Abstract. Assessment of soil quality is one of the key parameters for evaluation of environmental contamination in the mining ecosystem. To investigate the effect of coal mining on soil quality, opencast and underground mining sites were selected in the Raniganj coalfield area, India. The physical, chemical, and biological parameters of the soils, and trace metals and PAHs (polycyclic aromatic hydrocarbons) in the soils were evaluated. Soil dehydrogenase (+79 %) and fluorescein (+32 %) activities were significantly higher in underground mine (UGM) soil, whereas peroxidase activity (+57 %) was higher in opencast mine (OCM) soil. Content of As, Be, Co, Cr, Cu, Mn, Ni, and Pb was significantly higher in OCM soil, whereas Cd was higher in UGM. In general, the PAHs contents were higher in UGM soils, probably due to the natural coal burning at these sites. The observed values for the above properties were converted into a unitless score (0-1.00) and the scores were integrated into an environmental soil quality index (ESQI). In the unscreened index (ESQI-1) all the soil parameters were included and the results showed that the quality of the soil was better for UGM (0.539) than the OCM (0.511) soils. Principal component analysis was employed to derive ESQI-2 and accordingly, total PAHs, loss on ignition, bulk density, Be, Co, Cr, Ni, Pb, and microbial quotient (respiration: microbial biomass ratio) were found to be the most critical properties. The ESQI-2 was also higher for soils near UGM (+10.1 %). The observed indicators and the ESQI results revealed that soil quality assessment for these coal mining soils is largely depended on soil PAHs and potentially toxic trace metals. The proposed ESQI may be further refined by incorporating specific parameters related to human exposure risks and exposure pathways.

Abstract. Assessment of soil quality is one of the key parameters for evaluation of environmental contamination in the mining ecosystem. To investigate the effect of coal mining on soil quality, opencast and underground mining sites were selected in the Raniganj Coafield area, India. The physical, chemical, biological parameters, heavy metals, and PAHs contents of the soils were evaluated. Soil dehydrogenase (+79%) and fluorescein (+32%) activities were significantly higher in underground mine (UGM) soil, whereas peroxidase activity (+57%) was higher in opencast mine (OCM) soil. Content of As, Be, Co, Cr, Cu, Mn, Ni, and Pb was significantly higher in OCM soil, whereas, Cd was higher in UGM. In general, the PAHs contents were higher in UGM soils probably due to the natural coal burning in these sites. The observed values for the above properties were converted into a unit less score (0–1.00) and the scores were integrated into environmental soil quality index (ESQI). In the unscreened index (ESQI-1) all the soil parameters were included and the results showed that the quality of the soil was better for UGM (0.539) than the OCM (0.511) soils. Principal component analysis was employed to derive ESQI-2 and accordingly, total PAHs, loss on ignition, bulk density, Be, Co, Cr, Ni, Pb, and microbial quotient (respiration: microbial biomass ratio) were found to be the most critical properties. The ESQI-2 was also higher for soils near UGM (+10.1%). The proposed ESQI may be employed to monitor soil quality changes due to anthropogenic interventions.

This paper highlights an innovative approach where Multibeam Echosounder (MBES) and sub-bottom profiler (SBP) survey results in addition to conventional seismic data were utilized to demarcate locations for shallow coring. Multibeam and Shallow geochemical studies were planned to further de-risk hydrocarbon potential in frontier exploration areas. Following detailed 2D seismic interpretation, MBES survey area and 100 shallow cores were planned. The interpreted MBES data was used to pin point the final shallow core points. Due to the unfavorable weather window, the survey could not be fully completed. Hence, the remaining area was evaluated by an improvised workflow using preliminary processed 3D seismic data (seabed horizon slice) to fulfil the gap. This allows all proposed coring points to be evaluated. Numerous features like seabed scarps, wave form seabed, seabed mounds, and seabed depressions were identified on top of the observations of a number of active gas seepages and pockmarks. A notably hard seabed was encountered during the seabed sampling operations which resulted in low core recovery. The team effort in improvising a different workflow to identify various sea bed features and also demarcating shallow core location through integrating various geophysical data was very much useful.