Mariusz Samołyk

The Gardno Lake catchment on Wolin Island is located within the Wolin Range micro-region. Its coastal location and early glacial terrain within the temperate climate zone are the distinguishing features of this catchment. The catchment is non-run-off in character, and its area is dominated by beech forests and affected by a small degree of human impact. In the Gardno Lake catchment, atmospheric precipitation undergoes both physical and chemical conversion during its permeation in the beech forest zone, and then during infiltration through the slope cover, percolation to aquifers and subsequent drainage down towards the lake. A pattern of increased mineral content and higher pH at subsequent stages of water circulation were also identified. In the period 2010 – 2014, on a monthly basis, waters at the atmospheric stage ( precipitation, throughfall, stemflow ), transitional stage ( throughflow ), and lithospheric stage ( groundwaters, lake waters ) were examined in the Gardno  Lake catchment. The research study described herein allowed to determine changes in water physical and chemical characteristics at individual stages of its cycle and discrete solute loads reaching the studied catchment area. The annual variability of water mineral content circulating in the Gardno Lake geoecosystem – presented in the paper – was calculated via the total concentration of biogenic ions (NO 3 – , NH 4 + , K +), denudation-originated ions ( SO4 2– , Ca 2+, Mg 2+), and ions resulting from a large supply of marine aerosols ( Cl –– Na + ).

The endorheic catchment of Lake Gardno is located in  northwestern Poland on the Wolin Island at a distance of 0.2 km from the Baltic Sea cliff coast. Within the Lake Gardno catchment, on a monthly basis, water with its quantitative aspects and physicochemical properties was examined at every stage of its circulation. For the diagnosis of the circulation of water and solutes, as well asits mechanisms it was essential to determine the seasonal variability of the concentration of biogenic (NO₃^-, NH₄⁺, K⁺) and denudative ions (HCO₃^-, SO₄^2-, Ca²⁺, Mg²⁺), and ions supplied primarily from sea aerosols (Cl^-, Na⁺). At the first stage of the water cycle, atmospheric water reaching tree-tops has the lowest mineralization at 1.8  mS·m^–1. Throughfall and stemflow lead to an increase in the mineralization up to 8.7  mS·m^–1 on average. The next stage, connected with the underground water circulation and leaching of soils, increases the mineralization of water up to 46.3  mS·m^–1. The lake water was mineralized at 36.7  mS·m^–1. The seasonal variability of the hydrochemical activity of water circulating within the Lake Gardno geoecosystem was represented by groups: with increased concentrations of solutes, with average concentrations of solutes and with reduced concentrations of solutes. The analyzed geoecosystem is characterized by a high concentration level of chloride and sodium ions at every stage of water circulation, which is related to the supply of sea aerosols.

The presented results constitute a summary of a five-year study conducted from 2009 to 2013 in the upper catchment of the Lewińska Struga stream. Weekly research on the physical and chemical properties of Lewińska Struga waters at the Domysłów profile was combined with seasonal hydrochemical studies conducted in the following five flow-through lakes : Warnowo, Rabiąż, Czajcze, Domysłowskie and Żółwińskie. Across young glacial areas of the Polish Lowland, a drainage network is often produced by a fluvial-lacustrine system, in which a river links subsequent lakes via short sections. In such cases, this fluvial transport of solutes is sometimes disturbed in lakes, which are both their source and deposition area. The main research strategy of the paper was aimed at determining the functioning of the fluvial-lacustrine system of Lewińska Struga stream on Wolin Island. This paper also discusses the dynamics of fluvial transport of solutes carried with Lewińska Struga waters.