Seasonal variation and sources of heavy metals in hilltop of Dongargarh, Central India

• Heavy metals have the highest concentrations in winter due to inversions.
• Heavy metals were examined in relation to other air pollutants and weather conditions.
• Cd, Pb and Cu are having very high EF values which are anthropogenic sources.
• Product structures confirmed by computed NMR chemical shift.

An investigation to find out the presence of heavy metals (HMs) in aerodynamic particulate matter (PM2.5) in hilltop of Dongargarh, Central India was carried out in year 2011. This is the first such study in this part of India. Sum totals of 80 samples were collected during 12-h sampling by a fine particulate dust sampler using micro fibre filter paper. The mean concentration of PM2.5 was 121 ± 64.2 μg/m3. The annual concentration of Fe, Zn, Cu, Ni, Cr, Cd and Pb are 513.9 ng/m3, 320.6 ng/m3, 141.8 ng/m3, 120.7 ng/m3, 87.8 ng/m3, 81.2 ng/m3 and 289.0 ng/m3, respectively in descending order of Fe > Zn > Pb > Cu > Ni > Cr > Cd. Further, the concentrations of all the HMs were higher in winter and followed by post-monsoon, monsoon and summer. Meteorology played an important role in concentration of HMs in PM2.5. Turbulent conditions resulted in higher concentration owing to re-suspension and external input whereas, low wind speed, low temperature and high relative humidity favoured low concentration of the pollutants. The evaluation of enrichment factor revealed that Pb, Ni, Cu, and Cr are emitted, chiefly from anthropogenic sources and Fe and Zn are associated with natural sources.