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The influence of various types of agricultural activities on the dynamics of biogenic compounds of flowing water was broadly recognized in many spatial and temporal scales. However, relatively minor attention was paid to the hydrochemical functioning of horticultural catchments despite their importance and dominance in some regions of Europe. Thus, the current study investigated spatial and seasonal variations in inorganic nitrogen and phosphorous compounds in stream water in the Mogielanka River catchment, with 72% covered by apple orchards. Water samples were collected from fifteen sites distributed across the catchment in the monthly timescale from March 2020 to February 2021. Concentrations of NO3−, NO2−, NH4+, and PO43− were determined photometrically, while in situ water temperature, oxygen saturation, electrical conductivity, and pH, were measured with the use of portable devices. The impact of horticulture was mainly documented in the higher concentration of NO3− during the winter months; however, maximum values did not exceed 15 mg·dm−3 and were relatively low in comparison to catchments dominated by arable lands. The authors also found a clear impact of unstratified reservoirs and inflows from wastewater treatment plants on the dynamics of biogenic compounds. The correlations of PO43− with the sums of precipitation suggested, in turn, that increased PO43− concentration mainly results from poor sewage management. The results provided preliminary but unique and spatially extensive insight into the functioning of an orchard-dominated lowland catchment and allowed the researchers to point out the main recommendations for improving water quality in similar regions.

Pollen and nectar produced by flowers of species from the genus Salix are an im-

The search for the best landscape predictors explaining the spatial variability of stream water chemistry is one of the most important and recent research issues. Thus, in the current study, relationships between land cover indices and selected water quality parameters were evaluated regarding the example of 54 lowland temperate streams located in central Poland. From November 2021 to March 2022, water samples were collected in the monthly timescale, and the concentrations of NH4+, NO3−, and NO2−, as well as electrical conductivity, were correlated with the percentage of land cover types calculated for total catchment area, buffer zones, cut buffer zones, and radius. For such computing, Corine Land Cover 2018 and Sentinel 2 Global Land Cover datasets were used. In the case of both datasets, results indicate significant dependence of NO3−, and NO2− concentrations, as well as EC values on cover metrics. Overall, agricultural lands favored higher concentrations of NO3− and NO2−, whereas mainly coniferous forests reduced nitrogen pollution. Significant correlations were not documented in the case of NH4+ ions, the concentrations of which could be linked to point sources from municipal activity. Correlation performance was slightly better in the case of the S2GLC dataset, while the best spatial scales were generally seen for wider buffer zones (250 and 500 m) and total catchment area. The study provided spatially extensive insight into the impact of land cover predictors at different scales on nitrogen compounds in a lowland landscape.