Ecotoxicological assessment of leachate from Amilegbe dumpsite, Ilorin, Nigeria using Clarias gariepinus (Burchell 1822) and Allium cepa

Abstract

Indiscriminate discharge of solid waste materials from anthropogenic activities has become a major environmental problem in Nigeria. Leachate samples were collected from Amilegbe dumpsite in Ilorin. The physico-chemical qualities of the leachate as well as heavy metals content were analysed using standard methods. Different concentrations (3.625 %, 6.25 %, 12.5 %, 25.0 %, 50.0 % and 100.0 % (v/v leachate/distilled water)) of leachate samples were prepared. The 96–h LC₅₀ of leachate samples was determined for Clarias gariepinus fingerlings using Probit method. Allium cepa bulbs were also exposed to the different concentrations of the leachate and the root length inhibition and chromosomal aberration were investigated. The results showed certain sample-constituents of the leachate (e.g. pH, BOD, COD, heavy metals) to be at concentrations beyond the maximum permissible limits set by National Environmental Standards and Regulatory Enforcement Agency NESREA. The 96–h LC₅₀ of leachate to Clarias gariepinus fingerlings was 20.26%. Prior to the mortalities at various concentrations, symptoms of toxicity such as rapid and erratic swimming, uncoordinated movement and prolonged gaping of jaws were observed. These observations as well as mortality records were concentration–dependent. The root lengths’ mean of A. cepa exposed to different concentrations of the Amilegbe leachate when compared to the control, were statistically significantly different (p<0.05) with concentration dependent. The leachate concentrations were observed to induce different chromosomal aberrations with mitotic indices decreasing as the concentration rises. Leachates from the dumpsite have detrimental effects on both Clarias gariepinus and Allium cepa.

Keywords: Leachate, Clarias gariepinus, LC₅₀, Allium cepa, Chromosomal aberration, Mitotic index