Effects of benthic hydraulics on sediment oxygen demand in a canyon-shaped deep drinking water reservoir:Experimental and modeling study

• 作者: Nan Li Tinglin Huang Zhiying Chang Kai Li
• 来源期刊: 环境科学学报（英文版）
• 年，卷（期）: 2021,（4）
• 页码范围: 226-234
• 页数: 9页
• 语种: 英文

摘要

Sediment oxygen demand(SOD)is a major contributor to hypolimnetic oxygen depletion and the release of internal nutrient loading.By measuring the SOD in experimental cham-bers using in both dissolved oxygen(DO)depletion and diffusional oxygen transfer methods,a model of SOD for a sediment bed with water current-induced turbulence was presented.An experimental study was also performed using near-sediment vertical DO profiles and correlated hydraulic parameters stimulated using a computational fluid dynamics model to determine how turbulences and DO concentrations in the overlying water affects SOD and diffusive boundary layer thickness.The dependence of the oxygen transfer coefficient and diffusive boundary layer on hydraulic parameters was quantified,and the SOD was expressed as a function of the shear velocity and the bulk DO concentrations.Theoreti-cal predictions were validated using microelectrode measurements in a series of laboratory experiments.This study found that flow over the sediment surface caused an increase in SOD,attributed to enhanced sediment oxygen uptake and reduced substances fluxes,i.e.,for a constant maximum biological oxygen consumption rate,an increased current over the sediment could increase the SOD by 4.5 times compared to stagnant water.These results highlight the importance of considering current-induced SOD increases when designing and implementing aeration/artificial mixing strategies.