Comparison of chemical sediment analyses and field oiling observations from the Shoreline Cleanup Assessment Technique (SCAT) in heavily oiled areas of former mangrove in Bodo, eastern Niger Delta

Abstract

Trial pitting, borehole drilling, and soil, sediment and groundwater sampling are important components of oil spill response and contaminated land assessment. These investigations provide detailed information on the subsurface geology and contaminant occurrence and transport but have disadvantages including worker safety hazards, cost and time required for completion, and may cause cross-contamination among aquifers. An alternative to such investigations applied in oil spill response is the Shoreline Cleanup Assessment Technique (SCAT) approach, which relies heavily on direct visual observations to assess the severity of oil contamination and guide cleanup efforts. Here, we compare SCAT observations of oil type, surface coverage and pit oiling with collected surface and subsurface sediment samples taken concurrently and analysed for a suite of hydrocarbon constituents. Results indicate that although limited sampling and analysis is required to chemically characterize the contamination, SCAT observations can be calibrated using limited sediment sampling and are sufficient to steer physical cleanup methods. This is particularly evident as even closely spaced chemical samples show high variability. A coarser direct visual observation is fit-for-purpose considering the wide variability in contaminant distribution at even local levels. In this contribution, we discuss the limitations of the different methods. Supplementary material: The modified SCAT data collection form, figures showing subsurface versus ground surface total petroleum hydrocarbons (TPH) and a variogram of TPH measured in the ground surface and subsurface samples, and data tables are available at https://doi.org/10.6084/m9.figshare.c.4534682 Thematic collection: This article is part of the Measurement and monitoring collection available at: https://www.lyellcollection.org/cc/measurement-and-monitoring

Exposure, geochemical, and spatial distribution patterns of an oil spill in parts of the Niger Delta Region of Nigeria

“…The sediment THC and TPH recorded in this investigation may account for the extinction of mangrove vegetation in the study area, and is in agreement with the record of, that the oil spill has a deleterious effect on the sub-tidal and intertidal vegetation. Consequently, organisms such as periwinkles and mudskipper that are vulnerable to oil pollution are in extinction [33]. The high level of water and sediment THC and TPH above recommended limits in the environment accounts for the extinction of certain fish species and the observed dead fishes in the study area.…”

“…The high level of water and sediment THC and TPH above recommended limits in the environment accounts for the extinction of certain fish species and the observed dead fishes in the study area. High THC and TPH are ingested by microbiomes, planktons, crustaceans, crabs, periwinkles, and fish [33]. This ingested hydrocarbon is passed along the food chain.…”

Baseline PAHs, N-PAHs and 210Pb in Segment Samples from Bodo Creek: Comparison with Bonny Estuary, Niger Delta

“…The (Gundlach, 2018;Little et al, 2018;Bonte et al, 2019). Prior the oil pollution saga, the creek and mangroves are known to provide nutrient filtration, fish nursery, bird staging areas and local transport corridors for human access to vital natural resources such as food and wood for building, fuel and making of cultural artifacts (Fentiman & Zabbey, 2015).…”

Measurement and monitoring

“…Abesser et al focus on the use of fibre optic sensors and the next paper (by Puzrin et al, 2020) continues this theme, but this time for ground monitoring to determine displacements with a view to assessing geohazard risks. Contamination monitoring is the subject of the next two papers (by Hampton et al, 2020 andBonte et al, 2020), the first relating to groundwater nitrate concentrations and next relating to oil spills. The sixth paper (by Provenzano et al, 2020) moves from the surface and shallow subsurface to deep marine slopes where excess pore pressures can develop from continuous deposition above, leading to instability.…”

“…Ground pollution by petroleum-related activities is another category of contamination that needs careful monitoring to facilitate control and clean-up operations. Bonte et al (2020) describe a 'Shoreline Cleanup Assessment Technique' (SCAT) that has been implemented in a mangrove creek in the eastern Niger Delta that has been severely affected by oil spills. The affected area is very extensive and not an easy terrain or environment to install instrumentation that might allow real-time monitoring (e.g.…”