Preliminary mercury emission estimates from non–ferrous metal smelting in India

Mercury (Hg), a potential contaminant to the environment is of global concern because of its toxic nature, trans–boundary movement and its ability to bio–accumulate and bio–magnify. Previous research showed that Hg based chlor–alkali production, coal fired thermal power plants, traditional gold mining, healthcare equipments, waste incineration, and some industrial processes are the major sources of mercury release into environment. Primary non– ferrous metal smelting is considered to be an important anthropogenic Hg emission source in India, but data availability in this regard is a limiting factor. The study thus attempts a preliminary estimation of Hg emission range and creates an emission inventory from non–ferrous metal smelting operations in India. The emission estimates are for the time period 2003 to 2007. Emission in the year 2003 has declined from 5.5 – 7.6 ton where it has increased to 15.5 – 22 ton in year 2007. Zn and Cu smelting contributed maximum (80%) to the total emissions and the rest (20%) was from lead (Pb) smelting. The range of Hg–emission per unit area (g/km2) in the year 2007 was between 2.3 to 6.6 whereas the per capita emission was found between 7 and 19 mg from non–ferrous metal smelting industry in India. About 6 to 17 ton of elemental Hg (Hg0), went into the global circulation in the year 2007 whereas mercuric (Hg2+) emissions were in the range of 1.1 to 3.2 ton and the rest (3.8 to 10 tons) was in particulate–form (Hgp). Share of Hg2+ and Hgp in the total Hg–emissions is very small and has impacts on regional to local level.