Evaluation of Total Hydrocarbon Contents in the Leaves of Selected Crops Grown on Crude Oil Polluted Agricultural Soil

Abstract

Aim: The Total Hydrocarbon Content (THC) levels in the leaves of three edible plants (Allium cepa, Telfairia occidentalis and Zea mays) grown on soil polluted with 100 ml of crude oil were examined. Study Design: This experiment was conducted in two groups where the soil samples were polluted before planting (PB) and polluted 2 weeks after planting (PA). Place and Duration of Study: The research was carried out at the Federal University of Technology, Owerri (FUTO), Imo State, Nigeria, within a period of 4 weeks based on each group’s pollution time. Methodology: The tests for total hydrocarbon content (THC) were analyzed at different wavelengths for polluted soil and leaf samples using UV-Vis spectrophotometric method. Soil THC tests were determined on days 0, 14 and 28 respectively while THC tests on leaves of study plants were assessed on day 14 and 28. Results: The total hydrocarbon content values of the unpolluted soil (UPS) and the non-planted polluted soil (PS) subjected to this analysis on day zero were (UPS = 96.38 mg/kg; PS = 1082.80 mg/kg). However, results obtained on day 14 and 28 showed significant difference (P < 0.05) between the unpolluted soil sample (UPS) and all the planted polluted soil for Telfairia occidentalis (TOPB, TOPA), Allium cepa (ACPB, ACPA), Zea mays (ZMPB, ZMPA) as well as, the non-planted polluted soil (PS). For the leaf samples, TOPB had the highest THC value of 14.47mg/kg and 36.73 mg/kg for day 14 and 28 respectively while ZMPB had the lowest value of 5.38mg/kg at day 14 and ZMPA, the least THC value of 7.76mg/kg at day 28. Conclusion: Based on the varying THC levels observed in the leaves of crops used for this study; it was connoted that, bioaccumulation of hydrocarbons depends on the plants phytoremediation capability and the mode of pollution as observed in TOPB.