Water exchange in lake basins is a very important process in regulating the health of the aquatic environment, e.g., by shaping algal blooms. Thus, knowledge of the process is also required to ...develop management strategies. The paper presents a dynamic of water renewal time in the Uściwierz chain of lakes, in which the natural hydrological connectivity of the catchment areas has been altered due to human impact. Calculations of water renewal were limited to the part of the lake basin corresponding to the active (dynamic) retention layer. A comparative analysis of the rate of potential water renewal, based on the structure difference index, was used as an indicator of the degree of anthropogenic transformation of water distribution in the lake catchments. The smallest differences in the structure of the water renewal rate between the neighboring lakes in the chain system were observed in the cold period, and the largest differences were observed in the warm period. The results showed that the shorter the timescale (5-day period), the higher the similarity in the structure of the water renewal rate between the lakes. Very large differences between the structure of the potential water renewal rate in Lakes Uściwierz and Bikcze indicated a significant transformation of the water cycle down the lake chain. The water renewal rate proved to be a good indicator of the degree of anthropogenic transformation in the catchments located in close proximity.
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•Climate changes pose a threat to groundwater resources worldwide.•Decrease in number and yield of various type of springs is observed.•Drying-up process varies in different types of ...springs.•Increase of intensive precipitation and prolonged droughts causes springs disappearance.•Natural groundwater outflows needs better protection.
Groundwater is an extremely important natural resource, exploited for domestic, industrial, and agricultural use. Being a natural groundwater discharge at the topographic surface, springs are also important hotspots of biodiversity. The increasing demand for groundwater and climate change, are major threat to springs worldwide. This study presents the scale and diversity of the process of spring disappearance, as an indicator of continuous climate change. Various criteria: the age of the aquifer, the springs’ outflow character, altitude, and discharge were taken into account. The generalized linear model method was used to assess changes in the number of springs over the study periods, whereas a t-test was used to analyze changes in springs’ yield. Precipitation variation was investigated using the statistical quality control methods. The study showed that both the number of springs and yield decreased significantly in all the classes considered. The total yield of the studied springs decreased over the years 1990–2020 from 6939 L/s to 4285 L/s. 361 springs had disappeared, regardless of topographic setting or aquifer type. An increasing trend of days without precipitation, and sums of precipitation exceeding 0.9 percentile was observed. The changes in annual dynamic of precipitation, favor surface runoff, rather than infiltration, causing springs’ drying-up processes. Even the most abundant Cretaceous aquifer is susceptible to the process. The presented case study shows an immediate need for formal and legal actions, to protect springs as valuable groundwater sources.
As the population steadily ages, dementia, in all its forms, remains a great societal challenge. Yet, our knowledge of their etiology remains rather limited. To this end, genetic studies can give us ...insight into the underlying mechanisms that lead to the development of dementia, potentially facilitating treatments in the future. In this review we cover the most recent genetic risk factors associated with the onset of the four most common dementia types today, including Alzheimer’s disease (AD), Vascular Dementia (VaD), Frontotemporal Lobar Degeneration (FTLD) and Lewy Body Dementia (LBD). Moreover, we discuss the overlap in major underlying pathologies of dementia derived from their genetic associations. While all four dementia types appear to involve genes associated with tau-pathology and neuroinflammation only LBD, AD and VaD appear to involve amyloid genes while LBD and FTLD share alpha synuclein genes. Together these findings suggest that some of the dementias may exist along a spectrum and demonstrates the necessity to conduct large-scale studies pinpointing the etiology of the dementias and potential gene and environment interactions that may influence their development.
River floodplains are sites of extremely high environmental and ecological value due to high biodiversity. Floodplain lakes (FPLs) are essential parts of complex floodplain ecosystems’ biological and ...hydro-chemical processes. Clear seasonal cycles, determined by the regime of the parent river and closely linked to climatic conditions, are observed in these lakes. Both the quantity and the quality of water are determined by the functional phases of a floodplain lake; limnophase, when the lake is isolated from the river, and potamophase (inundation), when the floodplain lake is overflowed by the river waters. These phases highly modify lake bathymetry, water balance, chemistry, and biology. Human pressure, mostly dam construction and land use changes, alter the frequency, duration, and intensity of natural cycles of inundation. The majority of large rivers in the Northern Hemisphere have been impacted by human activity. Floodplain lakes are also affected by continuous climate change, due to the alterations of the hydrological regimes. Cyanobacterial blooms in floodplain lakes are often characterized by high qualitative and quantitative annual and long-term variability. The main forces driving cyanobacterial blooms can be found in the flooding dynamics and intensity influencing hydraulic residence time and the concentration of biogenic compounds in lake water. Cyanotoxin production and seasonal dynamics in floodplain lakes have been rarely studied, particularly in connection with the hydrological regime. Moreover, the effects of cyanobacterial blooms and their toxicity to organisms inhabiting floodplain lakes, connected rivers, and floodplains are poorly understood. Therefore, knowledge of the processes controlling floodplain lakes’ ecological conditions is crucial to implementing water management and restoration practices, protecting those fragile and precious ecosystems from degradation and possible extension.
Toxic cyanobacterial blooms are a well-known problem in eutrophic water bodies, but cyanobacterial toxicity in ambient springs is unexplored. Therefore, we studied the toxin content and effects of ...two extracts obtained from epilithic and benthic microbial mats containing different algae and filamentous cyanobacteria, Phormidium breve and Oscillatoria limosa, respectively, on fresh biomass, number of roots, and pigment content in duckweed Spirodela polyrhiza and on survivorship of Daphnia magna (Cladocera). Mat samples, used to prepare extracts for bioassays, were collected in the anthropogenically transformed limnocrenic Górecko spring, located (50°31′08″ N and 22°57′10″ E) in the Roztocze region (Eastern Poland). It drains an abundant aquifer built with Cretaceous sediments. Neither anatoxin-a (ANTX) nor microcystins (MCs) were detected in the extracts using HPLC techniques; however, negative effects of the extracts on tested organisms were observed. The Phormidium extract contained concentrations of cyanobacterial metabolites a few times higher than the Oscillatoria extract. In general, both extracts affected plants in a dose-dependent manner; however, the Oscillatoria extract influenced pigment production without a clear trend. The highest concentrations of Phormidium extract (p < 0.05) significantly decreased the number of roots and the content of chlorophylls and carotenoids in S. polyrhiza. The Oscillatoria extract caused a statistically significant (p < 0.05) decrease in biomass and number of roots; however, it generally positively influenced the production of pigments. The extract containing O. limosa metabolites was more toxic to D. magna than the extract containing higher amounts of metabolites of P. breve. Cyanobacteria inhabiting temperate springs may negatively affect hydrobionts by producing secondary metabolites other than ANTX and MCs; however, the contribution of algae cannot be excluded. Extensive research on cyanobacteria in springs, their metabolites, and their effects on living organisms should be conducted.
The role of confluence (flowability) in shaping the concentration of dissolved oxygen (DO), chlorophyll-a (chl-a) and pH was determined using a model approach. The calculations considered both ...horizontal and vertical variability of parameters. There was a general tendency for the pH and oxygen to increase along the transect connecting the place of surface water inlet, deepest point of the lake basin and the place of water outlet, and the reverse tendency for chlorophyll. The average gradient for particulate radius was calculated as arithmetic mean value of six partial gradients (corresponding to individual depths, every 0.5 m). Values of average gradients indicated high dynamics of DO and pH concentration changes as well as low chlorophyll-a variability. A slight inclination of the final resultant vector gradients of DO and pH from the surface water inlet, deepest point of the lake basin and the place of water outlet transect indicated the dominant role of confluence in these parameters variability (values amounted to 6.08 mg·km−1 and 3.34 pH units·km−1, respectively). The value of the chlorophyll-a gradient vector (1.86 µg·km−1) indicated a slight differentiation of the parameter in the basin, independent of the hydrological conditions. The concentration of chl-a in the polymictic Lake Bikcze resulted from the effect of the limnic conditions; the flowability of the lake was just one of many factors affecting the variability of the parameter.
Due to global warming and increasing water eutrophication, understanding in-lake relationships is paramount to prevent excessive pollution and further negative changes in lakes. The physico-chemical ...and biological parameters, as well as nutrient variabilities, both temporal and vertical (in the water column), were studied in the largest Łęczna-Włodawa lake. The study was conducted during two consecutive water years, from November 2015 to September 2017. The non-parametric Kruskal–Wallis ANOVA, test H was used to detect variability between years, and among seasons and lake depths in water temperature, electrical conductivity, pH, ORP, concentration of dissolved oxygen as well as concentration of NO3−, PO43−, TP and chlorophyll a. One-way analysis of variance (ANOVA) was used to detect any differences in Secchi depth (SD) and concentration of NH4+, NO2−, and TN. Ordination techniques: Detrended correspondence analysis (DCA), and Principal Components Analysis (PCA) were used to describe the relationships among 13 environmental variables and distribution of samples. Results showed significant differences (P < 0.05) between two years of the study for most variables except of water temperature, visibility, concentration of PO43−, TN and TP, which corresponded with highly different weather conditions in both years. All of the tested variables, except for nutrients, differed significantly among seasons. Most parameters showed fluctuation in depth, especially in summer and in winter, despite the fact that no hypolimnion or long-lasting thermocline was observed in the study period. However, variability of Chl-a was statistically significant only. The results emphasized complex and multi-directional relations between tested variables, dependent on both external (catchment) and internal (in-lake) processes.
In this study, allometric relations between all parts of lake-catchment systems have been investigated. Inflow and outflow discharges were the main hydrological factors of terrestrial part of the ...system. Lake water chemistry was presented not simply as ion concentration, but as ion mass accumulated in the lake basin, taking into account the volume of water stored in the lake basin at that time. Redundancy analysis was used to determine the most significant relations between hydrometeorological factors and lake water chemistry. Power of scaling was calculated afterward. The obtained results showed the strongest relations between the following: inflow 2 (I2) and total phosphorus (TP), outflow and magnesium (Mg
2+
) and chlorides (Cl
−
), flushing time (Tf) and phosphate (PO
4
3−
), as well as precipitation (P) and calcium (Ca
2+
)—inverse relation. In most cases, negative allometry was observed. The most stable allometric relations occurred between I2 and TP, the least stable between Tf and PO
4
3−
. Negative allometry proved a dominant role of hydrological conditions in shaping lake water chemistry. The inverse relationship between P and Ca
2+
resulted from the fact that Ca
2+
originated from Cretaceous sediments weathering, not atmospheric input.
Finding biomarkers constitutes a crucial step for early detection of Alzheimer's disease (AD). Brain imaging techniques have revealed structural alterations in the brain that may be phenotypic in ...preclinical AD. The most prominent polymorphism that has been associated with AD and related neural changes is the Apolipoprotein E (APOE) ε4. The translocase of outer mitochondrial membrane 40 (TOMM40), which is in linkage disequilibrium with APOE, has received increasing attention as a promising gene in AD. TOMM40 also impacts brain areas vulnerable in AD, by downstream apoptotic processes that forego extracellular amyloid beta aggregation. The present paper aims to extend on the mitochondrial influence in AD pathogenesis and we propose a TOMM40-induced disconnection of the medial temporal lobe. Finally, we discuss the possibility of mitochondrial dysfunction being the earliest pathophysiological event in AD, which indeed is supported by recent findings.
UE regulations focus on methods of water quality monitoring and their use in rational management practices. This study investigated horizontal and vertical variations of electrical conductivity (EC), ...pH, dissolved oxygen (DO), and chlorophyll a (Chl-a) in a shallow polymictic lake. Monitoring of short-term variability of physical and chemical lake water parameters is a critical component in lake management, as it influences aquatic life. Based on the field research, maps of spatial distribution of the parameters were drawn. Using two methods: (1) a classical approach to water column measurements, from the top to the bottom (TB), in which the reference point is always a surface layer (SL), and (2) a newly introduced method of lake water quality monitoring based on a nearest neighbor (NN) approach; a comparison of higher and lower layers of the water column. By subtracting partial maps of spatial variability for different depths, final raster images were obtained. The NN method is rather absent in the limnology literature worldwide. Vertical and horizontal variability of the tested parameters in the polymictic, shallow Lake Bikcze (Poland) was presented in the results. In the presented paper, the commonly used TB method emphasized the role of the surface layer in shaping the variability of physicochemical parameters of lake waters. It shows a general trend of parameters’ changes from the top, to the bottom. The newly presented NN method, which has a major advantage in its simplicity and objectivity, emphasized structural differentiation within the range of variability. The nearest neighbor method was more accurate in showing the actual structure of fluctuation of parameters with higher fluctuation in the water column. Its advantage is a detailed recognition of the vertical variability of selected parameters in the water column. The method may be used regardless of the lake depth, its location in climatic zone, and/or region.
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