One of the adverse environmental impacts of urbanization globally is the changes in the physical, chemical and the biological properties of basic natural resources such as soils, air and water. In the case of water for example, the pollution and contamination of this resource does not only affect its quality or physicochemical properties but equally serves as a threat to public health since humans depend on it for various purposes such as domestic use and agriculture (Nganje et al., 2007). Surface and ground water resources in urban areas are at risk of contamination from many human activities such as oil spills due to haphazard location of fuel filling stations and auto mobile repair workshops along surface water resources especially in developing countries. Spilled oil contains carcinogenic or toxic components such as heavy metals, total petroleum hydrocarbons (TPH) which affects human health both directly and indirectly (Nganje et al., 2007). With the increasing rate of urbanization in developing countries like Cameroon, there has been an increasing number of fuel filling stations and author-mobile repair workshops with high potentials risk of contamination of water resources which is yet to be investigated.

At gas stations, fuel is stored and transferred between tanker trucks, storage tanks, and vehicle tanks. During both storage and transfer, a small fraction of unburned fuel is typically released. If a spill occurs while runoff occurs, the hydrocarbon can be expected to float on top of the water sheet, because gasoline, diesel oil, and lubricants are typically less dense than water. While the fraction may be small, the cumulative release can be substantial because of the large quantities of fuel sold (Hilpert et al., 2015). At auto-mobile repair shops, spilled oil is often used oil. The US Environmental Protection Agency (EPA) (2001), defined used motor oil as “any petroleum-based or synthetic oil that has been used for vehicle lubrication and as a result of normal use, motor oil becomes contaminated with various impurities such as dirt, water, chemicals or metals from vehicle engine”. Once degraded motor oil escapes the engine, it has the potential to pollute waterways in the form of runoff and soil. The US EPA reported that 1 gallon of used motor oil can contaminate 1 million gallons of fresh water. Used oils are therefore considered as one of the most hazardous mainstream categories of environmental pollutants, posing a major threat to the environment and public health.

A common practice in Cameroonian cities is to allocate large tracts of land, sometimes reaching 5 ha or more to groups of small-scale auto-mechanic businesses and designate these as villages where they locate their workshops and repair yards to offer their services to the public (Adelekan and Abegunde, 2011). In most cities, fuel feeling stations are also located near sensitive ecosystems without any proper environmental impact assessment (Adelekan and Abegunde, 2011). Most of these fuel filling stations and auto-mobile repair workshops are located near streams and rivers which the population depend on for domestic and agricultural purposes. The city of Bamenda has witnessed an increase in the number of fuel filling stations and auto-mobile repair impacts of these activities on the surface water sources are yet to be investigated. It is against the backdrop of this knowledge gap that this study is conceived. In this research, the impacts of oil spills from fuel filling stations and auto-mobile repair workshops on the physico-chemical properties of surface water systems in some selected sites in the Bemanda city were investigated. The findings can then be used as a basis for improving the management of fuel filling stations and autho-mobile repair shops as well as guide environmental lanners on the suitable location of these activities in urban areas in Cameroon and other developing countries.

Study area

This study was carried out in Mezam division in the Bamenda highlands (17,300 km²) in the North West Region of Cameroon. The area is located within latitude 5°40’ and 7° North of the equator and within longitudes 9°45 and 11°10’ East of the Meridian (Law, 2010).

Sampling criteria and sample collection

Study sites selected for this study were based on their proximity to surface water resources to auto mobile repair workshops and fuel filling stations (Figure 1). Using this criterion, ten surface water sources which were located within a 10 to 20 m distance from the auto-mobile repair workshops and fuel filling stations were selected. Ten water samples were collected from five surface water resources (two fuel filling stations and three auto-mobile repair workshops) in the month of August 2017. Two samples were collected from each surface water system within a 100 m spacing. These samples were collected in 250 ml polythene bottles pre-washed with non-ionic detergents, rinsed with distilled water three times. Before sampling of water, the bottles were rinsed three times with the sampled water.

Sample analysis

Parameters like pH, temperature and electrical conductivity were tested in the field using, a Bluelab pH meter, Mercury in glass thermometer, and a WTW LF 91 meter, respectively. Samples were put in an ice cooler and transported to the chemistry laboratory of the University of Buea, Cameroon for further analysis of other physicochemical parameters.

The total hardness of water was measured using Ethylene Diamine Tetra Acid (EDTA) as titrant with Ammonium Chloride and Ammonium Hydroxide buffer solution (pH-10) and erichrome black T as the indicator. Alkalinity was determined using titrimetric method using standard solution of 0.01 M concentration of HCl and methyl orange used as indicator. Concentrations of Calcium, Magnesium and Chlorine were measured using complexometric titration. For Calcium concentration, EDTA was used alongside Patton’s and Reeder’s indicator with Sodium Hydroxide as buffer solution (pH-12). The concentration of Magnesium ion was determined using a standard solution of EDTA and Erichrome Black T as indicator with Ammonium Chloride and Ammonium Hydroxide as buffer solutions (pH 10).

The findings of this study noted that temperature, alkalinity, conductivity and hardness were within the WHO acceptable ranges for surface water sources around fuel filling stations and auto-mobile repair workshops. pH values were however lower than expected thus causing the alteration of other parameters like conductivity of surface water resources in both sites. The pH of water affects other parameters in water thus “out-of-limit” values of these parameters indicate that the water is not suitable for domestic use. Ca⁺ and Mg²⁺ concentration was within limits while Cl was above WHO recommended limits. It was concluded that the amount of waste oil generated at fuel filling stations and auto mobile repair workshops is significant to cause negative effects on the environment. This study also suggests proper wastemanagement of used oil and the relocation of these facilities from environmentally sensitive areas such as surface water systems to prevent the harmful effects of spilled oil on environment and human health.

The authors have not declared any conflict of interests.