Jacek Kubiak

Oxygen conditions and trophic state of Lake Głębokie (Szczecin, Poland) in the years 2008-2010

Oxygen conditions and trophic state of Lake Głębokie (Szczecin, Poland) in the years 2008-2010 The research in Lake Głębokie was conducted in the years 2008-2010. Sampling from three selected sites was designed in such a way that vertical profiles of the characteristics of interest were obtained. Measurements were performed to determine the content of dissolved oxygen, oxygen saturation expressed as a percentage, water temperature, total phosphorus, chlorophyll a, dry seston mass, and Secchi disk depth. During the course of a year, water temperature varied from 0.58°C to 24.72°C. However, a permanent thermal stratification was not observed in the summer season due to complete water mixing. Dissolved oxygen concentrations in the water varied within a range that started at hard-to-measure insignificant values and reached up to 9.63 mg O2 l-1, while oxygen saturation reached a maximum of 116% O2. At the same time, it was observed that oxygen conditions gradually worsened as the depth became greater. The largest oxygen deficits occurred in the winter season of 2009-2010. The oxygen conditions were typical for an eutrophic lake. Its high trophic state was confirmed by an analysis performed using the method proposed by Carlson (1977) as well as by an analysis performed according to the directives of the OECD (1982). The trophic state of this lake is borderline eutrophic and hypertrophic. The oxygen conditions found in this lake ought to be seen as not beneficial to fish.

Macroelements in the surface microlayer of water of urban ponds

Abstract Analyses were conducted concerning the accumulation of four metals representing the group of macroelements, i.e. sodium, potassium, calcium and magnesium in two ponds located in the city of Słupsk. Water samples for chemical analyses were collected from the surface microlayer using a Garrett net. At the same time subsurface water samples were collected. Concentrations of metals were determined using a mass spectrometer. Generally, amounts of sodium, potassium, calcium and magnesium were similar in surface microlayer and subsurface water. Only in the case of potassium and calcium was low enrichment observed in the surface microlayer in one pond, while the greatest extent for magnesium enrichment was observed in the spring period.

Anthropogenic pressure on the largest lakes of the River Tywa catchment

Abstract The largest lakes of the River Tywa basin i.e. Strzeszowskie, Dołgie, Swobnica and Dłużec (north-west Poland, West Pomeranian Lakeland) were studied in the period 2008–2013, usually in a six week cycle. The aim of the study was to determine the degree of anthropogenic pressure on the lakes. Anthropogenic pressure was assessed against the natural vulnerability of lakes to degradation and the actual rate of eutrophication, with particular consideration of the catchment areas. Catchments of the studied lakes were classified as III class – catchment with moderate possibility of matter supply to lakes. Lakes Swobnica and Dłużec are characterised by low resistance to degradation. Lake Strzeszowskie is categorised as having moderate resistance and Lake Dołgie is non-resistant to degradation and highly susceptible to external pressure. The rate of eutrophication of lakes Strzeszowskie and Dłużec was found to be moderate, whereas lakes Dołgie and Swobnica show a high rate of eutrophication. The analysis of nutrient loading reaching the waters of the aforementioned lakes shows that the main area source is arable land, and the fundamental point source is the inflow of river waters to each of the analysed reservoirs. Nutrient loading supplied by the river is several times higher than area load. Such conditions require protective action to be taken within the catchment area and particularly, intensive implementation of good agricultural practice. In the studied lakes, there is a significant predominance of incoming nutrient loadings over dangerous and admissible loads.

LOADING THE WATERS OF THE RIVER GWDA WITH BIOGENIC SUBSTANCES WITHIN THE ADMINISTRATIVE BOUNDARIES OF THE TOWN OF PIŁA (NORTH-WEST POLAND)

The results of hydrochemical tests of the Gwdy river in the area of the town of Piła are presented in this study. The catchment area of the Gwda river comprises the area of 4942.8 km2. The surface of catchment area is covered with forest in 43.1%, arable land constitutes 36.5%, and grassland 7.2%. The Gwda river is a right-bank tributary of the Noteć River of IV order. Water samplings were collected in 2009 from three measurement and control points located between 13 and 24 kilometre of the course of the river. During the tests thermal and oxygen conditions were marked and biogenic substances (nitrate acid, ammonia nitrogen, nitrite nitrogen, total nitrogen, total phosphorus and mineral phosphorus). Concentrations of most of the indicators examined qualified the waters of Gwda to the waters of good quality. The indicator whose concentrations exceeded the limit values for the waters of quality was general phosphorus.

CONCENTRATION OF URANIUM IN WATERS OF THE BIGGEST LAKES OF THE TYWA RIVER DRAINAGE BASIN

The paper presents the results of research of uranium concentrations in its different kinds – suspended and dissolved – in waters of the largest lakes located in the catchment area of the River Tywa – Strzeszowskie Lake, Dluzyna Lake, Dlugie Lake and Dluzec Lake. Small (or the order of several 0,01 µg/l) variations in concentration of uranium in different lakes were noted. The study has also shown a seasonal variation – in a similar range – in concentrations of the above species of uranium, as well as total uranium. The content of dissolved uranium was highest in the autumn and winter, lower in the spring and summer. Overall, total uranium was found in greatest concentrations during the fall, in other seasons concentrations were lower and similar to each other. Suspended uranium was found in largest concentrations in autumn and summer, in lower ones in spring and winter. Concentrations of the different species of uranium during the study period showed a small variation – variation coefficient below 10% for total uranium and dissolved uranium, and about 25% for suspended uranium. The observed concentrations of uranium were typical of uncontaminated unpolluted water.

Water thermal regimes in selected antropogenic resorvoirs in Western Pomerania

Lake Szmaragdowe and Czarnogłowy Reservoir are both characterized by atypical origin as both were formed when quarries were flooded. The geological substrates of the two basins are unique, and they are both highly valued as recreational and tourist destinations. These two basins are among the most interesting in northwestern Poland. Studies of their thermal regimes confirmed that water mass mixing in Lake Szmaragdowe is bradymictic. The waters in the Czarnogłowy Reservoir mix entirely to a depth of 20 m, and this layer is also characterized by bradymixia. Deeper waters do not mix. This indicates that mixing in this basin is of the meromictic type.

Evaluation of trophic level of the largest dimictic lakes of western Pomerania based on the Carlson criteria

Abstract : Between the years 1970-2010, using the Carlson model criteria, the rate of eutrophication and trophic level of the largest dimictic lakes of Western Pomerania were studied. It was found that during the testing period, Lake Ińsko Duże was a mesotrophic reservoir, and Lakes Wądół, Będzin and Ińsko Małe were characterized by a highly advanced eutrophy. Lakes Woświn, Morzycko, Krzemień, Chłop Duży and Jelenin had borderline characteristics between being mesotrophic and eutrophic, while Lakes Narost, Chłop Mały and Wisala were typically eutrophic reservoirs. During the study, changes in the trophic level of Lakes Ińsko Duże and Morzycko and Woświn were noted. The first of the reservoirs listed had the best water quality in the second half of the 1990s, during which time the other two lakes had the worst water quality, taking into account the whole study period. Such changes were not observed in the other reservoirs examined.