Potential ecological risk of metal pollution in lead smelter-contaminated agricultural soils in Khulna, Bangladesh.

Lead smelters are important source of metal pollution. This study assessed ecological risks of three heavy metals (Pb, As, and Zn) in agricultural soils surrounding five Pb smelters from Khulna district in Bangladesh. A total of 81 surface soil samples collected within 500-m radius of the smelters were analyzed using an atomic absorption spectrophotometer (AAS). Concentrations of Pb, As, and Zn ranged within 6-3902, 1.8-9.6, and 45.4-563 mg/kg, respectively. About half of the Pb samples (~ 51%) exceeded soil quality standard target value (85 mg/kg), and the concentrations gradually decreased with horizontal distance from the smelter. The value of pollution index (PI) measured for Pb, As, and Zn varied respectively in the range of 0-195, 0.6-3.2, and 0.67-8.28, with mean values of 11.7, 1.9, and 3.92. The value of integrated pollution index (IPI) calculated for these metals remained between 0.58 and 66.2 with a mean of 5.7, and that designates ~ 96% of the sampled soils as moderately or highly contaminated. Potential ecological risk (PER) calculated for the metals indicate that all the samples were within low to moderate risk, and the descending order of PER of the metals was Pb > As > Zn.