Heavy metal contamination and associated risks in agricultural soil and crops under industrial land sprawling in Central Bangladesh

Heavy metal (HM) contamination in agricultural soils and crops pose serious threats to agricultural productivity, environmental quality, and human health. Rapid industrial expansion in Bangladesh has increased concerns about HM accumulation in agricultural lands and the associated risks in industrial areas. This study investigated seasonal variations in potentially toxic HM concentrations (Cr, Cu, Mn, Ni, Zn, and Cd) in soils and crops collected from agricultural fields in central Bangladesh that are influenced by multiple industrial activities. Surface soil (0–15 cm) and edible crop samples (vegetables and rice) were collected during winter and summer, and HM concentrations were analyzed to determine bioaccumulation factors (BaF), pollution levels, sources, and ecological and human health risks. HM concentrations in both soil and crops were generally higher in winter than in summer, although metal-specific variations were observed. In soils, mean concentrations (mg/kg) of Cr, Cu, Mn, Ni, Zn, and Cd were 40.88, 5.16, 192.31, 55.80, 279.14, and 0.92 in winter, and 39.52, 4.27, 189.65, 56.62, 274.78, and below the detection limit (BDL) in summer. In crops, corresponding winter concentrations (mg/kg) were 83.34, 12.11, 390.80, 106.13, 891.89, and BDL, and 45.57, 12.21, 300.76, 92.18, 376.80, and BDL in summer. BaF values followed Zn>Cu>Cr>Mn>Ni>Cd in winter and Cu>Zn>Ni>Mn>Cr>Cd in summer. Correlation analysis suggested possible common sources and similar environmental behavior of several HMs. Pollution load indices (Pi ≤ 1.0) indicated relatively low-level soil pollution, while ecological risk indices showed low to moderate risks (Ri: 5.41–187.41). Despite relatively low soil pollution indices, the health risk assessment indicated potential chronic non-carcinogenic risks associated with dietary exposure to multiple HMs. These findings highlight the need for regular monitoring of agricultural soils and crops, effective management of industrial wastewater, and appropriate measures to minimize HM exposure in rapidly industrializing areas.