Ecotoxicity of local and industrial refined kerosene on key environmental pollution monitor, Nitrobacter sp. in tri-aquatic systems in Nigeria

Abstract

Nitrification process involves Nitrobacter species and their growth and activities in the microenvironment when impacted negatively would consequently adversely affect soil fertility. In view of the significance of this process, the toxicity of local refined kerosene (LRK) and industrial refined kerosene (IRK) on a key environmental pollution monitor, Nitrobacter was investigated. LRK and IRK were apportioned into six sets for each of the experiments using tri-aquatic systems or microcosms of freshwater (FW), marine water (MW) and brackish water (BW) at percentage concentrations of; 0, 3.25, 6.5, 12.5, 25 and 50 into which the test organism (Nitrobacter sp.) was inoculated at intervals of; 0, 4, 8, 12 and 24 hours. Toxicity results indicated that the sensitivity of the test organism was a function of both the contact time and concentrations, and also reflected lethal effects of the pollutants/toxicants (kerosene). The outcome of percentage median lethal concentration (%LC₅₀) on Nitrobacter sp. in the triaquatic microcosms with pollutants were as follows; in IRK + FW 34.41 < in IRK + MW 37.89 < in LRK + FW 39.43 < in IRK + BW 40.99 < in LRK + MW 41.56 < in LRK + BW 45.35. This study revealed that IRK + FW microcosm was the most toxic (LC₅₀) whereas LRK + BW microcosms was the least toxic. The inability of the organism to thrive well at kerosene concentration above 1% (v/v) is a warning signal of serious environmental pollution problem which could affect aquatic life forms and eventually humans. However, due to high fatality rate inherent from the use of LRK (though not reported here) and its toxicity to microbial life, it is hereby advocated that the public should rather resort to use IRK products.

Keywords: Toxicity, Percentage Median Lethal Concentration (%LC50), local and lndustrial refined kerosene, Nitrobacter