Heavy Metals and Hydrocarbon Contamination of Surface water in Azuabie Creek within Bonny Estuary, Nigeria

Abstract

The aim of this study was to assess some heavy metals (Cr, Ni, Cd, Pb, Zn and Cu) and hydrocarbon concentrations of Azuabie creek using the Okujagu creek as a control location. Seventy two samples were collected from four stations (AZ1, AZ2, AZ3 and OK) in six months (July – December 2016). Samples were analyzed using AAS and GC spectrophotometry while ANOVA and PCA were used for data analysis.The hydrocarbons (THC, 0.3 ± 0.07 – 84.6 ± 28.85 mg/l, TPH,0.07 ± 0.03 - 45.20 ± 13.88 mg/l & PAH, 0.001 ± 0.0003 – 0.384 ± 0.104 mg/l) were generally higher in Azuabie creek and showed increased concentration over time with significant difference (p<0.001) between locations and also between months. The increase in hydrocarbon level is due to oil bunkering and other anthropogenic activities in the study area. The concentration of Cr, Ni, Cd, and Pb generally exceeded WHO and USEPA limits in water while those of Zn and Cu fell below such regulatory limits. Site discrimination by PCA showed AZ1 & AZ2 as most dissimilar stations traceable to higher contaminant levels associated with such sites. In conclusion, the variables within Azuabie creek showed higher contaminant level compared to the control creek. Complete isolation of each site examined indicates dissimilarity in the water quality with respect to contaminant level within the creek hence regular monitoring is needed to detect water quality changes.

Keyword: Heavy metals, hydrocarbon, surface water, contamination