Abstract
The paper investigates the hypothesis that biotoxicities of trace metals depend not only on the concentration as expressed by the total amount, but also on their geochemical fractions and bioavailability. Airborne particles were collected using SKC Air Check XR 5000 high volume Sampler at a human breathing height of 1.5–2.0 meters, during the dry season months from November 2014 to March 2015 at different locations in Akure (7°10′N and 5°15′E). The geochemical-based sequential extractions were performed on the particles using a series of increasingly stringent solutions selected to extract metals (Cd, Cu, Cr, Ni, Pb, Zn, and Mn) into four operational geochemical phases—exchangeable, reducible, organic, and residual—and then quantified using an Atomic Absorption Spectrophotometer. The results showed metals concentration of order Pb > Cr > Cd > Zn > Ni > Cu > Mn. However, most metals in the samples exist in nonmobile fractions: exchangeable (6.43–16.2%), reducible (32.58–47.39%), organic (4.73–9.88%), and residual (18.28–27.53%). The pollution indices show ingestion as the leading route of metal exposure, with noncarcinogenic (HQ) and cancer risk (HI) for humans in the area being higher than 1.0 × 10−4, indicating a health threat.
Highlights
Dust is the finely divided particulate matter that can be readily lifted by wind from its place of origin and carried along by the turbulent atmospheric currents, settling either by gravity under calm condition or by being brought to the surface by precipitation [1]
The particulates were collected on the preweighed filter by pumping 2000 mL/min (2 L/min) volume of air through it for eight (8) hours
The particles accumulated on the filter paper were removed by tapping on glazing paper and we determined the amount of particles on the loaded filters
Summary
Dust is the finely divided particulate matter that can be readily lifted by wind from its place of origin and carried along by the turbulent atmospheric currents, settling either by gravity under calm condition or by being brought to the surface by precipitation [1]. Nonoccupational exposure to dust especially in urban centres has aroused much attention because it is associated with some trace metals and diseases. Dust is generated during human activities such as sweeping, quarrying, and metals fabrication. Once generated and released to the atmosphere, it travels long distances from the emission source. In the course of transportation, the particulate is bound to metals; it creates a reserve pool of metals in urban atmosphere [2]. The presence of these metals in dust particles poses a significant environmental risk to the people
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