Sources, distribution and variability of airborne particles and hydrocarbons in La Plata area, Argentina (original) (raw)

1999, Environmental Pollution

Total suspended particles (TSP), particulate-(ALIp) and semi-volatile aliphatic hydrocarbons (ALIsv) were measured in air sampled during the day and night over 7±8 months in industrial, commercial and residential sectors of La Plata, Argentina. TSP, ALIp and ALIsv ranges were 23±219 mg/m 3 , 11±447 and 12±719 ng/m 3 , respectively. Maximum values were recorded at a downtown site whereas the residential station showed lower levels. Concentrations were usually higher during the day and during fall and winter. Two-and three-way ANOVA were performed to evaluate the day-night, inter-station, and inter-month variability. The amount of total variability accounted by these factors was 14, 25 and 23% (p < 0.01) for TSP; 0.8, 11 and 39% (p < 0.03) for ALIp; and 0.6, 7.9 and 15% (p < 0.3) for ALIsv, respectively. Overall, the inter-month variability prevailed; inter-station dierences were most signi®cant in the summer when the day-night variability was lower. For the particulate phase, the day-night dierences were more signi®cant at the downtown and residential sites. The composition of ALIp and ALIsv re¯ected the contribution from biogenic long chain odd n-alkanes and petrogenic lower molecular weight n-alkanes. Plant cuticular waxes accounted for 34±96% of ALIp with higher values during the summer and at the Residential station. A principal component analysis clearly discriminated ALIsv, almost entirely derived from exhaust and diesel fuel emissions, from ALIp composed of mixed biogenic-petrogenic sources. The lowest day-night dierences observed during the summer were related to a higher proportion of biogenic``natural'' material during this period of full plant grow and lower vehicle circulation. The larger day-night dierences registered at the downtown station were related to an enhanced input of anthropic sources (vehicles, fossil fuels, lubricating oils) during the most active day period.