The aim of the statistical analyses carried out was to identify similarities and to point out differences between the various tributaries of the Narew River, to identify the factors and processes responsible for the transformations occurring in the aquatic environment and finally, to identify the main sources of pollution in the river catchment. For the purposes of statistical analysis, the results of studies conducted as part of diagnostic monitoring by the General Inspectorate for Environmental Protection in 2017–2018 were used. The studies included 8 measurement points located directly on the Narew River and 17 points located on its selected left and right tributaries. Analysis of the collected results indicates that the chemical condition of the water in the Narew catchment is assessed as being poor. This observation may be due to the fact that the Narew catchment is mainly used for agricultural purposes and, in addition, there is a relatively large number of potential anthropogenic sources. As part of the analysis, two potential sources of pollution affecting water quality in the Narew catchment were identified, which include surface run-off and treated wastewater inflow.

The objective of this work is to demonstrate for the first time the results of hydrogeochmical studies carried out in the Steinvik River catchment, in order to provide detailed information regarding the chemical composition of groundwater in the Hornsund region, SW Spitsbergen. The water chemistry in the non-glaciated Steinvik River catchment is largely controlled by hydrological processes related to thaw of the near surface permafrost. Groundwater runoff is generated from the fast flow through well-permeable active layer. Recharge from melting snow, permafrost and rain, together with short residence time of groundwater, favors the forming of low-mineralized water, reaching 41 and 50 μS/cm for surface and groundwater, respectively, with the dominance of HCO3−, Cl−, Mg2+, Ca2+ and Na+ ions. In some water samples, increased concentrations of aluminum (up to 268 μg/L ) were found. The highest concentrations of phosphate, nitrite and ammonium in water seem to be related to the presence of bird colonies. Groundwater of active layer in the studied catchment belongs to young meteoric water with the age limited to one summer season.

The intensification of agricultural production is one of the factors determining economic development. Increasing mechanisation and use of fertilisers in agriculture lead to higher yields, but at the same time they can pose a threat to the environment. The overuse of chemical fertilisers contributes to increased concentration of nutrients in agricultural runoff. One of such areas is the Szreniawa River catchment, the study area located in the southern part of Poland. In this catchment, intensive mostly mechanical ploughing is applied in, for instance, vegetable production. The area has loess soils, which with intensive ploughing are susceptible to erosion. The study aims to determine changes in the quality of flowing waters against the background of agricultural production and land-use characteristics. Surface waters were classified as class II and occurred at all analysed points. The highest concentrations of N-NO3, N-NH4 and P-PO4 were found at a point in the middle of the catchment (lower part of research area). There, the lowest concentrations were recorded in 2018, which was related to the amount of precipitation during the growing season. On the other hand, the volume of plant and animal production closely correlated with the quality of surface water in the area. This was also confirmed by the land use structure. In conclusion, intensive agricultural production, mainly in terms of plough tillage causes significant hazards associated with soil erosion especially on agriculturally sensitive soils, although it provides good yields.