Assessment of Ecological Risk of Sediment in Rivers of Eastern Slovakia

The physicochemical processes participating on the heavy metals accumulation in sediment are precipitation, adsorption, chelation, etc. Besides the natural processes, metals may enter into the aquatic system due to anthropogenic factors such as mining operation, disposal of industrial wastes and applications of biocides for pest. The concentration of metals in sediments depends not only on anthropogenic and lithogenic sources but also upon textural characteristics, organic matter contents, mineralogical composition and depositional environment of the sediment. In recent years, numerous sediment heavy metal contamination assessment methods have been developed, including the index method, the dynamic method, the synthesis methods in chemistry, ecology and toxicology, etc. The aim of this study is to assess the sediment quality in the 22 sampling sites in east of Slovakia using potential ecological risk index for four kind of heavy metals concentrations in the samples taken from different locations of this interest area. The potential ecological risk indices in the following order Cu > Cr > Pb > Zn were found. The results of ecological risk index was from 25.75 to 3798.25, whereas the highest values calculated around areas of mining activities demonstrated extremely strong risk of ecological damage. The potential ecological harms decrease with increasing distance from mining activities.