Water quality assessment and determination of pollution sources along the Axios/Vardar River, Southeastern Europe

The Axios/Vardar River, an interboundary river located in the Balkan Peninsula, drains the region of southern Serbia, almost 80% of the Former Yugoslav Republic of Macedonia territory and some parts of northern Greece. This study is based upon long-term data (1979–2003) of nitrate, nitrite, ammonium, total phosphorous, BOD5, Cd, Cr, Zn, Pb and water discharge from 22 sampling stations along the Axios/Vardar River collected on a monthly basis. For determination of spatial and temporal trends, average values were determined for the periods 1979–83, 1984–88, 1990–95 and 1996–2003. Moreover, interviews with scientists from 10 institutions have been conducted in order to comprehend the situation that prevails in terms of water management. The quality of the river water is affected by heavy metal pollution from smelter and fertilizer plants in Veles, Ferro-alloys plant in Jegunovce, the disposal of their solid waste near the river bed and also by the untreated industrial wastewater discharge deriving from the industries located in the watershed. The agricultural runoff from cultivated areas of Tetovo, Veles and Koufalia is a significant source of nutrient pollution. The untreated domestic wastewaters discharged directly into Axios/Vardar River constitute point sources of pollution, as well as the illegal landfills contaminating the surface water and groundwater.

The water quality of the Axios/Vardar River is affected by human activities. Significant pollution sources have been determined, resulting from industrial, agricultural and domestic activities. Primary sources of heavy metal pollution in FYROM are the industrial activities; the zinc and lead smelter “Zletovo’’ contributing with (Pb, Zn, Cd) in Veles and Ferro-alloys plant “Jugoxrom” (Cr, Cd) in Jegunovce. The pollution associated with these heavy metals is induced by the discharge in the river of untreated or partially treated industrial wastewater and the disposal of solid waste in illegal landfills located near the river network. In Greece, water pollution is related to the two industrial zones of Axioupoli-Polikastro and Koufalia-Gefira. Industrial influence has significant impact on Vardarovasi stream, which is source of organic pollution because it receives industrial, domestic and agricultural wastewater. Another source that contaminates the river is agricultural runoff. Agricultural activities, the use of fertilizers and pesticides, in the cultivated land fields in FYROM (Polog, Ovce Pole, Gevgelija) and Greece (Axioupoli, Chalastra) increase nutrient concentrations in the river water. Significant amounts of nutrients are supplied by the fertilizer industry in Veles and the region of Policastro-Axioupoli. The untreated domestic wastewater from the municipalities in FYROM (Tetovo, Gostivar, Skopje, Veles, Negotino, D. Kapija and Gevgelija) pollutes the surface river water with nutrients and heavy metals. Significant loads of pollutant are discharged due to the disposal of solid waste in the irregular landfills into the upper part of the Axios/Vardar River catchment. Domestic activities in Greece contribute to the river water pollution with the discharged wastewater of the regions (Axioupoli-Polikastro, Koufalia-Gefira and Chalastra) and the disposed solid waste (municipalities of Chalastra and Malgara) in the illegal dumping site located in the protected area of the Axios River delta. The water discharge of Axios/Vardar River in FYROM and Greece from 1979–83 to 1996 has significantly decreased, but in the period 1996–2003 there is an increasing trend. Therefore, water discharge has tripled since 1996 (47–130 m3/s). The urbanization and the development of the drainage basin of Axios/Vardar River lead to the increased water demands. The construction of dams, in order to meet the increased water demands especially in agriculture, induce the reduction of sediment supply in the delta plain; resulting in the erosion of the delta, degradation of wetlands and salinization of groundwater resources. The Axios/Vardar River is a polluted river presenting high values of heavy metals and nutrients resulting from human activities. The management of the water resources is ineffective and incomplete, with responsibilities in different institutions. The improvement of water quality and ecological status will be achieved with the implementation of the Water Directive 60/2000, and the integrated water resources management. The delay of application of the legal frame aggravates the situation by continually reducing the water quality in the drainage basin of Axios River. Moreover, there is a need for monitoring program that will provide a representative and reliable estimate of the quality of water resources.