Bioconcentration and translocation of Cd and Hg in a tomato (Solanum lycopersicum) from cultivated soils in southeastern Brazil.

ABSTRACT

Food is the main source of toxic metals like mercury (Hg) and cadmium (Cd) to humans. This study evaluated the accumulation and translocation of Cd and Hg in a soil-plant system in four tomato plantations and assessed the risk associated with ingestion of these metals. Ten soil samples (rhizosphere) and 10 samples of plant tissues (leaf, ripe fruit, green fruit, and roots) were collected in each plantation. Spatial variation in Cd and Hg concentrations was negligible. The Cd level in rhizosphere was lower in comparison with that of plant tissues. Hg levels in rhizosphere were similar to roots and higher than the value observed in aerial parts of plants. The Cd bioconcentration factor was approximately five times higher compared to that of Hg. Approximately 93% and 48.6% of Cd and Hg accumulated in roots reached aerial parts, respectively. Our results indicate that tomato readily absorbs Cd accumulated in soil, translocating it to aerial parts. Comparatively, the absorption of Hg is not efficient. Levels of Cd in tomatoes were over 17 times higher than the maximum residual levels in 57.5% of ripe fruits and in 27.5% of green tomatoes.