Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resource and Environmental Science , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , China.
Faculty of Agriculture & Life Science , Lincoln University , Lincoln 7647 , New Zealand.
Environ Sci Technol. 2019 Feb 19;53(4):2002-2012. doi: 10.1021/acs.est.8b03606. Epub 2019 Feb 11.
Microbial strains and indigenous microbiota in soil slurries have been reported to use electrons from electrodes for nitrate (NO) reduction. However, few studies have confirmed this in a soil matrix hitherto. This study investigated if, and how, an electric potential affected NO reduction in a soil matrix. The results showed that, compared to a control treatment, applying an electric potential of -0.5 V versus the standard hydrogen electrode (SHE) significantly increased the relative abundance of NO-reducing microbes (e.g., Alcaligenaceae and Pseudomonadaceae) and the abundances of the nrfA, nirK, nirS, and nosZ genes in soil matrices. Meanwhile, the electric potential treatment doubled the NO reduction rate and significantly increased the rates of production of ammonium (NH), dinitrogen (N), and nitrous oxide (NO). The amount of NO-N reduced under the electric potential treatment was comparable to the sum of the amounts of N observed in the increased NO, N, NH, and nitrite (NO) pools. An open-air experiment showed that the electric potential treatment promoted soil NO reduction with a spatial scale of at least 38 cm. These results demonstrated that an electric potential treatment could enhance NO reduction via both denitrification and dissimilatory NO reduction to ammonium (DNRA) in the soil matrix. The mechanisms revealed in this study have implications for the future development of potential techniques for enhancing NO reduction in the vadose zone and consequently reducing the risk of NO leaching.
已有研究报道，土壤悬浮液中的微生物菌株和土著微生物群落可以利用电极中的电子将硝酸盐（NO）还原。然而，迄今为止，很少有研究在土壤基质中证实这一点。本研究调查了在土壤基质中，外加电场是否以及如何影响硝酸盐的还原。结果表明，与对照处理相比，相对于标准氢电极（SHE）施加-0.5 V 的外加电场显著增加了 NO 还原微生物（如产碱杆菌科和假单胞菌科）的相对丰度，以及土壤基质中 nrfA、nirK、nirS 和 nosZ 基因的丰度。同时，外加电场处理使 NO 还原速率提高了一倍，并显著增加了铵（NH）、氮气（N）和一氧化二氮（NO）的产生速率。外加电场处理下 NO-N 的减少量与观察到的增加的 NO、N、NH 和亚硝酸盐（NO）池中 N 的量之和相当。露天实验表明，外加电场处理可促进土壤 NO 还原，其空间尺度至少为 38 cm。这些结果表明，外加电场处理可以通过土壤基质中的反硝化和异化硝酸盐还原为铵（DNRA）来增强 NO 还原。本研究揭示的机制对未来开发增强土壤包气带中 NO 还原的潜在技术具有重要意义，从而降低 NO 淋失的风险。
