Heavy metal concentrations in sultana-cultivation soils and sultana raisins from Manisa (Turkey)

Abstract

This paper describes the concentrations of heavy metals in soils and in raisins (sultanas) cultivated upon the Gediz Plain (Manisa), western Turkey, which is cut by major roads from Izmir to Istanbul and Izmir to Ankara. A total of 212 samples of surface soil and 82 raisin samples were analysed. Soil samples have nearly same mineralogy, quartz, calcite, magnetite, pseudo-rutile and clay minerals. Dolomite is seen especially in areas close to Neogene sediments. Clay minerals are mainly mica (illite–muscovite), chlorite/kaolinite, smectite and mixed layers (Sm-Il). The concentrations of 21 elements (Ba, Ni, Mo, Cu, Pb, Zn, Co, Mn, As, U, Sr, Cd, Sb, Bi, Cr, B, W, Hg, Sn, Li and organic C) were determined in the surface soils. The degree of element enrichment in soil can be measured in many ways, the most common of which are the geoaccumulation index (Igeo), enrichment factor and the pollution index. Arsenic and Sb showed the highest Igeo values, corresponding to Igeo classes 3–4. Hence, the area is characterised as “being heavily contaminated to polluted” by As and Sb. Arsenic contamination has been reported from all over world. Arsenic-related pollutants enter the groundwater system by gradually moving with the flow of groundwater from rains and irrigation. Gediz Plain forms the main groundwater supply of Izmir city. The enrichment factor (EFarsenic) of the analysed soil samples is around 76, which corresponds to “extremely high enrichment”. The concentrations of 33 elements (Al, Sb, As, Ba, Be, Bi, B, Cd, Ca, Cr, Co, Cu, Fe, Pb, Li, Mg, Mn, Hg, Mo, Ni, K, Se, Ag, Na, Sr, Ta, Th, Sn, Ti, U, V, Zn and Zr) were determined in the raisin samples. The Pb and Cd contents of raisins are of great concern due to their toxicity. Pb contents ranged between 0.05 and 0.46 mg kg−1, and average Cd content was 0.04 mg kg−1. Only one sample contained high level of Cd, 0.23 mg kg−1. After cleaning the raisins, the heavy metal concentrations were low as in the European Community (EC) regulation No: 466/2001 for allowable levels of Pb (0.2 mg kg−1) and Cd (0.05 mg kg−1).