Celebration-induced air quality over a tropical urban station, Pune, India

AbstractIn this paper, we studied the regional aerosol and air quality over an urban location, Pune, India during the period from 8 to 18 November 2012, encompassing a major Indian celebration, namely, Diwali Festival (12–14 November 2012) and also a clean (control) day (9 November 2012). A suit of ground–based measurements, employing solar radiometers (Microtops II and Cimel Sun–sky radiometer), Nephelometer, and satellite observations carried out over the study region have been applied for these investigations. The study revealed many interesting results which include (i) almost four–fold enhancement in AOD and fine mode dominated aerosol size distribution (ASD) during Diwali compared to clean day conditions; (ii) higher columnar water vapor (H2O), nitrogen dioxide (NO2), and lower ozone (O3) during Diwali period; (iii) higher cooling at bottom (–117W m−2) and top of the atmosphere (–33W m−2) and warming (+82W m−2) in the atmosphere during the festival period, (iv) abundance of fine mode anthropogenic scattering particles associated with greater real part and smaller imaginary part of refractive index, and higher single scattering albedo, (v) higher backscattering coefficient revealing intrusion of more aerosol particles, higher depolarization ratio indicating particles of non–spherical nature, presence of water–phase particles, more polluted smoke and dust particles, (vi) greater attenuation and poor horizontal/vertical visibility, and (vii) dominance of urban industrial/biomass burning aerosols among other aerosol types. These results have been compared with concurrent satellite products and found to be consistent. The results have been further explained with local meteorology, back–trajectory analysis and satellite rapid response images

Chemical composition and isotopic signatures of ice and snow over a Himalayan Glacier (Satopanth) in India

This study reports the chemical composition and isotopic signatures of snow and ice over a Himalayan Glacier in India. An observational campaign was carried out from September 22, 2016, to October 2, 2016, over Satopanth in central Himalaya. The pH value of ice and snow, respectively, was 5.6 ± 0.4 and 5.9 ± 0.35 over the glacier, indicating moderate acidity of the glacier components. Calcium (Ca2+) was the dominant component in snow (35.2%), while sulfate (SO42−) was dominant in ice samples (52.7%). The neutralization factor was estimated to find the extent of neutralization of acidic fractions by basic components. It is found that Ca2+ was the prominent neutralizing factor both in snow and ice over the region. Oxygen and hydrogen isotopic analyses of snow, surface layer ice and debris-covered ice suggest that the moisture source is common for all three components. δD and d-excess values of snow at Satopanth are different than that of those for Chorabari, Dokriani and Tiprabank Glacier, indicating the plausibility of different sources of moisture for these glaciers. Limited observations suggest that the interaction of ice with the debris has no impact on the isotopic signatures of the ice over the region; such non-alteration of isotopic signatures makes the region important for ice core-based paleoclimatic studies

Impact of nylon and teflon filter media on the sampling of inorganic aerosols over a high altitude site

Water-soluble inorganic aerosols constitute major fraction of PM2.5 play an important role in the Earth-climate system and affect adversely on human health. However, their measurement accuracy highly vary depending on choice of filter media and denuder usage. In most of the cases, denuders are either not deployed or their use is partially limited to removal of certain gases. Therefore, to understand the impact of undenuded ambient sampling and filter media type on depositional loading of water-soluble inorganic aerosols; three (1 teflon and 2 nylon based) different pore-sized filter media sampling was carried at a high altitude location in Western Ghats during winter season. Results show gas-phase adsorption was higher on nylon than hydrophobic teflon membrane. Decreased pH and overall increased conductivity observed on nylon media suggested higher adsorption of acidic species. Nylon showed increasing ionic concentration and their order followed Mg2+Na+>Ca2+>K+. ISORROPIA-II derived high NH3 and Cl(g) found on nylon than the teflon. Poor correlation between X-ray Fluorescence (XRF) and Ion Chromatography (IC) derived crustal specie (Ca) showing off-set between both the results, however, were found positively correlated for secondary species (Cl−, NH4+, NO3+ and SO42−). Neutralization efficiency revealed secondary NH4+ as the main neutralizer for secondary NO3+ and SO42− on nylon whereas on teflon, Ca2+ was found to be the main neutralizing component. On comparing Na+ and Cl+ effects over neutralization, an extensive Cl(g) adsorption on nylon than on teflon suggested prevalence of non-seasalt sources. Concentration weighted trajectory analysis for nylon minus teflon indicated an excess semi-volatiles (Cl−, NO3− and NH4+) on nylon were mostly driven by the oxidation of precursory gases originating from local and nearby coastal cities, whereas non-refractory ultrafine mode aerosols were found from inland and from majorly polluted North Indian region