Effects of landfill leachate on the pollution degree of heavy metals in the calcareous soils of Miandoab region

Nowadays, the heavy metal pollution caused by the landfill leachate becomes very serious because of their potential to impact on human health through the food chain. In this study, the effect of landfill leachate on the accumulation and selected indices of soil pollution to heavy metals (Zn, Cu, Cd, Pb, Ni, Mn) including contamination factor (CF), modified degree of contamination (mCd), and modified pollution index (MPI) were investigated in four different soil sites. Results indicated that soils were significantly enriched by the metals in the sequence of Zn> Cd> Ni> Cd> Cu> Mn. However, only the Cd contents exceeded the standard levels based on national and international references. Considering CF, Cd and Zn showed a high pollution class (3≤ CF< 6) in the majority of soil sites and other metals (Cu, Pb, Ni, and Mn) categorized as moderate pollution (1≤ CF< 3). Except site 1, the values of MPI were found to be moderate contamination (3<MPI <5) in the examined soils and its highest value observed in site 2.  The mean mCd content, appeared the moderate pollution class (2≤ mCd< 4), were in order of P2> P3 > P4> P1 in different soil site under the influence of leachate probably due to the quantity and quality of the leachate. Overall, the finding of the study can provide a valuable benchmark for the design of appropriate strategies and management of those agroecosystems by both local and national managers.