Comprehensive environmental monitoring and assessment of protected wetland and lake water quality in Croatia and Serbia.

The irresponsible and uncontrolled use of water bodies for long period of time leads to pollution and water quality degradation, particularly in sensitive protected terrestrial and aquatic areas as lakes and wetlands situated in the vicinity of human habitations. Vulnerable ecosystems, the Lake Zobnatica, Serbia and the Wetlands of Tompojevci, Croatia, are characterized as protected natural areas and are surrounded by agricultural land and developed anthropogenic activities. In the samples of surface, ground water and agricultural runoff the key physicochemical parameters were determined. The results of analysed water characterized the Lake water quality class as IV-V. The measured parameters for the Lake show the high values of nutrients, particularly in ground water and agricultural runoff, pH value higher than 8.5 and lower values of dissolved oxygen (DO) than 5 mg/L in the most of the examined water samples. According to the results and maximal allowable values Wetlands belong to the class V water quality, with high trophic state and poor eco-status according to Croatian and Serbian national Laws and By-Laws. The pH value higher than 8.5 of ground water in Wetlands of Tompojevci signifies alkaline groundwater. The maximum concentrations of orthophosphates in ground water and agricultural runoff (10.875 and 10.886 mg/L, respectively) imply the high level of agricultural pollution. Research study of water samples has been performed from 2017 to 2019 within the Interreg IPA CBC Croatia-Serbia Project AF_HR-RS135_SeNs_Wetlands. This type of parallel and comparative research in Serbia and Croatia was conducted for the first time.