Talks and Poster Presentations (without Proceedings-Entry):

M. Bücker, A. Flores-Orozco, C. Pita, A. Kemna:
"Case Study on the Effect of Anthropogenic Noise on Induced Polarization Images of an Oil- Spill Site in an Urban Environment";
Poster: 75. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, Hannover; 2015-03-23 - 2015-03-26.

English abstract:
Induced Polarization (IP) imaging is a promising tool for the characterization of different organic and inorganic contaminants, as well as for the monitoring of biogeochemical processes accompanying remediation activities. IP Imaging measurements at the field scale have demonstrated the ability of the method to delineate contaminant plumes. However, a quantitative interpretation of IP images from urban areas and industrial sites is often difficult. This is because the occurrence of anthropogenic structures in the subsurface, such as buried metallic pipes or reinforced concrete foundations, can strongly distort the IP response of the actual target, i.e. the contaminant plume. In order to understand the effect of anthropogenic structures on IP data and explore the possibility to remove its influence on the final images, we carried out time-domain induced polarization measurements at a former lube oil blending plant in Mexico City. Complementary electromagnetic-induction (EMI) surveys helped to delineate buried metallic structures. IP data were collected before and after the removal of the first 2 m of fill material containing most of the metallic structures, which permitted us to directly assess the dimensions of the anthropogenic sources of noise and their effects on the measured data. Resistivity images obtained from the inversion of IP measurements were only affected in the immediate proximity of the anthropogenic structures. In areas away from noise sources, a clear correlation between conductive anomalies and the known extensions of the oil plume was found. However, integral chargeability revealed a higher degree of distortion even for measurements collected at larger distances from the anthropogenic structures. Numerical modelling of this effect revealed consistency with field measurements. Based on our observations, we present different approaches to improve the collection of IP data in urban areas. The comparison of IP images obtained with different electrode configurations and using data collected before and after the removal of anthropogenic structures permits a direct evaluation of the benefits of our approach. Both properties solved for with the final IP images, i.e. resistivity and phase (or chargeability), show a good correlation with the geometry of the oil spill

Electronic version of the publication:

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