Wet and dry deposition of atmospheric pollutants around coal mining area of Dhanbad and Bokaro District

This paper provides baseline information about the wet and dry deposition of atmospheric pollutants in and around Dhanbad and Bokaro region. Rain water and free dust fall samples were collected on seasonal basis at six sites and analyzed for major ions and elemental composition to assess the wet and dry deposition of atmospheric pollutants. The analytical results show seasonal and spatial variation in elemental chemistry and rate of deposition of pollutants during monitoring months. On average, the ion composition of the rainwater follows the concentration sequence as: Ca2+>SO42–>Cl–>NH4+>Mg2+>Na+>F–>K+>NO3–. The calculated wet deposition fluxes were dominated by Ca2+, SO42– and NH4+; together contributing 60–65% of the total annual wet deposition flux. The dust fall rate was comparatively high in the summer months and highest dust deposition rate was observed at Jharia and lowest at the CMRI site. The concentration of measured elements in the free dust fall of the area shows the general abundance order as: Ba>Mn>Sr>Zn>Cr>V>Cu>Ni>Pb>Co. The average dry elemental depositional fluxes were dominated by Ba (2.75–10.0 kg/km2/month), Mn (3.19–11.68 kg/km2/month), Zn (0.45–8.54 kg/km2/ month) and Cr (0.34–1.72 kg/km2/ month) along with minor contribution from Cu (0.72 kg/km2/month), Ni (0.61 kg/km2/month), Pb (0.45 kg/km2/month) and Co (0.23 kg/km2/month).