Study on mercury in PM10 at an urban site in the central indo-gangetic plain: Seasonal variability and influencing factors

Abstract

Mercury (Hg) is among the most toxic metals possessing a major threat to human health and aquatic ecosystems over the globe. However, measurement of Hg concentrations and seasonal variability remain poorly understood over the IndoGangetic Plain (IGP) in northern India. In this study, we present one-year data of particulate-bound mercury (HgP) in aerosol samples (PM10) collected from Kanpur to understand seasonal variability and factors influencing concentration, as well as dry deposition flux. The HgP concentration exhibit a large temporal variability and ranged between 100 (on 14 June 2007) to 4340 pg m–3 (on 4 March 2007) with an annual average concentration of HgP is 776 ± 846 pg m–3. The HgP concentrations and HgP/PM10 ratios showed a marked seasonality with the highest in winter (Dec-Feb) followed by post-monsoon (Oct– Nov) and summer (April–June) seasons. HgP and HgP/PM10 were positively correlated (r2 = 0.77, p < 0.05, N = 58) during the sampling period and the estimated dry deposition flux of HgP was 104.7 µg m–2 y–1. Although this study provides a comprehensive data set on HgP in an urban atmosphere of the IGP revealing high levels of HgP, measurement of gaseous Hg is needed for estimation of the total Hg budget. Therefore, future studies should focus on identification of different sources as well as emission characteristics of all forms of Hg (organic and inorganic forms) for better mitigation strategy to prevent health risks associated with toxic Hg in the region.