This study has been conducted in January to June 2019 to assess of heavy metal contamination in soils of road site from Mymensingh to Valuka. Sixteen (16) soil samples were collected consisting of road side traffic area soil and adjacent to road side near agricultural field soil (within) 100 m. The collected soil samples were digested with acid mixture (HNO3:HClO4=2:1) and then the concentrations of four heavy metals Zn, Pb, Cr, and Cd were determined using Atomic Absorption Spectrophotometer. The concentrations of heavy metals in road site soil ranged from 51.167- 93.421 mg kg-1 Zn, 11.061-55.675 mg kg-1 Pb, 10.001-15.917 mg kg-1 Cr, 0.002-0.049 mg kg-1 Cd. The concentrations of four heavy metals (Zn, Pb, Cr, and Cd) in agricultural field soil were ranged from 59.865- 84.760, 8.005- 18.675, 8.516- 17.667 and 0.001-0.189 mg kg-1, respectively. The assessed heavy metal contents in road soil revealed that Pb concentration higher at point, whereas the field soil enriched with Zn.
Key words: Heavy metals, contamination, road soil, field soil.
Introduction Metal pollution has become one of the most severe environmental problems today as a consequence of increasing environmental pollution from human activities such as mining and smelting of metals, electroplating, gas exhaust, fuel production, fertilizer, sewage and application of pesticides, etc. (Ben et al., 2007). Humans play a significant role in trace element pollution by different ways especially combustion of fossil fuels and biomass, industrial processes and waste incineration (Rajsic et al., 2008). There are some natural sources which contribute trace elements to the atmosphere such as erosion, dusts from aerolian processes and weathering, volcanic activity, oceans, forest fires and sea spray near coastlines (Karanasiou et al., 2007, Hester and Harrison, 2009). In an urban area, key source of trace elements in a particular day depend on anthropogenic activities (Hester and Harrison, 2009) especially industrial activities and vehicle-based emissions. Road soil and vehicle use in urban environments are key contributors to urban air pollution and increase concentrations of carbon monoxide, polyaromatic hydrocarbons and particulate matter (Leonard et al., 2016). Heavy metals found in roadside soil are significant environmental pollutants of growing concern in recent years, that public and scientific attention has increasingly focused on its contamination and effects on human and other living creatures (Wang et al., 2005). From various epidemiological studies, it was revealed that suspended particulate matter with diameters less than 2.5 micrometers is strongly correlated with human morbidity and mortality (Huang et al., 2012). It is quite difficult to remove fine particles after being entered into the pulmonary systems (Donaldson et al., 2002).