Nitrogen as an indicator of mass transfer during in-situ gas sparging

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• 作者：Gerd U.  ; Balcke^a ;   ; ^d ; M.  ; Hahn^b ; Sascha E.  ; Oswald^c ;   ; ^d ;   ; ^{sascha.oswald@uni-potsdam.de}
• 关键词：Inter-phase mass transfer ; Groundwater ; Remediation ; Gas sparging ; Nitrogen ; Methane ; Kinetics ; Bitterfeld
• 刊名：Journal of Contaminant Hydrology
• 出版年：2011
• 出版时间：25 September 2011
• 年：2011
• 卷：126
• 期：1-2
• 页码：8-18
• 全文大小：2283 K

文摘

Aiming at the stimulation of intrinsic microbial activity, pulses of pure oxygen or pressurized air were recurrently injected into groundwater polluted with chlorobenzene. To achieve well-controlled conditions and intensive sampling, a large, vertical underground tank was filled with the local unconfined sandy aquifer material. In the course of two individual gas injections, one using pure oxygen and one using pressurized air, the mass transfer of individual gas species between trapped gas phase and groundwater was studied. Field data on the dissolved gas composition in the groundwater were combined with a kinetic model on gas dissolution and transport in porous media. Phase mass transfer of individual gas components caused a temporary enrichment of nitrogen, and to a lower degree of methane, in trapped gas leading to the formation of excess dissolved nitrogen levels downgradient from the dissolving gas phase. By applying a novel gas sampling method for dissolved gases in groundwater it was shown that dissolved nitrogen can be used as a partitioning tracer to indicate complete gas dissolution in porous media.