Oxygen Meter Research Articles

Internet based highly secure data transmission system in health care monitoring system

<span>The health care systems in our contemporary countries are advancing rapidly in terms of maturity and professionalism. In an effort to alleviate the current burden on the public health system and boost the popularity of regular health self-checks, this method has been developed for producing prediagnoses that are easier to use, quicker, and more accurate. To ascertain how well the heart is circulating oxygen throughout the body, a pulse test, a painless examination that measures an individual's degree of oxygen saturation, is used. It can be used to evaluate the state of any patient with a disease, particularly those with pulmonary problems. Diseases in these patients could need ongoing observation and care. Our system comes to the rescue in order to resolve this problem. This portable system is simple to use and may be taken anywhere by the subject. The internet of things (IoT) will update the pertinent parameters. This health monitoring system's controller is made up of an adaptor, a saturation of peripheral oxygen (SPO2 ) sensor (a blood oxygen meter), a temperature sensor, a heart rate sensor, a WiFi module, and a liquid crystal display (LCD).</span>

Determination of saturated dissolved oxygen concentration in iron sulfate solutions containing iron oxidizing microorganisms

Iron sulfate solutions and the extremophile lifeforms that can live within them are industrially and environmentally important in many applications and require proper assessments of solution properties. Determination of saturated dissolved oxygen concentration is an important parameter for monitoring iron biooxidation processes. However, its determination is not so straight forward using commercially available dissolved oxygen meters. Such meters utilize internal calculation models based on the saline properties of seawater which can be easily overlooked. A method for determination of the saturated dissolved oxygen concentration in acidic iron sulfate solutions with the inclusion of other inorganic salts is proposed in this work using the biooxidation of ferrous iron as an indicator measured with redox potential and converted to oxygen concentration through bioreaction stoichiometry. The technique was tested on a BioGenerator system over the course of four days and proved satisfactory in establishing a value for the saturated dissolved oxygen concentration of the bioreactor broth. Study of the lifespan properties of the microorganisms in absence of ferrous iron substrate was briefly examined to determine the effective handling period of solutions for assessment.

Appraisal on heavy metal contamination in tissues (gills, intestine, liver, and fillet) of <i>Parachanna obscura</i> and the physicochemical properties of Oguta Lake, South-Eastern Nigeria.

The aim of this study is to provide baseline data on the investigation of concentrations of copper (Cu), lead (Pb), iron (Fe), manganese (Mn), and zinc (Zn) in various tissues (gills, intestine, liver, and fillet) of Parachanna obscura in Oguta Lake, and to assess physicochemical properties of Oguta lake to determine level of pollution and contamination. Twenty fish samples in total were collected at the fishermen landing site of the lake and analyzed using the Atomic Absorption Spectroscopy (AAS). Dissolved oxygen and temperature were measured on site using dissolved Oxygen meter (model 5509) and Mercury-in-glass thermometer respectively, while other parameters were analyzed in the laboratory. Results indicated Fe had the highest concentrations (1.479±0.003 mg/kg) especially in the gills, while Mn recorded least concentrations (0.001±0.000) mg/kg) of all metals analyzed. Values for Cu (0.026±0.002 mg/kg), Mn (0.001±0.000 mg/kg), Zn (.782±0.015 mg/kg), and Fe (1.479±0.030 mg/kg) levels were within FAO/WHO permissible limits in all tissues, whereas Pb (1.438±0.015 mg/kg) exceeded standard limits especially in the gills and intestines, indicating potential contamination and threats to aquatic and human health. Heavy metal concentrations in the tissues followed the order: gills > intestine > fillet > liver. The physicochemical properties assessment of Oguta Lake indicated a stable temperature with mean value of (28.02±022 C). The lake's temperature supports aquatic life, but challenges like low transparency (1.22±0.13 m), acidic pH levels (5.83±0.09), elevated ammonium levels (0.63±0.03 mg/l), low nitrate-nitrogen levels (0.0±50.00 mg/l), and fluctuating dissolved oxygen (6.50±0.29 mg/l) levels suggests pollution from agricultural runoff or sewage. The findings proffer effective management through pollution control, enhanced buffering capacity, and rigorous monitoring to safeguard biodiversity and ensure longterm ecological health.

Effectiveness of an Endotracheal Tube Adjustable Stabilizing Set to Prevent Unplanned Extubation in Preterm Infants: A Quasi-experimental Study

Preterm infants born before 34 weeks of gestation often face respiratory challenges and may require resuscitation with an endotracheal tube and ventilator support. Unplanned extubation is a common problem for such infants, affecting their care and outcomes. This quasi-experimental study compared the incidence of unplanned extubation, stability of vital signs and oxygen saturation between a control group (n = 24) receiving routine care in a neonatal intensive care unit and an experimental group (n = 24) receiving routine care along with the use of the Endotracheal Tube Adjustable Stabilizing Set, developed by the researchers. The latter set comprises an endotracheal tube-holding cap, head-locked pillows, and an oxygen meter. Data were analyzed using descriptive statistics, t-tests, chi-square tests, and Fisher’s exact tests. Results show that the control group had an average tracheal tube insertion time of 78.94 hours, while the experimental group had an average of 39.35 hours. The incidence of unplanned extubation was 33.33% (8 cases) in the control group and 4.17% (1 case) in the experimental group. The unplanned extubation rate per 100 ventilator days was 4.41 times in the experimental group, significantly less than in the control group (23.84 times). The experimental group also exhibited significantly more time spent on vital signs and oxygen saturation within normal limits than the control group. In conclusion, using the Endotracheal Tube Adjustable Stabilizing Set in neonatal care can improve patient outcomes by reducing the incidence of unplanned extubation and stabilizing vital signs. This set has passed patentability evaluation for product design and enhances neonatal care by stabilizing endotracheal tubes, reducing slippage, and helping nurses provide more effective care. However, further testing in different settings with larger sample sizes and an equal average tracheal tube insertion time between the two groups is recommended to validate these findings.

Comparative Evaluation of Water Quality Properties: A Case Study of Coupled Commercial Aquaponics System

The current study intends to evaluate the influence of seasonal changes on the water quality parameters of a coupled commercial aquaponics system. The determined water quality parameters for the comparative study were total ammonium-nitrogen (TAN), nitrate-nitrogen (NO3-N) and phosphate (PO43-), water temperature (WT), water pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). The WT and DO analysis were carried out using a portable dissolved oxygen meter (Model: PDO-520, Taiwan). A portable electrode pH meter (Model: PH-220, Taiwan) was utilized for the pH measurement. The TDS and EC readings were obtained using a multi-parameter water quality meter (PHT-27, China). The TAN, NO3-N, and PO43- determinations were done using their individual Merck Spectro-quant® test kits. The research results indicated a significant (p0.05) difference. The observed significant increase of NO3-N, PO43-, EC, and TDS in the summer and autumn periods could be associated to the increased fish feeding rate (which increases waste production) as well as relative increase in microbial waste conversion/mineralization. The investigated water quality makers were within the recommended amounts in the aquaponics system. Thus, in this study, seasonal differences have induced variation in the NO3-N, PO43-, WT, pH, EC, and TDS amounts. However, these differences do not affect the TAN and DO levels.

SPATIO-TEMPORAL EVALUATION OF FERORO STREAM WATER QUALITY, CHIKUN LOCAL GOVERNMENT AREA OF KADUNA STATE, NIGERIA

Aquatic environment is faced with pollution problems most of which are anthropogenic in nature. Feroro stream water was evaluated for its quality and suitability for the growth of organisms. The temporal and spatial qualities of the water was observed to be deteriorating. Water sampling was done once monthly for twenty-four months from five stations along the stream. The water samples were put into 2-litre sterilized plastic bottles. Some physical and chemical parameters were determined using HANNA meter, Dissolved oxygen meter, titration and colorimeter methods. All the parameters tested ranged within Federal Ministry of Environment standard limits. Turbidity and Total Hardness are above the standard limits. There was significant difference temporally P<0.05. Electrical Conductivity was significant different in all the stations P<0.05, lowest at Station 1(137.55µS/cm) and high at Station 5 (235.21µS/cm). Across the wet and dry seasons, the parameters significantly varied except in Temperature (25.79±0.12 and 25.57±0.26) and Total Hardness (119.68±6.13 and 109.50±3.38) P<0.05.

The relationship between ischemic penumbra progression and the oxygen content of cortex microcirculation in acute ischemic stroke

The precise oxygen content thresholds of ischemic deep parenchymal (OCIDP) and that in cortical microcirculation (OCCM), which leads to ischemic penumbra converting into the infarcted core, remain uncertain. This study employed an invasive fiber-optic oxygen meter and a newly developed oxygen-responsive probe called RuA3-Cy5-rtPA (RC-rtPA) based on recombinant tissue-type plasminogen activator (rtPA) to examine the oxygen content thresholds. A mouse model of middle cerebral artery occlusion was generated and animals were randomly divided into a sham, 24-h reperfusion after 3-h ischemia (IR 3-h), and IR 6-h groups, all of which were sacrificed following reperfusion. Stroke severity was evaluated based on the infarction area, neurological symptoms, microcirculation perfusion, and microemboli in microcirculation. OCIDP was characterized based on its extent and distribution, whereas OCCM was measured using RC-rtPA. During ischemia, stroke severity escalation manifested as increasing infarction area, severe neurologic symptoms, and poorer microcirculation perfusion with more microthrombi depositions. OCIDP presented rapid decline following artery occlusion along with a gradual increase in the hypoxic area. Within 3 ​h following ischemia induction, the ischemic tissue that experienced hypoxia could be rescued, and this reversibility would disappear after 6 ​h. Within 6 ​h, OCCM continued to decrease. A significant decrease in oxygen content in cortical venules and cortical parenchyma was observed. These findings assist in establishing the extent of the ischemic penumbra at the microcirculation level and offer a foundation for assessing the ischemic penumbra that could respond positively to reperfusion therapy beyond the typical time window.

Photocatalytic water oxidation by iron and copper phthalocyanine complexes immobilized on Fe3O4@SiO2@TiO2 under visible light irradiation

In this research, the heterogeneous catalysts of Fe3O4@SiO@TiO‐FePc and Fe3O4@SiO@TiO‐ CuPcN (FePc = iron (II) phthalocyanine and CuPcN = copper (II) tetraazaphthalocyanine), termed respectively as nanocomposites 1 and 2, were prepared by immobilizing the FePc and CuPcN complexes on the Fe3O4@SiO@TiO surface and used for the photocatalytic water oxidation reaction. Since phthalocyanine complexes have received very little attention as photocatalysts for water oxidation, the advantage of the synthesized photocatalyst owes to the ability of the phthalocyanine complex grafted on the titanium substrate to oxidize water in the photocatalytic reaction. The prepared nanocomposites were then studied by diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), Fourier transform infrared (FT‐IR) spectroscopies, thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), Brunauer–Emmett–Teller (BET) analysis, ultraviolet diffuse reflectance (DRS), and photoluminescence (PL) spectroscopies. The photocatalytic response of water oxidation by nanocomposites 1 and 2 was investigated in the presence of silver nitrate as an electron recipient at ambient temperature. The progress of the water oxidation reaction was monitored with an oxygen meter. The amount of oxygen generated in the presence of nanocomposites 1 and 2 under visible light irradiation was found to be 2.6 and 2.1 mg L−1, respectively. Owing to the existence of magnetic material, these nanocomposites can be effortlessly removed from the response medium with an external magnet. The involved nanocomposites can be used up to three times in catalytic water oxidation reactions with no significant change in their photocatalytic activity.

DOxy: A Dissolved Oxygen Monitoring System.

Dissolved Oxygen (DO) in water enables marine life. Measuring the prevalence of DO in a body of water is an important part of sustainability efforts because low oxygen levels are a primary indicator of contamination and distress in bodies of water. Therefore, aquariums and aquaculture of all types are in need of near real-time dissolved oxygen monitoring and spend a lot of money on purchasing and maintaining DO meters that are either expensive, inefficient, or manually operated-in which case they also need to ensure that manual readings are taken frequently which is time consuming. Hence a cost-effective and sustainable automated Internet of Things (IoT) system for this task is necessary and long overdue. DOxy, is such an IoT system under research and development at Santa Clara University's Ethical, Pragmatic, and Intelligent Computing (EPIC) Laboratory which utilizes cost-effective, accessible, and sustainable Sensing Units (SUs) for measuring the dissolved oxygen levels present in bodies of water which send their readings to a web based cloud infrastructure for storage, analysis, and visualization. DOxy's SUs are equipped with a High-sensitivity Pulse Oximeter meant for measuring dissolved oxygen levels in human blood, not water. Hence a number of parallel readings of water samples were gathered by both the High-sensitivity Pulse Oximeter and a standard dissolved oxygen meter. Then, two approaches for relating the readings were investigated. In the first, various machine learning models were trained and tested to produce a dynamic mapping of sensor readings to actual DO values. In the second, curve-fitting models were used to produce a successful conversion formula usable in the DOxy SUs offline. Both proved successful in producing accurate results.

The use of Iron Sand as Filtration Media for Slaughterhouse Wastewater Treatment

An increase in slaughtering animals will have an impact on increasing the liquid waste produced. The resulting RPH liquid waste can damage the environment if it is not treated, so it is necessary to conduct research to reduce pollutant levels so that it is suitable for disposal into the environment. The technique used in processing RPH wastewater is iron sand filtration method. Iron sand filtration is a filtering process using renewable media, namely iron sand. Iron sand is known to contain the mineral magnetite (Fe3O4) which has the ability to absorb colloidal solids, so it has the potential to be used to remove pollutant content of RPH liquid waste. This research objective to determine the effect of variations in the thickness of the filtration media (cm) and grain size (mesh) on pollutant parameters. The thickness variations used were 20, 25, and 30 cm, with grain sizes of iron sand 40, 60 and 100 mesh. The experimental results showed that the iron sand filtration method was able to reduce Chemical Oxygen Demand (COD) and Total Suspended Solid (TSS) levels, increase the Dissolve Oxygen Meter (DO) value, and change the pH value. The highest reduction in COD was in the thickness variation of 30 cm with 100 mesh. the percentage of decrease in the value of Chemical Oxygen Demand (COD) was 95.05%, the highest decrease in Total Suspended Solid (TSS) value was in the media thickness variation of 30 cm with 100 mesh, the percentage of TSS value reduction was 97.11%, the pH value increased in the thickness variation media 30 cm with a mesh number of 100 from 5.8 to 7.4, and the value of Dissolve Oxygen Meter (DO) increased with variations in thickness of 30 cm with 100 mesh, increased from 1.2 to 15.2. Based on the parameter test results, it was concluded that iron sand filtration is effective in reducing pollutant levels below the quality standard, so that it is expected to be applied directly on a larger scale.

Determination of Henry's law coefficient of oxygen in LAB for JUNO

The Jiangmen Underground Neutrino Observatory (JUNO) requires that the detector use liquid scintillator with an extremely low background to achieve the desired measurement accuracy of neutrino mixing parameters. In addition, the production process of the liquid scintillator must avoid radon gas contamination caused by equipment leakage. Direct measurement of radon gas in liquid scintillator is an option for system leak detection. However, considering the low percentage of radon gas and high percentage of oxygen in air, the measurement of oxygen in liquid scintillator will have higher sensitivity. Based on Henry's law and the measuring principle of a dissolved oxygen meter, an experimental device is designed to measure Henry's law coefficient and calibrate the dissolved oxygen meter. Henry's law coefficient of oxygen in linear alkylbenzene (LAB) at 23.6 °C derived from an experimental measurement is 2.09 × 107 ± 2.54 × 106 Pa·L·mol-1. The feasibility of using a dissolved oxygen meter to measure the dissolved oxygen content in LAB is verified by calibrating the dissolved oxygen meter.

Evaluation of rise in pH and oxygen release at the site of simulated external root resorption cavities using different oxygen-releasing biomaterials: An in vitro study.

External inflammatory root resorption has rapid onset and progresses aggressively. It leads to cementum loss, which allows communication between the infected pulp and the periodontium through the denuded dentinal tubules. Primary management strategy includes adequate chemomechanical debridement and lesion arrest for which maintaining alkaline pH and aerobic conditions is essential for healing and repair of the resorption defect. The aim of this study is to evaluate rise in pH and oxygen release at the site of simulated external root resorption cavities using different oxygen-releasing biomaterials. In 40 extracted single-rooted teeth access opening and chemomechanical debridement were done. Cavities simulating resorption defect are prepared on the roots. The samples are divided into four groups (n = 10) based on the biomaterial used. After placing the biomaterial, the root apices were sealed. Half of the samples from each group were tested for oxygen release using dissolved oxygen meter and the other half for rise in pH using pH meter at 7, 14, 21, and 28 days. The pH values were analyzed using Friedman 2-way analysis of variance (ANOVA) and Kruskal-Wallis test. Oxygen release was measured using the two-way and repeated-measures ANOVA. Calcium peroxide group showed the highest mean pH and oxygen release than other groups at any given point of time. Incorporating oxygen-releasing biomaterials such as calcium peroxide and perfluorodecalin into intracanal medicaments, such as calcium hydroxide, creates an alkaline and oxygen-enriched milieu in the periapical tissues.

Prediction of Respiration Measurement Based on Temperature Differences of Fresh Strawberry (Fragaria x Ananassa var. Kelly Bright) in a Tropical Environment

Strawberry is a high-economic-value horticultural product that can be cultivated in tropical areas like Indonesia. Horticultural products retain their metabolism after harvest, such as respiration, which is an indicator of the degradation of products during storage. This study aimed to determine the best equation for predicting the respiration of strawberries cultivated using hydroponics in a greenhouse in Cangkringan, Yogyakarta. The respiration rate during storage was measured using an oxygen meter (DO-5510, Lutron, Taiwan) and a carbon dioxide meter (GH-2018 model, Lutron, Taiwan) in a closed system using an acrylic closed chamber. Five types of Michaelis-Menten equations were chosen as the best type based on R². The Arrhenius equation was used to get the highest value of R2 to predict the effects of temperature on respiration. Statistical analysis was used to determine the impact of treatments on the respiration rate. Based on the Arrhenius equation, the respiration of strawberries on postharvest in tropical environments depended on temperature. The best type for predicting the respiration of strawberries using the Michaelis-Menten mathematical model is competitive with an R2 value of 0.88. Therefore, the appropriate postharvest treatment is essential to add carbon dioxide or reduce oxygen levels.

Physical and Chemical Scrutiny of Obizi River in Awka South Local Government Area of Anambra State, Nigeria for Domestic Consumption

The Obizi River in the Awka South Local Government Area of Anambra State was examined physically and chemically to evaluate its contamination level and suitability for home use. It is important for recreational, fishing, cooking, drinking, and other applications. Its typical applications for drinking, cooking, fishing, recreational activities and other uses are limited since it flows through a canal that might be contaminated by industrial, agricultural, and other human activities. Nitrate mg/l, nitrite mg/l, magnesium mg/l, zinc mg/l, total dissolved solid (TDS) mg/l, hardness mg/l, sulphate mg/l, phosphate mg/l, alkalinity mg/l, acidity mg/l, sodium mg/l, biological oxygen demand (BOD) mg/l, chemical oxygen demand (COD) mg/l, total suspended solid (TSS) mg/l, TS mg/l, oxygen demand (OD) mg/l, and potassium mg/l are among the parameters that were evaluated. Total dissolved solids (TSS) were calculated as the difference between total solids and total dissolved solids. The zinc and nitrate elements within the samples were measured using the ultraviolet (UV) VIS spectrophotometric method. Sulphate was determined turbidimetrically by the absorption spectrophotometry. Magnesium content, total hardness, and alkalinity were measured through titration. TDS (mg/L) was measured with a Multi-Meter (HI 991300, Hanna Equipments, Romania), potassium and sodium ions were assessed by flame photometric technique, chemical oxygen demand (COD) was identified photometrically using the SpectroQuant Nova 60 COD cell test (Merck) in the range of 10 – 150 mg/L. Biological oxygen demand (BOD) was determined using the OxiDirect BOD system and total suspended solids (TSS) was calculated as the difference between total solids and total dissolved solids. Phosphates were measured using the ascorbic acid method, total solids were estimated gravimetrically, and oxygen demand (OD) was measured on-site using a dissolved oxygen meter JENWAY-3405 (Manufacturer: Barloworld Scientific Ltd., England). To find out if the results were significant or not, the parameters were subjected to an ANOVA single factor analysis. The analysis's conclusion was that the data were statistically not significant. Since nitrate and OD were above the World Health Organization's (WHO) limit while most other physicochemical parameters were below it, the ANOVA result showed that there was no significant difference between the physicochemical characteristics of the water samples. With the exception of nitrite and OD, which are above the WHO limit for domestic drinking water and other purposes, it was discovered that the majority of the physicochemical parameters fell within the organization's water quality standards for these purposes. As a result, the water quality is not good and should not be drunk unless treated.

Construction and validation of a method for automated time label segmentation of heart sounds.

Heart sound detection technology plays an important role in the prediction of cardiovascular disease, but the most significant heart sounds are fleeting and may be imperceptible. Hence, obtaining heart sound information in an efficient and accurate manner will be helpful for the prediction and diagnosis of heart disease. To obtain heart sound information, we designed an audio data analysis tool to segment the heart sounds from single heart cycle, and validated the heart rate using a finger oxygen meter. The results from our validated technique could be used to realize heart sound segmentation. Our robust algorithmic platform was able to segment the heart sounds, which could then be compared in terms of their difference from the background. A combination of an electronic stethoscope and artificial intelligence technology was used for the digital collection of heart sounds and the intelligent identification of the first (S1) and second (S2) heart sounds. Our approach can provide an objective basis for the auscultation of heart sounds and visual display of heart sounds and murmurs.

Determination of the efficiency of oxygen removal from water from the ratio of the concentrations of sodium sulfite and the iron catalyst

The main issue of corrosion activity is the removal of oxygen from water. Under certain conditions, inhibitors-passivators are effective. Other methods based on thermal and vacuum deaeration of water. These methods are energy-consuming and do not provide the necessary quality of water, so chemical reagents are used for deep deoxidation of water regardless of secondary pollution.
 In this work, distilled water with a certain concentration of oxygen was placed in a hermetic container. The calculated amount of sodium sulfite solution (sodium metabisulfite) was added to the water and after certain intervals the oxygen concentration in the water was recorded using an oxygen meter, the sensor of which was placed in the container before. In another series of experiments, calculated amounts of sodium sulfite and iron sulfate solutions were added to the water, the container was quickly closed and the oxygen concentration in the water was recorded at certain intervals.
 It has been shown that in distilled water at room temperature, sodium sulfite interacts very slowly with oxygen. In 1 hour, the rate of oxygen recovery increases from 27.7 % to 56.9 % when the sulfite concentration increases from 50 to 300 mg/dm3. It was established that iron (II) ions significantly accelerate the rate of oxygen reduction by sulfite already at an iron concentration of 0.1 mg/dm3 at a sulfite concentration of 50-300 mg/dm3. According to the integral kinetic curves of the 0th, 1st, 2nd, and 3rd orders, kinetic models of sulfite oxidation in distilled water with oxygen in the presence of iron ions were determined.
 It is shown that when the concentration of sulfite increases to 200, 300 mg/dm3, with an iron concentration of 0.5‑1.0 mg/dm3, the oxidation processes follow first-order reactions and their speed is determined by the oxygen concentration. When the concentration of iron and sulfite is reduced, the realization of oxidation processes according to the reactions of the 2nd and 3rd orders was noted, when the speed of the process depends not only on the concentration of oxygen, but also on the concentration of sulfite (2nd order) and iron ions (3rd order) .
 This work is aimed at solving the relevance of the problem of water deoxidation for water preparation in cooling systems. The direction of the research is very promising considering the satisfactory and effective results obtained and the inexpensive chemical reagents used. Further research will be aimed at finding ideal conditions for the reaction and finding optimal concentrations of reagents while ensuring maximum efficiency of the process, which in turn will bring mankind a solution to the problem of spending large amounts of money, chemical reagents and environmental pollution.

Proposed synergies between oceanography and metrology

Accurate and traceable measurements are required to understand ocean processes, to address pressing societal challenges, such as climate change and to sustainably manage marine resources. Although scientific and engineering research has resulted in advanced methods to measure Essential Ocean Variables (EOVs) there is a need for cross comparison of the techniques and traceability to recognized standards. Metrological laboratories are experienced in accredited methods and assessment of methodology. An EU INFRAIA-02-2020: Integrating Activities for Starting Communities project MINKE (Metrology for Integrated marine maNagement and Knowledge-transfer nEtwork https://minke.eu) brings European marine science and metrology Research Infrastructures together to identify synergies and create an innovative approach to Quality Assurance of oceanographic data. Quality depends both on the accuracy (that can be provided through the metrology component) and the completeness of the data sets. The collaboration between different Marine Research Infrastructures (RIs) places a fundamental role on assuring the completeness of the datasets, particularly at global scales. The MINKE project encourages enhancement through collaboration of national metrology laboratories and the oceanographic community. Metrological assessment of the accuracy and uncertainties within multidisciplinary ocean observations will provide data that are key to delivering policy information. Objectives across all the RIs are to facilitate ocean observation and build wider synergies. MINKE will investigate these synergies, then introduce metrology to the core of various EOV measurements. Currently the marine RIs cover laboratory and field operations, from the surface seafloor, coastal waters to deep sea, fixed ocean stations to ship and autonomous vehicle operations to ships of opportunity, and flux stations focusing on carbonate system variables. The nexus of these operations is the focal point for coordinated improvement of ocean observing methods. Measurement intercomparisons, traceability and uncertainty assessments should be at the core of the scientific observations. Specifically, MINKE will work with RIs and Metrology Institutes to improve the quality of dissolved oxygen, carbonate system, chlorophyll-fluorescence, ocean sound and current meter measurements, through access to metrology laboratories, Transnational Access and intercomparison studies across existing marine consortia and RIs. MINKE will also promote the development of absolute salinity observation, and improvements in marine litter measurements.

Seasonal variation of gross ecosystem productivity of periphyton in three post-mining lakes in the Czech Republic, Europe

We investigated the seasonal variation of gross ecosystem productivity (GEP) of periphyton biomass in three post-mining lakes in the Czech Republic. These lakes were established as part of recultivation efforts after coal mining activities and resulted in a unique series of anthropogenic oligotrophic lakes of gradual successional age. Periphyton is ubiquitous in aquatic habitats and performs numerous environmental functions such as nutrient cycling and self-purifying of aquatic ecosystems. Well-developed periphyton mat can be formed within a few weeks, so it can quickly become the dominant of littoral zone of newly established lakes. In studied post-mining lakes, the highly developed periphytic community covers the littoral zone of each lake to the depth of 2m (Bešta et al. 2022, Konopáčová et al. 2023) Fig. 1. We aimed to shed some new light on the processes controlling the dynamics of primary productivity in oligotrophic lakes. The accurate estimation of primary productivity is crucial for understanding the functioning of aquatic ecosystems, as primary productivity serves as the primary source of autochthonous carbon in these systems. In addition to phytoplankton, periphyton can significantly contribute to primary productivity in littoral zones, known for their high productivity and biodiversity. Conducting in situ measurements provides the most accurate means of inferring the metabolic activity of primary producers in littoral zones. We conducted detailed seasonal in-situ periphyton gross primary production (GPP) measurements in three post-mining lakes with different successional ages (Čapková et al. 2022). GPP and NPP of periphytic biomass were determined using direct in-situ measurement of O2 fluxes. O2 production and consumption were measured over 5 hours of in-situ light and dark gas-tight glass bottle incubation. Bottles were filled with the lake water from the corresponding depth, and a similar amount of periphytic biomass was enclosed Fig. 2. We used the Fibox3 fibre-optic oxygen meter coupled with a PSt3 oxygen sensor (PreSens, Regensburg, DE) to measure changes in O2 concentration. The O2 fluxes were normalized to periphytic biomass in each bottle (measured as total organic carbon). Data were corrected for O2 concentration changes in dark and light gas-tight bottles containing lake water without periphytic communities. This setup enabled us to monitor online oxygen flux, therefore, insights into metabolic activities. The primary productivity was measured in real-time, allowing us to capture the quantitative effect of various environmental drivers on periphyton productivity, i.e. phosphorus concentration and light intensity, as they are known to play significant roles in primary productivity. We showed that the primary production of periphyton mats exhibited seasonal variations, with higher productivity observed in spring compared to other seasons. This observation could be attributed to the occurrence of winter/spring upwelling events and vertical mixing, which resupply nutrients from the deeper strata. Furthermore, the physiological activity of periphyton was strongly influenced by the seasonal changes in light intensity, temperature, and nutrient concentration. We provided the first insight into the seasonal variation of primary productivity of the periphyton assemblage dominating the littoral zone of newly established post-mining lakes. We stress the importance of periphyton in aquatic ecosystems, particularly in anthropogenic oligotrophic lakes.

Unveiling the ecological significance of algal mats and meadows: Insights into phosphorus cycling and primary production of benthic algae in post-mining lakes

Post-mining lakes are anthropogenic water bodies increasing globally due to mining suppression and recultivation. These lakes have ecological and socioeconomic significance, providing freshwater sources, wildlife habitats, and recreation potential. However, research on primary producers in these lakes is limited, with most studies focusing on phytoplankton while neglecting algal mats and meadows. If developed in high biomass, algal mats and macroalgal meadows play a crucial role in aquatic ecosystems. They contribute to the trophic structure, nutrient fluxes, primary production and to the purification of entire waterbodies. Yet, there is a lack of knowledge regarding the nutrient acquisition and the contribution of algal mats and meadows to total primary production and phosphorus (P) cycling, especially in oligotrophic lakes, including post-mining lakes. Our team investigates the benthic algal primary producers - algal mats and meadows in the littoral zone of tree newly established post-mining lakes located in the Czech Republic (Europe). Our main objectives are to describe the quality and quantity of primary producers, quantify the contribution of algal mats and meadows to the primary production and phosphorus cycling in the oligotrophic post-mining lakes. We have studied them throughout all seasons with a special focus on the generally neglected winter/spring season. Our sampling strategy encompasses three gradients of variability along which the composition and ecological role of benthic algae change: spatial variability along the depth gradient within each lake, itemporal variability throughout the seasons within each lake and successional variability between the lakes of different age. spatial variability along the depth gradient within each lake, itemporal variability throughout the seasons within each lake and successional variability between the lakes of different age. The methodological approach consists of measuring the limnological and chemical parameters of lakes, taxonomic determination, biomass estimation and C:N:P stoichiometry of algal biomass along the whole gradient of the euphotic zone (0-15m). The in situ measurement of primary production of benthic algae from various depths using the oxygen meter Fibox 3 (PreSens, Germany) with a combination of laboratory experiments was employed too (Čapková 2022). We measure the kinetic parameters of P uptake of algal mats and meadows using 33P-labelled orthophosphates under controlled conditions similar to the nature (Konopáčová 2021). According to our survey, algal mats and meadows exhibited high productivity in the entire littoral zone. Algal mats dominate the depth up to 3m Fig. 1 and are highly diverse, with more than 400 identified taxa (Bešta 2022). Macroalgal meadows formed by the genus Chara together with the genus Vaucheria, are key taxa occupying the deeper zone (3-15m) Fig. 2. The distribution of benthic algae in lakes is influenced by depth gradients, substrate quality, seasonality and age of lakes foundation, resulting in complex spatio-temporal patterns. Specific emphasis is placed on the fate of P, which is the limiting nutrient in investigated lakes. High C:P molar ratios in microalgal mats indicate strong P deficiency in studied lakes. Over the vegetation season, microalgal biomass doubled, while the P content in biomass dropped to 60% of the values from the start of the vegetation season. The maximum uptake velocity and specific P uptake affinity decreased by an order of magnitude from April to October, and P uptake affinity was measured for comparison in plankton too. Based on our results, we proposed a possible mechanism underlying a stable coexistence of planktonic and benthic primary producers, with plankton prospering primarily in summer and autumn and algal mats and meadows in winter and spring seasons. By integrating data collected during five years of investigation, our study aims to provide a comprehensive understanding of the ecological roles of primary producers in post-mining lakes.

Density-mediated metabolic rate in Daphnia magna interacting with temperature

ABSTRACT Zooplankton change metabolic function as a physiological response to crowding. Unclear is whether zooplankton physiological responses also change according to species and measurement conditions, and whether the physiological responses to crowding are also changed by temperature. Further investigation is essential to unravel the intricate interplay between crowding-induced stress, energy allocation strategies, and behavioral adaptations. In this study, we determined the metabolic rates of cladoceran Daphnia magna at 3 different densities (1, 10, and 20 individuals [ind.] per 50 mL) at 2 temperatures (10 and 20 °C) using a highly accurate optical oxygen meter. We aimed to clarify how crowding and temperature together affect metabolic rate. At both temperatures, metabolic rates of D. magna in the 2 crowded treatments were significantly lower than those in a single treatment, and as temperature decreased the rate of metabolic decrease slowed. Q 10 values varied from 1.63 for the 20 ind. per 50 mL treatment to 2.29 for the 1 ind. per 50 mL treatment, suggesting that the slowing of metabolic rates due to crowding is slightly less pronounced at lower temperatures and may be linked to reduced food consumption.