Divya Prakash
Articles written in Journal of Earth System Science
Volume 124 Issue 6 August 2015 pp 1187-1199
The area around Darjeeling consists of medium grade metamorphic rocks and provides a classic example of inverted Himalayan metamorphism. The area under investigation shows upper amphibolite facies metamorphism (sillimanite-muscovite subfacies), rocks are intimately associated with the migmatites and granites. The presence of quartzite, calc-silicate rocks, graphitic schist and abundance of aluminous minerals like kyanite or sillimanite in these rocks indicate their metasedimentary character. Granetsillimanite bearing gneisses occupy most of the area of Darjeeling but not persistent throughout. Textural relationship suggests sequential growth of progressively higher-grade metamorphic minerals during D1 and D2 deformation. The relative XMg in the minerals varies in the order: biotite>staurolite>garnet, and the XMn decreases in the order: garnet>staurolite>biotite. The P–T evolution of these garnetsillimanite gneiss has been constrained through the use of conventional geothermobarometry, internally consistent TWEEQU programme and Perple_X software in the KFMASH model system, the combination of these three approaches demonstrates that the Darjeeling gneisses experienced peak pressure and temperature at 7.0 ± 0.3 kbar and 700 ± 30°C. The observation in this study has important bearing on the inverted metamorphism in the Himalayan metamorphic belt.
Volume 129 All articles Published: 10 November 2020 Article ID 0226 Research article
Fine particulate pollution and ambient air quality: A case study over an urban site in Delhi, India
JANHAVI SINGH PRIYANSHU GUPTA DEEPAK GUPTA SUNITA VERMA DIVYA PRAKASH SWAGATA PAYRA
The current study discourses the impact of variation in PM$_{2.5}$ concentration on the ambient air quality of Delhi. The 24-hourly PM$_{2.5}$ concentration dataset was obtained from air quality measurement site (Anand Vihar) of Delhi Pollution Control Committee (DPCC) for the duration of April 2015 to December 2018. The annual and seasonal variability in the trend of ambient PM$_{2.5}$ along with cumulative impact of meteorological parameters have been analyzed. The overall percentage increase in annual PM$_{2.5}$ concentration, compared to National Ambient Air Quality Standards (NAAQS) guidelines, is observed to be 286.09%. The maximum concentration of fine particulate matter was recorded to be 788.6 $\mu$g/m$^{3}$ during post-monsoon season and it was found to be associated with lower ambient temperature of 21.34${\circ}$C and wind speed of 0.33 m/sec. Further, PM$_{2.5}$ concentration was found to be correlated with CO (
$\bf{Highlights}$
$\bullet$ PM$_{2.5}$/PM$_{10}$ ratio was observed to be highest in November, December and January, attributing aggravated levels of particle pollution to anthropogenic sources.
$\bullet$ Seasonal analysis of PM$_{2.5}$ concentration indicated that particulate pollution was severe during post monsoon and winter months.
$\bullet$ Carbon monoxide (
Volume 130, 2021
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