Distribution Pattern of Metals in Atmospheric Settling Dust along Roads in Kano Metropolis, Nigeria

Abstract

The sequential extraction of Cd, Cr, Ni, Pb, Cu, and Zn in atmospheric dust particles collected along ten high traffic roads in Kano metropolis was carried out. Analyses of metals in the extracts were done using flame atomic absorption spectrometry (FAAS). The samples analyzed for metals indicated high levels of Cd, Cr, Ni, Pb, Cu, and Zn in the atmospheric dust samples. The sequential extractions that showed significant amount of Cd were associated with CO 3 2− and Fe-MnO fractions especially during the dry seasons. For Cr and Ni, their occlusion in crystal lattice of the soil fraction exhibited the highest percentage. Pb in the particulate dust samples is significantly associated with the carbonate bound fraction with range of 8.81-64.69% across the season. The behaviour of Cu is quite different from other metals in that percentage fractions are higher in the organic bound. As for Zn, significant amounts were associated with the residue fractions ranging from 0.96 to 87.50% across the seasons. This study revealed contamination of the particulate dust with Cd and Pb; this implies health risks to human, living or carrying out daily activities along the corridors of these roads.

Sequential Extractions and Toxicity Potential of Trace Metals Absorbed into Airborne Particles in an Urban Atmosphere of Southwestern Nigeria

“…The major sources of these metals include electronic wastes, traffic emission, or wearing of tire. The significance of high amounts of Zn in this fraction agrees with earlier observation of Okunola et al [ 8 ] that the metal is considered to be occluded inside crystalline structure and not readily available for absorption. This observation is also consistent with earlier reports in urban street dust in Nigeria.…”

“…In most of these studies, elevated levels of heavy metals have been observed in atmospheric suspended dust in most cities. Okunola et al [ 8 ] reported the presence of heavy metals such as Cd, Cr, Ni, Pb, Cu, and Zn in atmospheric settling dust in Kano metropolis of Nigeria. Meanwhile, Mafuyai et al [ 9 ] reported that the concentrations of some heavy metals were found to be far above the standard limits prescribed by WHO for respirable dust in Jos, Nigeria.…”

Trace Elements in Urban Particulate Matters: Variations in Serum Levels, Inhalation Bioaccessibility, Health and Disease Effects

“…Quite a lot of researchers have investigated elemental compositions of suspended particulate matters in cities worldwide [4][5][6][7][8][9]. In most of these studies, elevated levels of trace elements have been observed in atmospheric suspended dust in most cities.…”

“…For example, Okunola et al [8] reported the presence of Cd, Cr, Ni, Pb, Cu, and Zn in atmospheric settling dust in Kano metropolis of Nigeria. Meanwhile, Mafuyai et al [9] reported that the concentrations of some trace elements were found to be far above the standard limits prescribed by WHO for respirable dust in Jos, Nigeria. Therefore, urban dwellers are exposed to considerable amounts of these elements through inhalation of airborne particulates.…”

Particle-Size Distribution and Bioaccessibility of Metals-Loaded in Street Dust of Urban Center in Southwest Nigeria

“…Numerous researchers have investigated elemental compositions of suspended particulate matters in cities worldwide; Monterry, Mexico [4], Tehran, Iran [5], Nigerian cities [6][7][8][9][10]. In most of these studies, it was observed that urban dusts were typically elevated by total metal concentrations above the standard limits prescribed by WHO for respirable dust in most cities.…”