Atmospheric concentrations and dry deposition fluxes of particulate trace metals in Salvador, Bahia, Brazil

Abstract

Respiratory system is the major route of entry for airborne particulates, being the effect on the human organism dependent on chemical composition of the particles, exposure time and individual susceptibility. irborne particulate trace metals are considered to represent a health hazard since they may be absorbed into human lung tissues during breathing. Fossil fuel and wood combustion, as well as waste incineration and industrial processes, are the main anthropic sources of metals to the atmosphere. In urban areas, vehicular emissions—and dust resuspension associated to road traffic—become the most important manmade source. This work investigated the atmospheric concentrations of TSP, PM10 and elements such as iron, manganese, copper and zinc, from three different sites around Salvador Region (Bahia, Brazil), namely: (i) Lapa Bus Station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, including metal ores and concentrates and near industrial centers and; (iii) Bananeira Village located on Mare´ Island, a non-vehicle-influenced site, with activities such as handcraft work and fishery, although placed near the port. Results have pointed out that TSP concentrations ranged between 16.9 (Bananeira) and 354.0 mgm 3 (Aratu#1), while for PM10 they ranged between 30.9 and 393.0 mgm 3, both in the Lapa Bus Station. Iron was the major element in both Lapa Station and Aratu (#1 and #2), with average concentrations in the PM10 samples of 148.9, 79.6 and 205.0 ngm 3, respectively. Zinc, on the other hand, was predominant in samples from Bananeira, with an average concentration of 145.0 ngm 3 in TSP samples, since no PM10 sample was taken from this site. The main sources of iron in the Lapa Station and Aratu harbor were, respectively, soil resuspension by buses and discharge of solid granaries, as fertilizers and metal ores. On the other hand, zinc and copper in the bus station were mainly from anthropic contributions, probably heavy-duty vehicle ageing and wearing actions releasing off Zn from tires and Cu from brake linings. In the Aratu harbor, the high copper concentrations found were probably due to the port’s activities, as discharges of copper concentrate on its terminal, although other sources could be possible, as burning of diesel fuel on ships and heavy oil in heaters. Finally, the Bananeira site has been presented as a different profile, since this remote site has shown zinc as the most abundant element, demonstrating to have an unexpected anthropic contribution. On a mass-to-mass basis, both zinc and manganese were in high levels in the Bananeira site and their presence strongly suggest the impact of other sources, such as the Industrial Center of Aratu and/or a siderurgy plant, not far away from that location.