Quality Assessment and Levels of Polycyclic Aromatic Hydrocarbons in Oil Contaminated Soils in Parts of Rivers State Nigeria

Abstract The levels of Polycyclic Aromatic Hydrocarbons, Physicochemical Properties and Heavy Metals in Lube and Diesel Oil contaminated soils around automobile mechanic workshops in parts of Rivers State were assessed using standard methods recommended by APHA, Loganathan and EGASPIN for physiochemical parameters, Chromatograph (HP5890 Series II) for PAHs and Atomic Absorption Spectrophotometer for heavy metals. The spill or discharge of spent lube oil on soil was simulated and the results showed mean values of 6.64 ±0.336 pH, 507 ±72.054µS/cm electrical conductivity, 14.733±7.37meq/100g CEC,. 3.357 ±2.34% TOC, 2.375 ±2.12% TON, 0.1975 ±0.056mg/kg Available Phosphorus, 63.08 ±52.694mg/kg potassium, 501.13 ±138.407mg/kg Magnesium, 39.303±4.991mg/kg Manganese, 81.505±19.524mg/kg Total Hydrocarbon content, 0.147 ±0.134mg/kg Polycyclic aromatic hydrocarbons, 90.11 ±1.14% sand, 1.66±0.87% silt. The texture of the soil was predominantly sandy.The concentrations of PAH in unpolluted soil ranged from 5.9995×10-6ppm (chrysene) to 1.8095×10-3ppm (phenanthrene) with mean of 0.00038±0.0005. The PAH concentrations in polluted soil ranged from 1.0705×10-4 ppm(2-methyl naphthalene) to 2.0684×10-2ppm (benzo(b)fluoranthene) with mean of 0.0052±0.0054. The mean PAH concentrations in soils was 0.0199±0.0373ppm at Ibeto, 0.0095±0.0162ppm at Ogubolo and 0.0080±0.0153ppm at Ikoku. The levels of pH measured indicate that the soils are moderately acidic.The concentrations of toxic and carcinogenic PAHs such as Benzo(b)fluoranthene, Benzo(k)fluoranthene and Indeno(1,2,3-c,d)pyrene exceeded their permissible limits. The simulation with lube oil discharged on soil showed the contribution of used or spent lube oil to the levels of pollutants measured in soils at the study areas. The concentrations of all the toxic and carcinogenic PAHs in soils at the study areas except Benzo(a)pyrene and Indeno(1,2,3-cd) pyrene at Ibeto exceeded their permissible limits and therefore pose grave environmental and health concerns in the areas. There should be awareness campaign and local crude oil refining (Artisanal Refinery) activities and indiscriminate location of auto mechanic shops close to residential and farm lands should be discouraged.

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Updated: May 8, 2018 — 5:22 am