Oil spillage measures caused drastic reduction in total petroleum hydrocarbon levels in petroleum depot in Ibadan, Southwestern Nigeria

Abstract

The concentrations of total petroleum hydrocarbons (TPHs) in surface water samples from ten sampling sites in the streams around the Nigerian National Petroleum Corporation (NNPC) Depot, Apata, Nigeria were examined to evaluate the environmental quality and health risks of TPH using (ninety) 90 samples. Physicochemical parameters such as pH, temperature, acidity, alkalinity, nitrate, phosphate, total dissolved solid (TDS), electrical conductivity (EC) and chemical oxygen demand (COD) were determined using standard methods. Extraction of TPHs from the water samples was achieved by liquid-liquid extraction method and quantified by gas Chromatograph Mass Spectrometry (GC-MS). Results showed that physicochemical parameters determined were within the acceptable limit except phosphate. In addition, the even-numbered aliphatic hydrocarbons (C₁₈-C₂₂) were higher in concentration than their odd-numbered (C₁₅-C₁₉). Mean TPH concentrations ranged from 0.59 ± 0.01 to 34.60 ± 5.50 ng/L were generally below target values. The health risk assessment of non-carcinogenic effects showed HQ and HI values for benzo (a) pyrene and indeno (1,2,3-cd) pyrene were less than 1.0 for adults and children, indicating no adverse effects but the sum of CR was lower than the permissible limit of 1.0 × 10⁻⁴. Although pollution was low, there is a need for monitoring and regular checks to ensure public safety.

Keywords:

• TPH
• physicochemical parameters
• health risk assessment and surface water

PUBLIC INTEREST STATEMENT

TPHs are a large family of several hundred chemical compounds that originally come from crude oil. At low concentrations, they may not pose any immediate threat, but could trigger a great challenge over a long period of time. Activities within the depot have created environmental concern in the area due to leakages and oil spills during loading of petroleum products. Also, oil storage tanks that may sometime contain water are drained of the water prior to truck loading on a daily basis and are emptied into the depot surface water body which negatively affect the environment. Oil containment materials used in the depot to curtail the spread of oil are very effective. Furthermore, the health risk of TPH calculated revealed no adverse effect.

Competing Interests

The authors declare no competing interests.

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

O.O. Olayinka

O.O. Olayinka, Oluwafunmilayo O. obtained B.Sc in Chemistry (1996) from Ondo State University Ado-Ekiti, Ekiti State, Nigeria now Ekiti –State University, Masters in Analytical Chemistry (1999) and PhD in Industrial Chemistry (2010), both from University of Ibadan, Nigeria.

O.H. Adedeji

O.H. Adedeji obtained his Masters in Geography (1998) and PhD in (Biogeography) (2008) both from University of Ibadan, Nigeria. He also obtained a Post Graduate Diploma (Natural Resources Management) from Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, the Netherlands.

S. A Ahmed

S. A Ahmed had HND in Chemical Engineering (2014) from Kaduna Polytechnic, Kaduna State, Nigeria and B.EMT (2019) in Environmental Management and Toxicology from Federal University of Agriculture, Abeokuta, Nigeria.