ASSESSMENT OF ECOTOXICOLOGICAL IMPACTS OF HEAVY METALS ON NILE RATS IN CEMENT FACTORIES IN OGUN STATE, NIGERIA.

Abstract

This study was carried out to assess the ecotoxicological impacts of heavy metals on the skin, kidney and lungs of nile rats (Arvicanthis niloticus) in two cement factory sites in Ogun state, Nigeria. The two sites purposively selected for this research were located in Ewekoro and Sagamu. A total of 18 animal samples were trapped from the two cement factories locations and the control sites. Soil and plant samples (Siam weed, Chromolaena odorata and lemon grass, Cymbopogon citratus) were also collected. Atomic absorption spectroscopy was used to determine the concentrations of heavy metals in the collected samples. Data obtained was subjected to analysis of variance, where significant difference exists; the means were separated using Duncan’s multiple range test. In addition, studentized t-test was used to compare the concentration of heavy metals between cement factory sites. From the results obtained, the kidneys of the nile rats (Arvicanthis niloticus) at Sagamu generally had a higher proportion of heavy metals in comparism to the skin and lungs from the locations sampled. Also, the highest level of lead contamination was seen in the kidney of the nile rats (Arvicanthis niloticus) from Ewekoro control site, the skin of the nile rats (Arvicanthis niloticus) had a higher proportion of nickel in both study areas and Cadmium in lungs at Ewekoro was implicated for higher heavy metal load. Furthermore, the levels of lead in plants between the cement factory sites were found not to be significant (p > 0.05). The same trend with lead was observed between Ewekoro cement factory site and the control site. However, significantly higher levels of evaluated heavy metals were recorded in lemon grass in Sagamu. On the other hand, but for nickel and cadmium levels in the soil samples from Sagamu, the heavy metal concentration between cement factory sites and control sites were statistically similar. The pollution indices test evinced that lemon grass (Cymbopogon citratus) were greater than 1 (> 1) and this showed that the plant did take up metals directly from the soil at the study area. The similarity in levels of heavy metals on the biota life as expressed by the findings of this work demonstrates the extent of pollution in the area. As such, the chimneys of cement factories should be fitted with pollution filters to reduce the amount of dusts that are released into the environment. In addition, effective monitoring should be carried out by the Federal Ministry of Environment