The Dominant Role of the Water Column in Nitrogen Removal and N2O Emissions in Large Rivers

Abstract Rivers are important sites for nitrogen (N) cycling processes. N removal is thought to occur predominantly in the benthic zone and the role of the water column is frequently neglected. Here, we find that the water‐air and sediment‐water fluxes of N2 and N2O decreased, while the water column...

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Main Authors: Junfeng Wang, Xinghui Xia, Shaoda Liu, Sibo Zhang, Ling Zhang, Chenrun Jiang, Zhenrui Zhang, Yuan Xin, Xin Chen, Jing Huang, Jiaao Bao, William H. McDowell, Greg Michalski, Zhifeng Yang, Jun Xia
Format: Article
Language:English
Published: Wiley 2022-06-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1029/2022GL098955
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Summary:Abstract Rivers are important sites for nitrogen (N) cycling processes. N removal is thought to occur predominantly in the benthic zone and the role of the water column is frequently neglected. Here, we find that the water‐air and sediment‐water fluxes of N2 and N2O decreased, while the water column production increased with stream order through 4‐year observations across six river networks in China. The water column contribution increased with stream order and accounted for more than 50% in rivers above fifth order. The increase in the contact area of suspended sediment (SPS)‐water caused by higher SPS concentrations and river depths resulted in the shift as river size increased. N removal and N2O emissions would be underestimated approximately by 50% if neglecting water column processes for the six river networks. This study highlights the necessity and provides a pathway to incorporate water column processes into models to balance the global N budget.
ISSN:0094-8276
1944-8007