Cadmium contents of soils and durum and bread wheats on Harran Plain, southeast Turkey

Durum wheat (Triticum turgidum durum (Desf.) Husn.) is produced on a large scale in Turkey, northern Syria, Kazakhstan, Iran, southern Europe, and North America, and is widely used for making spaghetti, noodles, couscous, and flatbreads. Uptake of Cd by durum wheat species is well known. The objectives of this study were to determine the cadmium (Cd) level of the soils and durum and bread wheat grown on Harran Plain, southeast Turkey, and evaluate it in terms of food safety. Soil samples were taken from 16 selected grains, leaves, and roots of durum and bread wheats for analyses. The total Cd contents of the surface and subsurface horizons were below the internationally acceptable threshold levels (<0.2 ppm). The soils in the northern part of the plain had <0.2 ppm of Cd. Ten phosphorus fertilizer samples, commonly used in the area, had >2 ppm of Cd. The amounts of bioavailable Cd in bread wheat were lower than those in durum wheat. However, the bioavailable Cd contents in durum wheat grains were <0.05 mg kg(-1), which is less than those in Canada and Italy (>0.1 mg kg(-1)). A lower Cd content was attributed to the presence of high amounts of carbonates (>20%), Fe-oxy-hydroxides (>5%), clay percent (>50%), and the nature of silicate clay mineralogy in the soils we studied. Durum wheat cultivars used in the area could be another reason for the lower contents of Cd. We confirmed that durum wheat grown on Harran Plain in southeast Turkey is quite suitable for consumption from the standpoint of Cd contents.