[A-GE27] 地質媒体における流体移動、物質移行及び環境評価

[AGE27-P05] Multi-disciplinary approach to understand a Cr contaminated site at Rania-Khan Chandpur, India

*Pankaj Kumar Gupta^1,2、Vivek Nair¹、Vivek Dalvi¹、Sumit Dhali¹、Anushree Malik¹、Kamal Kishore Pant^3,4 (1.Applied Microbiology Laboratory, Centre for Rural Development and Technology (CRDT), Indian Institute of Technology (IIT) Delhi Hauz Khas, New Delhi 110016, India、2.Wetland Hydrology Research Laboratory, Faculty of Environment, University of Waterloo, 200 University Ave W, Waterloo ON N2L3G1, Canada、3.Catalytic Reaction Engineering Group, Department of Chemical Engineering, Indian Institute of Technology (IIT) Delhi Hauz Khas, New Delhi 110016, India、4.Indian Institute of Technology (IIT) Roorkee, Roorkee, Uttarakhand 247667, India)

キーワード：Soil-Water System, Chromium, Contamination, Microbiome, Remediation

Contaminants can exist in a soil matrix as free-, colloidal-, dissolved- or gas-phase subsequently posing risks to soil-water quality. Given the regulatory requirement is to return contaminated site to the pristine capacity-class, it is essential that we must have the knowledge of characterising the soil-water system to translate remediation concepts into successful practices/design. The aim of this research is to perform field-laboratory-numerical modeling studies to understand the soil-water system at Rania-Khan Chanpur villages, Kanpur Dehat-India, which is extremely contaminated by hazardous biproducts of the chromite ore processing residue (COPR). Two COPR dump sites are in Rania village, whereas Khan Chandpur is neighbouring village located in downgradient (~130 cm below Rania) side. To achieve this aim, i) the surface elevation was prepared using high-resolution LiDAR and IfSAR data from remote sensing survey; 2) undisturbed COPR and soils cores were analysed for hydraulic and transport properties; 3) solute transport and soil-water quality was tested in the field; 4) soil microbiome was explored using metagenomic data; 5) vegetations were identified and collaborated with GHG dynamics. We found that stratification of chromate leachate continues to move with underlaying advective flow in a narrow stretch (~500 m width) towards south-west in Khan Chandpur village. This is corroborated with extreme Cr concentrations (>10mg/L) in 95% monitoring wells located in Khand Chandpur and with the site hydrology. We found that Rania village is hydrogeologically different than the Khan Chandpur village, where multiple chromate plumes are active and its mobility is due to diffusive fluxes, which is reflecting as moderate Cr concentrations (<10 mg/L) in ~35-40% monitoring wells. High soil moisture drives in such a way that little surface leachate is imbibed into deeper zones, thus deep soils are safe as we move away from the COPR dump site. Areas with high soil moisture contents step up CH₄ fluxes. Likewise, the vegetation biodiversity is comparatively high in area where soils are safe. 16S rRNA sequencing data reveals that COPR has an active microbiome, but structurally distinct from soil microbial communities. In this talk, we will present our integrated approach that is the blend of hydrogeology, biogeochemistry, and microbial ecology to highlight a thorough understanding of the contaminated site investigation conducted by our research group at the Indian Institute of Technology (IIT) Delhi. We will describe some of our key contributions related to monitoring of soils, surface water, groundwater, plants, and microbiome across Cr contaminated zones, and some of our ongoing work and potential future applications. In addition, the talk will reflect on the field scale hydrological practices to improve soil-water quality and restore it's pristinity. From industrial point of view, this talk will help the audience to rethink the steps involved in the management of contaminated site to cut the remediation costs. From research and academia point of view, this talk will provide the audience an excellent opportunity to understand the key takeaways from a field-scale study, which is rarely reported in the field of hydrogeology/contaminant hydrology.