Evaluation of the Levels of Heavy Metals, Total Petroleum Hydrocarbon and Total Hydrocarbon Content in Tympanotomus fuscatus and Sediment, Qua Iboe River, Akwa Ibom State, Nigeria

Abstract

This study assesses the levels of heavy metals and  hydrocarbons in Tympanotomus fuscatus and the sediments of Qua Iboe River, Akwa Ibom State; the interest in the study area was due to the several industrial and oil exploration activities in the area. The heavy metals (HM) of interest were Pb, Cd, Cu, Se, Zn, As, Cr, Fe, Ni and Hg, determined using Atomic Absorption Spectroscopy while Total Hydrocarbon Content (THC) and Total Petroleum Hydrocarbon (TPH) were determined by the GC-FID method. Results obtained indicated that the heavy metal concentration in Tympanotomus fuscatus ranged as follows:  Pb (1.037 – 2.002 mg/kg), Cd (0.00 – 0.088 mg/kg), Cu (0.0037 – 10.01 mg/kg), Se (2.364 – 5.063 mg/kg), Zn (0.025 – 1.393 mg/kg), As (0.0113 – 0.355 mg/kg), Cr (1.075 – 3.055 mg/kg), Fe (2.384 – 10.022), Ni (0.045 – 1.223 mg/kg), Hg (0.037 – 1.003 mg/kg) while heavy metal concentration in sediments were: Pb (1.399 – 2.345 mg/kg), Cd (0.0267– 0.222 mg/kg), Cu (0.017 – 10.0197 mg/kg), Se (1.388 – 3.369 mg/kg), Zn (5.688 – 8.038 mg/kg), As (0.003 – 0.0317 mg/kg), Cr (0.0157 – 2.057 mg/kg), Fe (27.351 – 86.686), Ni (0.017 – 5.0413 mg/kg), Hg (0.06 – 1.53 mg/kg); generally, heavy metals levels were higher in dry season than in wet season. The levels of TPH ranged from 160.86 – 1081.52 mg/kg in Tympanotomus fuscatus and 175.97 – 3143.91 mg/kg in sediments; meanwhile, the concentration of TPH ranged from 728.47 – 2442.04 mg/kg in Tympanotomus fuscatus and 492.41 – 7186.25 mg/kg in sediments. Multiple correlation coefficient matrixes were carried out to ascertain the relationship between the pollutants concentration in the biota and sediments. Furthermore, predictive modeling of pollutant concentration in flesh and shell of Tympanotomus fuscatus was estimated. The results indicate that the amounts of HM, TPH and THC in some of the study sites were above the maximum permissible limit set by WHO and FMEnv; thus, pose health risk to humans.