Abstract Plants play an essential role in methane (CH4) production, transport and release processes of constructed wetlands but as yet there has been no consistent and clear consensus of their impacts on CH4 emissions. In this study, we used plant presence, species richness, plant species-specificity, and harvesting activity information obtained by reviewing papers published from 1993 to 2018 to elucidate the key factors that drive CH4 emission from constructed wetlands. Although it was not statistically significant, plant presence increased the CH4 emissions compared to unvegetated conditions and relatively lower values were observed for constructed wetlands planted with Acorus calamus, Cyperus papyrus or Juncus effusus. The use of a single plant species not only changed the production and consumption of CH4 by affecting the functioning of roots but also influenced the process of CH4 entering the atmosphere under different transport capacities. The CH4 flux reached 1.0686 g CH4 m−2 d−1 from the Zizania latifolia system, which is eight times larger than that of the Phalaris arundinacea system. The mixed systems exhibited a positive increase in CH4 flux with plant species richness due to the complementary effects of the root exudates excreted from different plants. The minimum CH4 value (−0.0084 g CH4 m−2 d−1) was observed in the three-species system (Oenanthe javanica, Phalaris arundinacea and J. effusus). These results demonstrate that selecting several species with lower methane fluxes such as Typha latifolia and C. papyrus and suitably regulating harvesting in constructed wetlands can be more effective for mitigating the potential of CH4 emissions while maintaining the efficiency of sewage purification.

中文翻译：

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人工湿地甲烷排放概述：植物如何影响废水处理过程中的甲烷通量？

摘要 植物在人工湿地的甲烷（CH4）产生、运输和释放过程中发挥着重要作用，但目前尚未就其对 CH4 排放的影响达成一致和明确的共识。在本研究中，我们利用通过回顾 1993 年至 2018 年发表的论文获得的植物存在、物种丰富度、植物物种特异性和收获活动信息来阐明驱动人工湿地 CH4 排放的关键因素。尽管在统计上不显着，但与未植被的条件相比，植物的存在增加了 CH4 排放，并且观察到种植菖蒲、香附或蒺藜的人工湿地的值相对较低。单一植物物种的使用不仅通过影响根的功能改变了 CH4 的生产和消耗，而且还影响了 CH4 在不同运输能力下进入大气的过程。Zizania latifolia 系统的 CH4 通量达到 1.0686 g CH4 m-2 d-1，比 Phalaris arundinacea 系统大 8 倍。由于从不同植物排出的根系分泌物的互补作用，混合系统表现出 CH4 通量随着植物物种丰富度的正增加。在三物种系统（Oenanthe javanica、Phalaris arundinacea 和 J. effusus）中观察到最小 CH4 值（-0.0084 g CH4 m-2 d-1）。这些结果表明，选择几个甲烷通量较低的物种，如香蒲和香蒲。