Pre-monitoring geochemical research of the river sediments in the area of Ada Tepe gold mining site (Eastern Rhodopes)

Abstract

The article depicts the geochemical properties of the landscapes in the Ada Tepe gold mine area before its launching. The research is conducted by examining the heavy metals (Cu, Pb, Zn, Co, Cr, Mn and Ni) content in samples of river sediments in the local landscapes. The research aims to analyse the concentration of heavy metals before the launch of gold mining. The study implements the coefficient of Clarke concentration. The deviation from the background concentrations is a ratio between the element concentration in the collected environmental samples and the Clarke value of the element. The coefficient has a scale from 0 to a particular positive value, corresponding to the level of enrichment of the sample in comparison to the background Clarke value. The values corresponding to the Clarke concentration are equal to 1, the lower values are between 0 and 1 (dispersion) and any value higher than 1 is a case of concentration (enrichment). The obtained results display the researched territory as a natural background area. The content of heavy metals in the river sediments of the researched area (mg/kg, median value) by chemical elements is Cu (15), Zn (72), Pb (17), Mn (461), Ni (35), Co (8) and Cr (60). That is the reason it could be defined as not impacted by human activities and it is not influenced by natural geochemical anomalies. Heavy metals do not pollute the researched landscapes before mining. This outcome is obtained by the geochemical content of the investigated heavy metals in the river sediments.