Zooplankton can be used as a reliable bioindicator of the physical and chemical conditions in the aquatic environment. An analysis of the structure of the zooplankton community in Lake Długie was based on the material collected in the years 2001–2003 (after restoration using PAX) and in 2007 (control year). It was found that the number of zooplankton species, their abundance and biomass varied greatly and depended on lake trophy and abiotic environmental factors. The cutoff of sewage inflow and the restoration of the lake resulted in gradual changes in the structure of the zooplankton community, consisting in an increase in species diversity and a marked decrease in the number and abundance of the indicator species of high trophy levels. As shown by the values of zooplankton-based indices, the waters of Lake Długie before restoration were eutrophic with some features of polytrophy, while after restoration they were mesoeutrophic/mesotrophic.

Studies carried out in the hydrological year 2006 aimed at investigating the impact that a storage reservoir, built on a watercourse flowing into a lake, makes on the phosphorus inflow from an agricultural catchment to the lake. Hydrological measurements were made once a week on the watercourse, and water samples for laboratory analyses were collected at two-month intervals at the sites of flow measurement. It was found that the mean concentrations of total phosphorus in the outflow from the catchment depended on the pattern and intensity of land use, and were higher in a drained agricultural catchment than in an afforested catchment. The total phosphorus concentrations were lower in the growing period than outside of this season. The phosphorus load carried away from the unit area of catchment depended on the land use pattern, being higher in the drained agricultural catchment 0.18 kg P· ha^–1 · year^–1) and lower in the afforested catchment (0.12 kg P· ha^–1 · year^–1). The load of phosphorus delivered from the catchment per unit area of the reservoir surface (0.5 g · m^–2) is almost 4 times heavier than the maximum allowable value, which results in accelerated eutrophication and accumulation processes. The reservoir forms a barrier that traps the phosphorus compounds running off from the catchment. The amount of P_tot accumulated during the year 2006 in the reservoir basin was 21.5 kg (i.e. 0.86 kg P_tot · ha^–1), with most of it being retained in the growing period.

Cyanobacterial blooms produce various highly toxic substances (hepatotoxins, neurotoxins, endotoxins, etc.) whose mutagenicity and cancerogenicity is well known, therefore it is necessary to determine the factors that affect the yield of cyanobacterial blooming and the effectivity of the biosynthesis of toxins as well as to understand the mechanisms whereby they are released. Continuing earlier studies in the area of the Sulejów Reservoir, further research was carried out in the season 2002 into the effects of various environmental factors on the bloom yields of cyanobacteria and the synthesis of cyanobacterial hepatotoxins – microcystins. The first part of the paper focuses on physicochemical factors such as water temperature, pH and hardness, and the concentrations of dissolved oxygen and soluble and total organic carbon. It was confirmed that water temperature in the season belongs to the more important factors influencing bloom yields and microcystin production. Oxygen concentration in water is negatively correlated with bloom yields and the amount of synthesised toxins. Total and soluble organic carbon contents are positively correlated with bloom yields and the amount of microcystin-LR in the cells of cyanobacterial colonies.

Continuing earlier studies in the area of the Sulejów Reservoir, further research was carried out in the season 2002 into the effects of various environmental factors on the bloom yields of cyanobacteria and the synthesis of cyanobacterial hepatotoxins – microcystins. The second part of the paper looks at chemical factors such as the concentrations of biogenic substances and chosen metals (Ca, Mg, Zn, Cu, Ni, Co, Mn, Cr, Cd and Pb) in water. The levels of microcystin-LR in the cells of cyanobacteria were negatively correlated only with the concentration of nitrates(V), total nitrogen and dissolved organic nitrogen. The ratio of total nitrogen to total phosphorus did not show any effect on cyanobacterial bloom yields or the efficiency of microcystin production. No effect was also found for the metals, probably because of their quite low concentrations in water in the season 2002.

The paper describes the most common methods used for reclaiming water reservoirs. It reviews the most important publications from recent years, outlines the historical background to the problem in question, and provides some examples of the practical applications of each method. The reclamation methods were characterised in detail, taking into account general assumptions, usability, efficiency and cost. Reclamation should be considered as the last resort and employed in cases when earlier protective activities within a catchment have not produced the desired effect. For some strongly eutrophic reservoirs, however, such a measure is necessary in order to achieve improvement in water quality. Reclamation activities should always be preceded by a thorough, interdisciplinary examination of the catchment and the reservoir itself.

The studies on the chemical composition of particulate matter PM10 constituted a part of the research project carried out at the Department of Meteorology and Climatology of the WULS in Warsaw. Particulate matter samples for analysis were collected at the MzWarszSGGW air quality monitoring station where PM10 concentration was also measured (the mean daily concentrations were considered in this study). From those, 34 samples were randomly selected for qualitative analysis. The levels of chosen elements were determined at the Warsaw Institute for Environmental Protection, by employing microwave solution in HNO3 + HCLO4 and PN-ICP-AES(A) measurements. The data on the mean daily concentrations of heavy metals in PM10 (measurements PN-ICP-AES(A) and (AAS), obtained at the station MzWarszBernWoda and provided by WIOŚ in Warsaw, were used for comparison. The values of heavy metal concentration in the Warsaw conurbation were referred to the target values specified in the Directive 2004/107/EC. It was found that the concentrations of arsenic, cadmium and nickel in the PM10 fraction at the stations MzWarszBernWoda and MzWarszSGGW in the years 2005 and 2006 remained at a low level and did not exceed the target values. For the MzWarszSGGW station, the mean concentrations of these elements ranged from 16 to 22.6% of the allowable limit, however, the maximum daily concentrations of arsenic and cadmium accounted for 120.1 and 126%, respectively, of the yearly limit proposed in the Directive.