Heavy Metals, Polycyclic Aromatic Hydrocarbons, Total Petroleum Hydrocarbons and Total Hydrocarbon Contents in Drilling Mud Effluents From Eastern Obolo Oilfield In The Niger Delta Region Of Nigeria

Abstract

The objective of this paper is to evaluate the concentrations of heavy metals, polycyclic aromatic hydrocarbons (PAHs), total petroleum hydrocarbons (TPH) and total hydrocarbon content (THC) in drilling mud effluents from Eastern Obolo Oilfield in the Niger Delta region of Nigeria using appropriate standard methods. The TPH and THC of OBM and WBM analyses with UV-Vis spectrophotometer indicated 1.60 mg/kg for OBM and 1.30 mg/kg for WBM. A value of 5.35 mg/kg was obtained for OBM compared to 5.15mg/kg for the OBM in the THC. Generally, the result indicated that TPH<THC and was found to be far lower than 50 mg/kg allowable for drilling mud in the environment. GC-MS analysis for TPH indicated a range of n- alkanes with a higher concentration (46118.28 ug/l) in the OBM compared to WBM concentration (17185.95 ug/l) compared to the UV-Vis spectrophotometer. The analysis of TPH using GC-MS revealed a more comprehensive range of n- alkanes present in the OBM and WBM. The heavy metals indicated considerable differences of the concentration in OBM and WBM. The concentrations viewed significantly with the range for the WBM; Fe>Zn>Cr>Pb>Cu>Ni>Cd. The concentrations range in the OBM were; Fe>Cr>Zn>Ni>Cu>Pb>Cd. The evaluation of the concentrations of these elements in drilling mud are of environmental significance from pollution viewpoint especially ferrochrome lignosulphate (Chromium pollution) and lead compounds (lead pollution). The results from this study which indicates the presence of varying concentrations of heavy metals and petroleum hydrocarbons in the drilling mud is valuable and significant when making the choice for subsequent disposal of drilling mud effluents and, particularly in the study area where extensive oil/gas operation is ongoing.