Study on Mercury in PM10 at an Urban Site in the Central Indo-Gangetic Plain: Seasonal Variability and Influencing Factors

Junming Guo,Jie Huang,Pengfei Chen,Prakriti Sharma Ghimire,Kirpa Ram,Lekhendra Tripathee,Shichang Kang

doi:10.4209/aaqr.2019.12.0630

Abstract

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 Indo-Gangetic 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.

Highlights

Mercury (Hg) is a highly toxic trace metal that poses a major threat to human health and aquatic ecosystems (Keeler et al, 1995; Li et al, 2017; Wright et al, 2018)
In addition to anthropogenic emissions, long-range transport of aerosols by westerly and northwesterly winds assisted by high ambient temperature and low surface pressure occurs in summer (Singh et al, 2005)
High HgP concentrations were detected during the winter months, with the highest concentration in March (4340 pg m–3 on March 4) and lowest during summer (June 14, 100 pg m–3 on June 14; Figs. 2(a) and 2(b))

Summary

Introduction

Mercury (Hg) is a highly toxic trace metal that poses a major threat to human health and aquatic ecosystems (Keeler et al, 1995; Li et al, 2017; Wright et al, 2018). Sources of Hg emission can be natural, such as volcanoes and forest fires, or anthropogenic, such as coalfired power plants, nonferrous metal smelters, waste incinerators, and cement production plants (Pacyna et al, 2010; Chou et al, 2018). In polluted urban-industrial regions and during atmospheric Hg depletion events, HgP concentrations can exceed 300 pg m–3 (Lindberg et al, 2007; Das et al, 2016). HgP in industrialized regions is mostly anthropogenic and can account for up to 40% of atmospheric Hg (Xiao et al, 1991)

Methods

Results

Conclusion