Physical and Chemical Characterization of Aerosol at Bhubaneswar

TRUPTI DAS*, Anuradha Das, Haragobinda Srichandan, Namrata Das, Gautam Roy Chaudhury and Surendra Nath Das

Institute of Minerals and Materials Technology, Bhubaneswar, Orissa, India

     Abstract Number: 428
     Last modified: November 24, 2009

Abstract
Industrialization along with rising anthropogenic activities is having a strong impact on our environment. The changes are more prominent in certain regions undergoing rapid industrialization and associated mining/transport/urbanization and consequently the air environment is severely affected. Bhubaneswar, the capital of Orissa is geographically located in the eastern coastal plains of the state, situated between 21 degree 15' North Latitude 85 degree 15' East Longitude and at an altitude of 45 meters above sea level. In the current study, an attempt has been made to characterize the physical and chemical properties of the atmospheric aerosols collected through various monitoring devices during the observation period (December 2008-November 2009). The Suspended Particulate Matter (SPM) in the atmosphere was monitored using an indigenous High Volume Sampler. The average mass concentration of the suspended particles varied between177 to 32 microgram per cubic meter. Aerosols were collected in both coarse (PM10-2.5) and fine (PM2.5 downwards) modes through impregnated filter pack method and the samples, after processing in a clean environment, were analyzed for water soluble ions like sodium, potassium, magnesium, calcium, fluoride, sulfate, nitrate and phosphate using ion chromatograph. Higher concentration of ionic species (cations + anions) was observed during summer season whereas during rainy season the concentration decreased. The dominant water soluble species were sodium, chloride, ammonium, sulfate and potassium ions out of which Na ion contributed 33% in coarse mode and ammonium ion contributed 31% in fine mode. Aerosol Optical Thickness (AOT) has been measured using a 5- channel Sun Photometer [Solar Light Co. USA] at 380, 500, 575, 936, 1020 nm. The average AOT values ranged between 0.81 (January 09) and 2.23 (September 2009). Continuous real-time aerosol particle size distribution from 0.23 to 20 µm was measured through a 15-channel optical particle counter (GRIMM model 1.108). The particle mass concentration was found to be between 25-103 microgram per cubic meter in coarse mode and 17-63 micro-gram per cubic meter in fine mode. The size distribution was observed to vary significantly with respect to change in temperature and humidity conditions. A striking correlation has also been observed between environmental conditions and increase/decrease in fine/coarse particle concentration in the diurnal data. Similarly the mass of Black Carbon (BC) in ambient air over the region, has been monitored through a 7-wavelength Aethalometer (Magee scientific, USA). The monthly average BC concentration varied between 2.3 and 8.5 micro-gram per cubic meter. The overall aerosol physical and chemical characteristics of the region provide an insight to the strong seasonal variation in the atmosphere. The region is undergoing faster industrialization and development leading to emission of acidic gases (sulfur dioxide and oxides of nitrogen) and corresponding aerosols. Dry deposits and wet precipitation in absence of dust fall show higher acidity corresponding roughly to the rise in fossil fuel consumption, which is found to be effectively neutralized by the components derived from soil and agriculture.