Diffuse Pollution and Ecological Risk Assessment in Ludaš Lake Special Nature Reserve and Palić Nature Park (Pannonian Basin)

Diffuse water pollution from agriculture (DWPA) is one of the major factors causing water pollution in Lakes Palić and Ludaš, the two largest shallow lakes of the Pannonian Basin in Serbia. These two lakes are protected under national and international law. On the basis of the number of strictly protected bird species, Ludaš Lake has been classified as a wetland of international importance since 1977 (Ramsar site 3YU002); in 2021, both lakes were nominated as potential Natura 2000 areas. Despite the degree of protection and ecological significance of the area, agricultural land prevails. By a process of land expropriation during 2019, the buffer zone began to expand around the lakes, which should lead to a reduction in pollution. One of the goals of buffer-zone development is to enhance and restore the ecological connectivity of the remaining forest-steppe habitats. During the expropriation process, soil was sampled to record areas with the highest pollution. This paper assesses the environmental risk caused by phosphorus, nitrogen, and the accumulation of heavy metals (Zn, Cu, Pb, Cr, Ni, Mn, Cd, and Hg). For each heavy metal, the corresponding pollution indices (Igeo, PI, EF, Eri, RI, Nemerow) and soil contamination level were calculated. Pollution indices indicate the ecological risk under the influence of heavy metals in the following order: Cd > Cu > Ni > Zn > Pb > Cr > Hg. Results showed that concentrations of Cd exceeded the maximal permissible concentration in all examined soil samples, and high ecological risk areas were determined. High concentrations of nitrogen, phosphorus, and potassium were detected, which could be as a result of intensive agricultural activity. Current conservation measures in this area have not provided adequate protection of the natural environment. Accordingly, existing measures must be controlled or new, more restrictive measures must be prescribed.