Chemical characteristics and oxidative potential of summertime PM2.5 over an urban location on the east coast of India

Abstract

The oxidative potential of PM2.5 is investigated for the first time in Bhubaneswar using dithiothreitol (DTT) assay, an urban coastal city in eastern India. PM2.5 samples were collected for four years during summertime and analyzed for metals, water-soluble ions, black carbon, and brown carbon. Overall mean PM2.5 mass concentration was 31.93 +/- 14.91 mu g m(-3), in which (NH4)(2)SO4 (44%) was the dominant species. The analysis employing the Conditional Bivariate Probability Function indicates that PM2.5 mass concentration in the summer season is predominantly influenced by transport facilitated by south-southwest and southeast winds. The primary origin is identified as non-buoyant local sources. The volume-normalized and mass-normalized DTT followed the same trend as PM2.5 mass concentration. No significant inter-year variation in DTT activity indicated a potential constancy in the source strength during the study period. The observed DTTv (0.48 +/- 0.30 nmol min(-1) m(-3)) and DTTm (15.36 +/- 7.67 pmol min 1 mu g(-1)) were comparatively lower than those reported in most other locations in India. Multiple linear regression analysis suggested that Cu (34%) and Zn (32%) were dominant contributors to DTTv activity. However, further studies are required for a comprehensive understanding of PM2.5 toxicity.