Assessment of lead accumulation on soils and vegetables grown along major roads within Nakuru town

Abstract

Lead has been found to be toxic to human beings even at low concentrations due to its negative effects on IQ, impaired hearing, behavioral problems (aggression) and delayed bone growth alongside causing death in some cases. The main objective of the study was to assess levels of lead in soils and vegetables grown along Kipande, Eldoret- Nakuru and Nakuru - Nairobi roads within the Nakuru County. All samples were collected, digested and analyzed for the presence and levels of lead using atomic absorption spectroscopy. The results indicated high levels of lead in analyzed soils to have ranged from 23 to 130 mgPb/Kg which were more than 100 times higher than the recommended lead values in soils by the EPA. Samples of leafy vegetables (kales) were collected and analyzed for residual lead showed levels of lead to range from 1.62 to 6.50 mgPb/Kg with high levels recorded in samples collected along the main roads than in samples collected 60 meters from the roads. The results showed high statistical correlation (p < 0.05, r = 0.9372) between levels of lead in soils and sampled vegetables. The concentrations of lead in the sampling sites decreased linearly with distance from the edge of the road and dropped to the minimum levels at about 60 meters. The study found that vehicle emissions could be a major contributing factor of high levels of lead in soils and vegetables grown along the main roads under study. It is therefore recommended that growing of vegetables for both human and animal consumption should be discouraged and proper legislation put in place to prevent roadside usage as farmlands in Kenya.