Climate Change Accelerates Recovery of the Tatra Mountain Lakes from Acidification and Increases Their Nutrient and Chlorophyll a Concentrations

We evaluated changes in the concentration of cations, anions, nutrients (dissolved organic carbon, DOC; phosphorus, P; and nitrogen forms including nitrate, NO3− and total organic nitrogen, TON), and chlorophyll a (Chl-a) in 31 Tatra Mountain lakes in Slovakia and Poland during their recovery from acidic deposition (1992–2018). Typical effects of decreasing acidic deposition on the lakes’ water composition, such as decreasing base cation concentrations, were confounded by climate change and catchment characteristics, including areal proportions of well-developed soils and scree. A climate-related increase in physical erosion provided freshly exposed unweathered granodiorite (the dominant bedrock) to chemical weathering. Dissolution of accessory calcite in the granodiorite increased the in-lake Ca2+ and HCO3− concentrations and reversed the Ca2+ trends, which originally decreased in parallel with strong acid anions. These changes were most pronounced in steep, scree-rich areas, which are most sensitive to physical weathering. Fresh apatite [Ca5(PO4)3(F, Cl, OH)] in the crushed granodiorite acts as a P source at soil pH’s between 4 and 5 and in the presence of chelating organic acids within soils. These conditions enhance apatite solubility, which in part explains increasing P in lakes with scree-dominated catchments. Soil recovery from acidification due to decreasing acidic deposition and the neutralizing effect of weathering of erosion-derived accessory calcite were the most likely causes of elevated DOC and P export from soils. Their elevated leaching was accompanied by increasing in-lake concentrations of Chl-a and TON. The increasing TON concentrations were, as for Ca2+, most pronounced in the scree-rich catchments, and represented the most sensitive indicator of the changes in the lake water nutrient composition

The technological development of drinking water treatment plants in the Czech Republic

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Factors affecting the leaching of dissolved organic carbon after tree dieback in an unmanaged European mountain forest

Forest disturbances affect ecosystem biogeochemistry, water quality, and carbon cycling. We analyzed water chemistry before, during, and after a dieback event at a headwater catchment in the Bohemian Forest (central Europe) together with an un-impacted reference catchment, focusing on drivers and responses of dissolved organic carbon (DOC) leaching. We analyzed data regarding carbon input to the forest floor via litter and throughfall, changes in soil moisture and composition, streamwater chemistry, discharge, and temperature. We observed three key points. (i) In the first 3 years following dieback, DOC production from dead biomass led to increased concentrations in soil, but DOC leaching did not increase due to chemical suppression of its solubility by elevated concentrations of protons and polyvalent cations and elevated microbial demand for DOC associated with high ammonium (NH4+) concentrations. (ii) DOC leaching remained low during the next 2 years because its availability in soils declined, which also left more NH4+ available for nitrifiers, increasing NO3– and proton production that further increased the chemical suppression of DOC mobility. (iii) After 5 years, DOC leaching started to increase as concentrations of NO3–, protons, and polyvalent cations started to decrease in soil water. Our data suggest that disturbance-induced changes in N cycling strongly influence DOC leaching via both chemical and biological mechanisms and that the magnitude of DOC leaching may vary over periods following disturbance. Our study adds insights as to why the impacts of forest disturbances are sometime observed at the local soil scale but not simultaneously on the larger catchment scale

Radon in a lake – an estimation of ground water input.

A balance study of radon activity in Lake Plešný and its tributaries was carried out in 2020 to refine the estimate of groundwater resources. The balance is based on quantification of sources, monitoring of the amount of water draining from the lake, and lead concentrations in the overlying sediments

Composition and efficiency of organic matter removal at DWTP Studena.

The paper describes the composition and removal efficiency of natural organic matter in the treatment of drinking water at the DWTP Studena

Seasonal photochemical transformations of nitrogen species in a forest stream and lake.

The photochemical release of inorganic nitrogen from dissolved organic matter is an important source of bio-available nitrogen (N) in N-limited aquatic ecosystems. We conducted photochemical experiments and used mathematical models based on pseudo-first-order reaction kinetics to quantify the photochemical transformations of individual N species and their seasonal effects on N cycling in a mountain forest stream and lake (Plešné Lake, Czech Republic). Results from laboratory experiments on photochemical changes in N speciation were compared to measured lake N budgets. Concentrations of organic nitrogen (Norg; 40-58 µmol L-1) decreased from 3 to 26% during 48-hour laboratory irradiation (an equivalent of 4-5 days of natural solar insolation) due to photochemical mineralization to ammonium (NH4+) and other N forms (Nx; possibly N oxides and N2). In addition to Norg mineralization, Nx also originated from photochemical nitrate (NO3-) reduction. Laboratory exposure of a first-order forest stream water samples showed a high amount of seasonality, with the maximum rates of Norg mineralization and NH4+ production in winter and spring, and the maximum NO3- reduction occurring in summer. These photochemical changes could have an ecologically significant effect on NH4+ concentrations in streams (doubling their terrestrial fluxes from soils) and on concentrations of dissolved Norg in the lake. In contrast, photochemical reactions reduced NO3- fluxes by a negligible (<1%) amount and had a negligible effect on the aquatic cycle of this N form