Investigation of aerosol trace element concentrations nearby Algiers for environmental monitoring using instrumental neutron activation analysis

Abstract

The aim of this study was to enhance the use of instrumental neutron activation analysis (INAA) for long-term monitoring of air pollution and to identify critical sources of air pollution. For the collection of total suspended particulate matter (TSP), a filter unit low volume sampler (LVS) was employed. One hundred and seventeen samples were collected during 2010, 2011, and 2012, both on weekdays and weekends at a monitoring station located in Draria city, a suburban site near Algiers, Algeria. The concentrations of 25 trace elements (As, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Eu, Fe, Gd, Hf, K, La, Mn, Mo, Na, Sb, Sc, Se, Sm, Sr, V, and Zn) were determined by INAA using short and long neutron irradiation technique. Generally lower concentration values were observed during the weekends compared to the weekdays for almost all elements. The mean TSP concentration (34.8μg/m3) showed a seasonal pattern with higher levels during summer. The weekday/weekend ratio of TSP was 1.3 higher during summer than in winter. The concentrations of the elements Sb, Se, and Cd are found to be highly enriched in atmospheric particulate matter. According to their high enrichment factors (EFs), it was possible to establish that these elements are of anthropogenic origin coming from automobile exhausts which is the main source of emission in this area. The typical suburban background TSP and trace element levels were compared with literature data from other regions around the world, and were lower than those reported in an urban site in Algiers in a previous study. Significant correlations between elements were found (Pearson's coefficients >0.5) suggesting that the contaminant trace elements may be discharged from the same sources.