Dynamic behavior of sediment resuspension and nutrients release in the shallow and wind-exposed Meiliang Bay of Lake Taihu

Chunyan Tang; Yiping Li; Chao He; Kumud Acharya

doi:10.1016/j.scitotenv.2019.135131

Dynamic behavior of sediment resuspension and nutrients release in the shallow and wind-exposed Meiliang Bay of Lake Taihu

Sci Total Environ. 2020 Mar 15:708:135131. doi: 10.1016/j.scitotenv.2019.135131. Epub 2019 Nov 22.

Authors

Chunyan Tang¹, Yiping Li², Chao He³, Kumud Acharya⁴

Affiliations

¹ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; South China Institute of Environment Science, the Ministry of Ecology and Environment of PRC, Guangzhou 510535, China.
² Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
³ Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China. Electronic address: hechao25@mail.sysu.edu.cn.
⁴ Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, NV 89119, USA.

PMID: 31787278
DOI: 10.1016/j.scitotenv.2019.135131

Abstract

Wind-induced sediment resuspension frequently occurs in Lake Taihu, a typical large shallow lake in China. Internal nutrients release accompanied by sediment resuspension is supposed to sustain the eutrophic status and algal boom persistence. In this study, high-frequency and synchronous in situ observation of the wind field, currents, waves, suspended sediments, and nutrients were collected to understand the dynamic behaviors of sediment and nutrients under multiple natural disturbances in Meiliang Bay, Lake Taihu. Results suggest that both wind speed and wind fetch length could effectively activate the sediment layer and trigger particles entrainment into the overlying water. Wind speed of 4 m/s with long wind fetch (between east and southeast wind direction) was the critical value for sediment resuspension. Furthermore, wind-induced wave shear stress and stochastic nature of turbulence at the water-sediment interface were the driving force for sediment resuspension. Specifically, incipient motion of sediment occurred when shear stress was ranging from 0.02 to 0.07 N/m². Wind-induced sediment resuspension had significantly contributed to nutrients release of particulate N and P, whereas dissolved nutrients concentration was less affected. Internal nutrients release by wind could maintain a significant potential for obstinate eutrophication and algal bloom. This study has revealed the dynamic response of nutrients release to sediment resuspension and wind-induced hydrodynamics. Therefore, a better understanding of the mechanism of internal nutrients release will benefit the effective and sustainable management of the shallow and wind-exposed lakes.

Keywords: Nutrients release; Sediment resuspension; Shallow lake; Turbulence; Wave shear stress.