Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan 430074, P.R. China.
College of Life Sciences, University of Chinese Academy of Sciences , Beijing 100049, P.R. China.
Environ Sci Technol. 2017 May 16;51(10):5483-5491. doi: 10.1021/acs.est.6b06521. Epub 2017 May 3.
Riparian wetlands play a critical role in retaining nitrogen (N) from upland runoff and improving river water quality, mainly through biological processes such as soil denitrification. However, the relative contribution of abiotic and biotic factors to riparian denitrification capacity remains elusive. Here we report the spatiotemporal dynamics of potential and unamended soil denitrification rates in 20 wetlands along the Han River, an important water source in central China. We also quantified the abundance of soil denitrifying microorganisms using nirK and nirS genes. Results showed that soil denitrification rates were significantly different between riparian and reservoir shoreline wetlands, but not between mountain and lowland wetlands. In addition, soil denitrification rates showed strong seasonality, with higher values in August (summer) and April (spring) but lower values in January (winter). The potential and unamended denitrification rates were positively correlated with edaphic conditions (moisture and carbon concentration), denitrifier abundance, and plant species richness. Path analysis further revealed that edaphic conditions could regulate denitrification rates both directly and indirectly through their effects on denitrifier abundance. Our findings highlight that not only environmental factors, but also biotic factors including denitrifying microorganisms and standing vegetation, play an important role in regulating denitrification rate and N removal capacity in riparian wetlands.
河岸湿地在截留来自高地径流水体中的氮（N）和改善河流水质方面发挥着关键作用，主要通过土壤反硝化等生物过程实现。然而，非生物和生物因素对河岸带反硝化能力的相对贡献仍不清楚。本研究报告了中国中部重要水源地汉江上 20 个湿地潜在和未添加土壤反硝化速率的时空动态。此外，还利用 nirK 和 nirS 基因量化了土壤反硝化微生物的丰度。结果表明，河岸带湿地和库岸湿地的土壤反硝化速率存在显著差异，但山地湿地和低地湿地之间没有差异。此外，土壤反硝化速率具有很强的季节性，夏季 8 月和春季 4 月较高，冬季 1 月较低。潜在和未添加的反硝化速率与土壤条件（水分和碳浓度）、反硝化菌丰度和植物物种丰富度呈正相关。路径分析进一步表明，土壤条件可以通过直接和间接影响反硝化菌丰度来调节反硝化速率。本研究结果强调，不仅环境因素，包括反硝化微生物和植被等生物因素，也在调节河岸带湿地的反硝化速率和 N 去除能力方面发挥着重要作用。
