Water Temperature Values Research Articles

Experimental Investigation on Thermo-Economic Analysis of Direct Contact Membrane Distillation for Sustainable Freshwater Production

Treatment of extremely saline water such as the brine rejected from reverse osmosis water desalination plants, and produced water from shale oil and non-conventional gas extraction, is considered a global problem. Consequently, in this work, hollow fiber membrane distillation (HFMD) is experimentally evaluated for desalinating extremely saline water of a salinity ranging from 40,000 to 130,000 ppm. For the purpose of comparison, the HFMD is also tested for desalinating brackish (3000–12,000 ppm) and sea (25,000–40,000 ppm) water. Firstly, the HFMD is tested at two values of feed water temperature (65 and 76 °C) and flow rate (600 and 850 L/h). The experimental results showed that the HFMD productivity significantly increases when the temperature of feed water increases. Increasing the feed water flow rate also has a positive effect on the productivity of HFMD. It is also concluded that the productivity of the HFMD is not significantly affected by increasing the salt concentration when brackish and sea water are used. The productivity also slightly decreases with increasing the salt concentration when extremely saline water is used. The decrement in the productivity reaches 27%, when the salt concentration increases from 40,000 to 130,000 ppm. Based on the conducted economic analysis, the HFMD shows a good potential for desalinating extremely saline water especially when the solar collector is used as a heat source. In this case, the cost per liter of freshwater is reduced by 21.7–23.1% when the evacuated tube solar collectors are used compared to the system using electrical heaters. More reduction in the cost per liter of freshwater is expected when a high capacity solar-powered HFMD plant is installed.

Reconstructing the experienced temperature during the larval oceanic migration of anguillid eels from otolith stable oxygen isotopes

Migration routes and the depth patterns of anguillid eel larvae migrating long distances from spawning grounds in the ocean remain poorly understood. We used otolith stable isotope analysis to study the oceanic migrations of anguillid eels by reconstructing experienced water temperature histories of larvae. The otolith stable oxygen isotopes (δ18Ootolith) of recruited Anguilla japonica glass eels were analyzed to assess the relationship with the experienced water temperature of the early larval stage in laboratory experiments. A negative linear relationship between rearing water temperature and δ18Ootolith values was observed for eel leptocephali reared at five different temperatures between 19 °C and 27 °C. Subsequently, the obtained equation between water temperature and δ18Ootolith was applied to estimate the water temperature experienced by wild-caught glass eels during their larval oceanic migration according to recruitment latitude, season, and species. The δ18Ootolith values of A. japonica glass eels were significantly higher at higher recruitment latitudes from Taiwan to Japan and later recruitment periods of 6 months, from November to March, indicating that the individuals were exposed to lower water temperatures along the Kuroshio flowing northward as they reached the higher latitudes in the later recruitment seasons. Furthermore, the δ18Ootolith values of the temperate A. japonica were higher than those of the tropical Anguilla marmorata, recruited at the same locations in southern Japan and Taiwan. This suggests that larval migratory behavior in the ocean may differ between the two eel species, although they have sympatric spawning areas in the western North Pacific. Collectively, these results suggest that δ18Ootolith provides a reasonable estimation of the experienced water temperature and may prove useful for reconstructing the early migratory history of anguillid eels in the ocean.

Coal-to-nuclear modernization of an existing power plant with a IV-th generation nuclear reactor

The paper presents an analysis of a transition from a coal-fired power plant to a nuclear unit. The main focus is set on the extensive usage of the existing parts of the already operating system. The key problem is the correct matching of a nuclear reactor and the steam island. It is assumed here that the reactor module operates under nominal conditions and the steam turbine is adapted to fit the reactor. The paper describes the numerical model of the steam turbine cycle for the off-design simulations. The developed model allows us to determine the changes in the steam cycle in order to match the required water and steam temperature values at the inlets and the outlets of the steam generator. The paper presents the suggested modifications and the evaluation of the operation after the transition.

The Effect of Water Flow Velocity on Heat Collection Performance of Active Heat Storage and Release System for Solar Greenhouses

In order to explore the influence of water velocity on the heat collection performance of the active heat storage and release system for solar greenhouses in Table l and, six different flow rates were selected for treatment in this experiment. The comprehensive heat transfer coefficient of the active heat storage and release system at the heat collection stage was calculated by measuring the indoor solar radiation intensity, indoor air temperature and measured water tank temperature. The prediction model of water temperature in the heat collection stage was established, and the initial value of water temperature and the comprehensive heat transfer coefficient were input through MATLAB software. The simulated value of water temperature was compared with the measured value and the results showed that the best heat transfer effect could be achieved when the water flow speed was 1.0 m3h-1. The average relative error between the simulated water tank temperature and the measured value is 2.70–6.91%. The results indicate that the model is established correctly, and the variation trend of water temperature can be predicted according to the model in the heat collection stage.

HEAT TRANSFER ANALYSIS AND TURBULENCE MODELS INVESTIGATION OF NUCLEATE BOILING FLOW IN NUCLEAR REACTOR APPLICATION

Boiling water exhibits an exceptionally high heat transfer coefficient, making it a valuable tool across numerous applications. However, once the heat flux surpasses a certain elevated threshold, the heated surface can no longer sustain continuous liquid contact. This is associated with a significant decline in heat transfer efficiency. The result may be a sudden spike in surface temperature within a heat flux-controlled system, or a dramatic decrease in power transferred in a temperature-controlled system. In the present study, the heat flux has been investigated in a circular channel heated by two roads. Parameters with emphasis on water flow velocity correlated with different heat transfer values from the roads. The methodology contains both laboratory experiments and a simulation model. The obtained results indicate that different heating surfaces play an important role in boiling heat transfer. Also, there is a clear relationship between the water flow and surface temperature. The amount of absorbed temperature increases by about 13% in a flow of 0.45 m/s. while in the water flow velocity 0.89 m/s and 1.34 m/s vary to 16.3% and17% respectively. The other impressive result is the phenomenon of alternate water temperature values due to certain regional temperatures. It's observed that there is a difference in heat absorption based on the amount of heat flux from the surface. The general rate of heat flux in the system was 6736.557 W/1°C for each square meter of heat generation. The obtained information is useful in controlling the boiling water reactor from sudden shutdown and also in controlling the boundaries in the design phase.<p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/soc/0789/a.php" alt="Hit counter" /></p>

Bi-Level Operation Optimization and Performance Analysis for a Distributed Energy System with Energy Network

The increasing energy crisis and environmental problems promote the development of distributed energy systems (DESs) that utilize combined heat and power technology, renewable energy technology, and waste heat recovery technology to meet various load requirements. Although there is existing work and research on a variety of DESs, most previous studies tend to focus on energy production with little consideration of a distributed energy network and its energy loss, which results in large errors in energy-efficiency calculations and performance analyses. In this paper, a new DES model is proposed with full consideration of an energy network and the full use of solar energy, terrestrial heat, and exhaust gases. At the same time, an effective bi-level optimization method is also proposed for the daily operation of the DES in order to improve the system performance and benefits in the energy, the economy, and the environment. Specifically, the co-generation energy station and water heating network in the DES are optimized separately with two different optimization models. The first-level optimization model is used to seek the optimal values of water mass flow rate and water temperature of the water heating network, and the second-level optimization model is built to determine the optimal energy purchasing strategy and the optimal energy outputs of the co-generation energy station. In order to verify the advantages and effectiveness of the proposed system and method, a contrastive simulation study is undertaken to provide a comparison of the global optimization method. Simulation results show that energy loss, energy cost, and energy consumption of the DES using the bi-level optimization operation strategy only account for 22.51%, 33.42%, and 51.31% of the quantities of the global optimization method, respectively. The hourly curves of the optimal operating variables also demonstrate that the proposed bi-level optimization method can improve the operating stability of the DES better than the global optimization method.

First use of Chironomid Pupal Exuvial Technique in freshwater biomonitoring in Cameroon: Ecological aspect and morphological description of Chironomidae (Insecta: Diptera)

The biodiversity of urban streams is gradually degrading as a result of anthropogenic pollution. In this study, chironomid pupal exuviae were used as surrogates to assess urban streams and a lake in Douala Cameroon. We compared these assessments with samples collected from a suburban forest stream. Based on their highly adaptive capability, we predicted that chironomid communities would present high diversity and abundance in urban habitats. Chironomid pupal exuviae were collected using the chironomid pupal exuvial technique in 14 urban and 2 forest reference stations during dry and rainy seasons. Measurements of the environmental variables were done simultaneously. Physicochemical analysis revealed that all urban sites have had very poor ecological health status whereas forest site had good water quality as shown by the hierarchical cluster analysis. This ecological survey identified 8 species/morphotypes of chironomids all belonging to the subfamily Chironominae, tribe Chironomini. These are Chironomus holomelas(?), Chironomus sp.1, Chironomus sp.2, Chironomus sp.3, Chironomus (Lobochironomus) sp., Stenochironomus sp., Dicrotendipes sp. and Dicrotendipes pulsus. No midge pupal exuviae were recorded at the forest stations (S1 & S2) and the stations S6 and S7 located downstream industrial mill effluents. The species richness of the study sites was significantly very low as compare to other Afrotropical studies. Canonical redundancy analysis revealed that high values of water temperature, ammonium, nitrates and phosphates, and low oxygen concentration were significant predictors of the distribution and high abundance of Chironomidae. This survey highlighted the impacts of anthropogenic activities on chironomid diversity and distribution, with great decrease of their diversity due to industrial pollution.

Detection and monitoring of MC-LR and MC-RR in the artifical irrigation ponds at Oltu district

Although it is defining as natural organic pollutant, surface water resources which are frequently exposed to Harmful Algae Blooms (HABs) due to the increasing nutrient loading in recent years, the increase in temperature caused by climate change and the increase in surface run-off caused by extreme rainfall as a result of the risk of the increasing concentrations of algal toxins into drinking water. Although HABs have caused the problem of eutrophication in surface waters especially at hot seasons in the past decades due to the water pollution, increasing surface water temperatures with climate change cause this problem to extended periods out of season and to be permanent for the year. Therefore, studies including the detection and monitoring of algal toxins are gaining importance in order to observe HAB events at their source. As global temperature increases, HAB events have spread to regions that have even cold climates. Consequently, Microcystin-LR (MC-LR) and Microcystin-RR (MC-RR), which are the main indicators of HAB events in surface waters were aimed to detect and monitor at the artificial ponds designed for agriculture and animal husbandry purposes in Oltu District of Erzurum Province which has cold climate, for the first time in this study.Microcystins (MCs) concentrations were measured in the samples taken from ponds in four seasons for one year, by LC-MS/MS and; water temperature and pH values were also determined simultaneously. The relationship between the MC-LR and MC-RR distributions and, the pH and temperature were calculated by Pearson Correlation Coefficient (r).

SST trends in certain areas of the Barents Sea in the winter season and mechanisms of their formation

The climate changes observed over the past few decades are most clearly manifested in the Arctic Ocean. Sea surface temperature (SST) is one of the most reliable indicators of climate change. In this paper we analyze the changes of winter SST for the western, northeastern and southeastern regions of the Barents Sea and examine the relationship of the emerging STS trends with the influence of various external factors. The working data set is represented by average monthly SST values taken from the ERA-5 reanalysis for the period 1949–2023 with a spatial resolution of 0.25×0.25° and average water temperature values on the Kola Meridian section in the 0–50 m layer. Additionally, the Arctic Oscillation (AO), Arctic Dipole (AD) and Atlantic Multidecadal Oscillation (AMO) indices were used as external factors that may affect SST variability. The time series analyzed was divided into three periods: 1949–1969, 1970–1990, 1991–2023, where the variability of the analyzed parameters was different. Thus, in the first period the trend in SST changes was negative, for the second period it was slightly negative or neutral, and for the third period it was positive. It is shown that SST in all the regions of the Barents Sea has undergone significant changes, which were most noticeable in the “warm” period of 1991–2023, when the rate of SST increasing was up to 10·10-2 °C/year in areas under the warm Atlantic water influence. The analysis of SST variability in the Barents Sea shows that the positive anomalies observed in the recent years are most likely associated with the changes in the atmospheric circulation. The Wavelet coherence analysis showed the closest agreement between the changes in the sea surface temperature and the AD index in the winter season, and with the AMO index.

Impacts of Adding Porous Media and Phase Change Material on Performance of Solar Water Distiller System Under Iraq Climatic Condition: An Experimental Study

ABSTRACTThis current investigation involves an experimental inspection of adding porous medium and phase change material (PCM) above the absorber surface to enhance the performance of a single slope and single basin solar water distiller system. To demonstrate the effectiveness of adding porous medium and PCM, the performance of the modified system and conventional system is compared under similar operating conditions. The system that uses porous medium and PCM is called MSS‐FPP, whereas the conventional system is called MSS‐F. Rectangular fins are fixed above the absorber plate for both models. For MSS‐FPP model, three different types of porous medium (stones, nuts, and black glass balls) are used in addition to paraffin wax filled inside circular tubes as a PCM. The data are collected in November and December 2023 in Mosul City, Iraq. The experiments are carried out under different water depths. The findings confirm that the performance of MSS‐FPP model is better than MSS‐F model by 41.32% (for water depth 3 cm) and 30.61% (for water depth 5 cm). The results also indicated that the water productivity of MSS‐FPP model is higher than MSS‐F model by 41.67% (for water depth 3 cm) and 30.65% (for water depth 5 cm). For MSS‐FPP model, the maximum water productivity and efficiency are obtained when using black glass balls as compared to nuts and stones types, where the highest water temperature and water productivity values are found equal 54°C and 1.01 kg/m2 for water depth 3 cm. The enhancement in the performance of modified solar water distiller system (MSS‐FPP) shows that using a porous medium and PCM has considerable impacts on the evaporation rate, heat exchange, and rate of heat transfer.

Water quality assessment in the Moulouya Estuary (Northeastern Morocco): The effect of wastewater on microbiological and physicochemical properties

The study concerns the Moulouya Estuary River, the second-longest African river that flows into the Mediterranean Sea, to evaluate the impact of wastewater discharges on water quality regarding its physicochemical and microbiological composition. The results showed that most studied parameters were influenced by seasonal variation and changed significantly from upstream to downstream (p < 0.05). The mean values of water temperature (22.5°C), pH (8.4), dissolved oxygen (6.7 mg/l), orthophosphate (0.03 mg/l), biological oxygen demand (5.9 mg/l), nitrates (10.12 mg/l), total suspended solids (89.75 mg/l), copper (7.8 µg/l), fecal streptococci (36 CFU/100 ml), fecal coliforms (81.5 CFU/100 ml), and total coliforms (179.5), conforms with the recommended surface water quality limits indicating excellent to good quality, except for, electrical conductivity (31618 µs/cm), sulfate (1049 mg/l), lead (116.67 µg/l), and cadmium (5.09 µg/l) indicating poor surface water quality. The mean values of Pb, Cu, and Cd exceed the limits values recommended for aquatic life. The water quality index (CCMEWQI) represents the overall quality, showing that the river studied is frequently threatened, and the conditions often deviate from desirable levels for aquatic life. The pollution index (PI) indicates that the water of Moulouya Estuary is slightly affected by Pb. However, the Metal Index (MI) indicates a significant environmental risk. Furthermore, a gradient of the Metal Pollution Index (MPI) was recorded in studied sites following the order: S2>S3>S4>S1. Although the study area does not present a significant microbial contamination problem, heavy metals and high-water mineralization are major concerns. These factors can have adverse effects on aquatic organisms and ecosystems, requiring attention and appropriate management measures to limit their impact.

Wpływ działalności antropogenicznej w dorzeczu górnego Dunaju na reżim temperatury wody Dunaju w Bratysławie

The man activity in the basin affects the water temperature in the increasingly higher levels (construction of water reservoirs, construction of thermal and nuclear power plants or drainage of waste water to streams). In this paper, we focused our attention on the evaluation of the impact of anthropogenic activity to increase the thermal load of the Danube River for the period 1926–2020 at the Bratislava (Slovakia) station. In the first part, the long-term trends of a series of monthly and annual water temperatures in the Danube (period 1931–2020) are identified. In the second part, the dependence of the range of daily water temperature values is analysed at the temperature of the atmosphere in Vienna. The impact of an increase in the temperature of the Danube water due to human activity was tried to identify for lower, average, and higher flows (for Danube discharge at Bratislava water gauge 1500 m3s-1, 2000 m3s-1, and 3000 m3s-1) by comparing two periods: 1932–1961, and 1991–2020. As the effect of water heating in the river stream is most noticeable during low flow (dry) periods and high air temperatures, only daily water and air temperature data from the warm months between May and September were used in the calculations. At monthly flow rates of 1500 m3s-1, the water temperature was, on average, 0.5°C higher during the period of 1991–2020 than it was during the period of 1932–1960. This growth could be attributed to human activities in the Danube basin above Bratislava (warming of water in the built tanks, the wastewater flow to the Danube flow, etc.)

Effects of different brewing conditions on acrylamide levels in Turkish black tea and health risk assessment

In this study, the effects of different brewing parameters (brewing method, teapot spout shape, brewing time, brewing water temperature) on acrylamide levels in black tea were investigated. Then, the level of acrylamide exposure from black tea consumption was evaluated in terms of carcinogenic and non-carcinogenic health risks. The average acrylamide level of all black tea samples brewed with 24 different methods was 53.2±17.1 µg/L. There was no significant difference in acrylamide levels (median) between brewing parameters except for the brewing water temperature value (p < 0.01). Individuals aged 15 years and over living in Türkiye were found to have an acrylamide exposure level in the range of 0.06−0.27 µg/kg bw/day. Consumption of brewed black tea according to different brewing parameters in light, normal and over-brewed forms was found to be safe in terms of non-carcinogenic health risks. However, acrylamide exposure levels indicate the presence of potential and significant health risks in terms of carcinogenic risks considering similar consumption patterns. When all the data are evaluated together, in order to reduce the acrylamide exposure level and potential health risks of acrylamide, black tea should be brewed with water at 95 ℃ and over-brewed tea consumption should be avoided.

A hybrid deep learning approach to predict hourly riverine nitrate concentrations using routine monitored data

With high-frequency data of nitrate (NO3–N) concentrations in waters becoming increasingly important for understanding of watershed system behaviors and ecosystem managements, the accurate and economic acquisition of high-frequency NO3–N concentration data has become a key point. This study attempted to use coupled deep learning neural networks and routine monitored data to predict hourly NO3–N concentrations in a river. The hourly NO3–N concentration at the outlet of the Oyster River watershed in New Hampshire, USA, was predicted through neural networks with a hybrid model architecture coupling the Convolutional Neural Networks and the Long Short-Term Memory model (CNN-LSTM). The routine monitored data (the river depth, water temperature, air temperature, precipitation, specific conductivity, pH and dissolved oxygen concentrations) for model training were collected from a nested high-frequency monitoring network, while the high-frequency NO3–N concentration data obtained at the outlet were not included as inputs. The whole dataset was separated into training, validation, and testing processes according to the ratio of 5:3:2, respectively. The hybrid CNN-LSTM model with different input lengths (1d, 3d, 7d, 15d, 30d) displayed comparable even better performance than other studies with lower frequencies, showing mean values of the Nash-Sutcliffe Efficiency 0.60–0.83. Models with shorter input lengths demonstrated both the higher modeling accuracy and stability. The water level, water temperature and pH values at monitoring sites were main controlling factors for forecasting performances. This study provided a new insight of using deep learning networks with a coupled architecture and routine monitored data for high-frequency riverine NO3–N concentration forecasting and suggestions about strategies about variable and input length selection during preprocessing of input data.

Response Surface Optimization of Refractance Window Drying of Bitter Gourd Slices

This study was conducted to investigate the drying behavior of bitter gourd (Momordica charantia L.) slices in a refractance window dryer. Various drying parameters such as water temperature (70, 80 and 90 °C), sample thickness (1, 2 and 3 mm) and blanching time (2, 3 and 4 min) were investigated for their effects on drying time, dehydration ratio and color change. Out of the 18 experimental runs determined by the Box Behnken design, six central experiments, often referred to as center points, were specifically chosen to assess the reliability of results. Four different empirical models viz. Exponential, Henderson and Pabis, Page's, and Power law model were selected based on their established applicability in similar studies, and fitted to the kinetics data of refractance window drying of bitter gourd. Adequacy of fit was assessed using the coefficient of determination (R2 ) and standard error of estimate (SEE). Page’s model demonstrated an excellent fit to the experimental drying data with a higher R2 value of 0.996 and correspondingly lower SEE of 0.0217 compared to the other three models. Furthermore, the drying process parameters were optimized for the responses using the Response Surface Methodology (RSM). The best values (within the chosen range) of water temperature, sample thickness and blanching time were found to be 90 °C, 1 mm and 4 min, respectively at desirability value of 0.889. At above condition of water temperature (90 °C), sample thickness (1 mm) and blanching time (4 min), the predicted values for the drying time, dehydration ratio and color change were found to be 52.2 min, 9.7 and 55.25, respectively. The findings of this study will be useful for refractance window drying of bitter gourd in particular and for high moisture foods in general.

Chemical separation of petroleum crude oil emulsions using two new poly(ionic liquid)s

AbstractThis work aims to prepare new poly(ionic liquid)s (PILs) and use them for crude oil emulsion separation (EES). PILs were synthesized by an opening ring reaction of hexadecylsuccinic anhydride (HAS) using polyethyleneimine branched MW 600 (PEI) and triethylenetetramine (TTA) in a one‐step procedure, obtaining PILs, HSPI‐PIL, and HSTA‐PIL, respectively. Chemical structure, interfacial tension, aggregate size, and thermal behavior were verified using several techniques. The efficiency of HSPI‐PIL and HSTA‐PIL toward EES was explored using different parameters, including water content (WC), demulsifier concentration, temperature, and pH value. The results indicated that EES proportionally increased with increased WC and temperature. The data also revealed that increased demulsifier concentration improved EES at low WC, for example, 10% and 30%; however, this parameter showed no significant effect with crude oil emulsion containing high WC, for example, 50%. Furthermore, HSPI‐PIL and HSTA‐PIL gave the maximum EES values at a pH of 7, while they decreased in acidic and basic mediums.

Dynamic modeling of a centrifugal chiller with hybrid falling film evaporator including pressure drop computation

Over the last decade, the introduction of new technologies such as falling film evaporators and advanced control techniques has significantly enhanced chiller efficiency while reducing refrigerant charges. However, the complexity of the involved transport phenomena poses significant challenges in simulating the behavior of these devices, resulting in very few validated models that encompass such advances. This study introduces a novel dynamic model for centrifugal liquid chillers with a hybrid evaporator (one that combines features of falling film and flooded designs). Employing the moving boundary method, the model incorporates the intricacies of the transport phenomena, including the pressure drop across the tube bank, with relatively low computational requirements. Implemented in OpenModelica, the model was validated using performance data from a 550 TR centrifugal chiller, yielding normalized residual errors of less than 0.5% for values of supply water temperature and power consumption. This provides a comprehensive tool suitable for analyzing chiller performance as a function of the evaporator geometric characteristics and enabling optimal dynamic control of central cooling systems incorporating this kind of chillers, as long as contributes to the development of dynamic and steady state models of vapor compression centrifugal chillers with falling film evaporators.

Dynamics of changes in the temperature coefficient of electrical conductivity of distilled water in conductometric cells during heating and cooling

The problem of taking into account the influence of air on the properties of distilled water is considered, namely the lack of a single generally accepted method for calculating such an influence. The sensitivity of the structure of water to the influence of external factors is described and the possibility of recording and studying such factors by changes in the temperature coefficient of electrical conductivity of water is shown. The dependences of the temperature coefficient of electrical conductivity of distilled water on the rate of change in water temperature, the degree of filling of conductometric cells, as well as on the intensity of the exchange of carbon dioxide between water and air across their interface have been studied. It is noted that these metabolic processes are currently insufficiently studied. A hardware-software measuring complex has been developed and manufactured to study the temperature coefficient of electrical conductivity of water when its temperature changes within the range of 20–55 °C. The temperature coefficient of electrical conductivity of water in sealed conductometric cells was measured at different degrees of filling the cells with distilled water and the rate of heating and cooling of water. The degree of filling of the cells varied within the range of 10–100 %, the rate of change in water temperature varied within the range of 0.04–2.00 °C/min. With a constant heating and cooling time of 15 minutes in all experiments, the change in speed was achieved by changing the temperature of the heating element. The integral temperature coefficient of electrical conductivity is calculated based on the initial and final values of electrical conductivity and water temperature in each measurement cycle. The dependences of the temperature coefficient of electrical conductivity on the rate of change in water temperature at several constant degrees of cell filling were obtained. It has been shown that with a constant ratio of the volumes of water and air in the cell and an increase in the rate of heating of water, the temperature coefficient of electrical conductivity of water decreases by 19–22 %. It has been established that at a constant rate of water heating, with a decrease in the volume of water in the cell, the temperature coefficient of electrical conductivity of water decreases by 40–42 %. The results obtained can be used to quantify the dissociation coefficient of carbonic acid, the mobility of hydrogen ions, as well as the intensity of the gas exchange process under various external influences on water. Refinement of data on the electrical conductive properties of water and processes at the water/air interface is necessary for the development of models of atmospheric phenomena and climate change, as well as for the creation of sensors for weak changes in environmental parameters for the purposes of both environmental monitoring and medical diagnostics.

Ecological risk assessment, source identification and spatial distribution of organic contaminants in terms of mucilage threat in streams of Çanakkale Strait Basin (Türkiye)

In this study, the spatial distributions of organic contamination stressors in water of fluvial habitats in the Çanakkale Strait (ÇS) watershed were investigated and the data were assessed in terms of human health and mucilage threat. Seven significant riverine ecosystems flowing into the ÇS were defined in the basin. Water samples were taken in the spring season (2023), when the phytoplankton communities reach their highest densities. Then they were tested for a total of 8 limnological parameters.The Nutrient Pollution Index (NPI) and Water Quality Index (WQI) were applied to assess the comprehensive quality characteristics of waters. The Hazard Quotient (HQ) and Hazard Index (HI) were applied to indicate the prospective non-carcinogenic human health risks of organic stressors. Principal Component Analysis (PCA) and Cluster Analysis (CA) were applied to categorize the investigated habitats and define the sources of investigated contamination parameters. Also, Geographic Information System (GIS) was used to make an effective assessment through visualization.The determined spatial mean values of the measured variables in ÇS watershed as follows: 18.21 °C for temperature, 8.51 mg/L for DO, 4.57 NTU for turbidity, 3.95 mg/L for suspended solids, 1.11 mg/L for NO3–N, 0.012 mg/L for NO2–N; 0.173 mg/L for PO4–P and 2.32 mg/L for BOD. It has been determined that the organic pollution loads and water temperature values of the investigated sub-basins increase from the upstream to the downstream locations and Çanakkale Stream was recorded as the riskiest fluvial habitat for the ÇS watershed. According to the results of health risk assessment indices, non-carcinogenic risks of organic pollutants would not be expected for all age groups.

Land use in catchments of small streams and a hydrological urban heat island – a case study in Kielce city (Poland)

ABSTRACT This article presents the spatial and temporal value and dynamics of water temperature in small streams flowing through a city of 200,000 inhabitants. The analysis is based on stationary measurements of a water temperature in eight (8) catchment outlets of various uses (including forest, suburban, urbanised). The water temperature was measured daily for 4 years (06 UTC; electronic thermometers; accuracy: 0.1°C). The study has shown that the water temperature in streams is clearly modi fied by the nature of land use prevailing in the catchment, represented by the imperviousness index. Urbanised areas caused a significant increase in minimum, mean and maximum temperature values on a daily, monthly and annual cycle. The determined relationship indicates that every 1% increase in impervious catchment area causes a water temperature increase of 0.1°C. The presented and documented facts justify the use of the term ‘hydrological urban heat island’, which began to appear in the literature.