Air

Abstract

Air pollution has arisen from both natural (meteoric, terrestrial, marine, volcanic, erosion and surface winds, forest fires, biogenic) and anthropogenic (coal and fuel combustion, industry, automobile, agriculture) sources. The steady global increase of trace element concentrations in the atmosphere has been observed and monitored in some countries for over 30 years. The majority of trace element emitters have been located in the northern hemisphere (mainly between 40–55† N). Buat-Ménard (1984) calculated that emissions of trace elements in the Northern Hemisphere are several times higher than in the Southern Hemisphere and are about 80% and 30%, respectively of anthropogenic origin. However, at the global scale, the natural emissions of trace elements cannot be neglected because large amounts of dusts containing trace elements come from natural sources. The estimated principal trace elements emissions for natural sources are as follow: 50% of Cr, Mn, and V, and >20% of Cu, Mo, Ni, Pb, Sb and Zn. Volcanic activities may contribute over 20% of the atmospheric Cd, Hg, As, Cr, Cu, Ni, Pb, and Sb. Sea salt aerosols may also contribute about 10% of total trace element emissions to the atmosphere (Allen et al. 2001). Differentiating natural and anthropogenic sources of metals is not easy and some methods for monitoring various sources of metal pollution have been discussed (Dias and Edwards 2003).