Determination of Heavy Metals in Soots from Petroleum Vehicles Exhaust Tailpipes

In recent times, the skyrocketing vehicular population has been accompanied by a decreasing level of vehicle maintenance, aging of vehicle, and increasing inclusion of metal-based additives in fuel. Heavy metals have deleterious health implications ascribed to their propensity to displace the functional groups of enzyme thereby modifying physiological and biochemical processes within the body. With the aid of a plastic spatula, accumulated soot particles were scrapped and collected from the inner surface of the tailpipe of vehicles located at Maraban Jos and Pantaker of Kaduna State. Samples were analyzed for the presence of Cd, Hg, Cu, Pb and Fe via atomic absorption spectrophotometer (AAS). The results showed that Fe emission was the most significant with 1153.560±0.361 mg/kg and 796.816±0.522 mg/kg being the mean concentration for gasoline engine vehicle (GEV) and diesel engine vehicle (DEV) respectively. Pb followed in the order of higher concentration having an average concentration of 14.097±0.644 mg/kg for (GEV) and 11.278±0.028 mg/kg for (DEV). Mercury average concentration was found to be 5.899±0.070 mg/kg for GEV while 2.044±0.054 mg/kg was obtained for DEV. 3.083±0.034 mg/kg for GEV and 1.453±0.051mg/kg for DEV was attributed to Cu. Cd had the least concentrations for both engines, with 0.044±0.036 mg/kg and 0.0403±0.037 mg/kg for GEV and DEV respectively. Hence, the result shows GEV to have higher heavy metals pollution as compared to DEV. There exists also a similar trend associated with the emitted metal concentrations of the two fuels (gasoline and diesel) engine which follow the order of Fe > Pb > Hg > Cu > Cd. All the results exceeded the maximum permissible limit for air control given at 0.5 mg/Nm3 of an averaging period of 30 minutes to 8 hours according to (European commission 1991) with the exception of Cd from all the samples and lead from two sample of the diesel engine which recorded no detection. It is therefore inferred that soots from the exhaust tail pipes of petroleum vehicles are a major source of toxic heavy metals which are capable of altering physiological health states.