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Toxicity is a measure of the degree to which something is toxic; it deals with the effect of chemical substances on organisms. The problem of contamination of aquatic environment with various brands of detergents by individuals and industries has since been in practice, as such the role of microbes in food chain and as agents of degradation of subs...
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... Waste management in general has emerged as a major problem for urban cities (Aina et al., 2009). Adopting inappropriate mean in the management of wastes could result in environmental pollution (Giri et al., 2007;Ogundiran and Afolabi, 2008;Wemedo and Nrior, 2017). ...
Three brands of spent mobile phone batteries (lithium-ion and Li-Polymer) were used as toxicant in freshwater sample with Aspergillus nidulans. The 24h Median Lethal Concentration (LC50) was used as indices for ecotoxicological assessment. Aspergillus nidulans survive and multiply in the Samsung contaminated freshwater with median lethal concentration (LC50 = 84.5659%) which is higher than the maximum toxicant concentration of 75%. Nokia (LC50 = 73.0401%) which is slightly lower than the maximum toxicant concentration showing that Aspergillus nidulans is slightly susceptible to the toxicant in fresh water. Tecno mobile phone battery is a Li-Polymer battery (LC50 of 66.3615%) which is lower than the maximum toxicant concentration showing that Aspergillus nidulans is susceptible to the toxicant in fresh water. Cumulative analysis of mean % mortality showed that Aspergillus nidulans is not susceptible to spent Samsung battery, slightly susceptible to spent Nokia battery and susceptible to spent Tecno phone battery. Mean % log mortality at different dose 0%, 5%, 15%, 25%, 50% and 75% revealed Samsung: 0, -5.618, 1.18, -1.87, -19.822, -17.042; Nokia: 0, 4.642, 3.974, -0.156, 4.018, 1.366; Tecno: 0, 4.59, 8.072, 4.458, 11.394, 17.23 [Note: the negative % log mortality values indicates growth above % control]. There were significant differences in the toxicants at 95% probability level; showing that Tecno battery is more toxic than Nokia and Samsung mobile phone battery. Samsung mobile phone battery might have been manufactured with green awareness. Spent mobile phone batteries should be handled as toxic materials that require special treatment. Implementation of a well-coordinated management strategy for spent batteries is urgently required to check the dissipation of large doses of toxic chemicals and rare heavy metals into the environment. However, the ability of Aspergillus nidulans to utilize battery chemical component for growth up to 45% concentration shows that this organism is a very potential tool for biodegradation of spent mobile phone batteries, thus industries concerned should mix broth cultures of Aspergillus nidulans with spent chemicals of phone batteries before discharge into the environment. It can also be used as a bio-marker to detect low and high level pollution in freshwater.
... On the other hand, earlier Laboratory investigations have shown that nitrifying bacteria could utilize kerosene and other petroleum products as carbon source which may vary both in rates of utilization and growth profile (Eze et al., 2013a,b). Furthermore, the influence of salinity on the sensitivity of Nitrobacter to various microcosms was which corroborates earlier work reported (Wemedo and Nrior, 2017). The percentage median Lethal Concentration (%LC50) of microcosms, toxicant effect and toxicant ratio of Nitrobacter exposed for periods of 0, 4, 8, 12 and 24h at different (%) concentrations of; 0, 3.25, 6.5, 12.5, 25 and 50 in LRK and IRK are represented in Figures 4A-C. ...
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 24hours. 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.
