Status of Atmospheric Mercury Research in South Asia: A Review

Abstract

Mercury (Hg) is a highly toxic metal, which is known as a global pollutant due to its ability to undergo long-range transport in the atmosphere. Methylated mercury can pose serious adverse effects on human health and environment. Mercury is emitted into the atmosphere by various natural and anthropogenic sources. The largest anthropogenic source of mercury is coal combustion, which contributes ~62% of global emissions. Total global emissions of atmospheric mercury are estimated to be 5600 Mg/year from natural and anthropogenic sources, respectively, contributing around 37% and 63% of total atmospheric mercury. About 40% of global anthropogenic emissions are contributed by East and Southeast Asia with the largest emissions from China (75%) followed by South America and Sub-Saharan Africa. Latter regions are mainly responsible due to increase in artisanal and small scale gold mining. The present estimates of mercury emissions have large uncertainties in global budget, which are mainly due to lack of knowledge of mercury exchange between various components of ecosystem with its speciation in spatial and temporal distribution. Special efforts are needed in the regions of growing economy especially in South Asia where atmospheric mercury is almost unattempted. In order to reduce uncertainties and get more realistic emission figures, there is need to develop an extensive monitoring network to measure various forms of mercury in air, soil and aquatic systems in south Asia. Controlling the emissions of global atmospheric mercury is a big challenge to the scientists and policymakers. Probably, it can be achieved by focusing on implementation of the available technologies and by developing new technologies for mercury removal through developing an extensive partnership between industries and governmental organizations.

Influences of Copper(II) Chloride Impregnation on Activated Carbon for Low-Concentration Elemental Mercury Adsorption from Simulated Coal Combustion Flue Gas

“…Mercury (Hg) and its compounds emitted from anthropogenic sources, e.g., coal-fired power plants, industrial boilers, waste incinerators, sinters, and cement plants, have tempted substantial attention due to their high toxicity, bioaccumulability, and global transport behaviors in atmosphere (Kumari et al, 2015;Chen et al, 2016;Marusczak et al, 2016;Wang et al, 2016). Coal-fired power plants were reported as the largest single source in most countries in Hg emissions (Pacyna et al, 2010).…”

DiMIZA: A dispersion modeling based impact zone assessment of mercury (Hg) emissions from coal‐fired power plants and risk evaluation for inhalation exposure

“…This value is higher than or equal to those of most of the European cities (0.1–5 ng/m 3 ), at the same level with those of some South and East Asian urban measurements (e.g., Seoul [3.22–5.26 ng/m 3 ]), and lower than several cities in China (e.g., Guiyang [7.40–9.72 ng/m 3 ], Beijing [7.9–34.9 ng/m 3 ], Changchun [18.4 ng/m 3 ]) 30‐32 . Kumari et al 30 attributed much higher Hg levels in Indian cities (e.g., Bhilai, 140–1830 ng/m 3 ) than the others (e.g., those in China, Korea, and Japan) to the reason that most of the studies on Hg concentrations in Indian cities were carried out in the vicinity of coal‐fired power plants. The present study also finds higher Hg levels at the locations closer to the CHPP, but still not as elevated as in some of the cities mentioned.…”

Soil–atmosphere exchange flux of total gaseous mercury (TGM) at subtropical and temperate forest catchments

“…Photo-reduction is a major driver of TGM evasion from the Earth's surface (Howard and Edwards, 2018;Kuss et al, 2018;Gao et al, 2020). This process is due to a photochemically mediated reduction that converts soil water Hg(II) to volatile Hg(0) and enhances the Hg(0) pool in soil pores (Xin and Gustin, 2007;Choi and Holsen, 2009a).…”