Evaluation of Hydrocarbons and Heavy Metals in Iko River, Eastern Obolo L.G.A, Akwa Ibom State, Nigeria

Abstract

This study evaluates hydrocarbons and heavy metals in water and sediment samples within the up and down streams of Iko River, Akwa Ibom State, Nigeria. The water and sediment samples were collected in triplicate from five designated stations of the up and down streams of the River using standard analytical procedures. The samples were analysed for hydrocarbons and heavy metals using gas chromatography with flame ionization detector (GC-FID) and atomic absorption spectroscopy respectively. Electrical conductivity (EC), salinity, temperature, PH, Total dissolved solids (TDS), and dissolved oxygen (DO) were also analyzed to ascertain the portability of the water samples. The results showed that Total petroleum hydrocarbon (TPH) in the up and downstream of the River (water samples) had a range of 3.743 to 5.518 mg/L, whereas Total hydrocarbon content (THC) in the water samples of the up and downstream had a range of 3.029 to 10.017 mg/L. Considering sediment samples, TPH in the up and downstream ranged from 479.611 to 638.391 mg/kg while THC had 724.275 to 2,574.247 mg/kg. TPH and THC values obtained were above the 50 mg/kg permissible limit of the Department of Petroleum Resources (DPR). The result obtained from the heavy metals analysis in the up and downstream of the water samples were from the ranges of 0.01 to 1.80 mg/L while heavy metals in the sediment ranged from 0.01 – 18.40 mg/kg, which is above the World Health Organisation and National Environmental Standard and Regulations Enforcement Agency (WHO/NESREA) standards (0.001 – 5.0 mg/kg). The physicochemical analysis recorded the following results within the up and downstream of the water samples; salinity (0.07 – 0.94 mg/L), TDS (0.40 – 1905 mg/L), EC (3.00 – 16.77 µS/cm), DO (2.29 – 3.44 mg/L), Temperature (30.7 oC), and PH (6.07 – 6.36), while the sediment had the following results; salinity (0.07 – 0.49 mg/kg),EC(0.66 – 1,560 µS/cm), Temperature (27.8 - 30.6 oC) and PH (6.02 – 6.28). All the results from the Analysis when compared with WHO standards were above the permissible limit indicating that the area is polluted. Hence there is need for early remediation to avoid potential health risk, encouraging healthier and cleaner environments. In addition the study has provided valuable information on the levels of heavy metals and hydrocarbons which will assist the environmentalist, public health specialist, law makers and government in their planning.