Origination and assessment of metal pollution in Qarechay River bed sediments.

In the present investigation, bulk and chemical partitioning of elements (Cu, Mn, Ni, Zn, Fe, Ca) together with organic matter as a loss in ignition in the Qarechay River bed sediments have been studied. The concentration of metals in Qarechay River bed sediments is governed by the geological units of the study area. The study of anthropogenic portion shows that a small proportion of elemental concentration belongs to this phase. However, Mn has a large portion of anthropogenic sources (43 %). Also, Mn has a share of 13.6 % in sulfide fractions. This result indicates that Mn is a highly mobile element and can easily enter the water column. The presence of Mn in sulfide fraction might be indicative of initial stages of conversion of oxidation state into reduction in Qarechay River. Share of metals in anthropogenic portion is in the following order: Mn (43 %) > Cu (19 %) > Zn (10 %) > Ni (3 %) > Fe (0 %). Organic metallic bonds are not significantly present in the study area. Geochemical index (I geo), pollution index (I poll), enrichment factor (EF), and pollution load index (PLI) values are indicative of a clean environment throughout the river course. These values are in well agreement with results of chemical partitioning data. Eventually, based on the results of chemical partitioning, regional standard of elements for Qarechay River bed sediments has been established.