Eco-Environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, PR China; Shanghai Engineering Research Centre of Low-carbon Agriculture (SERCLA), Shanghai, 201415, PR China.
Eco-Environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, PR China; Shanghai Engineering Research Centre of Low-carbon Agriculture (SERCLA), Shanghai, 201415, PR China.
J Environ Manage. 2024 Sep;367:121873. doi: 10.1016/j.jenvman.2024.121873. Epub 2024 Jul 25.
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 FeCl-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 NH-N, NO-N, and NO-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.
在处理碳氮比（C/N）较低的农业径流时，人工湿地（CWs）的高效氮去除仍然具有挑战性。然而，使用生物炭、铁矿石和 FeCl 改性生物炭（Fe-BC）作为添加剂可能会提高 CWs 中的总氮（TN）去除效率，但添加这些基质的潜在机制尚不清楚。在这项研究中，构建了五个 CWs：石英砂人工湿地（对照）、生物炭人工湿地、Fe-BC 人工湿地、铁矿石人工湿地和铁矿石+生物炭人工湿地，以比较它们的处理性能。分析了根际微生物群落组成及其共现网络，以揭示驱动其处理性能的潜在机制。结果表明，尽管所有处理都提高了 CWs 中的 TN 去除效率，但铁矿石是最有效的添加剂。氨氧化菌、异养反硝化菌、硝酸盐依赖型厌氧亚铁氧化菌（NAFO）和 Feammox 菌的丰度在铁矿石系统中更高，导致 NH-N、NO-N 和 NO-N 的同时去除。共现网络的可视化表示进一步表明，在铁矿石系统中，与氮和铁循环相关的属之间的共生互惠（正链接的高比例）和更复杂的相互作用增加，（特别是氨氧化菌、异养反硝化菌、NAFO 菌和 Feammox 菌），这最终有助于实现最高的 TN 去除效率。本研究为如何利用不同的铁矿石或生物炭基质来处理 CWs 中的农业径流提供了重要的见解。
