Diffusive Fluxes of CH4 and CO2 at the Sediment-Overlying Water Interface in Reservoir Ecosystems

The work detailed here has concerned CH4 and CO2 fluxes at the sediment-overlying water interface in Maziarnia and Nielisz Reservoirs, SE Poland. The research in question was conducted in the 2009-2011 period, samples of sediment and overlying water being collected at two stations located in the upper and lower parts of each Reservoir. Concentrations of CO2 and CH4 in pore water and overlying water were measured by the headspace method, using a Pye Unicam gas chromatograph (PU-4410/19) equipped with a methane analyzer allowing low CO2 concentrations to be detected. Diffusive fluxes of the analyzed gases at the sediment-overlying water interface were calculated on the basis of Fick's first law, and were found to range from -0.01 to 3.48 mmol m-2 d-1 for CH4 and from -1.27 to 47.02 mmol m-2 d-1 for CO2. Comparable fluxes elsewhere typify reservoirs experiencing far-reaching eutrophication. No dependent relationships were found between calculated values for fluxes and either season of the year or sediment characteristics

Quantitative Fluxes of the Greenhouse Gases CH4 and CO2 from the Surfaces of Selected Polish Reservoirs

Research carried out in the years 2009–2011 and 2018–2019 sought to determine the magnitudes of fluxes of methane (CH4) and carbon dioxide (CO2) from the surfaces of three eutrophic reservoirs in SE Poland. The “static chamber” method was deployed at five or six stations located along the reservoirs, where the water column at its deepest slightly exceeds 2 m. Obtained values for the fluxes of CH4 varied across a wide (0–2513.48 mmol·m−2·d−1) range, with many of these values therefore exceeding those characteristics for large tropical reservoirs. The reservoirs studied were not found to differ significantly in terms of average CH4 flux, however. Where obtained values for CO2 fluxes in the range from −10.96 to 621.69 mmol·m−2·d−1 were concerned, most fell within the range given for temperate-zone reservoirs, while differences between reservoirs were noted for average values in this case

Supplementary data related to the reseach on Vertical Diversification of Methane Production Pathways in Freshwater Sediments of Reservoirs. Case Nielisz Reservoir, Poland

The file contains data on selected parameters of pore water and sediments, which can be used to determine the methan production pathways in sediment of reservoir

The content of selected heavy metals and their bioavailable fraction in sediments of Solina Reservoir (Poland)

Research on sediments of Solina Reservoir, Poland, were characterized by a content of copper higher than other heavy metals (Cr, Ni, Cd and Zn). The strongest correlations between pairs of heavy metals were Zn–Cu and Ni–Cr, were revealed while there was also a correlation between total contents of chromium and nickel, and between pH value and sediment percentage of organic matter. The content of copper at levels exceeding the geochemical background (more than 20–fold), sediments could only by classified as of the 3rd purity class (according to the PIG criterion) or the 5th purity class (according to Müller’s classification). Ecotoxicological criteria indicate that levels of chromium, copper, nickel and cadmium are all high enough to affect aquatic life. However, the heavy metals analyzed differ in their mobility and bioavailability. The highest percentage value for the ion–exchangeable fraction was noted for cadmium, the lowest for chromium. This means that sediments have a greater capacity to release cadmium into the water column, with the consequence being secondary pollution source for the aquatic ecosystem

Heavy metal contamination in sediments of Rzeszów Reservoir (Poland)

Sediments of Rzeszów Reservoir were characterized by a higher content of zinc compared to other heavy metals (Cu, Cr, Ni and Cd). The strongest correlations between pairs of heavy metals were Cr-Ni, Ni-Zn, Cu-Ni and Cr-Zn, while there was also a clear relationship between the total chromium and nickel content and the pH value, as well as the percentage of organic matter in the sediments (Cr, Zn, Cu, Ni). The content of chromium and copper occurred at levels exceeding the geochemical background, and the sediments could be classified as of purity class 2 (according to the PIG criterion) or class 3 (according to the Müller’s classification). Ecotoxicological criteria indicate that levels of chromium, nickel and cadmium could affect aquatic life. However, the heavy metals differ in mobility and bioavailability. The highest percentage of ion exchangeable fraction was recorded for nickel, and the lowest for chromium. This means that sediments have a greater ability to release nickel into the water column, as a result of which they are a secondary source of pollution for the aquatic ecosystem

Anaerobic oxidation of methane in freshwater ecosystems

Anaerobic oxidation of methane (AOM) is a biochemical process that plays an important role in aquatic ecosystems, as it significantly reduces the emission of methane (CH4 ) to the atmosphere. Under anaerobic conditions, CH4 can be oxidized with electron acceptors, such as sulphates (SO42-), nitrates (NO3-) or nitrites (NO2-), iron (Fe3+), manganese (Mn4+) and humic substances. The anaerobic oxidation of methane is mainly regulated by anaerobic methanotrophic archaea (ANME) and sulphate reducing bacteria. The AOM process is crucial to understand the CH4 cycle and anticipate future emissions of the gas from water reservoirs. The process is widely described in marine environments, however very little is known about its occurrence and importance in freshwater systems. There is a great demand for this kind of the research, especially in ecosystems exposed to long-term anaerobic conditions, which may be in degraded reservoirs

Influence of the manner of water discharge from dam reservoirs on downstream water quality

The study was carried out in the area of three dam reservoirs: Blizne and Maziarnia (Voivodeship of Podkarpackie) and Nielisz (Voivodeship of Lublin). The main parameter differentiating the reservoirs was the water retention time and the manner of water discharge from the reservoirs. Three test sites were designated in the area of each reservoir: in the river zone of the reservoir, in the central part of the reservoir, and near the reservoir dam. At these sites, the concentrations of suspended sediment in the water and the content of organic matter in it, the concentrations of total phosphorus and total nitrogen, as well as chlorophyll a were monitored. In addition, two control sites were established: on the river upstream of the reservoir and on the river downstream of the dam, respectively. At these points, the concentrations of suspended sediments in the water and their organic matter content were recorded. The obtained results of the study and multivariate analysis of the data showed that morphometric parameters (including water retention time) of reservoirs and the method of water discharge influence water quality in downstream rivers. It was found that by using lower discharge and ensuring a sufficiently long retention time of water in the reservoir, it is possible to effectively limit the negative aspects of hydrotechnical structures’ impact on the natural environment. In practice, the observed relationships may constitute an important and missing link in the aspect of minimising undesirable side effects of this type of hydrotechnical objects

Production pathways for CH4 and CO2 in sediments of two freshwater ecosystems in south-eastern Poland.

This paper presents the results of research into pathways leading to the production of methane (CH4) and carbon dioxide (CO2) in sediments of two eutrophic reservoirs (Maziarnia and Nielisz), located in south-eastern Poland. In seeking to identify the pathways in question, use was made of analysis of stable carbon isotopes in CH4 and CO2 dissolved in pore water. This determined that CH4 is mainly produced through acetate fermentation, though the hydrogenotrophic methanogenic process may also be of importance, especially in deeper layers of sediments. Both the presence of autochthonous organic matter and increased pH values are shown to favour acetate fermentation. In turn, methanogenesis in sediments is assessed as capable of accounting for the generation of a considerable amount of CO2. Indeed, the role of methanogenesis in CO2 production is increasingly important further down in the layers of sediment, where allochthonous organic matter is predominant

Denitrification-Dependent Anaerobic Oxidation of Methane in Freshwater Sediments of Reservoirs in SE Poland

The results presented here concern the anaerobic oxidation of methane (CH4) coupled with denitrification (i.e. a process abbreviated to DAMO) in the freshwater sediments of dam reservoirs located in Rzeszów, Maziarnia and Nielisz, SE Poland. The DAMO rate was determined experimentally by adding a 13CH4 isotope marker and NO3as an electron acceptor. The sediments were collected once, in autumn (September), with incubation of the 0–5, 5–10 and 10–15 cm layers then carried out at 10°C, as the temperature corresponding to the in situ conditions at the given time of the year. The DAMO rates were set against the results for the anaerobic oxidation of methane (AOM), which were obtained by incubation of reservoir sediments with the 13CH4 isotope marker alone. The DAMO rates noted were of 0.03–0.69 nmol∙g-1∙h-1 for Rzeszów Reservoir; 0.04–0.47 nmol∙g-1∙h-1 for Maziarnia Reservoir and 0.19–1.04 nmol∙g-1∙h-1 for Nielisz Reservoir. Overall, it was typical for the DAMO rates to be about twice as high as the rates of AOM with no electron acceptor added. The addition of NO3did not accelerate the methane oxidation significantly in any of the sediment layers from Maziarnia Reservoir, while the effects in Rzeszów Reservoir sediments were confined to the 10–15 cm layer. While the DAMO rates were progressively higher in the deeper layers of sediment from Maziarnia Reservoir, the trend was the reverse (downward) with depth at the Rzeszów and Nielisz sites. The results indicate that the process abbreviated as DAMO takes place in dam reservoirs and is related, not only to the presence of NO3-, but also to the sediment parameters