Tom 15 (2015): Zeszyt 2 (June 2015)

Changes in sedimentological conditions in Lake Jamno during its development throughout the Holocene are presented in this paper. For this purpose, selected granulometric and geochemical parameters were used, which describe the nature and dynamics of the environment, as well as determining primary production capacity and origin of the matter. On the basis of these parameters, the environmental conditions occurring in subsequent stages of lake development were distinguished.

The main goal of the presented work is to determine the current trophic state of 31 lakes located in Poznań Lakeland. These lakes are included in the lake monitoring programme executed by the Voivodship Environmental Protection Inspectorate in Poznań. The place in the trophic classification for investigated lakes was determined as well as the relationships between their trophic state indices. The trophic state of investigated lakes in the research area is poor. More than a half of the investigated lakes are eutrophic. Depending on the factor that is taken into account the trophic state of investigated lakes differs radically.

Interdisciplinary studies on environmental evolution during the last 650 years based on the analysis of mill pond deposits have been conducted in the valley of the Jarosławianka Stream (left-bank tributary of the River Wieprza). According to historical data, confirmed also by radiocarbon dating, the water mill was located in the valley in 1351 and operated until the 1960s. The sequence of stratified deposits with a thickness of up to about 2 metres was accumulated in mill pond basin during this period. The vertical variability in the physical and chemical properties of these deposits reflects temporal environmental changes in the catchment, particularly the intensity of chemical and mechanical denudation and human activity. Analysis of subfossil Cladocera suggests four phases in the development of the mill pond. Changing along with the intensity of the pond basin water flow, redox and nutritional conditions are reflected in the spatial variability of deposits, especially their textural parameters, pH and abundance in organic carbon, nitrogen and carbonates.

The purpose of the paper was to assess the changes in the concentration of selected metals in the bottom sediment and interstitial water of the River Chotla in northwest Poland. The research was conducted on the river section flowing through Zaspy Małe and a salmonid fish breeding farm. Samples of water and bottom sediment were taken in four control and measurement points, located above and below the village and on a backwater above the trouteries and below the fish breeding ponds. The pH and the concentration of the metals potassium, iron, calcium, manganese and zinc were determined in the water and sediment samples. The lowest concentrations of the metals were found in the samples collected above and below Zaspy Małe, while the highest concentrations of metals in the water and sediment were found in the samples taken in the backwater, above the fish breeding ponds. Exceptions were calcium and potassium, with the highest concentrations of metals in the water being found in the samples taken below the fish breeding ponds. The content of metals in sediments of the analysed section of the River Chotla was mainly determined by the content of organic matter, which varied as it is dependent on water accumulation processes and the operation of nearby fishery facilities. The slightly alkaline pH facilitated long-lasting accumulation of metals in sediments.