Comparative study of Cu, As AND Sb toxicity between dump-fields of abandoned Cu-deposits Ľubietová and Špania Dolina (Central Slovakia)

Abstract

Ľubietová and Špania Dolina mining areas belong to the most important Central European historic Cu-deposits. The ore mineralization contain not only Cu but also toxic As and Sb which contaminate the country components. The Eh/pH diagrams enable informative indication of As speciation in sediments and soils in the surrounding of the abandoned deposits. The most important As form in technogenous sediments of both studied ore fields Ľubietová and Špania Dolina is the less toxic As5+ speciation. The Eh/pH stability diagrams indicates predominantly occurrence of Fe(OH)4As, H2AsO4-, HAsO42- forms. Only in several few samples of technogenous sediments and soils As falls to the As3+ stability fields, e.g. to the Fe2+ + As3+(aq) field. Arsenic content in water depend on arsenopyrite FeAsS and tetrahedrite (Cu,Fe,Ag,Zn)12(AsSb)4S13 decomposition. Its redeposition is realized by adsorption on Fe-oxyhydroxides surface. Arsenic content is controlled also by next degradation of secondary As phases under changed thermodynamical conditions. Both main As speciations (As3+ and As5+) occurs in groundwater approximately in a balanced portions. Arsenic in samples falls mainly to the H2As5+O3-, HAs5+O42- and H3As3+O30 stability fields. Arsenic speciation in surface water from both localities is in comparison with those of groundwater more close to the less toxic form As5+ (H2AsO3-, HAsO42-, H3AsO30). Technogenous sediments and waters at Ľubietová and Špania Dolina are also contaminated by Sb. In sediments and soil from Ľubietová Sb prevail in less toxic degree Sb5+ and is present in SbO3- form, while in dump-field and in tailings at Špania Dolina one part of samples characterized by Eh<0,1 values is concentrated in Sb3+ stability fields of valentinite Sb2O3 and stibnite Sb2S3. Arsenic and antimony in surface waters and groundwater at both localities indicate application of Eh/pH stability diagrams presence of Sb predominantly in Sb4O6 and Sb2O3 forms, it means in form of more toxic Sb3+. The samples from Špania Dolina are in comparison with those from Ľubietová mowed down to more negative Eh values.