Assessing the level of heavy metals pollution in the agriculture soil of Zahab plain, Kermanshah (Case study: As, Pb and Cd)

Soil is the main component of biological biomes and is necessary for survival on the Earth. Today, soil has been contaminated by human activities. Defining the boundaries between human activities and outcomes is essential. This study was done to evaluate the concentrations of metals such as arsenic, lead and cadmium in surface soils of agricultural land around Zahab plain and the environmental risk in 2014. The sampling points were recorded by GIS and then imported to the GPS. The soil samples were taken from depths of 0 to 30 cm soil by field assessment. The samples were then transported to the laboratory and necessary preparation actions were done. Total concentrations of As, Pb and Cd were measured by atomic absorption (SHIMADZU-AA-6300). The soil chemical and physical parameters such as clay, silt, sand, organic matter, lime, gypsum, gravel percent, EC and pH were also measured. Pearson correlation test showed that there is a significant correlation among As, EC and organic matter (p<0.05). Comparison of concentrations with the international standards showed that these metals are in good condition. Pollution index showed that Pb poses more contamination than other two metals. Classification of the environmental risk showed that 83/22 % of the region falls in moderate risk. Low concentration of the metals in Zahab zone is due to traditional and small scale farming because farmers could not apply chemical fertilizers and they used mostly manure in their farms. As a result, the metals produced by agricultural activities do not pose a threat to crops and also environment.