Limnol. Rev., Volume 18, Issue 3 (September 2018) – 4 articles , Pages 93-126

In the vegetation seasons 2016–2017, a survey of 30 pit lakes localized in the eastern part of the Muskau Arch (Western Poland) was carried out. The aim of the study was to characterize the habitat conditions of the selected lakes, based on the physico-chemical water characteristics. We hypothesized that the age and genesis of pit lakes are the main factors responsible for their hydro-chemical diversity. Therefore, in each of the lakes 27 physico-chemical parameters and chlorophyll a were measured in the water surface, in the peak of the vegetation season (July–August). Additionally, they were described in terms of genesis, origin and age. The results showed that the investigated lakes display a high diversity of habitat conditions reflected in varied physico-chemical water properties (significant lake-to-lake differences). The parameters mostly responsible for the differences were: Secchi depth (transparency), pH, EC, colour, hardness, TP, TN, TC, Ca²⁺, Mg²⁺, Fe, Al, Mn, S and Chl a. The comparison of the type of excavated aggregate showed significant differences for four parameters only. Much greater differences were found for the genesis of lakes (mining method) – 15 of the 28 analysed parameters significantly differentiated the lakes. Further analysis showed that half of the studied parameters were significantly correlated with the age of the pit lakes. Our results suggest that in addition to natural changes, secondary human-caused transformations (mostly neutralization and fertilization of the water) were among the key factors responsible for the differentiation of the lakes. Full article

The objective of this work is firstly an ecobiological study, which aims to determine whether salinity is favorable for a good reproduction rate of cysts in the Artemia salina L., a species known for its use in aquaculture. Secondly, a short-term test of ammonium sulfate toxicity on its vitality is carried out as its environment is permanently subjected to sulphate-laden waste. The work consists of subjecting the species to different salinities in order to produce a good yield in cysts, which once recovered, hatching and breeding is maintained until individuals reach the adult stage. A toxicological study using toxicity test (CL50) is then conducted to study the resistance of these adults with various concentrations of ammonium sulphate. The results obtained from the ecobiological study show a mean similar to the natural environment (p > 0.05) with a favorable concentration for the reproduction of the species at a salinity of about 75 g dm⁻³. The toxicity test indicates a CL50 equal to 75 mg dm⁻³ after 24 h. It is obvious that Artemia salina L. can be cultivated by controlling its reproduction by varying the salinity rate for its use during different seasons of the year, thus ammonium sulphate from waste is considered as a limiting factor. Full article

This article is an attempt to analyse and compare several selected parameters regarding ice phenomena using the correlation analysis of two lakes, which are benchmark lakes located in the central part of the Kashubian Lakeland. These lakes are: Raduńskie Górne, a larger one (387.2 hm²) and Ostrzyckie, a smaller one covering an area of 308.0 hm². The analysis covered measurement sequences for the period 1971–2010. The material for analysis regarding data on ice phenomena on Lake Raduńskie Górne was obtained from the University of Gdańsk Limnological Station in Borucino while the data for Lake Ostrzyckie was obtained from the Institute of Meteorology and Water Management (IMGW). Relations between the following parameters of the ice regime were analysed: duration of the ice phenomena, duration of the ice cover, average and maximum thickness of the ice cover. The analysis and data comparisons have revealed that there are strong and very strong relations between the analysed parameters, which made it possible to develop proper statistical models. Hence, should there be a lack of data on the ice-cover pattern for one of these lakes it is possible to recreate them using the elaborated empirical models and data for the other. Full article

The dimensions of many water streams, which satisfy proper hydraulic conditions, may not be compatible with the designed dimensions of an irrigation work that needs to be constructed in some locations. The design requirements of such irrigation works may involve a contraction in the channel width in the required location. This contraction, of course, affects different flow properties and the scour hole formed downstream of these structures. Therefore, the present experimental study aims to investigate the effect of the transition angle and the contraction on the flow properties and on the scour phenomenon downstream water structures. Through 460 experimental runs, carried out on 20 experimental models, the study proved that, for an efficient hydraulic performance and economic design, the best transition angle (θ) for the approaches of water structures is 30° with a relative contracted width ratio (r = b/B) not less than 0.6. Full article