Geochemical Speciation, Partitioning, and Mobility Hazards of Trace Metals in Urban Roadside Dust Matrices

International Journal of Chemistry | Vol. 2, No. 9, September 2011 | pp. 92–99

DOI: 10.46882/2011/IJC/000036

Article Type: Original Research Paper

Title: Geochemical Speciation, Partitioning, and Mobility Hazards of Trace Metals in Urban Roadside Dust Matrices

Names of Authors: C. I. Obi¹, S. O. Akpan², P. A. Nwachukwu¹*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, University of Port Harcourt, Port Harcourt, Nigeria.
²Department of Chemistry, Akwa Ibom State University, Ikot Akpaden, Nigeria.

Abstract: Heavy metals in urban street dust present significant health hazards to pedestrian populations through ingestion and inhalation pathways. This study determines the total concentration and geochemical speciation fractions of lead (Pb), cadmium (Cd), nickel (Ni), and copper (Cu) in street dust samples collected from five major intersections in Port Harcourt. Metals quantification was achieved via Atomic Absorption Spectrophotometry following the classic modified BCR three-step sequential extraction procedure. The total metal contents followed the decreasing sequence: Pb > Cu > Ni > Cd. Speciation profiling revealed that a substantial fraction of lead (41.5%) and cadmium (48.2%) was associated with the acid-soluble fraction, which is highly unstable and bioavailable. Conversely, nickel and copper were bound within the reducible and residual crystal lattices, suggesting lower mobility under neutral pH environments. The contamination factor (CF) and geoaccumulation index (Igeo) pointed to high pollution indices for Pb and Cd at high-traffic intersections. Strong positive Pearson correlations between Pb and Cu point toward automobile brake wear and exhaust emissions as the primary anthropogenic sources, highlighting a need for urban dust containment.

Keywords: Street dust; Trace metals; BCR sequential extraction; Bioavailability; Geoaccumulation index; Urban pollution

Manuscript Timeline: Received: March 20, 2011; Revised: April 30, 2011; Accepted: May 20, 2011; Published: September 11, 2011.

Citation: Obi, C. I., Akpan, S. O., & Nwachukwu, P. A. (2011). Geochemical Speciation, Partitioning, and Mobility Hazards of Trace Metals in Urban Roadside Dust Matrices. International Journal of Chemistry, 2(9), 92–99.

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