Stingless Bee Honey as Bio-Indicator of Heavy Metals Pollution in and around the University of Ilorin Environ Kwara State, Nigeria

Abstract

Honey from stingless bees was examined as an indicator to evaluate the level of heavy metal pollution at six sampling locations (Oyun A, Oyun B, Bolounduro A, Bolounduro B, Jalala and Quarters) in and around University of Ilorin. Using the dry ashing digestion method the concentration of metals (Pb, Cr, Cd, Cu, Zn) were analyzed using Atomic Absorption Spectrometer. The concentration of metal (μg/kg) in the honey samples ranged from 0.010-0.001 for Cd, 3992.33-1755.67 for Zn, 2319.33-592.33 for Cu, 29.67 - 4.33 for Cr while Pb with concentration of 1μg/kg was found in only Quarter sample. Zn was the most abundant metal detectable in all the samples with the highest and least concentration obtainable from Oyun B and Bolounduro B respectively. Statistical analysis of the studied metals showed Cu and Zn differ significantly out of the five studied metals. The highest concentration of Cu was observed in Oyun A sample the least was found in the Bolounduro A. Highest concentration for Cr was found in Oyun B while the least was obtained in Oyun A sample. Cd presented the lowest concentration level in all tested samples.All the detected heavy metals in the honey samples were at concentrations within their respective WHO permissible limit.Physicochemical Parameters like density, moisture content, free acidity, pH, ash content and electrical conductivity of the honey samples were also predetermined. The mean density of the honeys is 1.44±0.02, moisture content 14.25±2.52, pH 4.61±0.25, free acidity 44.08±2.46, Ash 1.48±0.64 and electrical conductivity 0.04±0.03. There was significant difference noted between the studied physicochemical parameters and strong correlations observed among some of the studied parameters.Some of the positive and negative detection of the result were found to correlate with activity and suspected pollutant in some of these sampling locations.

Keywords: Honey, Stingless Bee, Heavy Metals, Atomic Absorption Spectrometry