College of Wildlife Resource, Northeast Forestry University, Xiangfang District, Harbin, People's Republic of China.
PLoS One. 2019 Mar 28;14(3):e0214456. doi: 10.1371/journal.pone.0214456. eCollection 2019.
Nitrate [Formula: see text] pollution of surface and groundwater systems is a major problem globally. For some time now wetlands have been considered potential systems for improving water quality. Nitrate dissolved in water moving through wetlands can be removed through different processes, such as the denitrification process, where heterotrophic facultative anaerobic bacteria use [Formula: see text] for respiration, leading to the production of nitrogen (N2) and nitrous oxide (N2O) gases. Nitrate removal and emission of N2O in wetlands can vary spatially, depending on factors such as vegetation, hydrology and soil structure. This study intended to provide a better understanding of the spatial variability and processes involved in [Formula: see text] removal and emission of N2O in riparian wetland soils. We designed a laboratory experiment simulating surface water flow through soil columns collected from different sites dominated by different plant species within a wetland. Water and gas samples for [Formula: see text] and N2O analyses were collected every 5 days for a period of 30 days. The results revealed significant removal of [Formula: see text] in all the soil columns, supporting the role of riparian wetland soils in removing nitrogen from surface runoff. Nitrate removal at 0 and 10cm depths in sites dominated by Phragmites australis and Carex schnimdtii was significantly higher than in the site dominated by Calamagrostis epigeio. Nitrous oxide emissions varied spatially and temporally with negative flux observed in sites dominated by P. australis and C. schnimdtii. These results reveal that in addition to the ability of wetlands to remove [Formula: see text], some sites within wetlands are also capable of consuming N2O, hence mitigating not only agricultural nitrate pollution but also climate change.
硝酸盐[公式：见正文]污染地表水和地下水系统是一个全球性的主要问题。湿地已经被认为是改善水质的潜在系统有一段时间了。在水通过湿地的移动过程中溶解的硝酸盐可以通过不同的过程去除，例如反硝化过程，其中异养兼性厌氧细菌使用[公式：见正文]进行呼吸，导致氮气（N2）和一氧化二氮（N2O）气体的产生。硝酸盐的去除和湿地中 N2O 的排放会因植被、水文学和土壤结构等因素而在空间上有所不同。本研究旨在更好地了解[公式：见正文]在湿地河岸带土壤中去除和排放 N2O 的空间变异性和相关过程。我们设计了一个实验室实验，模拟地表水通过取自湿地不同地点的土壤柱的流动，这些地点主要由不同的植物物种组成。每隔 5 天收集水和气体样品，用于[公式：见正文]和 N2O 分析，为期 30 天。结果表明，所有土壤柱中都有显著的硝酸盐去除，这支持了河岸带湿地土壤从地表径流中去除氮的作用。在以芦苇和獐毛为主的地点，0 和 10cm 深度的硝酸盐去除率明显高于以草地为主的地点。一氧化二氮的排放具有空间和时间上的变化，在以芦苇和獐毛为主的地点观察到负通量。这些结果表明，除了湿地去除硝酸盐的能力外，湿地内的一些地点也能够消耗 N2O，从而不仅减轻了农业硝酸盐污染，而且减缓了气候变化。
