Seasonal progression of atmospheric particulate matter over an urban coastal region in peninsular India: Role of local meteorology and long-range transport

Measurement of particulate matter (PM) over an urban site with relatively high concentration of aerosol particles is critically important owing to its adverse health, environmental and climate impact. Here we present a 3 years' worth of measurements (January 2012 to December 2014) of PM2.5 (aerodynamic diameter of less than 2.5 μm) and PM10 (aerodynamic diameter of less than 10 μm) along with meteorological parameters and seasonal variations at Bhubaneswar an urban-coastal site, in eastern India. The concentrations of PM were determined gravimetrically from the filter samples of PM2.5 and PM10. It revealed remarkable seasonal variations with winter values (55.0 ± 23.4 μg/m3; 147.3 ± 42.4 μg/m3 for PM2.5 and PM10, respectively) about 3.5 times higher than that in pre-monsoon (15.7 ± 6.2 μg/m3; 41.8 ± 15.3 μg/m3). PM2.5 and PM10 were well correlated while PM2.5/PM10 ratios were found to be 0.38 and 0.32 during winter and pre-monsoon, indicating the predominance of coarse particles, mainly originating from long range transport of pollutants from northern and western parts of India and parts of west Asia as well. Concentration weighted trajectory (CWT) analysis revealed the IGP and North Western Odisha as the most potential sources of PM2.5 and PM10 during winter. The PM concentrations at Bhubaneswar were comparable with those at other coastal sites of India reported in the literature, but were lower than few polluted urban sites in India and Asia. Empirical model reproduced the observed seasonal variation of PM2.5 and PM10 very well over Bhubaneswar.