SOURCE AND METAL CONCENTRATIONS IN URBAN DUST FROM ARID ENVIRONMENT AND POSSIBLE IMPACT ON HUMAN HEALTH

The constrainment of metals concentrations in urban dust is extremely important since several studies have demonstrated the negative impact on human health. Metal concentrations in urban dust may be associated to several anthropogenic activities (i.e. mining, agriculture, industry, construction, transportation) or may be associated to geologic sources. Few decades ago, population growth and associated activities were not a concern to the sustainable urban development. Regardless the size of human settlement, the anthropogenic activity has an impact on human health. Studies relating the spatial and chemical composition of urban dust with the spatial distribution of chronic diseases are scarce. Therefore, the constrainment of pollution is fundamental to identify potential sources and to assess risk health. Hermosillo, located in northwestern Mexico, has experienced a noticeable population and industrial growth for the past three decades. Recent studies show high metal concentration in dust deposited on roofs of elementary schools and airborne particulate matter. Pb isotopes ratios in these samples and the geologic materials around Hermosillo, define clearly three groups: 1) a more radiogenic Pb group defined by the rocks (geogenic end-member), 2) a less radiogenic Pb group defined by the airborne particulate matter (anthropogenic end-member), and 3) an intermediate group (dust on roofs). The Pb isotope signature of dust deposited on roofs is similar to leaded gasoline used in Mexico two decades ago. The Pb isotope signature of the anthropogenic end-member could be the mixing result either with Australian, Canadian or Asian products. Spatial distribution of elemental lead concentration and isotope ratios in airborne and sedimented dust suggests a complex re-suspension/sedimentation dominating process controlled by erosion, traffic and topography. In this study we analyzed the metals concentration of road dust and urban soils. The data suggests a close relationship between high metal concentrations, heavy traffic, and the well-defined zones with remarkable anthropogenic influence in the city, supporting the anthropogenic influence of the urban dust and particulate matter. The new data also correlate with the spatial distribution of chronic diseases in the city.