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

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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.

Abstract. In areas of urban infrastructure, ponds play an important role. They are places of rest and recreation, and they facilitate contact between city dwellers and the aquatic environment. They are also a place for living waterflow and ichthyofauna. Urban ponds are susceptible to anthropogenic influences, and their self-cleaning capacity is limited due to their small size. The city of Słupsk is located in northern Poland. Coal combustion in domestic boilers and transport cause dust emissions to be released into the atmosphere. The concentration of particulate matter and heavy metals in PM10 in Słupsk is much higher than in neighbouring village Gać. This affects metals deposition from the atmosphere. Two urban ponds in Słupsk were the object of the research. Sampling station No. 1 was located in the southern part of the Raj Pond situated deep into the forest area, a considerable distance from urban buildings. Sampling station No. 2 was located at the Juniorów Pond located near the city centre. Water samples were taken from a depth of 10 cm. To investigate the deposition from the atmosphere, atmospheric precipitation was collected in a collector located in the city of Słupsk. The concentrations of Li, Al, Cr, Mn, Fe, Ni, Se, As, V, Sr, Cd and Pb were analyzed in the obtained water samples. Measurements were made using an ICP-MS mass spectrometer. From the obtained results, it was observed that the concentrations of Li, Al, Cr, Mn, Fe, Se, Sr and Cd were higher at station No. 2 located near the city centre.