Ecological risks from trace elements in Quaternary agricultural soils of Lebanon- East Mediterranean.

Abstract

Soil contamination by trace elements (TE) causes health and environmental risks. This work focused on arable lands of Central Bekaa of Lebanon, East Mediterranean. The spatial distribution of TEs in the cultivated soils was mapped. Results showed accumulation of Cr and Ni, in the soil-plant interface layer, exceeding the multifunctional land use (soil threshold I <50 and <40 mg kg-1 , respectively) and controlled land use (soil threshold II-100 mg kg-1 ). The index of geoaccumulation (Igeo) showed no hazards from Zn with moderate to strong contamination from Pb and moderate hazard from Ni, Cu, Cd and Cr. A cross sectional soil sampling from the Litani river to the eastern hill of Terbol showed accumulation of TEs at foot slopes and at river’s banks. Human activities within the plain contribute to further soil contamination with risk of pollutants transfer to food chain. Additional sampling of plant and corresponding soil in hot spots showed TE content in the plant leaves to be mostly within or slightly above the permissible values in wheat and potato. Considering the soil quality regarding chemical pollution is a necessary factor in land use planning for the elaboration of adapted to local soil conditions thresholds of TEs content in the soil for suitable land use, either in agriculture or alternative uses.