Evaluation of physicochemical, microbiological and polycyclic aromatic hydrocarbon content of top soils from Oka Market Waste Collection Site, Benin City, Nigeria

Abstract

The aim of this study was to evaluate the physicochemical, microbiological and polycyclic aromatic hydrocarbon composition of top soil samples from Oka market waste collection site. Standard analytical and microbiological procedures were adopted. pH and electrical conductivity ranged from 6.45 to 7.39 and 230 to 940 μS/cm respectively. The highest content of organic carbon was observed in sample 2 (5.91 %), while that of sodium and potassium were 2.44 meq/ 100g (soil 2) and 0.23 meq/ 100g (soil 3) respectively. Calcium and magnesium content in the soil ranged from 2.60 to 7.72 meq/ 100g and 0.69 to 1.38 meq/ 100g respectively. The total hydrocarbon content ranged from 2.4 to 15.9mg/kg. The results of particle soil analysis revealed high content of sandy soil (88.2 to 90.7). Iron had the highest concentration among studied heavy metals, ranging from 193 to 649.2 mg/kg. Total heterotrophic bacterial and fungal counts were in the magnitude of 104, ranging from 3.6 to 17.4 cfu/g and 2.3 to 6.9 cfu/g. Tentative bacterial isolates were Bacillus sp., Micrococcus sp., Staphylococcus spp. and Enterobacter sp., while fungal isolates were Aspergillus sp. Candida sp. and Penicillium spp. The highest concentration of Polycyclic Aromatic Hydrocarbon was 16.5 mg/kg, with its components ranging from 0.08 mg/kg (Dibenzo(a,h) anthracene) to 2.1 mg/kg (Benzo(k) fluoranthene). The quality of soil is as a result of all the processes that act on it, therefore, informing the public of the dangers inherent in improper management of soil environment should be considered as an important aspect of scientific research.

Keywords: market, physicochemical, microbial, PAHs, waste, heavy metals