The Toxicity and Genotoxicity of Drilling Fluids Used During Crude Oil Recovery

Abstract

The Drilling of crude oil to bring it up to the subsurface of the earth cannot be accomplished without the use of drilling fluids. Used oil-based drilling fluid was introduced to Clarias gariepinus and Allium cepa in the determination of its toxic and genotoxic characteristics. This study made use of spent oil- based drilling fluid/ mud which was gotten from oando gas plant, in sterilized plastic containers. Test subjects were acclimatized and stored respectively which lasted for 14days.After both acclimatization and storage of test subjects, test solutions were prepared in different concentrations after a range finding test was conducted. At the end of 96h, LC50 of 71.589 %, 96.052 %, 96.052 % and 59.508 % were obtained at 24hr, 48hr, 72hr and 96hr respectively. It was observed that the higher the concentration the higher the mortality as well as the EC50 which showed relationships between root tip-growth inhibitions and increase in toxicant concentration. Polycyclic aromatic hydrocarbons (PAHs) contents such as Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Phenathrene, Anthracene, Fluoranthene, Benzo (K), Pyrene, Benz (a) anthracene, Chrysene, Benzo (b) fluoranthene, Benzo (k) fluoranthene, Benzo (a) pyrene, Indeno (1,2,3-cd) pyrene, Dibenz (a,h), anthracene and Benzo (g,h,i) perylene of oil based drilling mud was analysed using Atomic Absorption Spectrophotometer. These parameters may be responsible for the toxic effects on fish and onion root tips. Hence, the disposal of drill fluids after crude oil recovery should be well monitored so as to ensure the fulfilment of the necessary regulatory standards set up by regulatory bodies.