Data Descriptor : A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.Peer reviewe

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature

Escherichia coli jako potencjalny wskaźnik wzbogacania wód rzeki Biebrzy

The number of Escherichia coli cells in the waters of the Biebrza River was analyzed. The results were compared with the values of select chemical water quality indicators and with the Biebrza River catchment development. Organic contamination was detected along the entire run of the River and was caused by the presence of substances washed off the adjacent marshy areas and the influx of household and agricultural wastewaters. The highest number of bacteria was found in the Middle and Lower Basins of the Biebrza River. The incease in the number of E. coli in the spring to over 24 MPN·cm–3 is a result of the numerous presence of water birds in the area of the National Park. Of consequence are also meltwaters that introduce contamination from peat lands into the watercourse. The increased number of E. coli cells in the summer is related to runoff from the areas along the River with numerous farms and dairy cattle pastures. The number of bacteria in the river is most probably influenced by changes in water levels and types of accumulated sediment. The Escherichia coli count allows determining the source of the contamination of surface waters, which is of particular significance for planned water management on protected areas. The number of E. coli below 7 MPN·cm–3 in the waters of the Biebrza River is at the natural background level, whereas counts of over 24 MPN·cm–3 are related to the influx of household wastewaters.W wodzie rzeki Biebrza analizowano liczebność Escherichia coli. Wyniki zestawiono z poziomem wybranych wskaźników jakości chemicznej wody oraz danymi, dotyczącymi zagospodarowania zlewni. Stwierdzono zanieczyszczenie organiczne na całej długości biegu rzeki, wywołane obecnością substancji wymywanych z okolicznych terenów bagiennych oraz dopływem ścieków bytowych i rolniczych. Największą liczebność bakterii stwierdzono w środkowym i dolnym basenie rzeki Biebrzy. W okresie wiosennym wzrost liczebności E. coli do ponad 24 NPL·cm–3 wynika z licznego występowania ptactwa wodnego na obszarze Parku Narodowego. Wpływ mają też wody roztopowe wnoszące do cieku zanieczyszczenia z terenów torfowych. Latem wzrost liczebności E. coli związany jest ze spływem z sąsiadujących z rzeką terenów, na których są gospodarstwa i pastwiska bydła mlecznego. Na liczebność bakterii w wodzie mają także prawdopodobnie wpływ zmiany poziomu wód, uruchamiające zasoby osadów dennych. Dzięki określeniu liczebności Escherichia coli można określić źródła zanieczyszczenia wód powierzchniowych, co jest szczególnie istotne dla planowej gospodarki wodnej na obszarach chronionych. Liczebność E. coli w wodach Biebrzy poniżej 7 MPN·cm–3 jest naturalnym poziomem, natomiast ponad 24 MPN·cm–3 wskazuje na napływ ścieków bytowych

Suitability of sewage from the production of organic polymers for biological treatment

The possibility of biological treatment of sewage from the production of organic polymers was assessed. The chemical quality of raw and treated sewage (CODCr, BOD5 , ammonia nitrogen, nitrate nitrogen, total suspension, pH, chlorides and sulfates) was analyzed. The level of reduction in the analysed sewage quality indicators (%), sewage biodegradability (α) and the technical efficiency of treatment (Psw) were determined. It was shown that the limited effectiveness of the treatment process results from the excessively high load of organic contaminants. The analysed sewage contains substances which do not biodegrade easily, negatively influencing the conditions for activated sludge processes in the bioreactor. The activated sludge is characterized by low biodiversity and has an insufficient structure. The treatment process requires an introduction of technological changes which will lead to a decrease in the load of sewage entering the bioreactor

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.Peer reviewe