Determination of Toxicity Metals Concentration and their Emission Source in Urban Areas (Case study: Mashhad city)

Extended abstract
1- Introduction
In many developing countries of Asia, Latin America and Africa, air pollutants emission has been increasing over the last two decades. Air pollution is a serious problem in many heavily populated and industrialized areas in the world. This has been primarily due to rapid economic growth in many of developing countries, resulting in increasing urbanization, transportation, industrialization, and energy generation (UNEP, 1997: 55). For this reason many air pollution studies have appeared in the international literature (Simpson and Layton, 1983: 1650). The study area was the City of Mashhad, a Holy City located at 36.20º latitude north and 59.35º longitude east, in the valley of the Kashef in the North-East of Iran. The aim of study is the determination of heavy metals level in air of Mashhad city with observation of their emission resources. Manjunatha (2001) and Rahn (1979) have used this factor to define the major source of atmospheric particles. Values of EF near unity suggest that crustal erosion is the primary source of element X values much greater than unity imply the importance of other sources, such as anthropogenic activities, erosion of soil and dust.

Methodology
Sampling of air was carried out in two different areas of Mashhad city and 20 km far away from the city center on 2007-2008. For the chemical analysis of air, twenty-four hours sampling was done, using a high volume sampler (Dehm & Zinkeisen Firm) which sacks air pollutant and aerosol through Teflon filters (Fluopore membrane filter, Millipore firma). Teflon filters of