当以低碳氮比(C/N)处理农业径流时,在人工湿地(CWs)中有效去除氮仍然具有挑战性。然而,使用生物炭,铁矿石,和FeCl3改性的生物炭(Fe-BC)作为改良剂可以潜在地提高CW中总氮(TN)的去除效率,但添加这些底物的潜在机制尚不清楚.在这项研究中,五个CW:石英砂人工湿地(对照),生物炭人工湿地,Fe-BC人工湿地,铁矿人工湿地,铁矿石+生物炭人工湿地,是为了比较它们的治疗性能而建造的。分析了根际微生物群落组成及其共现网络,以揭示驱动其治疗性能的潜在机制。结果表明,铁矿石是最有效的改良剂,尽管所有处理都提高了CW中TN的去除效率。氨氧化,异养反硝化,硝酸盐依赖性厌氧亚铁氧化(NAFO),和Feammox细菌在铁矿石系统中的丰度较高,并导致同时去除NH4-N,NO3--N,和NO2--N.共现网络的视觉表示进一步表明,合作共生(正链接的比例很高)和与氮和铁循环相关的属(尤其是氨氧化细菌,异养反硝化细菌,NAFO细菌,和Feammox细菌)在铁矿石系统中,最终实现了最高的TN去除效率。这项研究为如何使用不同的铁矿石或生物炭基质来处理CW中的农业径流提供了重要的见解。
Efficient nitrogen removal in constructed wetlands (CWs) remains challenging when treating agricultural runoff with a low carbon-to-nitrogen ratio (C/N). However, using biochar, iron ore, and FeCl3-modified biochar (Fe-BC) as amendments could potentially improve total nitrogen (TN) removal efficiency in CWs, but the underlying mechanisms associated with adding these substrates are unclear. In this study, five CWs: quartz sand constructed wetland (Control), biochar constructed wetland, Fe-BC constructed wetland, iron ore constructed wetland, and iron ore + biochar constructed wetland, were built to compare their treatment performance. The rhizosphere microbial community compositions and their co-occurrence networks were analyzed to reveal the underlying mechanisms driving their treatment performance. The results showed that iron ore was the most efficient amendment, although all treatments increased TN removal efficiency in the CWs. Ammonia-oxidizing, heterotrophic denitrifying, nitrate-dependent anaerobic ferrous oxidizing (NAFO), and Feammox bacteria abundance was higher in the iron ore system and led to the simultaneous removal of NH4+-N, NO3--N, and NO2--N. Visual representations of the co-occurrence networks further revealed that there was an increase in cooperative mutualism (the high proportion of positive links) and more complex interactions among genera related to the nitrogen and iron cycle (especially ammonia-oxidizing bacteria, heterotrophic denitrifying bacteria, NAFO bacteria, and Feammox bacteria) in the iron ore system, which ultimately contributed to the highest TN removal efficiency. This study provides critical insights into how different iron ore or biochar substrates could be used to treat agricultural runoff in CWs.