Assessment and characterization of natural and anthropogenic sources of potentially harmful element in artificial lake-water in selected abandoned quarry sites, south-west Nigeria

Abstract

This study was aimed at assessing the quality and evaluation of potentially harmful element in these reservoirs using standard analytical and laboratory techniques. Water samples were collected from three (3) artificial lakes located on the abandoned quarry sites in Ojoru, Parakoyi and Unico Company (Sogbe-Erunwon). The collected samples were consequently assessed for physico-chemical parameters namely pH, Total Dissolve Solid, Electrical Conductivity among others; major Cation and Anion; heavy metal concentrations using Atomic Absorption Spectroscopy and Microbial/Protozoans Isolates using Laboratory and analytical procedures. The output from this study clearly reveals concentration levels of the identified parameters with the major physicochemical parameters and heavy metals concentration being found within WHO permissible standard. pH of 25% of the entire samples ranged from 5.0 to 6.7 which is slightly acidic; 2.8% were found to be within 7.0 which is neutral and the remaining 72.2% were found to be in the range of 7.1 to 9.8 which is alkaline, presence of dissolves mineral is attributable to these results. Also, 25% of the samples possess low EC and TDS values while 75% of the samples have high EC and TDS values. The observed high temperature was due to the effect of solar radiation of the exposed reservoir surface water while the recorded value of EC and TDS was due to the varying human activities on these water sources. Consequently, all the water samples seemed to meet the WHO standard for domestic and irrigation in terms of bacterial, protozoans, cations and anions level respectively. The concentrations of heavy metals (potentially harmful elements) in the samples were found to be low except for OJ (Ojoru) water samples that have higher concentration of cadmium (0.004) and Lead (0.026) compare to WHO of 0.003 and 0.015 respectively. This could be due to high level of human activities and the period (dry season) at which the samples were taken.