Density-dependent solute transport in a layered hyporheic zone

Jiang, Qihao; Jin, Guangqiu; Tang, Hongwu; Shen, Chengji; Cheraghi, Mohsen; Xu, Junzeng; Li, Ling; Barry, David Andrew

doi:10.1016/j.advwatres.2020.103645

Cited by 17 publications

(19 citation statements)

References 60 publications

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“…This could be an important mechanism to enhance the N 2 O production and consumption rate. Previous studies have also demonstrated that the variable‐density flow could notably accelerate salt transport and mixing in the lower areas of the streambed (Jiang et al., 2020; Jin et al., 2011), and the denitrification reaction was more active in the middle and lower parts of the riverbed (Bardini et al., 2013; Kessler et al., 2013; Zheng et al., 2016). The combination of these two conditions creates a perfect environment to promote the denitrification reaction rate in the hyporheic zone.…”

Section: Resultsmentioning

confidence: 96%

“… (a) Experimental (symbols) conducted by Jiang et al. (2020) and simulated (lines) normalized concentrations, C salt , t / C salt , 0 , in the stream water of Model 1 and 2. (b) Experimental and simulated saltwater plumes within streambed at different times in Model 1 and 2.…”

Section: Resultsmentioning

confidence: 99%

“…Then, the model is expanded and coupled with variable‐density flow induced by the infiltrating saltwater from stream, and the density effect is validated (in Section 3.1.2) using the data obtained from the recirculating flume experiment of Jiang et al. (2020). Specifically, this study has focused on (a) N 2 O production and consumption processes in the bedform under the effect of salinity gradient; (b) the physical mechanism regulating the N 2 O transformation processes in the small‐scale streambed; and (c) the source‐sink function and yield of N 2 O in the salinity‐impacted hyporheic zone.…”

Section: Introductionmentioning

confidence: 99%

“…The chloride concentration of some streams even reach nearly 25% of that of seawater (5,000 mg L −1 ) (Hintz & Relyea, 2017; Kaushal et al., 2005). The stream‐groundwater interactions can be driven by the buoyancy forces related to temperature and input saltwater concentration gradients (Boano et al., 2009; Jiang et al., 2020; Jin et al., 2011; Konikow et al., 2013; Musgrave & Reeburgh, 1982), and the resulting density gradient can significantly increase the hyporheic exchange flux (Boano et al., 2009) and mainly dominate in the deep areas of the riverbed (Jin et al., 2011). Thus, the mixed convection processes, that is, pumping exchange and free convection, in the small‐scale bedform could affect the denitrification reaction in the hyporheic zone.…”

Section: Introductionmentioning

confidence: 99%

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N₂O Production and Consumption Processes in a Salinity‐Impacted Hyporheic Zone

et al. 2021

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Nitrous oxide (N 2 O) is a potent greenhouse gas and contributes significantly to the destruction of the stratospheric ozone (Ravishankara et al., 2009). However, its concentration in the atmosphere has grown by approximately 20% since 1750 and will continue to increase at an annual rate of 0.2%-0.3% in years to come (Quick et al., 2019). Rivers with excess nitrogen resulting from human activities such as sewage effluents and agricultural practices have become an important contributor to the global N 2 O budget (Beaulieu et al., 2011) and an active source of N 2 O emissions (Yao et al., 2020).Considerable attempts have been made to quantify the regional and global N 2 O emissions from rivers based on watershed-scale measurements and numerical models (Marzadri et al., 2017;McMahon &

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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N₂O Production and Consumption Processes in a Salinity‐Impacted Hyporheic Zone

et al. 2021

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“…Jin, Tang, Li, and Barry (2011, 2015) found that even small density variations could accelerate the hyporheic flow and restrain the release of pollutants back to the stream, and solute fingers appeared in the homogenous hyporheic zone (Figure 1d). Jiang et al (2020) further investigated the density‐driven flow in a layered bedform and showed the narrowed finger in the bottom layer. However, these studies have not addressed the critical conditions of finger flow along the sediment–water interface (SWI) considering pumping exchange.…”

Section: Introductionmentioning

confidence: 99%

The effect of density‐driven flow on the transport of high‐concentration solutes in the hyporheic zone

Jin

Hao

Wei

et al. 2020

Hydrological Processes

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In this study, both laboratory experiments and numerical simulations were conducted to investigate the effect of density‐driven flow on the transport of high‐concentration pollutants in the hyporheic zone. The results show that the density gradient can change the flow of pore water and the strong density‐driven flow can lead to an unstable flow, which increases the effect of preferential flow and thus causes the appearance of solute fingers in the hyporheic zone. Notably, these solute fingers become more obvious with the increase of depth. The appearance of solute fingers depends on the relative strength of the pumping exchange and density gradient, which are represented by the dimensionless number M* and N* respectively. Finger flows appear near the interface when M* is less than 0.5 N*. This study may contribute to better understanding the transport and destination of solutes and thus may provide some insights into the assessment on pollution incidents.

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