Comparative Study of Levels of Trace Metals in Airborne Particulates in Some Cities of the Niger Delta Region of Nigeria

Abstract

This study measured and compared the levels of trace elements (Pb, Hg, Cr, Ni, V, Cu, Cd, Mn, Fe, Zn, Co, and As) in airborne Suspended Particulate Matter (SPM) (PM₁₀) collected between July–September, 2005 and January–March, 2006 at four major cities (Calabar, Eket, Aba and Port Harcourt) in the Niger delta region of Nigeria. The SPM concentrations varied from 27.72±11.33 ?g/m³ in Calabar to 75.50±25.60 ?g/m³ in Aba. Atomic Absorption Spectroscopy (AAS) results show that the air basin at all sites contain concentrations of elements (Pb, Hg, Cr, Ni, V, Cu, Cd, Mn, Co and As) < 15 ?g/m³. Higher concentration of Fe (41.26±9.84 µg/m³) was recorded at Calabar and of Zn (39.76±6.15 µg/m³) and (22.91±6.26 µg/m³) at Aba and Port Harcourt respectively. Paired independent t-test at p ? 0.05 (df = 34, n = 36) confirmed significant seasonal variations in the concentrations of the metals with greater concentrations during the dry season. Enrichment factor (EF) analysis was adopted to identify the sources and their contributions to particulate matter. Our results revealed that the background atmosphere in the studied cities was highly affected by anthropogenic pollution, in the order PH > Aba > Eket > Calabar, and demonstrated that high heavy metal concentrations occurred but with significant EF values during the dry season. The present study provides base line information about the region. The results are useful for effective environmental pollution monitoring in the in the Niger Delta air basin.