Strong turbulence accelerates sediment nitrification-denitrification for nitrogen loss in shallow lakes

Lin Zhu; Wenqing Shi; Jian Zhou; Jianghua Yu; Lingwei Kong; Boqiang Qin

doi:10.1016/j.scitotenv.2020.143210

Strong turbulence accelerates sediment nitrification-denitrification for nitrogen loss in shallow lakes

Sci Total Environ. 2021 Mar 20:761:143210. doi: 10.1016/j.scitotenv.2020.143210. Epub 2020 Oct 27.

Authors

Lin Zhu¹, Wenqing Shi¹, Jian Zhou², Jianghua Yu¹, Lingwei Kong³, Boqiang Qin⁴

Affiliations

¹ Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technologies, Jiangsu Key Laboratory of Atmospheric Environmental Monitoring & Pollution Control, School of Environmental Science & Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.
² Taihu Lake Laboratory Ecosystem Station, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
³ School of Engineering, Westlake University, Hangzhou 310024, China.
⁴ Taihu Lake Laboratory Ecosystem Station, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; School of Geography & Ocean Science, Nanjing University, Nanjing 210093, China. Electronic address: qinbq@niglas.ac.cn.

PMID: 33158538
DOI: 10.1016/j.scitotenv.2020.143210

Abstract

Due to energy dissipation, turbulent energy reaching bed sediment greatly differs in lakes with different depths, which potentially affects sediment denitrification and thereby nitrogen loss. In this study, we explored the impacts of turbulent energy reaching sediment on sediment nitrification rate using turbulence simulation experiments, and analyzed its role in determining sediment nitrogen loss in global lakes by investigating the relationship between denitrification rate with lake depth. Results demonstrated that sediment denitrification rate is affected by water depth in lakes with a depth of <~10 m, in which the rate was negatively correlated with lake depth, and maintained stably at low levels of <2.4 mg N m^-2 day^-1 in lakes with a depth of >~10 m. In shallow lakes, stronger turbulence reaching on sediment yielded higher nitrogen loss rate. Compare with the control, cumulated nitrogen loss from sediment increased by 10% at the turbulent velocity of 4.33 cm s^-1 upon sediment. It is possibly because turbulence promoted faster transport of oxygen to surface sediment and enhanced the mineralization of buried organic matters to feed nitrification, which subsequently accelerated denitrification and thereby nitrogen loss. This study can add to our understanding of the role of lake morphology in nitrogen biogeochemical cycles.

Keywords: Denitrification; Lake depth; Nitrification; Nitrogen loss; Turbulence.