Transient migration behavior of VOC vapor in layered unsaturated soils subjected to multiple time-dependent point pollution sources: Analytical study

Ding, Xiang-Hong; Feng, Shi-Jin; Zheng, Qi-Teng; Peng, Chun-Hui; Zhu, Zhang-Wen; Yang, Chun-Bai-Xue

doi:10.1016/j.scitotenv.2021.150370

Cited by 15 publications

(7 citation statements)

References 40 publications

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“…By using ordinary differential equation solving module of Mathematica 7.0 (Wolfram Research 2008), the solution of Equation (31) subject to the boundary conditions Equations (19)(20)(21)(22)…”

Section: Analytical Solution Of the Modelmentioning

confidence: 99%

“…15,16 Experimental and numerical studies have been devoted to investigating VOC transfer within the landfill cover. 4,5,11,12,[17][18][19][20] The layered structure of landfill covers is often unsaturated in service. For example, although infiltrated rainfall water during rainy seasons can elevate the degree of soil saturation, it is yet improbable to render it fully saturated.…”

Section: Introductionmentioning

confidence: 99%

“…42 Some analytical techniques are available for VOC diffusion in unsaturated cover systems, mainly with the assumption of uniform water distributions along with depth. 19,27 For example, an analytical model was presented for gas migration in layered landfill cover by assuming a uniform water distribution along the depth in the soil layer. 42 However, the water distribution along with the depth is not uniform for the layered soil.…”

Section: Introductionmentioning

confidence: 99%

“…A quantitative assessment of VOC migration through the layers is crucial for the efficient design of a landfill cover system 15,16 . Experimental and numerical studies have been devoted to investigating VOC transfer within the landfill cover 4,5,11,12,17–20 …”

Section: Introductionmentioning

confidence: 99%

“…In addition, analytical solutions play a unique role in verifying newly proposed numerical methods 42 . Some analytical techniques are available for VOC diffusion in unsaturated cover systems, mainly with the assumption of uniform water distributions along with depth 19,27 . For example, an analytical model was presented for gas migration in layered landfill cover by assuming a uniform water distribution along the depth in the soil layer 42 .…”

Section: Introductionmentioning

confidence: 99%

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Analytical solution for one‐dimensional steady‐state VOCs diffusion in simplified capillary cover systems

Yan

Xie

Rajabi

et al. 2023

Num Anal Meth Geomechanics

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The analytical solution for a one‐dimensional and steady‐state model is proposed to investigate the diffusion of VOCs within landfill capillary cover systems under unsaturated water flow and stable conditions. Examples of coupled water flow and VOCs diffusion are evaluated by the proposed analytical solution to discuss the effects of the evaporation rate and clay thickness. The proficiency of the unsaturated cover system in minimising VOC emissions was also investigated. It was found that the non‐uniform distribution of water content can cause one order of magnitude reductions in the effective diffusion coefficient of VOCs, resulting in the attenuation of VOCs in the cover system. The concentration profile of VOCs is lower for the case with a larger evaporation rate. Ignoring the non‐uniform distribution of water content induced by water flow would underestimate the surface flux of VOCs by a factor of 1.8. The water content and VOC concentration in the cover system can be effectively diminished with the thickness of the clayey layer increasing. The surface flux of VOCs is considerably decreased with increasing thickness of clayey layer. Increasing the thickness of clayey layer from 0.2 to 1 m leads to a reduction in the surface flux of VOCs by a factor of 2.9. The sensitivity analysis provides further insights into the critical role of water flow in affecting VOC transport through the unsaturated cover system. The outcomes highlight that the impacts of unsaturated water flow within the covering system should be considered for assessment of VOC emissions.

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