Levels and Sources of Trace Metals and TPH in Aerosol Particles in Some Cities of the Niger Delta Region of Nigeria: Statistical Approach | Chapter 3 | Challenging Issues on Environment and Earth Science Vol. 1

This study calculated and compared seasonal trace element levels (Pb, Hg, Cr, Ni, V, Cu, Cd, Mn, Fe, Zn, Co, and As), total petroleum hydrocarbons (TPH) and suspended particulate matter (PM10) in aerosol particles collected in four major cities (Calabar, Eket, Aba and Port Harcourt) in the Niger delta region between July-September 2005 and January-March 2006. PM10 concentrations ranged from the lowest in Calabar, 27.72 ± 11.33 μg/m3, to the highest in Aba, 75.50 ± 25.60 μg/m3, while TPH ranged from 6.56 ± 3.36 μg/m3 in Calabar to the highest in Eket, 35.95 ± 16.30 μg/m3. The results of the trace metal analysis showed that the aerosols in the air basin contain concentrations of elements (Pb, Hg, Cr, Ni, V, Cu, Cd, Mn, Co and As) < 15 μg/m3 at all sites in the Niger delta region of Nigeria. In Aba and Port Harcourt, higher mean Fe concentrations (41.26 ± 9.84 μg/m3) recorded at Calabar and Zn (39.76 ± 6.15 μg/m3) and (22.91±6.26 μg/m3) were registered. The median highest TPH concentrations (35.95 ± 16.30) and (33.05 ± 16.21 μg/m3) were obtained in the dry season (January-March 2005) at Aba and Eket respectively, while the lowest mean concentration (6.56 ± 3.36 μg/m3) was obtained at Calabar. Significant seasonal differences in metal concentrations with higher concentrations during the dry season were confirmed by a paired independent t-test at p ⁇ 0.05 (df = 34, n= 36). To classify the origins and their contributions to the aerosol particles, enrichment factor (EF) analysis was adopted. Our findings showed that Pb, Hg, Cr, Ni, V, Cu, Cd, Mn, Zn, Co, and As of anthropogenic origin, in the order Port Harcourt > Aba > Eket > Calabar, were highly enriched in the atmosphere in the cities studied. Multivariate statistical analyses (Principal Component and Cluster) validated the trace metal sources, as well as their local meteorological factor controls. This study provides the region's baseline information and is useful for successful monitoring of environmental pollution in Nigeria's Niger delta region.

Author (s) Details

B. O. Ekpo
Environmental and Petroleum Geochemistry Research Group (EPGR), Department of Pure and Applied Chemistry, University of Calabar, P. M. B. 3766, Calabar, C. R., Nigeria.

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