• Kaushar Ali

      Articles written in Journal of Earth System Science

    • Chemistry of snow and lake water in Antarctic region

      Kaushar Ali Sunil Sonbawane D M Chate Devendraa Siingh P S P Rao P D Safai K B Budhavant

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      Surface snow and lake water samples were collected at different locations around Indian station at Antarctica, Maitri, during December 2004-March 2005 and December 2006-March 2007.Samples were analyzed for major chemical ions. It is found that average pH value of snow is 6.1. Average pH value of lake water with low chemical content is 6.2 and of lake water with high chemical content is 6.5.The Na+ and Cl are the most abundantly occurring ions at Antarctica. Considerable amount of SO$^{2-}_{4}$ is also found in the surface snow and the lake water which is attributed to the oxidation of DMS produced by marine phytoplankton.Neutralization of acidic components of snow is mainly done by NH$^{+}_{4}$ and Mg2+. The Mg2+, Ca2+ and K+ are nearly equally effective in neutralizing the acidic components in lake water.The NH$^{+}_{4}$ and SO$^{2-}_{4}$ occur over the Antarctica region mostly in the form of (NH4)2SO4.

    • Surface ozone scenario at Pune and Delhi during the decade of 1990s

      Kaushar Ali S R Inamdar G Beig S Ghude Sunil Peshin

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      Data on surface ozone concentration compiled for a 10-year period from 1990 to 1999 for Pune and Delhi are analyzed in terms of its frequency distribution, annual trend, diurnal variation and its relation with various meteorological and chemical parameters. It is found that the surface ozone concentration range showing highest frequency of occurrence at Pune is 0–5 ppb during winter and post-monsoon seasons and 15–20 ppb and 5–10 ppb during summer and monsoon seasons, respectively. It is 0–5 ppb at Delhi during all the seasons. The surface ozone concentration has shown a decreasing trend at Pune during the observational period with an average rate of decrease of 1.54 ppb/year. On the other hand, there is no trend whatsoever in the variation of surface ozone concentration at Delhi. Minimum value of surface ozone occurs before sunrise and maximum in the afternoon hours. Regression analyses of surface ozone with maximum temperature (𝑟 = 0.46 for Pune and 0.51 for Delhi, significant at more than 0.1%) and NO2 at respective locations indicate that surface ozone at these locations is mainly produced by photochemistry. Transport mechanism is also understood to have contributed significantly to the total concentration of ozone. Inverse relationship obtained between surface ozone concentration and relative humidity indicates that major photochemical paths for removal of ozone become effective when humidity increases at these locations.

    • PM$_{2.5}$, PM$_{10}$ and surface ozone over Lumbini Protected Zone, Nepal, during monsoon season of 2012

      Kaushar Ali Trivedi D K Dilip M Chate Gufran Beig Prodip Acharja Trimbake H K

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      Physical characterisation of PM$_{2.5}$, PM$_{10}$ and surface ozone measured during the period from 17 July to 21 August 2012 at four strategic locations in and around the Lumbini Protected Zone, Nepal, is done to assess air quality of the region and understand qualitatively source mechanisms of these pollutants. The measurement locations are Panditarama Lumbini International Vipassana Meditation Centre, Parsahawa, Bhairahawa and Tilaurakot, representing monastic, industrial, urban and control areas, respectively. The overall average concentration of PM$_{2.5}$ at these locations is $\sim$19 $\pm$ 12, 35 $\pm$ 13, 35 $\pm$ 11 and 25 $\pm$ 6 $\mu$g/m$^{3}$ and of PM$_{10}$ is $\sim$25 $\pm$ 11, 103 $\pm$ 41, 58 $\pm$ 15 and 32 $\pm$ 7 $\mu$g/m$^{3}$, respectively. PM$_{2.5}$ never crosses the safe limit of the National Ambient Air Quality Standards of Nepal (NNAAQS) in the monastic and control areas but either crosses the NNAAQS occasionally or remains in its vicinity at the other two locations. The PM$_{10}$ concentration frequently exceeds the safe limit in the industrial area but not in the other remaining areas. The analysis indicates the dominance of the impact of local sources and boundary layer thickness on the atmospheric loadings of the particulate matter. The daily average mixing ratio of surface ozone remains normally low at all the four observational sites although the mixing ratio of ozone at Panditarama Lumbini International Vipassana Meditation Centre is much lower than the NNAAQS but higher than that observed at Tilaurakot.

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