Spatial variability and ecological risk assessment of heavy metals in surface sediments of the Unete River in the department of Casanare (Colombia)

Abstract

Surface sediment samples obtained from 46 sites of the Unete River in Casanare (Colombia) were analyzed to evaluate the concentrations of the heavy metals As, Cu, Ni, Pb and Zn as well as to determine their geographic spatial distribution and potential ecological risk. The measured concentrations were compared with the background values (BV), threshold effect concentration (TEC) and probable effect concentration (PEC) from consensus-based Sediment quality criteria guidelines (SQGs) for heavy metals in freshwater ecosystems in order to determine the level of concern of the contaminant concentrations. Based on these results and on the indices of determined potential ecological risk, As and Pb were shown to be the heavy metal contaminants of most concern in surface sediments. The possible sources causing the concerning concentrations were then discussed.