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Research article2021Peer reviewed

Integrating experiments with system-level biogeochemical modeling to understand nitrogen cycling of reservoir sediments at elevated hydrostatic pressure

Wu, Hainan; Bertilsson, Stefan; Zhang, Wenlong; Li, Yi; Hui, Cizhang; Wang, Haolan; Li, Jie; Niu, Lihua


Impoundment of rivers to construct reservoirs for hydropower and irrigation greatly increase the hydrostatic pressure acting on river sediments with potential repercussions for ecosystem-level microbial activity and metabolism. Understanding the functioning and responses of key biogeochemical cycles such as that of nitrogen cycling to shifting hydrostatic pressure is needed to estimate and predict the systemic nutrient dynamics in deepwater reservoirs. We studied the functioning of bacterial communities involved in nitrogen transformation in bioreactors maintained under contrasting hydrostatic pressures (0.5 MPa-3.0 MPa) and complemented the experimental approach with a functional gene-informed biogeochemical model. The model predictions were broadly consistent with observations from the experiment, suggesting that the rates of N2O production decreased while the sediment concentration of nitrite increased significantly with increasing pressure, at least when exceeding 1.0 MPa. Changes in nitrite reduction (nirS) and aerobic ammonia oxidation (amoA) genes abundances were in accordance with the observed changes in N2O production and nitrite levels. Moreover, the model predicted that the higher pressures (P > 1.5 MPa) would intensify the inhibition of N2 production via denitrification and result in an accumulation of ammonia in the sediment along with a decrease in dissolved oxygen. The results imply that increased hydrostatic pressure caused by dam constructions may have a strong effect on microbial nitrogen conversion, and that this may result in lower nitrogen removal.


Hydrostatic pressure; Reservoir sediment; Nitrogen; Bacterial communities; Biogeochemical model; Denitrification

Published in

Environmental Research
2021, Volume: 200, article number: 111671

    UKÄ Subject classification

    Oceanography, Hydrology, Water Resources
    Environmental Sciences

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