**Heavy metals**

Contrary to presented results for the river water bodies (Fig. 13), the concentrations of heavy metals detected in the waters of selected Prespa Lake sampling sites (Fig.25) point to *copper, iron* and *zinc* as dominant metals. For *copper* the detected values were almost entirely in III-IV category, but the increased presence of the other two metals in detected concentrations also confirms the prolonged input.

There is also a marked presence of the toxic *mercury* and *arsenic* in Prespa Lake waters. Their increased detected concentrations in July 2010 clearly support the argument for intensified human activities in the spring period; *mercury* appears at the L2 sampling site as a result of the Golema River influence and is detected almost in all samples with concentrations high above the V water quality class. Its presence is striking on L5 (v.Dolno Dupeni) with almost eight times increased concentration compared to the 1 mg\*L-1 level for V quality class. *Arsenic* is also present in all sampled waters of Prespa Lake, but in much lower concentrations than *mercury*. It rose to III-IV water quality range only in L4 (v.Nakolec – mouth waters of river Brajčinska) in July 2010. Nevertheless, its accumulation and persistence in Prespa Lake waters is evident.

Fig. 25. Detected concentrations of heavy metals in the water of selected sampling sites of Prespa Lake.
