Bioavailability and heavy metals speciation assessment in the contaminated soils of Doustbaglu mineralized area, NW Iran

The behavior, bioavailability and toxicity of heavy metals in soil essentially relies on their chemical spices. This paper attempts to quantify the spices bound various fractions at five sampling stations (S1–S5) from Doustbaglu area, NW Iran, ascertain bioavailability, using sequential extraction. results revealed that more than 90% Cr Cu were retained residual fraction, signifying geogenic origin due acid rock drainage surrounding mineralized zones. Ni, Pb Zn; assigned a group presenting mostly (ranging 60 90%) Fe/Mn oxy-hydroxide fractions, so reflecting limited toxicity. mean concentration As Sb non-residual was significant (57.4 67.3%, respectively), primarily exchangeable as well carbonate thus they have high potential be released into pore-water if conditions become acidic. highest contamination factors (Cf) obtained for (at S4-S5), while lowest Cf found Cr, Cu, Zn. risk assessment code (RAC) (37.8%) (39.5%) suggest situation, meanwhile, S2 (50.4%), S5 (51.6%); (53.1%) seems crossing threshold very condition. order based RAC (As > Sb) Ni Zn Cu.