Potentially Toxic Element Transfer and Bioconcentration in Food Crops Across Contrasting Tropical Soils

Potentially toxic element (PTE) transfer to food crops depends strongly on soil properties. This study evaluated the accumulation of Ba, Cd, Cu, Ni, and Zn in lettuce, rice, sunflower, and tomato grown in an Entisol and an Oxisol under two crop-specific base saturation conditions representing contrasting levels of soil acidity correction by liming. Bioconcentration factors (BCF) and transfer factors (TF) were determined from PTE concentrations in soils and plant tissues. BCF and TF varied with crop species, soil type, and base saturation. In general, the sandy Entisol showed greater soil-to-plant transfer than the clayey Oxisol. For example, Cd BCF in lettuce shoots ranged from 17.0 to 26.9 in the Entisol and from 2.2 to 3.4 in the Oxisol. Cd showed the greatest overall transfer and internal translocation, especially in lettuce, sunflower, and tomato, whereas Ba and Cu were generally more restricted within plants. Nominal PTE additions were based on prevention values established by Companhia Ambiental do Estado de São Paulo (CETESB). These findings indicate that soil-specific properties should be incorporated into assessments of PTE transfer to crops and into soil management decisions aimed at limiting accumulation in edible tissues.