TY  - JOUR
A1  - Balcke, Gerd U.
A1  - Hahn, M.
A1  - Oswald, Sascha
T1  - Nitrogen as an indicator of mass transfer during in-situ gas sparging
JF  - Journal of contaminant hydrology
N2  - 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.
KW  - Inter-phase mass transfer
KW  - Groundwater
KW  - Remediation
KW  - Gas sparging
KW  - Nitrogen
KW  - Methane
KW  - Kinetics
KW  - Bitterfeld
Y1  - 2011
U6  - https://doi.org/10.1016/j.jconhyd.2011.05.005
SN  - 0169-7722
VL  - 126
IS  - 1-2
SP  - 8
EP  - 18
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Schaffer, Mario
A1  - Idzik, Krzysztof R.
A1  - Wilke, Max
A1  - Licha, Tobias
T1  - Amides as thermo-sensitive tracers for investigating the thermal state of geothermal reservoirs
JF  - Geothermics : an international journal of geothermal research and its applications
N2  - The application of thermo-sensitive tracers is a promising technique for evaluating the thermal state of geothermal reservoirs. To extend the compound spectrum for hydrolyzable compounds to reservoir temperatures between 100 and 200 degrees C carboxamides were studied. The kinetic parameters of 17 self-synthesized amides were determined in hydrothermal batch and autoclave experiments. The influence of the molecular structure and the role of pH/pOH on hydrolysis kinetics were studied. Additionally, the thermal stabilities of the hydrolysis products were evaluated. The results demonstrate the high potential of tracers based on amide hydrolysis for use in medium enthalpy reservoirs. (C) 2016 Elsevier Ltd. All rights reserved.
KW  - Thermo-sensitive tracers
KW  - Amides
KW  - Hydrolysis
KW  - Kinetics
KW  - Reservoir temperature
KW  - Molecular design
Y1  - 2016
U6  - https://doi.org/10.1016/j.geothermics.2016.05.004
SN  - 0375-6505
SN  - 1879-3576
VL  - 64
SP  - 180
EP  - 186
PB  - Elsevier
CY  - Oxford
ER  -