Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Hubei Field Observation and Scientific Research Stations for Water Ecosystem in Three Gorges Reservoir, China Three Gorges University, Yichang 443002, China.
Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
Water Res. 2024 May 1;254:121317. doi: 10.1016/j.watres.2024.121317. Epub 2024 Feb 15.
Nitrogen (N) cycling in rivers is particularly active and dynamic due to excess nutrient inputs worldwide. However, the multidimensional spatial patterns of the activity and community structure of N-cycling microorganisms in rivers remain unclear, limiting our understanding of river ecological functions, especially N removal capacity. Here, we measured the nitrification and denitrification rates and identified nitrifying and denitrifying microorganisms using high-throughput sequencing of archaeal amoA, bacterial amoA, nirK, and nirS genes in channel sediments, riparian rhizosphere soils, and riparian bulk soils of 30 N-polluted rivers across China. Results showed that in the lateral dimension, nitrification rates in sediments did not differ significantly from those in rhizosphere and bulk soils, but denitrification rates were higher in sediments than in bulk soils. However, the archaeal amoA gene abundance in sediments was considerably lower than that in rhizosphere and bulk soils, and bacterial amoA gene abundance in sediments was greater than that in rhizosphere soils. In the vertical dimension, both nitrification and denitrification rates in riparian bulk soils decreased with soil depth, and topsoils harbored more nitrifying and denitrifying microbes than subsoils. Denitrification but not nitrification rates increased with latitude and altitude but decreased with increasing mean annual temperature and precipitation. Overall, these results provide new insights into the multidimensional spatial patterns of river N cycling at a large scale, which is crucial to evaluating the N removal function of global rivers.
由于全球范围内过量的营养物质输入，河流中的氮循环特别活跃和动态。然而，河流中氮循环微生物的活性和群落结构的多维空间格局仍然不清楚，这限制了我们对河流生态功能的理解，尤其是氮去除能力。在这里，我们使用高通量测序技术测定了氨氧化古菌（archaeal amoA）、氨氧化细菌（bacterial amoA）、nirK 和 nirS 基因，测量了中国 30 条受氮污染河流的河道沉积物、河岸根际土壤和河岸土壤中的硝化和反硝化速率，并鉴定了硝化和反硝化微生物。结果表明，在横向维度上，沉积物中的硝化速率与根际和土壤中的硝化速率没有显著差异，但沉积物中的反硝化速率高于土壤中的反硝化速率。然而，沉积物中的氨氧化古菌基因丰度明显低于根际和土壤中的氨氧化古菌基因丰度，而沉积物中的氨氧化细菌基因丰度大于根际土壤中的氨氧化细菌基因丰度。在垂直维度上，河岸土壤中的硝化和反硝化速率都随土壤深度的增加而降低，表土中的硝化和反硝化微生物比底土中的多。反硝化速率而不是硝化速率随着纬度和海拔的增加而增加，但随着年平均温度和降水量的增加而降低。总的来说，这些结果为大规模评估全球河流的氮去除功能提供了河流氮循环多维空间格局的新见解。
