Environmental impacts of heavy metals (Fe, Ni, Cr, Ca) in soils of Triada in Euboea from ultrabasic rocks and nickeliferrous mineralization, Greece

Soil samples were collected from the Triada area of Central Euboea and analysed for heavy metals in order to evaluate their environmental impact. The geology of the area studied includes ultrabasic rocks overlaid by Upper Cretaceous limestones, whereas Fe - Ni mineralization is intercalated between either the ultrabasic parent rocks or the karstified Jurassic/Triassic carbonates and the transgressive Upper Cretaceous limestones. The soil samples were digested with aqua regia (1:3 HNO3 and HCl) and were analyzed for heavy metals by using atomic absorption spectroscopy. The range of metal concentrations are as follows: Fe: 64.000 - 384.000ppm, Ni: 480 - 4000ppm, Cr: 240 - 2720ppm, Co: 40 - 208ppm, Mn: 46 - 1680ppm, Pb: 16 - 56ppm, Zn: 40 - 144ppm, Cu : 2 - 82ppm. These values are much higher than the values found for Ni, Cr, Co, Fe and Mn in normal soils around the world. The intercorrelated elements Fe, Ni, Cr, Co of the Triada soils reflect their association with the ultrabasic rocks and with the Fe - Ni mineralization. The elevated Fe, Ni, Cr, Co contents in the Triada soils are potentially toxic for the growth of vegetation.