的MFC系统的氧化还原电位均显着高于非MFC系统，而N2O通量水平显着低于非MFC系统。水稻繁殖阶段应用MFC抑制N2O通量最有效。然而，外部施加电压对抑制 N2O 通量的影响仍不清楚。 MFC 系统中孔隙水中无机氮的保留效率较高，这与 N2O 通量差异一致。 MFC 系统的反硝化氮比例估计为 2.3%，而非 MFC 系统的反硝化氮比例为 6.6%。我们通过盆栽实验证实了 MFC 控制土壤氧化还原电位从而抑制反硝化的适用性。
Controlling the denitrification rate could help reduce the losses of applied nitrogen (N) fertilizer in fields. The applicability of microbial fuel cell (MFC) for controlling denitrification in flooded rice soils was investigated based on MFC theory coupled with redox changes. Because the soil about 10–20 cm beneath water and the soil near the water surface are anaerobic and aerobic, respectively, gradients of electric potentials could be generated between them, upon connecting them through insulated wires. Electrons released through the oxidation of organic matter during microbial metabolism can be utilized by this set-up, generating electricity. This can reduce the availability of electrons for reductive half-reactions of nitrate, to suppress denitrification. We studied the N losses in soil using planting pots with gas chamber experiment under three conditions: MFC systems, MFC systems with an externally applied voltage, and non-MFC systems as a control. Each system was set in triplicate, supplied with the same N fertilizer amounts, and flooded with automatic irrigation. Soil redox potential, N2O flux, and inorganic nitrogen concentration in soil pore water were periodically monitored. The redox potentials of both MFC systems and MFC systems with externally applied voltage were significantly higher than that of non-MFC systems, while N2O flux levels were significantly lower than that of non-MFC systems. The rice reproductive stage was the most effective on suppressing N2O flux with MFC application. However, the effect of externally applied voltage on suppressing N2O flux remains unclear. Inorganic nitrogen retention efficiencies in pore water were higher in MFC systems, which is consistent with the N2O flux difference. While the proportion of denitrified N estimated for MFC systems was 2.3%, that of non-MFC systems was 6.6%. We confirmed the applicability of MFCs to control soil redox potential and thereby suppress the denitrification based on planting pot experiments.