Natural Background Concentrations Determination for Metals in Surface Waters, Gediz River Basin

In this study, an approach was developed for natural background concentration determination of metals and metalloids (Ag, Al, As, B, Co, Cr, Cu, Fe, Sb, Sn, V, Zn, Ti, Cd, Ni, Pb and Hg) listed in By-law on Surface Water Quality (OG: 30.11.2012/28483) as priority substances or specific pollutants. Gediz River Basin was selected as a pilot area and seasonal monitoring studies were conducted in the selected surface waters during 2015-2016. For determination of NBC, it is necessary to distinguish whether the presence of metals detected in the receiving environment is natural or anthropogenic. In this context, anthropogenic sources were monitored and evaluated according to the pollution contribution of each pressure; natural sources of investigated metals were considered according to mining activities and geothermal source distribution. A methodology was developed and applied by indicating the relative contribution of pollutant resources and whether critic value was exceeded or not. Pollution contribution was calculated representing the relative effect of anthropogenic sources. This approach was found suitable for determining NBC and could be helpful for decision makers by establishing critical factors (e.g. which facility should be established where; which plant can discharge its pollutant in which amount; what kind of precautions should be taken in agricultural activities; as well as how to reduce the pesticides used) while comparing the effect of pollution sources.