DOI: 10.5194/hess-21-1381-2017
Scopus记录号: 2-s2.0-85015031575
论文题名: Experimental study on retardation of a heavy NAPL vapor in partially saturated porous media
作者: Kleinknecht S ; M ; , Class H ; , Braun J
刊名: Hydrology and Earth System Sciences
ISSN: 10275606
出版年: 2017
卷: 21, 期: 3 起始页码: 1381
结束页码: 1396
语种: 英语
Scopus关键词: Air
; Aquifers
; Argon
; Biodegradation
; Carbon
; Carbon disulfide
; Groundwater
; Hydrogeology
; Porous materials
; Seepage
; Air water interfaces
; Break through curve
; Conservative tracers
; Gas chromatographs
; Nonaqueous phase liquids
; Partially saturated porous media
; Relative contribution
; Theoretical approach
; Phase interfaces
; adsorption
; aquifer
; argon
; biodegradation
; concentration (composition)
; experimental study
; interface
; plume
; porous medium
; seepage
; tracer
; vadose zone
英文摘要: Non-aqueous-phase liquid (NAPL) contaminants introduced into the unsaturated zone spread as a liquid phase; however, they can also vaporize and migrate in a gaseous state. Vapor plumes migrate easily and thus pose a potential threat to underlying aquifers. Large-scale column experiments were performed to quantify partitioning processes responsible for the retardation of carbon disulfide (CS2) vapor in partially saturated porous media. The results were compared with a theoretical approach taking into account the partitioning into the aqueous phase as well as adsorption to the solid matrix and to the air-water interface. The experiments were conducted in large, vertical columns (i.d. of 0.109-m) of 2-m length packed with different porous media. A slug of CS2 vapor and the conservative tracer argon was injected at the bottom of the column followed by a nitrogen chase. Different seepage velocities were applied to characterize the transport and to evaluate their impact on retardation. Concentrations of CS2 and argon were measured at the top outlet of the column using two gas chromatographs. The temporal-moment analysis for step input was employed to evaluate concentration breakthrough curves and to quantify dispersion and retardation. The experiments conducted showed a pronounced retardation of CS2 in moist porous media which increased with water saturation. The comparison with an analytical solution helped to identify the relative contributions of partitioning processes to retardation. Thus, the experiments demonstrated that migrating CS2 vapor is retarded as a result of partitioning processes. Moreover, CS2 dissolved in the bulk water is amenable to biodegradation. The first evidence of CS2 decay by biodegradation was found in the experiments. The findings contribute to the understanding of vapor-plume transport in the unsaturated zone and provide valuable experimental data for the transfer to field-like conditions. © 2017 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/79232
Appears in Collections: 气候变化事实与影响
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作者单位: Facility for Subsurface Remediation, Institute for Modelling Hydraulic and Environmental Systems, University of Stuttgart, Pfaffendwaldring 61, Stuttgart, Germany; Department of Hydromechanics and Modelling of Hydrosystems, Institute for Modelling Hydraulic and Environmental Systems, University of Stuttgart, Pfaffendwaldring 61, Stuttgart, Germany
Recommended Citation:
Kleinknecht S,M,, Class H,et al. Experimental study on retardation of a heavy NAPL vapor in partially saturated porous media[J]. Hydrology and Earth System Sciences,2017-01-01,21(3)