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In the present situation, Covid-19 is considered to be an unbeaten global pandemic. In every single fleeting moment, this SARS-CoV-2 (coronavirus-2) causes greater damage to our life including the physical world including drastic imbalance of the whole economic condition of any country. The lockdown governed in two consecutive years (2020 and 2021) in the world to control the spreading of the virus poses an undue threat to the industrial sectors including the coal mining sectors that determine the economic growth of the country. With these negative impacts of coronavirus-2 in our life, this present review aims to explore some of the positive influences of the Covid-19 pandemic through the restoration of the environmental system which are otherwise not possible. This quantitative review finds that spreading of the Covid-19 pandemic indirectly improves the air and water quality by reducing the number of vehicles, reduces the CO2, NOx, particulate matter, and other polluting gases emission from coal-based power plants through periodical lockdown in the country. Moreover, the lockdown implemented to minimise the spreading of the Covid-19 significantly reduces the coal dust production from the mining and transportation of coal that indirectly reduces environmental pollution. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is one of the major problems in high sulfur coal mining areas generating acidic water. The acidic mine water generated contain hazardous elements in varying concentrations. The Northeastern Indian coalfield produces considerable amounts of AMD. The AMD and metal leaching from coal and mine over burden (OB) are the two important naturally occurring processes. In order to know the AMD potential, the aqueous leaching experiment of a few coal and OB samples from the Ledo colliery of the Northeastern coalfield, Mergherita (India), at different time periods (1, 3, 5, and 8 h) and at different temperatures (25, 45, 65, and 90 °C) were performed in the laboratory. The physico-chemical analysis of the aqueous leachates shows the pH, electrical conductivity (EC), and total dissolved solid (TDS) in the range of 1.62-3.52, 106-2006 µs/cm, and 106-1003 ppm for the raw coal samples respectively. The OB samples produced pH, EC, and TDS in the range of 3.68-6.92, 48.6-480 µs/cm, and 69.5-240 ppm respectively. From the study, it was revealed that the concentrations of major (Si, Al, K, Na, Fe, Ca, Mg), minor (Mn) and trace/hazardous elements (As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, Zn) considerably change with leaching time as well as with leaching temperature. Out of these elements As, Cd, Hg, Pb, Cr, and Se are of greater environmental importance. Alteration of the physico-chemical structure of the coal and OB samples resulting from leaching was also studied by field emission scanning electron microscope- energy-dispersive X-ray spectroscopy method. The release of the potentially hazardous elements from the raw coal and OB during leaching time periods to the leachates was detected by inductively coupled plasma-atomic emission spectroscopy and ion-chromatographic analyses. The major minerals found in coal and OB are quartz (SiO2), pyrite (FeS2), hematite, marcasite, and kaolinite. The association of different functional groups in minerals and their mode of association were studied by Fourier-transform infrared spectroscopy and X-ray diffraction analytical techniques. The present laboratory study will be useful in relating the characteristics of aqueous leaching from coal and mine OB with the natural weathering condition at the coal mine area. [ABSTRACT FROM AUTHOR]