## 2 Materials and Methods  
### Characteristics of the Study Area  
The RNP was established in 1974. It is located in Roztocze, which is a geographical region of south-eastern Poland straddling the border between Poland and Ukraine. The area consists of limestone hills that stretch from the Lublin Upland to Podolia. Roztocze is distinguished by its characteristic landscape, which is unique in Europe [20; 21]. It is distinguished from neighbouring areas by its topography, geological structure, hydrological regime and climate. Moreover, the soils and vegetation are also different. Various types of forests make up as much as 95% of the RPN [22]. The RNP occupies an area of 8482.83 ha. Pursuant to the Nature Conservation Act, the main purpose of the park is to protect the region's natural and cultural heritage and to provide a setting for nature education, tourism and scientific research. RNP employees also monitor the natural conditions and processes in the park, as well as the socio-economic phenomena in its buffer zone [23]. The RNP runs the Integrated Monitoring of the Natural Environment (IMNE) programme for the model catchment area of the River Swierszcz. In this area and its vicinity are located the rainwater, surface water and groundwater sampling points from which water was collected for the physicochemical, organoleptic and microbiological tests reported in the present study (Figure 1). The catchment of the River Swierszcz is situated in the central part of the RNP and covers an area of 4651 ha. Forty percent (40%) of the catchment lies within the park. The catchment is a wooded space, with forests of various types occupying 64% of its area. The remaining part of the catchment is mainly covered by arable land, meadows and pastures belonging to the villages of Sochy, Szozdy, Stara Huta and Lasowe. The forest settlement of Florianka is dominated by meadows and pastures, which the park uses for breeding primitive breeds of cattle and sheep, and in particular, the Polish konik horse. In the northern part of the catchment, in the lower section of the River Swierszcz are located Stawy Echo (Echo Ponds) (52 ha), which are fed by the river; a water axis with ponds; and the so-called \"church\" pond. The Swierszcz is an approx. 9 km long mid-forest river. It has its source in swamp forests and raised bogs at an altitude of approx. 250 m above sea level. The estuary to the River Wieprz is located at an altitude of 220 m above sea level [24]. The catchment of the River Swierszcz is part of two subregions: Roztocze Szczebrzeszynskie and Roztocze Tomaszowskie [25]. The catchment is crossed from NE to SW by the valley of the Swierszcz stream and is lined with river and aeolian sands, forming dune ridges and dunes. The eastern and western parts of the catchment are covered with Upper Cretaceous gaizes, marls and opokas [26] (Figure 2). Figure 1: Location of water-sampling points in the Swierszcz river catchment. Own elaboration. The hydrological regime of the catchment of the River Swierszcz is influenced by climatic and terrain conditions. Climatic factors affect the amount of water introduced into the water cycle and the seasonal and annual variability of water supply. Terrain conditions, mainly the geological structure and relief, soil, vegetation and land use, determine surface water and groundwater retention and the amount of surface runoff. Simultaneously, these factors modify the annual and seasonal outflow rhythm resulting from the distribution of precipitation, infiltration and evapotranspiration. According to [PERSON]'s classification [27], the climate of Roztocze, where the RNP is situated, is a Central Uplands climate of the region of the Lublin-Lviv Uplands and Ridges (D4). It is a temperate transitional climate, which has a slightly higher proportion of continental features in relation to other regions of Poland [28]. The RNP is one of the coolest areas of the region, with an average annual air temperature of approx.