Mikołaj Major

Abstract

The basic form of closed landform form is a terrain depression. Sometimes, this type of depression is filled with water, forming a reservoir – a pond or a wetland. Each depression has its own closed catchment. The clustering of adjacent closed catchments forms a surface non-draining area, the extent of which is determined by the watershed of peripheral catchments (Drwal, 1975; Major, 2009, 2010, 2012). Among the 76 genetic types of lake basins identified worldwide (Hutchinson, 1957), meteorite lakes (kettle ponds) represent one such type. The specific geographical environments of closed catchments, particularly their geological structure, determine the existence of two types of basins based on water circulation mechanism: closed evapotranspiration basins and closed absorptive basins. Applying this concept on a smaller scale, from a hydrological perspective, we can distinguish precisely two types of closed depressions: evapotranspirational and absorptive.

In the nature reserve established in 1976 near the “Morasko Mountain” there are a total of seven meteorite craters. Five of them contain permanent or periodic kettle ponds, indicating an evapotranspirational character, while the remaining two are absorptive. Nearly half of its area lies within the Różany Strumień catchment (Fig. 1, Fig. 2), located in the northern part of Poznań, covering approximately 7.7 km².

Hydrochemical studies of the kettle ponds were conducted in this unique location during the hydrological years 2018-2022, with the exception of the first year when, for administrative reasons, the surveys began only in May. The amount of water filling the kettle ponds varied throughout the study period, and the ponds often disappeared completely.

The primary aim of the study was to identify prevailing weather conditions and determine their influence on the chemical composition and water supply of the kettle ponds in the meteorite depressions located in the “Meteoryt Morasko” reserve.

Based on the results, it was found that meteorological conditions (Fig. 3) have a significant impact on the functioning of kettle ponds in the studied area. These conditions influence the chemical composition of surface waters (Fig. 4), determine the type of pond supply, and decreasing amounts of precipitation along with increasing air temperature and evaporation rates, play a decisive role in the periodic disappearance of the kettle ponds (Table 1). Similar conclusions were reached by Korytowski et al. (2023) in a study of a mid-forest kettle pond in the Prosna catchment (central Poland).

The waters of the examined kettle ponds were characterized by a normal or slightly elevated pH levels, while specific electrolytic conductivity values showed significant spatial variability. The dominant components were calcium, bicarbonates, and sulfates, which are products of chemical weathering and determined the hydrogeochemical types of water (Fig. 5). Other chemical components in the examined depressions exhibited significant temporal variability (Fig. 6).

Using ionized silica (SiO₂) as an indicator of water supply, three groups of depressions with distinct water supply types were identified in the “Meteoryt Morasko” reserve: ground-rain, rain-ground, and rain. Depressions 1 and 7 were classified as ground-rain, characterized by elevated SiO₂ concentrations in surface, similar silica concentration to groundwater, and a wide range of SiO₂ variability. Kettle ponds 3 and 4 exhibited rain-ground characteristics, where precipitation supply predominated over groundwater, as indicated by slightly lower ionised silica concentrations in surface waters. Similar concentrations were observed across individual seasons, even after periods of intense rainfall, as well as smaller ranges of SiO₂ variability. In contrast, kettle ponds 5, representing the third type of supply (rain), was sampled only in May 2018, recording very low concentrations of SiO₂ at that time (Table 2, Fig. 7).

Similar SiO₂ concentrations results were obtained in studies of non-draining depressions in the upper Parsęta watershed during the hydrological years 1999-2001 (Major, 2009) and in the Parsęta River basin during the hydrological years 2005-2010 (Major, 2012).

Keywords: meteorite depressions, kettle ponds, “Meteoryt Morasko” reserve, water chemical composition, water supply

Maciej Major [maciej.major@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Stacja Zintegrowanego Monitoringu Środowiska Przyrodniczego „Poznań-Morasko”; Uniwersytet im. Adama Mickiewicza w Poznaniu, Instytut Geoekologii i Geoinformacji
Maria Chudzińska [maciej.major@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Stacja Zintegrowanego Monitoringu Środowiska Przyrodniczego „Poznań-Morasko”
Mikołaj Major [mikolaj.majewski@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Stacja Zintegrowanego Monitoringu Środowiska Przyrodniczego „Poznań-Morasko”; Uniwersytet im. Adama Mickiewicza w Poznaniu, Instytut Geoekologii i Geoinformacji

Citation

APA: Major, M., Chudzińska, M., & Major, M. (2024). Wpływ warunków pogodowych na skład chemiczny i zasilanie oczek w zagłębieniach meteorytowych (rezerwat „Meteoryt Morasko”, Poznań). Przegląd Geograficzny, 96(3), 351-366. https://doi.org/10.7163/PrzG.2024.3.3
MLA: Major, Maciej, et al. "Wpływ warunków pogodowych na skład chemiczny i zasilanie oczek w zagłębieniach meteorytowych (rezerwat „Meteoryt Morasko”, Poznań)". Przegląd Geograficzny, vol. 96, no. 3, 2024, pp. 351-366. https://doi.org/10.7163/PrzG.2024.3.3
Chicago: Major, Maciej, Chudzińska, Maria, and Major, Mikołaj. "Wpływ warunków pogodowych na skład chemiczny i zasilanie oczek w zagłębieniach meteorytowych (rezerwat „Meteoryt Morasko”, Poznań)". Przegląd Geograficzny 96, no. 3 (2024): 351-366. https://doi.org/10.7163/PrzG.2024.3.3
Harvard: Major, M., Chudzińska, M., & Major, M. 2024. "Wpływ warunków pogodowych na skład chemiczny i zasilanie oczek w zagłębieniach meteorytowych (rezerwat „Meteoryt Morasko”, Poznań)". Przegląd Geograficzny, vol. 96, no. 3, pp. 351-366. https://doi.org/10.7163/PrzG.2024.3.3