Mechanisms of Nitrate Concentration Effects on N₂O and N₂ Fluxes Across Different River Widths

Zitong Shao; Jiarui Du; Hao Wang

doi:10.54691/stwek692

Authors

Zitong Shao
Jiarui Du
Hao Wang

DOI:

https://doi.org/10.54691/stwek692

Keywords:

Nitrate Concentration; River Width; N₂O Flux; N₂ Flux; Denitrifying Microorganisms; Nitrogen Cycle; Benthic Niche; qPCR.

Abstract

This study systematically investigated the mechanisms by which nitrate concentrations influence N₂O and N₂ fluxes in rivers of varying widths (20–800 m) within the Haihe River Basin, Luanhe River Basin, and independent rivers flowing into the sea in the Beijing-Tianjin-Hebei region. Through a combination of field sampling and laboratory analysis, nitrate concentrations and gas fluxes at the sediment-water interface were measured, while qPCR technology was employed to analyze the abundance of nitrogen-functioning microbial genes. Results indicate that nitrate concentration significantly influences N₂O and N₂ fluxes by providing denitrification substrates and regulating microbial community structure. River width further modulates nitrate influence intensity and pathways by altering water dilution capacity and microbial habitat. Narrow rivers exhibit heightened sensitivity to nitrate, yielding higher gas fluxes, whereas wide rivers promote nitrate conversion to N₂ due to dilution effects and stable environments. This study provides microbial mechanism-level insights into understanding river nitrogen cycling and its environmental effects.

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