Antimony: a traffic-related element in the atmosphere of Buenos Aires, Argentina

Abstract

Vehicular traffic is one of the main sources of antimony in highly populated urban areas like Buenos Aires where an overall traffic density of 1 500 000 vehicles per day (corresponding to 7500 vehicles km⁻²) is estimated. In this context, a study was undertaken to ascertain the levels of Sb and other traffic-related elements (TRE) in the atmosphere of this city. To this end, sixty-seven samples of PM-10 particulate matter were collected during eight days in nine representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km². The collection of particulate matter was performed on ash-free glass-fibre filters using high volume samplers with PM-10 sampling heads. A combination of aqua regia and perchloric acid was used for leaching metals from filters. The resulting solutions were evaporated and then diluted with 0.1 mol l⁻¹ HCl. Antimony was determined by inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) at ng g⁻¹ levels. Concentrations of Sb varied from 12.9 ± 0.9 to 375 ± 23 μg g⁻¹ (equivalent to 0.87 ± 0.06 to 15.3 ± 0.8 ng m⁻³). Statistical analysis was performed on the data set including the measured PM-10 mass and Sb concentrations for the monitored period. Correlations of Sb with other TRE namely, Cu and Mo were also assessed. The highest concentrations of Sb were detected at two sites (Hospital Alemán and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars and showing a “stop-and-go” pattern in peak hours. Antimony levels in the Buenos Aires PM-10 are by far below the level of 0.5 mg m⁻³ (for an 8 hour workday, 40 hour work week) set by the US Occupational Safety and Health Administration (OSHA) for occupational exposure. However, monitoring of Sb and other TRE should be carried out in a systematic fashion to detect the possibility of increases in from the present levels.