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Research article - Peer-reviewed, 2021

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

Authors' information

Wu, Hainan
Hohai University
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Zhang, Wenlong
Hohai University
Li, Yi
Hohai University
Hui, Cizhang
Hohai University
Wang, Haolan
Hohai University
Li, Jie
Hohai University
Niu, Lihua
Hohai University

UKÄ Subject classification

Oceanography, Hydrology, Water Resources
Environmental Sciences

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