Rivers on the Qinghai-Tibet Plateau (QTP) are likely significant contributors to nitrous oxide (N2O) emissions globally. However, direct measurements remain scarce, leaving the underlying mechanisms of N2O emission poorly understood. This study investigated N2O dynamics in the Xuerong Zangbo River on the QTP by integrating in situ measurements, chemical analysis, molecular techniques, and 15N-pairing experiments. Mean dissolved N2O-N concentration was 0.522 ± 0.166 μg L–1 in summer and 0.795 ± 0.271 μg L–1 in winter, with emission rates ranging from −62.7 to 86.2 μg m–2 h–1 and from −57.5 to 75.8 μg m–2 h–1. Denitrification was the main contributor to the N2O. Microbial community analysis revealed more intense competitive interactions in summer, which were negatively correlated with N2O concentrations and emission factors (EF5r). This implied that microbial competition may disrupt N2O production. The Structural Equation Model (SEM) indicated that warming could inhibit N2O generation by intensifying competition among microorganisms. Additionally, the synergistic effect of wind speed and flow velocity was an important factor controlling the N2O emission rates. This study revealed the mechanisms underlying N2O production and emission of a Tibetan river, offering new insights into the riverine N2O biogeochemical processes on the QTP.
Qiu et al. (Fri,) studied this question.