Speciation, Risk Assessment and Bioavailability of Metals in the Agricultural Soils of the Goksu Delta, Turkey

This study determined the total concentrations, chemical speciations and their potential ecological risks of 11 metals from soil samples collected from 13 different locations in the Goksu Delta, a special environmental protection site in Turkey. In accordance with the total metal concentration results the contamination levels caused by the 11 heavy metals decreased in the following order: zinc (Zn) > nickel (Ni) > chromium (Cr) > lead (Pb) > vanadium (V) > arsenic (As) > copper (Cu) > cobalt (Co) > selenium (Se) > cadmium (Cd) > molybdenum (Mo). As a result of the speciation test, it was determined that the most mobile metals in the soil samples were Cd, Se and Zn. It was concluded that presence of Cd and Zn in particular were anthropogenic and that the metals other than As, Se and Zn were mostly bound to the organic fraction (F4) in soils. The ecological risk factors of As and Cd were found to be above the limit value in most soil samples. According to the Risk Assessment Code (RAC), the soils were in a high-risk group in terms of Zn and were in a moderate-risk group in terms of Cd, Mo and Se.