PM_(2.5) CHEMICAL CONSTITUENTS AT A RURAL SITE OF AGRA IN INDO-GANGETIC PLAIN: SOURCES AND TRANSPORT

摘要

Fine particulate matter (PM_(2.5) aerosols) has been observed to adversely affect human health, visibility and climate change. PM_(2.5) aerosol samples were collected from January to December 2015 during summer and winter seasons at Sikandarpur, Agra. The samples were analysed for carbonaceous aerosols (Organic and Elemental Carbon- OC and EC) and water soluble ions (F, Cl~-, NO_3~-, SO_4~(2-), Na~+, NH_4~+, K~+, Mg~(2+)and Ca~(2+)). PM_(2.5) mass concentrations showed higher concentration during winter (109.6+17.8 μg m~(-3) ) as compared to summer (73.6±20.2 μg m~(-3)). Carbonaceous aerosols (Organic Carbon: OC and Elemental Carbon: EC) and most of the water soluble ionic constituents (NO_3~-, SO_4~(2-), NH_4~+ and K~+) also showed enhanced concentrations during winter season while Ca~+ high concentrations in summer season. The variation in summer and winter concentrations is due to the difference in meteorological parameters and different sources of emissions in both the seasons. This is further supported by air mass back trajectory analysis. In summer, long range transport from north western region was prominent while in winter season localized contributions dominated which could be due to enhanced biomass burning and other anthropogenic activities that occur in winter season to combat cold.