Delineation of LNAPL plumes in a clay-rich site in Gyeongsangnam-do Province, South Korea: integration of geophysical survey data with borehole data and soil sampling information

• Published in: Environmental monitoring and assessment 2024-01, Vol.196 (1), p.47-47, Article 47
• Main Authors: Kim, Bitnarae, Joung, In Seok, Yu, Huieun, Jeong, Juyeon, Song, Seo Young, Son, Jeong-sul, Yu, Youngchul, Shin, Jehyun, Jo, Ho Young, Kwon, Man Jae, Nam, Myung Jin
• Format: Article
• Language: English
• Subjects: Aeration zone; Atmospheric Protection/Air Quality Control/Air Pollution; Biodegradation; Boreholes; Chemical analysis; Clay; Conductivity; Contaminants; Cost analysis; Drilling; Earth and Environmental Science; Earth Sciences; Ecology; Ecotoxicology; Electrical resistivity; Electricity; Environment; Environmental Management; Environmental Monitoring - methods; Geological structures; Geology; Geophysical data; Geophysical exploration; Geophysical methods; Geophysical surveys; Ground penetrating radar; Groundwater; Groundwater - chemistry; Groundwater levels; Hydrocarbons; Induced polarization; Mineral resources; Monitoring/Environmental Analysis; Nonaqueous phase liquids; Oil; Oil pollution; Oils & fats; Physical Phenomena; Physical properties; Plumes; Radar; Sampling; Sciences of the Universe; Seismic refraction; Seismic surveys; Soil contamination; Soil sampling; Spatial data; Spatial distribution; Surveys; Three dimensional models; Tomography
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-023-12202-9

To effectively delineate the spatial distribution of oil contaminant plumes, geophysical methods indirectly measure the physical properties of the subsurface and can provide spatial information and images on a large scale, as opposed to traditional direct methods such as borehole drilling, sampling, and chemical analysis, which are time-consuming and costly. However, interpreting geophysical responses over non-aqueous phase liquid (NAPL)–contaminated sites is not straightforward due to inconsistent responses from biodegraded oil contaminants. In this study, we performed multi-geophysical surveys including seismic refraction, ground-penetrating radar, electrical resistivity tomography (ERT), and induced polarization (IP) surveys, to locate NAPL-contaminated zones in a clay-rich site. To reduce ambiguity in discriminating between oil contaminants and clay layers, we first figure out the geological structure of the site by interpreting geophysical data incorporating with borehole data. The ERT data highlighted the heavily contaminated regions in the unsaturated zone but were less distinctive below groundwater levels. Conversely, IP responses revealed potential hotspots within the clay layers, extending beneath the groundwater. Considering the 3D geological model, NAPL-contaminated zones are properly delineated through interpretation of ERT and IP data together with borehole data, and the contaminant source zone was properly estimated within the site.