Using soil heavy metal enrichment and mobility factors to determine potential uptake by vegetables

This study investigated copper (Cu) and lead (Pb) enrichment factor (EF) and mobility factor (MF) as possible indicators of their uptake by spinach (Spinaceae oleraceae) and carrots (Daucus carota) grown on a sludge-amended luvisol (SAL). Sewage sludge was applied to luvisol at different rates and spinach and carrots planted. Enrichment of Cu and Pb in SAL was determined, and values regressed with those of Cu and Pb concentrations in spinach and carrots. Concentration of Cu and Pb in vegetables was calculated using the regression model obtained, and calculated values compared with actual values. Pb MF were higher than Cu MF but Cu and Pb EFsoil values were < 3.0, indicating minor enrichment from sludge addition. EF had 10% reliability in predicting Cu and Pb uptake in vegetables. MF was more than 70% reliable in predicting carrot Cu uptake and spinach Pb uptake. EF and MF are not effective as predictors of heavy metal uptake by vegetables. The role of other soil components including root exudates and by-products from microbial activities should also be investigated.