Civil and Environmental Research www.iiste.org ISSN 2224-5790 (Paper) ISSN 2225-0514 (Online) Vol.8, No.12, 2016 97 Environmental Pollution from Road Transport System in Ogbomosoland, Southwestern Nigeria Osuolale, O. M. 1* , Agbede, O. A. 2 and Osuolale, F. N. 3 1 Department of Civil Engineering, Ladoke Akintola University of Technology, Ogbomoso, Nigeria. 2 Department of Civil Engineering, University of Ibadan, Ibadan, Nigeria 3 Department of Civil Engineering, Ladoke Akintola University of Technology, Ogbomoso, Nigeria. ABSTRACT Environmental pollutions from road transport system in Nigeria poses serious health hazards to the ecosystem because of presence of heavy metals and other pollutants. There are researches on assessment of heavy metals contamination of road side soils but most of them investigated the concentration of the heavy metals at the edge of the road pavements but did not considered the concentration at various distances away from the edge of the road pavement. This research therefore focussed on the investigation of the concentration of the contaminants at the edge of the road and at various distances away from the road pavement. A total of 225 soil samples were collected at three sampling depths (0, 10 and 20cm) using three sampling distances of 0.2, 1.5 and 3.0m from Federal, State and Local roads. The soil samples were digested using perchloric acid and trioxonitrate (v) acid and the resulting filterate was analysed using Atomic absorption spectrophotometer for concentrations of Lead (Pb), Copper (Cu), Zinc (Zn), Nickel (Ni) and Cadmium (Cd) at each road. The heavy metals concentration at depth 0cm and distance 0.2m show that the Federal roads had the highest mean concentration of 154.67, 49.43, 124.71, 27.40 and 2.19µg/g for Pb, Cu, Zn, Ni and Cd respectively and the least being Local roads (110.60, 35.57, 104.26, 23.99 and 1.12µg/g). The mean heavy metals concentrations decreased with increasing soil depths and sampling distance for Federal, State and Local roads. Some of the heavy metals concentrations were above the permissible limit (Canadian Council of Ministers of the Environment, 2004). The study revealed that there are heavy metals in the road-side soils and concentrations for some of the roads were found to be above the permissible limits and this possesses serious health challenges to people around the neighbourhood. The concentrations also decreased with increasing sampling depth and distance for all the roads. Keywords: Environmental Pollution, Heavy metals, Road-side Soils, Sampling depth and distance 1.0 Introduction Road transport is one of the major means of conveying goods and services from one origin to another destination in Nigeria. This system has provided a great comfort to human beings and improved efficiency in term of delivery of goods and services. In fact, the national economy of every country mostly relies on the efficiency of this system. Likewise, local economy relies on transport links to the national network. Improved transport links are therefore essential if a country is to continue to develop and prosper. However, as good as the transport system is, it has significant negative impacts, such as road traffic accidents, environmental pollution, traffic congestion, nuisance and so on (Figueroa et al, 2005). The pollution from road transport has been found to contribute to climate change, which is a serious global problem that requires urgent attention (Ajayi and Dosunmu, 2002). The environmental pollutions from road transport can be in form of air, soil, noise and water pollutions. The soil contains natural trace of heavy metals, which are beneficiary to plant, animal and human but are harmful when they are at elevated concentrations in the soil. The high concentration have been found from anthropogenic sources such as agricultural pesticides, waste disposal, industrial activities and emission from automobile parts and exhaust (Onianwa et al, 2001). The common heavy metal pollutants from automobiles are Lead, Zinc, Copper, Nickel and Cadmium. They are released during processes such as fuel combustion (petrol and diesel), component wears (tyres, brakes and body parts), fluid leakages (brake, power steering, clutch fluids), radiators, batteries and so on (Akar et al, 2006). It was reported in 1994 that approximately 28,390 tons of Pb was emitted in the atmosphere, with a contribution of 70% from road transport at the vicinity of highways in part of former Soviet Union (Han et al, 2009). Several researches have been conducted on heavy metals contamination of roadside soils and vicinities of other automobile related activities (Day et al, 1975; Olsen and Skogerboe, 1975; Harrison, 1979; and Harrison, 1980; Farmer and Lyon, 1977; Duggan and Williams, 1977; Solomon and Hartford, 1976; Day, 1977, Olajire and Ayodele, 1997; Li et al, 2001; Liu et al, 2002, Uwagboe and Hymore, 2001, Onianwa et al, 2001, Amusan et al, 2003, Fakayode and Olu-Owolabi, 2003, Akbar et al, 2006). Most of the researches were conducted in urban areas of developed and developing countries of the world and less has been done on underdeveloped town like Ogbomoso. Also, in most of the researches, soil samples were only collected either from the top soils or at the edge of the road pavements except Fakayode and Olu-Owolabi, 2003 that considered the variation of the heavy