Limnol. Rev., Volume 10, Issue 1 (March 2010) – 6 articles , Pages 3-56

The results of the monthly examinations of Lake Chełmżyńskie carried out during the vegetation periods in the years 2007–2009 made it possible to define seasonal variability in the concentrations of phosphorus compounds. The examinations showed that the bottom deposits constitute a considerable source of phosphates. The release of phosphates from the deposits began as early as in mid May and with the occurrence of anoxic conditions. A particularly high concentration of phosphates in the near-bottom layer was recorded in the southeast pool of the lake (max. 0.658 mg P l⁻¹). The central part of the lake showed a lower concentration of phosphates near the bottom, yet due to the partial thermal stratification of its waters, it was the main place for the transport of the bio-element to the euphotic zone. The intense transport of phosphates occurred mainly during the short periods of strong winds. The analysis of the meteorological data obtained from the Integrated Natural Environment Monitoring—Station Koniczynka prove that winds, whose mean daily velocity values exceeded 8.0 m s⁻¹, brought about particularly intense and deep water mixing. A very significant increase in the concentration of phosphorus compounds in the epilimnion was recorded in the years 2007 and 2008, and it resulted in the violent development of phytoplankton. The results of the examinations conducted in the years 2007–2009 showed that Lake Chełmżyńskie was classified as a strongly eutrophic lake. The ecological condition of the lake was defined as poor according to the Water Framework Directive. Reclamation works including the inactivation of phosphates in the bottom deposits are indispensable in order to improve the ecological and trophic state of the lake. Full article

This paper presents research on evaporation from the lake surface within the reed bed zone. The main focus of the research was the process of evaporation of water adhered to reed culms in different weather conditions. The process of transpiration, i.e. evaporation of water from plants due to their physiological processes was ignored. To avoid any ambiguity and to stress the different nature of both processes, the studied phenomenon is referred to as “mechanical evaporation”. The analysis was based on measurements taken on Powidzkie Lake. The results showed that “mechanical evaporation” from reed culms above the water level can considerably increase evaporation rate of an aquifer. The values of total evaporation within the reed bed zone were estimated. These were compared to the values of evaporation from the open lake surface. The rate difference was at the level of 10–30%. Furthermore, the study showed that the value of “mechanical evaporation” varied depending on the reed species, wind speed and direction, wave height, and width of lakeshore with vegetation. Seasonal variations of the lake's water surface were of slightly lesser importance. Full article

The aim of the study was to evaluate the effect of shallow lakes on reactive, total phosphorus and potassium concentrations in the river water and analyse the effect of changes in water retention in lake on nutrient concentrations in river waters. The study was carried out in the Samica Steszewska River. This is lowland river, which flows through two polymictic lakes. The study site is located in the Wielkopolska Lowland, Central-west Poland. Water samples were collected at depths of 0.5 m below the water surface. Reactive, total phosphorus and potassium were analysed monthly by standard methods. The study was carried out from January to December 1999–2002 (period with high water retention), 2005–2008 (period with low water retention), at four control points. Sites were located at the inflow and outflow of the Samica Stęszewska River into and out of Niepruszewskie and Tomickie Lakes. From 1974 to 2002, Lake Niepruszewskie was regulated at its outlet by a weir. In 2002, the water level was reduced. Changes of water retention in Niepruszewskie Lake influenced water discharge of the Samica Stęszewska River. The results indicate that changes in water retention have significantly influenced water quality in the river, particularly total and reactive phosphorus concentrations; however, this influence was not observed in respect to potassium concentrations. Nutrient concentrations in river strongly depend on water quality of the lake ecosystem and their buffering capacity. Additionally, by improving water quality, increased oxygen concentrations, and decreasing dissolved nutrient concentrations, as well as increased amplitude of water level fluctuations in lakes may increase P-fixation rates in outlet streams. Full article

Reconstruction of development of Lakes Rakutowskie and Żłoby in the late Pleistocene and Holocene was the aim of this research. Analysis of content of calcium carbonate, organic matter and C14 datings (7 samples) were done for two cores of sediments of 750 cm long. An average rate of accumulation was counted. Sediments of Lake Rakutowskie show homogeneity along the core which indicates similarity of sedimentation conditions. Sediments of Lake Żłoby were diversified and show variety related to cyclic changes. A common feature is a thick layer of fine sand without carbonate deposited during the older dryas, shown in both cores. The difference in sediment features of both lakes (which have similar depths) indicates that the Lake Żłoby is the more dynamic, filtering element, preceding Lake Rakutowskie in system of water catchment. Full article

The results of emission measurements of carbon dioxide and methane from the surfaces of three man-made lakes in southeastern Poland (two little dam reservoirs—in Rzeszów and Wilcza Wola, and the biggest Polish reservoir situated in Solina) are presented in this paper. The experiments were conducted in summer and autumn of 2009. The gas fluxes on the water—atmosphere interface were measured in the littoral area by so called “static chamber” method. Carbon dioxide and methane concentrations in collected gas samples were measured using a Pye Unicam gas chromatograph (model PU-4410/19) equipped with a methanizer to detect low levels of CO₂ concentrations. The fluxes of determined gases ranged from −24.98 to 162.51 mmol m⁻² d⁻¹ for carbon dioxide and from 0 to 235.60 mmol m⁻² d⁻¹ for methane. The highest values of flux for both CH₄ and CO₂ were observed for Rzeszów Reservoir, the lowest ones—for Solina Reservoir. In some studied cases emission of CO₂ and CH₄ was as much high as in tropical reservoirs. Full article

The morphometric features of 10 small (0.1–2.9 ha) and shallow (4–16 m) peatland lakes, located in basins filled with peat, were examined. The elongation of such lakes and the development coefficient of their shorelines are very low. The mean depth is close to the maximum value (7.0 ± 4.8 and 7.8 ± 3.9 m, respectively), as the lake bottom is normally flat and the basin walls are often vertical. In terms of morphometric features, the peatland lakes were divided into large (1.92 ± 1.12 ha) and small (0.33 ± 0.33 ha). The former are surrounded by a relatively narrow belt of peatlands and characterized by low values of Ohle coefficient and Schindler factor (1.81 ± 2.04 and 0.32 ± 0.13), which makes them very susceptible to the effect of peatlands. The smallest lakes are located in the central part of big peatlands. Their values of Ohle coefficient and Schindler factor are five times higher, whereas their volume is ten times less (13,750 m³ as compared to 125,000 m³; p < 0.001). The bottom slope angle is considerable. In peatland lakes, there is little space that could be occupied by vegetation. In deep moraine-dammed lakes plants occur only on vertical walls, whereas in shallow water bodies, plants also thrive on the bottom. Full article