Prakash Kumar Singh

Textural analysis of pyrite has been carried out in the lignites of Kachchh Basin to decipher its micro-morphological character. The study entails the intermediate stage and authigenic sunflower structured pyrite. The origin, characteristics, shape and distribution of pyrite within Tertiary lignites has been comprehensively explored through petrography, ultimate analysis and scanning electron microscopy (FE-SEM). Along with the sunflower structure, the study has also revealed the presence of variouspyrite-textures of such as pyrite-framboids, massive type of pyrite, discrete-pyrite, fissure and cavity filling pyrite, disseminated pyrite gains, euhedral pyrite and subhedral pyrite of which the dominating one is framboidal pyrite. Wide variation in the size of framboidal pyrite (6 µm – 11 µm) indicates epigenetic process of its formation and the deposition of lignite in a suboxic/ dysoxic environment. The presence of high sulfur concentration in lignite is further suggestive of a marine origin. The initial study indicates that the lignite in western Kachchh is not significantly agreeable to beneficiation, whether through physical or biological method and also prone to spontaneous combustion that leads to environmental issues. In addition, close association of pyrite with macerals also sheds light on the influence and active participation of organic matter in the pyrite formation.

Energy security and environmental sustainability are now crucial strategies for emerging countries like India. Peat is a versatile geo-material that can serve as a fossil energy source and industrial raw material used in horticulture/agriculture, but also as an archive of geological and palaeoenvironmental records. At the same time, peatlands globally play a critical role in carbon storage, water regulation and biodiversity. Peatlands in Southeast Asian countries (primarily Indonesia and Malaysia) are extensively studied, but in India peatland is a relatively obscure ecosystem and one of the least studied geological environments. This review aims to summarise the peat and peatland research that has been done so far in India. We find that peatlands have been studied in parts of Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Assam, Manipur, Tripura, Kerala, Tamil Nadu and West Bengal. However, India has no centralised comprehensive database on peatlands. In fact, the study and inventory of peatlands in India remains significantly under-developed in terms of global standards, resulting in limited availability of information about the locations, extent and characteristics of these ecosystems. Active development of peat and peatlands research in India could benefit carbon storage and climate regulation bodies, water storage and supply organisations, biodiversity conservation agencies, flood control and prevention agencies, fish farming and agriculture, as well as the energy sector.

Despite evidence of palaeo-wildfires during the formation of Indian coal deposits, studies on their fire intensity, temporal variability and relation to palaeo-oxygen levels remain limited. A comprehensive investigation of wildfire signatures in Indian Permian coals is required to bridge this knowledge gap. The Carboniferous to Permian Period is characterised by prevalent coal formation and a substantial occurrence of palaeo-wildfires. However, the occurrence of these wildfires and their spatial distribution exhibited temporal variability throughout this period. An inclusive investigation (including petrological compositions, especially inertinites and scanning electron microscopy (SEM)) was executed on coal samples from Bastacolla Mines, Jharia Coalfield, India, to investigate variations in palaeo-wildfire signature and palaeo-wildfire temperature during peat formation. The dominance of vitrinite with a significant inertinite content (as a by-product of palaeo-wildfire) in studied coal samples reveals that wildfire activity occurred during peat formation. The inertinite reflectance values ranging from 1.42% to 2.62% (mean: 1.88%) and 1.20% to 2.48% (mean: 1.67%) in Bottom-II and Top-III seam, respectively, indicate wildfire in Permian was dominated by mainly ground fires and partially surface fires. SEM images show various typical structures, including cellular/fibrous structure, uniseriate and biseriate tracheid, indicating the dominance of gymnosperm flora during peat formation. Further, the presence of typical structures by SEM, charcoal lenses on the sample surface (macroscopic) and high inertinite in investigated coal seams reveals the occurrence of wildfire during its formation. The significantly high atmospheric oxygen levels (pO ₂ ˃23%) provide compelling evidence for frequent wildfires in the Jharia Coalfield during the coal-forming period.

Azo dyes are used as coloring agent in textile industries at larger scale. As a result, large quantity of dye-enriched waste water is generated which subsequently poses environmental problems. Biological tool involving bacteria having azoreductase enzyme has proved to be more effective and efficient in dye effluent treatment. Current work focuses on Staphylococcus caprae (S. caprae) for degradation and decolorization of Reactive Red-195 (RR-195) azo dye. For this purpose, factors such as pH, temperature, inoculums, carbon and nitrogen sources, and dye concentrations have been optimized for maximum decolorization and degradation. S. caprae (4 mg/mL) efficiently resulted into 90% decolorization of RR-195 dye under static condition at 100 µg/mL concentration, 30 °C and pH 7.0 at a 12-h contact period. FTIR analysis has revealed the formation of new functional groups in the treated dye such as O–H stretch at 3370 cm⁻¹, C-H band stretching at 2928 cm⁻¹, and new band at 1608 cm⁻¹ which specify the degradation of aromatic ring, 1382 and 1118 cm⁻¹ represents desulfonated peaks. Biodegraded metabolites of RR-195 dye such as phenol, 3, 5-di-tert-butylphenol, and phthalic acid have been identified respectively that find industrial applications. Phytotoxicity test has shown non-toxic effects of treated dye on germination of Vigna radiata and Triticum aestivum seeds. Further, antibiotic diffusion assay has confirmed the biosafety of S. caprae.

Mineral matter in coal is the host of several environmentally sensitive elements and a potential source of Rare Earth Elements (REE). During combustion, some trace elements are liberated as gas, while others get concentrated in ash, contaminating soil and local water bodies. Minimizing the inorganic content makes the coal clean and eventually increases its calorific value. Bacteria serve as an eco-friendly remediation tool, particularly neutrophilic ones that facilitate the treatment at mild pH and ambient temperatures. Use of native bacteria accelerates the treatment process by readily adapting to substrates. We present the remediation potential of three native neutrophilic bacteria in this study. After six days of treatment, Bacillus sp. CpH06 has reduced ash yield by 15.96%, trace elements by 26% to 75%, and REE by 24% to 50%. Bacillus anthracis CpH08 has reduced ash yield by 22.6%, trace elements by 6.4% to 70.5%, and REE by 8.4% to 37%. Maximum ash yield reduction of 22.91% was attained by the Cronobacter sp. CpH10 including reduction of 8.1% to 73% of trace elements and 26% to 48% of REEs. The FTIR spectra reveal alterations in both peak intensity and position of inorganic functional groups resulting from the removal of elements, formation of new bonds, and the elimination of certain pre-existing functional groups. XRD spectra indicate bio-oxidation mechanism, exhibited by the removal of copper sulfate hydroxide and pyrite along with formation of Jarosite and metal-sulfide peaks. The findings encourage further research on the effectiveness and performance of these bacteria on diverse types of coals.

The present paper discusses the evolution of the coal bearing sequences of Tharad Formation of Cambay Basin (Gujarat) based on coal petrological and organic geochemical signatures. Cambay Basin is a craton margin rift basin of Late Cretaceous age which is narrow and elongated. This north-south trending graben hosts huge sub-surface lignite/coal deposits of Early to Middle Eocene age. These coals have been petrographically and geochemically characterized to understand the type of flora, coal facies, depositional environment and coalification. Thickening of seams with depth is towards central part. Vitrinite rich Cambay Basin coals contain a considerable amount of liptinite indicating their derivation from the forest type of vegetation that grew under humid tropical climate while its high resin content indicates growth of conifers and gum-producing plants. High collodetrinite relates to soft woody tissues from herbaceous/bushy plant sources. Abundance of bioclasts in the western flank of the Sanchore low occur in stack indicating poor transportation and abrupt drop in bathymetry under tidal flat environment. The palynofloral assemblages indicate tidal deposition. Gas chromatography-mass spectroscopy (GC-MS) studies indicate low amount of oleanane suggesting a terrestrial source. The microlithotypes suggest limnic and telmatic mixed environment with typical forest floral input with intermittently changing water table conditions. The maceral composition of the coals indicates terrestrial origin having high tree-density. Marine influence caused influx of calcium rich water promoting decomposition of organic matter due to high bacterial activity and high pH values with depth. The ground water flow index (GWI) values indicate ombrotrophic hydrological condition while the vegetation index (VI) values support herbaceous plants. The swamp, therefore, suffered oxic and anoxic condition alternatingly with influence of reed marshes favouring the growth of anaerobic bacteria in high bathymetric region. The depth of burial of coal seams in Sanchore is extrapolated to be 1350-1800m with a temperature range of 40-80°C.

Owing to a rapid rate of depletion of conventional energy resources and to keep pace with the ever increasing energy demand, scientists all over the world are looking for some alternate source. Coal bed methane (CBM) is one of them. With the discovery of coalbed gas from an oil and gas producing basin- the San Juan basin in Colorado and New Mexico by AMOCO in early 1980’s, the attention of world-wide hydrocarbon industry shifted to evaluation of CBM potential of Tertiary basins. The Tertiary Cambay basin in Gujarat is a known onland hydrocarbon province of India and has been producing oil since 1958. During drilling for petroleum, thick Eocene coal seams are encountered at varied depths in Mehsana area and further north. In 2004, few coalbed methane (CBM) blocks were awarded in northern Cambay basin and contagious Barmer Basin. The present paper entails the results of investigation carried out for CBM in the deep-seated coals of Sanchore and Tharad area in north Cambay basin. The methane content of the desorbed gases varies from 20–68%. The stable carbon isotope study (δ¹³C) shows that the desorbed gas is dominantly biogenic but the compositional analysis of desorbed gas reveals significant fractions of ethane (C₂) and butane (C₃) indicating the gases to be of mixed origin. Further, presence of high CO₂ content is observed which varies from 20–45% of the total volume of desorbed gas. The estimated mean CBM resource of the study area is ∼ 46 billion cubic meters.