The agricultural catchment of the Zagożdżonka river is situated in the Mazowiecka Lowland, one of Poland’s regions with the highest frequency of droughts. The records on discharge at the Plachty Stare gauging station on the Zagożdżonka river from the years 1963–2007 were investigated and the parameters of streamfl ow droughts were determined. To identify low-fl ow periods in daily discharge hydrograms, truncation levels SNQ (mean value of the minimum annual outfl ow) and Q90% (discharge determined from the fl ow duration curve) were used. The streamfl ow drought of 1964 was found to be the longest and most severe in the study period. The whole 45-year period had no winter droughts. In the recent years, streamfl ow droughts in the Zagożdżonka river have occurred with a frequency of almost one per year, but their extent and intensity have been smaller than those observed previously.

The study assessed the quality and usability of water in the Bąbola stream that drains a 3.25 km2 catchment situated in the Beskid Makowski Mts. (southern Poland). A water storage reservoir is to be built on the stream as part of the Small Retention Programme for the Malopolska Region. Field research was conducted on 24 randomly selected dates in 2007 and 2008, and included measurements of temperature, pH, dissolved oxygen concentration, and water electrolytic conductivity. Total suspended solids, dissolved solids, biogenic compounds (NH4⁺, NO^– 2, NO^– 3, PO³4 ^–), minerals (SO²4 ^–, Cl^–, Mn²⁺, Mg²⁺, Ca²⁺), BZT5, ChZTMn,) BOD₅, COD_Mn, and metals ( Fe^2+/3+, Mn) were determined in the laboratory. Heavy metals (Cr, Zn, Cd, Cu, Ni, Pb) assay, and coliform and fecal coliform counts were done once a quarter. The water of the stream showed a very good quality (I class). After physical and chemical processing it would be fit for consumption. It is also suitable for recreational purposes (bathing, swimming) and for fish culture. The low concentrations of biogenic components in the stream water suggest that the projected reservoir will not be threatened with eutrophication.

Storage reservoirs play various roles in the circulation of biogenic substances in river and reservoir systems. Research into the infl uence of rubble (bottom deposits) was done in 2004 and covered the Pokrzywnica reservoir (max. area 154 ha, max. capacity 4.35 M m³) in the Pokrzywnica river catchment in the Wielkopolska Lowland. The scope of the research included determination of the physicochemical composition and the oxygen indexes of water above the bottom and on the surface; preparation of a bathymetric plan; determination of the granulometric composition of rubble, the chemical composition and ChZT-Cr of bottom deposits, the mean concentrations (oxygen indexes) of chemical components of infl owing and outfl owing waters, and the accumulation of total phosphorous and nitrogen in the reservoir. It was found that the considerable adsorption of clay minerals (particularly colloidal clay), delivered to the reservoir together with the suspended sediment load (varicoloured clays, so-called Poznań-type clays), and of humus substances (colloidal humus) delivered especially in the case of a fl ood wave, reduces the concentrations of biogenic substances in waters while increasing their contents in bottom deposits (sedimentation). For shallow reservoirs, biogenic substances accumulated in bottom deposits constitute a source of secondary pollution of the reservoir’s water (“internal” supply). The values of oxygen indexes and concentrations of biogenic compounds (and less frequently total nitrogen and Kjeldahl nitrogen) in the Pokrzywnica reservoir are higher above the bottom than in the surface water.

The research carried out in the Niepołomicka Forest near Kraków (southern Poland) on a pleistocene terrace of the Wisła river assessed the impact made by a mass grave on the concentration of chemical components in its vicinity. The soil in this area is temporarily moist sand with an admixture of clayey minerals in the upper part of the soil profi le. The concentrations of chemical components in the soil, common hair moss, pine-tree resin, bracket fungus, and air in the area of the mass grave were compared with those determined at 10 sites in southern Poland having similar natural conditions. As follows from the research, a mass grave has a signifi cant impact on its environment: relatively high amounts of the elements derived from human corpses, such as P, S, N, C, Cl, Na and Ca, were found in the vicinity of the grave in the Niepołomicka Forest. An elevated concentration of P in the soil and air was especially characteristic of this area. The bracket fungus showed relatively higher concentrations of heavy metals.