Caracterisation et origine des PM10 et des elements metalliques dans une zone urbaine de la ville de Constantine.

Abstract

Exposure to PM10 containing metallic elements is a major health concern, particularly in urban areas, the aim of this work is to characterize the metal fraction of fine particles emitted in urban areas and identify their main sources. PM10 samples were collected at the urban site of Zouaghi for a yearlong period (January 2015-February 2016) using a high volume sampler (HVS). This study aimed to characterize and identify the main sources of the associated metallic elements. After acid digestion, PM10 were analyzed for a total of 48 elements by ICP-AES and ICP-MS for major elements and trace elements respectively. The annual mean concentration (55.7 μg/m3) was almost 3 times higher than the WHO recommended ambient air quality guide value (20 μg/m3). A clear seasonal pattern, with higher concentrations in spring and autumn, was observed. However, metal species concentrations did not show significant seasonality. Ca was the most abundant element. Enrichment factor analysis indicated that Pb, Sb, Cd, Bi, As, and Zn were mainly originated from anthropogenic sources. Cu/Sb, Ca/Al, Zn/Pb, La/Ce, and V/Ni ratios were calculated and compared to ratios reported in previous studies. A significantly higher Ca/Al ratio was dominant indicating the influence of construction dust, while a low Zn/Pb ratio was the consequence of high Pb concentrations due to leaded gasoline use. Principal Component Analysis allowed to identify four main groups of sources: crustal aerosol for Al, Fe, Ti, Li, Mg, Ba, Sr and rare earth elements (REE’s) (47%), soil and road resuspension for Cr, As, S, P, V, Ca, Zn, Sn, Nb, K, Mg, Ba, Sr and Li (27%), traffic emission for Pb and Be (8%), and a metallurgical Cd and W source (6%). The results of the source apportionment analysis indicate that natural dust originating from Saharan dust outbreaks (SDO) and resuspended dust is the main source of elements in PM10 in the region of Zouaghi in Constantine.