Comparative Assessment of Single Extraction Methods for Evaluating Copper and Lead Bioavailability in Co-contaminated Soils with Diesel and Heavy Metals

다국어 초록 (Multilingual Abstract)

Soil contamination by heavy metals and petroleum hydrocarbons (PHs) poses significant environmental and health risks. This study evaluated the extractability and bioavailability of copper (Cu) and lead (Pb) in soils co-contaminated with heavy metals and diesel using two chelating agents (EDTA and DTPA) and two neutral salts (NaNO3 and CaCl2). Maize and tall fescue were cultivated for 60 days to assess heavy metal uptake. The results showed that chelating agents extracted significantly greater amounts of Cu, likely due to their strong complexation with metal ions. However, neutral salts exhibited stronger correlations between extractable Cu in soil and its uptake by plant roots (R2 = 0.676–0.924). Additionally, the bioaccumulation factor (BF) for Cu was higher when neutral salts were used (0.80–3.96) compared to chelating agents (0.08–0.36), suggesting that neutral salts more accurately reflect the bioavailable Cu fraction for plant uptake. In contrast, Pb exhibited low extractability and bioavailability across all extractants, with no significant correlations between total and extractable fractions or plant uptake. These findings suggest that while neutral salts are suitable for evaluating Cu bioavailability, single extraction methods may not be appropriate for assessing Pb dynamics in co-contaminated soils.