Assessment of heavy metal soil pollution in the agricultural land of North Western Bangladesh

The research is designed to analyze the soil contamination, especially heavy metal (HM) (Zn, Cu, Pb, Cd, Cr, Ni, and Fe) concentrations in the agricultural lands in North Western region of Bangladesh. Samples of soil examined in this research were collected from 10 villages of the study area. Plots with the highest number of crop rotation were selected to acquire the finest result from where the samples were collected during the fallow period between crops. In addition, to reduce the margin of error, soil samples were collected from four plots of each village and mean value of each HM was calculated. Collected samples were tested in the labs of the Soil Resource Development Institute of Rajshahi and Dhaka. To identify the pollution level, Single Pollution Index (SPI) and Nemerow Composite Pollution Index (NCPI) methods were used, while to analyze the spatial pattern of pollution, Transform Value measuring and Geographic Information System techniques were applied. The SPI analysis result indicates that Pb, Cd, Cr, and Fe were found severely polluted, while Zn from severe to moderate, and Cu and Ni from mild to moderate pollution. Whereas NCPI analysis indicates that the study area is severely polluted by all the parameters except Cu, which is mildly polluted. Spatial analysis portrays scenery of an over drift in the whole study area by the HMs, but the western part, especially Sarishakuri, Sharmongla, and Karnahar, showed the most significantly high contamination of Cu, Zn, Cr, and Ni. Contrariwise, the eastern part, especially Tetulia, Hujuripara, Bajitpur, Dharmahata, and Radhanagar found as the highest contaminated area of Pb, Cd, and Fe.