Assessment of Heavy Metals in Air around Industrial Area of Bonny Island, Rivers State, Nigeria

Abstract

Heavy metals are naturally found in the environment. However, industrial activities can enhance their concentrations in various environmental media. This is of great concern because of their lethal effects on the ecosystem even in small concentrations. Consequently, the concentrations of Cd, Cr, Pb, Fe, Zn, Cu, Mn and As in PM2.5 around industrial area of Bonny Island were investigated. Air samples were collected using the Environmental Monitoring Systems (EMS) High Volume Air Sampler (HVAS). The instrument was set to operate at the specified flow rate for each monitoring period. The filter collected from each of the study stations was prepared for Flame Atomic Absorption Spectrophotometer (FAAS) analysis. The results showed that the concentrations of Cadmium (Cd), Copper (Cu), Lead (Pb) and Arsenic were generally low across the study stations. Whereas Fe, Zn, Cr and Mn had mean concentrations of 36.04 µg/m3, 15.57 µg/m3, 1.51 µg/m3 and 0.60 µg/m3 respectively. The heavy metals investigated in this study were distributed in this order: Fe>Zn>Cr>Mn>Cd≥Pb≥Cu≥As. The enrichment factor (EF) of Cd, Cu, Pb, Zn and As, ranged between <1 and <10, the EF of Mn was >100 but <1000 while the EF of Cr was >1000. The concentrations of Cr and Mn obtained in PM2.5 exceeded the 8-hour time weighted average (TWA) exposure limit of 1.1 μg/m3 and annual average limit of 0.15 μg/m3 respectively by the World Health Organization. This implies that the residents of Bonny, especially those who live around the industrial area and vehicular traffic hotspots such as Finima roundabout, Wilbros Junction, etc, might be exposed to high concentrations of Cr and Mn. Hence, regular monitoring of heavy metals around industrial areas and vehicular traffic hotspots is strongly recommended for a healthy environment.