Heavy Metal Pollution in the Soil-vegetable System of Tannery Estate

Abstract

The heavy metal toxicity has the connection with the numerous deadly diseases in human body that includes but is not limited to the diseases related to DNA damage, cancer, hemolysis, gastrointestinal hemorrhage, and pulmonary edema. The metals, Cr, Cu, Ni, Cd and Pb, widely used in the Tannery industries have the potential to show similar toxicity. Therefore, we studied the environmental pollution caused by a recently relocated Hemayetpur Tannery Estate, Dhaka, Bangladesh. A comparative study has been carried out between Tannery Estate soil and nearby non-industrial agricultural area soil. To accomplish this study, laboratory based analytical tools to statistical analysis were used for the assessment of extent of pollution and its health risks indices. The results revealed that the Tannery Estate soil and vegetables contain a very high concentration of heavy metals (20.15, 19.67, 12.93, 10573.02 and 4.02 mg/kg in soil; 18.13, 12.17, 7.63, 201.63 and 1.60 for B. alba; 15.67, 9.87, 8.03, 16.00 and 1.20 for A. gangeticus of Ni, Pb, Cu, Cr and Cd, respectively) compared to the samples collected from non-industrial agricultural area. The order of all the studied metals posing cancer risk is Cr > Pb > Ni > Cd and non-cancer risks is Pb > Cd > Ni > Cu > Cr which were supported by the statistical analysis (ANOVA, PEARSON Correlation and Principal Component Analysis). The tanning agents and inefficient treatment of the effluent could play the crucial role to contaminate the soil-vegetable system in the Tannery Estate areas. Therefore, this study indicates that the metals pollution in soils can be minimized by translocating the studied metals in non-edible plants (as of Plant Transfer Factors) followed by effective and careful monitoring of the disposal of solid and liquid wastes during the processing of leather and leather products after appropriate treatments.