Evaluation of the water quality of borehole water from a partially remediated oil spill site in Ikot Ada Udo, Akwa Ibom State, South–South Nigeria

Abstract

The quality of borehole water from Ikot Ada Udo was studied. Borehole water ( n = 48 ) samples were aseptically collected for 1 year. Samples were collected from 3 boreholes (BH 1, BH 2, BH 3) which were 500, 800, and 1000 meters respectively from the Ibibio 1 capped oil well. Control samples were collected 10,000 meters (Ibagwa, Abak) from the study site. Produced water ( n = 3 ) was also collected. Samples were analyzed for lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr), iron (Fe), vanadium (V), cobalt (Co), arsenic (As), manganese (Mn) using an inductively coupled plasma optical emission spectrometer; for total petroleum hydrocarbon (TPH) using Agilent 6890N Flame Ionization Detector Gas chromatography; for physico-chemical parameters using their respective equipment and methods. The heavy metals, TPH, and physico-chemical parameters levels varied between boreholes of the study site. The mean heavy metals, physico-chemical parameters (except pH, DO, temperature), and TPH levels of the borehole water from the study site were higher compared to the control. The mean values of Pb, Cd, Cr, and Fe in boreholes were above WHO and NSDWQ acceptable standards for drinking water. The contaminants in the borehole water were potentially introduced by produced water. Water quality index values of boreholes 1 and 3 is not an indication of good water quality. The study revealed unacceptable levels of some contaminants in the borehole water. A thorough clean-up of the spill site is therefore recommended for the total restoration of the aquifer and environment back to normal. • The 2007 spillage led to the release of crude oil into Ikot Ada Udo farmlands.. • Despite the remediation excercise in 2008, recent studies indicate that the site is still contaminated. • No study exist on the water quality of boreholes from the study site. • Borehole water from the study site is contaminated with Pb, Cd, Cr and Fe. • Water quality index revealed poor water quality for boreholes 1 and 3.