Assessment of the impact of benzene, toluene, ethylbenzene, and xylene (BTEX) on soil microbial population in selected areas of Port Harcourt City, Nigeria

Abstract

Human activities are on the rise in these areas and consequently, the discharge of BTEX to the environment is on the rise. Benzene, toluene, ethylbenzene, and xylenes (BTEX), are known to cause cancer and mutagenesis. These elements are common in soil, water, and air samples from the environment, which raises the possibility of human exposure. The purpose of this study was to determine the concentrations of BTEX (benzene, toluene, ethylbenzene, and o-xylene) in soils, to determine the effects of BTEX concentrations on the population of fungi and bacteria in the soil, and to investigate the possible sources and spatial distribution of BTEX in the selected areas. The concentrations of BTEX were measured using a Gas Chromatograph (FID, ECD) in 9 contaminated and 3 control sites over 3 months. The spatial distribution of BTEX revealed that the highest concentrations were in the agricultural area (2.49±0.94 ppm) followed by industrial area (2.14 ±1.02 ppm) and the lowest in an urban area (1.32±0.44 ppm). BTEX assessment showed that the benzene concentration in all contaminated areas was above the recommended US EPA standard of 0.005 ppm (5 µg/kg). In addition, the mean concentrations of ethylbenzene were above the recommended U.S. EPA limit of 0.370 ppm in three areas; agricultural (0.76±0.61 ppm), in dustrial (0.89±0.68 ppm) and urban control (0.89±0.31 ppm). There was a significant difference in concentration of o-xylene between the study samples and control samples F (11, 24) = 5.374, P < 0.000. Pearson correlation showed a significant positive correlation between BTEX and total fungi (TF), r = 0.351. Pearson correlation also showed that o-xylene was significantly positively correlated with total fungi (TF), r = 0.331. The result showed a significant threat of benzene and ethylbenzene to soil health. Increased and regular monitoring is thus recommended to manage the increased concentrations of BTEX in future and reduce the adverse impacts of its effluence on soils and human health.