Temporal Variations In Concentrations Research Articles

High-Resolution Daily Spatiotemporal Distribution and Evaluation of Ground-Level Nitrogen Dioxide Concentration in the Beijing–Tianjin–Hebei Region Based on TROPOMI Data

This study utilized TROPOMI remote sensing data, MODIS remote sensing data, ground observation data, and other ancillary data to construct a high-resolution spatiotemporal distribution and evaluation of ground-level NO2 concentrations in the Beijing–Tianjin–Hebei (BTH) region using the Geographic Temporal Neural Network Weighted Regression (GTNNWR) model. Through this model, we obtained the daily distribution of ground-level nitrogen dioxide (NO2) concentrations in the Beijing–Tianjin–Hebei region at a resolution of 500 m for the period of 2019–2022. The research results exhibited higher accuracy and more detailed features compared to other models, enabling a more accurate reflection of the spatial distribution and temporal variations of ground-level NO2 concentrations in the region, while retaining more details and trends and excluding the influence of noisy data. Furthermore, we conducted an evaluation analysis considering important events such as public health incidents and the Winter Olympics. The results demonstrated that the GTNNWR model outperformed the Random Forest (RF), Convolutional Neural Network (CNN), and Geographic Neural Network Weighted Regression (GNNWR) models in performance metrics such as R2, RMSE, MAE, and MAPE, showcasing greater reliability when considering spatiotemporal heterogeneity and spatiotemporal non-stationarity. This study provides crucial data support and reference for atmospheric environmental management and pollution prevention and control in the Beijing–Tianjin–Hebei region.

Monitoring total suspended solids concentration in Poyang Lake via machine learning and Landsat images

Study regionPoyang Lake, Jiangxi Province, China. Study focusTotal suspended solids (TSS) represents an important water quality parameter in inland waters. This study compared the performance of empirical models, semi-analytical models, and four machine learning models. Then, based on field-measured data, the back propagation neural network (BPNN) model with best performance (R2 = 0.89, RMSE = 20.03 mg/L, MAE = 10.8 mg/L, MAPD = 24.89%) was established and applied to Landsat images for retrieval. The spatial-temporal distribution of TSS in Poyang Lake from 1988 to 2022 was obtained. The various effects of driving forces on temporal and spatial variations of TSS concentration in Poyang Lake were analyzed. New hydrological insights for the regionThe BPNN model proposed in this study has good performance in the testing dataset and two independent datasets, indicating good generalization ability and spatial portability. The TSS concentration showed an increasing trend over the past 35 years. The seasonal characteristics of TSS are distinct, with higher concentrations in the dry season and obvious variation in summer months. Before 2001, the TSS concentration was highly correlated with precipitation (r = −0.74) and wind speed (r = 0.60). Thereafter, sand mining (r = 0.66) became the main driving force underlying interannual variations in TSS concentration.

No long-term variation of 240Pu/239Pu atom ratio in liver of Japanese common squid (Todarodes pacificus) collected from seven sea areas around Japan during 2003–2018

The 239+240Pu concentrations and 240Pu/239Pu atom ratios were determined to trace the temporal variability in concentration and atom ratio in liver of the Japanese common squid during 2003–2018. The differences in their concentrations and atom ratios and the dependency on the collection areas and migratory history were compared. The organ affinity of Pu in mantle, limb, liver, and internal organs except liver was also investigated. The average 239+240Pu concentrations were the highest in liver followed in order by internal organs except liver, limb, and mantle. The Pu accumulation in liver could be explained by a mechanism for foreign substance processing. A significant difference in the average 239+240Pu concentrations in liver was found among the sea areas for specimen collection during 2003–2018. In spite of a noticeable difference in the average 239+240Pu concentrations, the 240Pu/239Pu atom ratios showed no significant temporal variability around Japan; thus, they were continuously uniform during 2003–2018.

Persistent Organic Pollutants in Sewage Sludge: Occurrence, Temporal Concentration Variation and Risk Assessment for Sewage Sludge Amended Soils

In this study, the occurrences, temporal concentration variations and ecotoxicological risks were determined for 18 polycyclic aromatic hydrocarbons (PAHs); 7 congeners of polychlorinated biphenyls (PCBs), and 18 selected organochlorine pesticides (OCPs) in the anaerobically digested sewage sludge samples obtained from a conventional wastewater treatment plant (WWTP) in Konya, Turkey. Flowrate of the evaluated WWTP was 200,000 m3/day, with the production of 140 tons/day treated sewage sludge. Total 18 PAHs were in the range of 1,203 – 17,599 μg/kg of dry matter (dm); total PCBs were in the range of 51.26 – 561.37 μg/kg dm, and total OCPs were in the range of 4.90 – 13.11 μg/kg dm. The highest concentrations were determined for fluoranthene among PAHs, with 2445 μg/kg dm, PCB118 congener with 514 μg/kg dm, and δ-HCH among OCPs with 2.44 μg/kg dm. Considering the average daily production amounts of treated sludge, the highest mass loads were 1,785 g/day for total PAHs; 79 g/day for total PCBs; and 1 – 2 g/day for total OCPs, while the annual mass load was estimated to be approximately 7.3 kg. An ecotoxicological risk assessment was performed by estimation of risk quotients (RQs). High risk for soil ecosystem was identified due to PAHs and PCBs ingredient of sludge, while lower risk was determined for OCPs compounds. The highest RQ values were determined for pyrene (RQ: 1337) among PAHs, PCB118 congener (RQ: 7608), and γ-HCH (RQ: 5.23) among OCPs. Findings of this study show that sewage sludge can be an important source in the spread of persistent pollutants to the environment, and may pose a risk for soil ecosystem.

Development of a UAV Based Framework for CH4 Monitoring in Sludge Treatment Centres

With the increasing trend in the global average temperature, the UK’s water industry has committed to achieve Net Zero by 2030 and part of this includes cutting CH4 emissions from sludge treatment facilities. Currently, emissions are estimated following the carbon accounting workbook guidelines and using default emission factors. However, this method might not be a true representation of emissions as these vary depending on many factors. The use of unmanned aerial vehicles (UAVs) has proved cost effective for environmental monitoring tasks requiring high spatial resolution information. Within the context of CH4 emissions and in the last decade, the technology has been curtailed by sensor weight and size. Recent advances in sensor technology have enabled the development of a fit-for purpose UAV CH4 sensor (U10) which uses Tuneable Diode Laser Absorption Spectroscopy. This study intends to develop a framework for CH4 data collection strategies from sludge treatment centres using UAV-U10 technology and asset level CH4 enhancement estimations based on geostatistical interpolation techniques and the mass balance approach. The framework presented here enables the characterization of spatial and temporal variations in CH4 concentrations. It promotes asset level CH4 enhancement estimation based on on-site measurements.

Investigation of organochlorine pesticides in the Wang Lake Wetland, China: Implications for environmental processes and risks

Wang Lake Wetland is an important habitat for many fish and migratory birds. To explore the effect of periodic hydrological changes on the transfer and ecological risk of OCPs in the multimedia system of the wetland, eight sampling sites were selected for collecting soil (SS), sediment (SD) and water, to acquire dissolved phase (DP) and suspended particulate matter (SPM) samples during low- and high-flow periods. The results indicated that OCPs are pervasive in the various media of Wang Lake Wetland, and there was a significant temporal variability in concentration of ∑23OCPs in the SPM samples. Several OCPs exist certain ecological risks to aquatic organisms, but higher level of OCPs do not always equal to higher ecological risk. The residues of OCPs are largely attributed to their historical use, but recent inputs of some of them are still non-ignorable. The relatively higher values of organic carbon normalized partition coefficient (KOC) for SPM-W (KOC(SPM-W)) were obtained, which reflected the more frequent exchange of OCPs in the SPM samples. The sediment of the Wang Lake Wetland is likely to be a sink for several OCPs with high n-octanol/water partition coefficient (KOW) (e.g., DDTs and its metabolites), and high-temperature and rainfall-driven changes may promote the migration of OCPs with low KOW to the DP.

Spatial and Temporal Variations of Atmospheric CH4 in Monsoon Asia Detected by Satellite Observations of GOSAT and TROPOMI

Space-based measurements, such as the Greenhouse gases Observing SATellite (GOSAT) and the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor satellite, provide global observations of the column-averaged CH4 concentration (XCH4). Due to the irregular observations and data gaps in the retrievals, studies on the spatial and temporal variations of regional atmospheric CH4 concentrations are limited. In this paper, we mapped XCH4 data over monsoon Asia using GOSAT and TROPOMI observations from April 2009 to December 2021 and analyzed the spatial and temporal pattern of atmospheric CH4 variations and emissions. The results show that atmospheric CH4 concentrations over monsoon Asia have long-term increases with an annual growth rate of roughly 8.4 ppb. The spatial and temporal trends of XCH4 data are significantly correlated with anthropogenic CH4 emissions from the bottom-up emission inventory of EDGAR. The spatial pattern of gridded XCH4 temporal variations in China presents a basically consistent distribution with the Heihe–Tengchong Line, which is mainly related to the difference in anthropogenic emissions in the eastern and western areas. Using the mapping of XCH4 data from 2019 to 2021, this study further revealed the response of atmospheric CH4 concentrations to anthropogenic emissions in different urban agglomerations. For the urban agglomerations, the triangle of Central China (TCC), the Chengdu–Chongqing City Group (CCG), and the Yangtze River Delta (YRD) show higher CH4 concentrations and emissions than the Beijing–Tianjin–Hebei region and nearby areas (BTH). The results reveal the spatial and temporal distribution of CH4 concentrations and quantify the differences between urban agglomerations, which will support further studies on the drivers of methane emissions.

Partial and Temporal Variations in Concentration of Micro Plastic in Drinking Water of Al-Hilla River

Partial and Temporal Variations in Concentration of Micro Plastic in Drinking Water of Al-Hilla River

Synchronism of sediment erosion and deposition processes during high-turbidity events in a large shallow lake

High-turbidity events (HTEs) frequently occur in shallow lakes and can deeply influence lake ecosystems. However, the processes of sediment erosion and deposition are not fully understood. To investigate these processes, two investigative campaigns that integrate bed sediment measurements, sediment settling experiments, in-situ observations, or a hydrodynamics-sediment model were conducted to quantitatively study wind-induced HTEs in Lake Taihu, China. Cohesive sediments were massively entrained from the lakebed by wind waves when the wind speed exceeded its critical value of 7 m s−1, as estimated by water depth, triggering HTEs with turbidity waves of > 100 nephelometric turbidity units. The suspended sediment concentration was the net sediment flux of erosion (average: 5.9 mg m−2 s−1) and deposition (average: 5.5 mg m−2 s−1), which occurred synchronously for most of the HTEs and resulted in high temporal variation in suspended sediment concentration. This synchronism was determined by the critical erosional stress of lakebed sediments, which was spatially heterogeneous (0.017–0.055 N m−2) in a large lake. Equations for erosion and deposition processes were derived following the investigative campaigns and used to develop a cohesive sediment transport model for simulating HTEs in Lake Taihu. Simulations indicate that the synchronism of sediment erosion and deposition led to a near-lakebed turbid water layer during an HTE, which sustained the sediment lutocline in Lake Taihu. Further investigation should be conducted on the role of the near-lakebed turbid water layer during endogenous pollution in large eutrophic lakes.

Remote sensing monitoring of total suspended solids concentration in Jiaozhou Bay based on multi-source data

Total suspended solids (TSS) concentration (mg/L) is a significant indicator of coastal water environments monitoring. First, quantitative retrieval models of TSS concentrations in Jiaozhou Bay (JZB) were developed based on Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) data, and the retrieved TSS concentrations in JZB from 1984 to 2021 were obtained. Then, the reliability of the retrieved TSS from Landsat and MODIS was evaluated, and the temporal and spatial variation in TSS concentration was analyzed. Finally, the main factors influencing the variation in TSS concentration in JZB were analyzed. The results show that both Landsat and MODIS retrieval models proposed in this study have good accuracies (Landsat: R2 = 0.64, RMSE = 2.09 mg/L, MAPD = 33.96%; MODIS: R2 = 0.71, RMSE = 2.54 mg/L, MAPD = 32.81%). The TSS concentration in JZB fluctuated between 1984 and 2021, showing a downward trend. The TSS concentration in JZB exhibited an obvious seasonal variation, with a higher concentration in spring and winter owing to strong winds and a lower concentration in summer and autumn. TSS decreased gradually from northwest to southeast. The average spatial variation scale of TSS monitoring in JZB was 72 m and the optimal observation time window was 10:16–12:16. Although the retrieved TSS of Landsat and MODIS were highly consistent (R2 = 0.70, RMSE = 2.09 mg/L), differences were still observed. The exponential function in the retrieval models was the main reason for the large difference between Landsat TSS and MODIS TSS in the nearshore high-value area. The different spatial resolutions, image acquisition times, and signal-to-noise ratios of Landsat and MODIS were also important reasons for the differences. Wind speed was the main factor influencing the annual, seasonal, and monthly variation in TSS concentration in JZB, while the Jiaozhou Bay Bridge only had an effect on the TSS concentration during the construction period.

Investigation of the effects of parallel electric field on fog dissipation

Fog dissipation by charge and electric field has become a research hotspot due to its affordability and high efficiency compared with traditional technologies. However, the mechanism by which the electric field affects the temporal variation of droplet concentration is unclear. Therefore, a cylinder fog chamber with a radius of 0.15 m and a height of 1 m is established to analyze the influence of electric field on the concentration change of partially charged fog (50% of fog droplets are charged). The distribution of electric field in the fog chamber is simulated by an electrostatic model in COMSOL, and the electric field in the fog chamber is regarded as a parallel electric field. A percentage concentration α, the ratio of the real droplet concentration n, and the initial droplet concentration n 0 are introduced to describe the effects of fog dissipation. The results show that visibility can increase from 10 m to 150 m after applying the electric field. The shortest time is 12 s, which is much smaller than the natural settling time (102 s). Furthermore, α first increases, then decreases, and finally gets close to zero with electric field E regardless of the charged state (neutral or partially charged) at the beginning of applying the electric field (t = 60 s). Besides, α without charging is smaller than that with partially charging. Finally, α decreases with electric field E regardless of the charged state at the end of the applied electric field (t = 240 s). These findings can be explained by the relative strength of electrostatic force effect induced by the electric field on neutral and charged droplets and gravitational effect, which are quantified by the calculation analysis of various forces. The results can be used to guide and optimize the structure of experimental setups for outdoor fog dissipation in the future.

Exposure Concentrations and Inhalation Risk of Submicron Particles in a Gasoline Station—A Pilot Study

Gasoline is a globally used primary fuel. The submicron particles at gasoline stations have not been extensively investigated. This study aimed to evaluate the exposure concentrations and inhalation risk of submicron particles at a gasoline station. Temporal variations in particle concentrations and size distributions were measured using a real-time system. The effective doses of submicron particles deposited in different organs were analyzed using a computational fluid dynamics model and the value of environmental monitoring (including the size distributions of particles by number). The number concentration (NC) was higher during working hours than that of the background. Submicron particles gathered predominantly at 30.5 nm and 89.8 nm during working time. The effective doses of submicron particles deposited in the olfactory system and lungs were 0.131 × 10−3 and 0.014 mg, respectively, of which 0.026 × 10−3 mg potentially reached the brain. In a female worker with 3 years of exposure, the average daily effective doses in the olfactory system, lungs, and brain were 2.19 × 10−7 mg/kg·d−1, 2.34 × 10−5 mg/kg·d−1, and 4.35 × 10−8 mg/kg·d−1, respectively. These findings indicated that workers at this gasoline station had a high inhalation risk of submicron particles. This study provides baseline data on submicron particles at gasoline stations and a critical basis for investigating disease risk in longitudinal epidemiological studies.

Triplex qPCR assay for Campylobacter jejuni and Campylobacter coli monitoring in wastewater

Campylobacter spp. is one of the most frequent pathogens of bacterial gastroenteritis recorded worldwide. Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) are the two major disease-associated species, accounting for >95 % of infections, and thus have been selected for disease surveillance. Monitoring temporal variations in pathogen concentration and diversity excreted from community wastewater allows the early detection of outbreaks. Multiplex real-time/quantitative PCR (qPCR) enables multi-target quantification of pathogens in various types of samples including wastewater. Also, an internal amplification control (IAC) is required for each sample when adopting PCR-based methods for pathogen detection and quantification in wastewater to exclude the inhibition of the wastewater matrix. To achieve reliable quantification of C. jejuni and C. coli towards wastewater samples, this study developed and optimized a triplex qPCR assay by combining three qPCR primer-probe sets targeting Campylobacter jejuni subsp. jejuni, Campylobacter coli, and Campylobacter sputorum biovar sputorum (C. sputorum), respectively. This triplex qPCR assay not only can directly and simultaneously detect the concentration of C. jejuni and C. coli in wastewater but also can achieve the PCR inhibition control using C. sputorum primer-probe set. This is the first developed triplex qPCR assay with IAC for C. jejuni and C. coli, to be used in the wastewater-based epidemiology (WBE) applications. The optimized triplex qPCR assay enables the detection limit of the assay (ALOD100%) and wastewater (PLOD80%) as 10 gene copy/μL and 2 log10 cells/mL (2 gene copies/μL of extracted DNA), respectively. The application of this triplex qPCR to 52 real raw wastewater samples from 13 wastewater treatment plants demonstrated its potential as a high-throughput and economically viable tool for the long-term monitoring of C. jejuni and C. coli prevalence in communities and the surrounding environments. This study provided an accessible methodology and a solid foundation for WBE-based monitoring of Campylobacter spp. relevant diseases and paved the road for future WBE back-estimation of C. jejuni and C. coli prevalence.

Assessment of indoor bioaerosol exposure using direct-reading versus traditional methods—potential application to home health care

Home healthcare workers (HHCWs) can be occupationally exposed to bioaerosols in their clients’ homes. However, choosing the appropriate method to measure bioaerosol exposures remains a challenge. Therefore, a systematic comparison of existing measurement approaches is essential. Bioaerosol measurements with a real-time, fluorescence-based Wideband Integrated Bioaerosol Sensor (WIBS) were compared to measurements with four traditional off-line methods (TOLMs). The TOLMS included optical microscopic counting of spore trap samples, microbial cultivation of impactor samples, qPCR, and next-generation sequencing (NGS) of filter samples. Measurements were conducted in an occupied apartment simulating the environments that HHCWs could encounter in their patients’ homes. Descriptive statistics and Spearman’s correlation test were computed to compare the real-time measurement with those of each TOLM. The results showed that the geometric mean number concentrations of the total fluorescent aerosol particles (TFAPs) detected with the WIBS were several orders of magnitude higher than those of total fungi or bacteria measured with the TOLMs. Among the TOLMs, concentrations obtained with qPCR and NGS were the closest to the WIBS detections. Correlations between the results obtained with the WIBS and TOLMs were not consistent. No correlation was found between the concentrations of fungi detected using microscopic counting and any of the WIBS fluorescent aerosol particle (FAP) types, either indoors or outdoors. In contrast, the total concentrations detected with microbial cultivation correlated with the WIBS TFAP results, both indoors and outdoors. Outdoors, the total concentration of culturable bacteria correlated with FAP-type AC. In addition, fungal and bacterial concentrations obtained with qPCR correlated with FAP types AB and AC. For a continuous, high-time resolution but broad scope, the real-time WIBS could be considered, whereas a TOLM would be the best choice for specific and more accurate microbial characterization. HHCWs’ activities tend to re-aerosolize bioaerosols causing wide temporal variation in bioparticle concentrations. Thus, the advantage of using the real-time instrument is to capture those variations. This study lays a foundation for future exposure assessment studies targeting HHCWs.

The temporal variation of radon concentration at different depths of soil: A case study in Beijing

Variations in soil radon concentrations are a potential precursor of earthquake and volcanic events. However, the unclear migration and variation mechanisms of radon concentrations in soil still limit its effective application. To elucidate the temporal variation and its possible influence factors on radon concentrations at different soil depths, a case study was performed at a suburban site in Beijing. A long-term continuous measurement system consisting of ten radon-in-soil monitors at depths from 0.1 to 5.0 m and other meteorological sensors was employed. The monitoring was carried out from January 8th to July 29th, 2022, covering 3445 h in total. Radon concentrations generally increased with soil depth. Diurnal variation of soil radon concentrations at depths of 1.2 and 1.6 m in winter and spring was observed, and a negative correlation between the soil radon concentration and the residual air pressure was found. This finding indicates a possible air exchange channel between the soil and the atmosphere at the study site. In addition, the soil radon concentration at 4.0 m depth was unexpectedly lower than that of neighboring depths and was steady throughout the measurement period. This is attributed to a possible clay layer in the soil structure at 4.0 m depth. The results of this field study indicate that the complexity of temporal variation of soil radon concentrations should be considered for its application in predicting earthquake and volcanic events.

Measuring Temporal Variation of Concentration of ALD Precursor TEMAZ in Process Chamber Using UV Absorption Method

The UV light densitometer was developed to measure concentration of gases having absorption in the ultraviolet region using UV absorption method. The developed densitometer was applied to monitor temporal variation of concentration of ALD precursor TEMAZ introduced into a chamber, where TEMAZ was introduced alternately with purge Ar gas to simulate ALD process. We could successfully capture temporal variation of gas concentration such as time delay in arrival of gas in the chamber due to presence of gas flow. Such phenomenon cannot be measured by the pressure gauge.

Spatial and Temporal Variations of Arctic Sea Ice during 1992-2021

The variation of polar sea ice is an indicator of polar environmental change, which plays an important role in the study of regional and global climate change. The arctic is a region in transition to a warmer climate and one of the most visible signs of that change is in the declining sea ice cover. Sea ice in the arctic is one of the most rapidly changing components of the global climate system. The extent of area covered by arctic sea ice is an important indicator of changes in global climate because warmer air and water temperatures are reducing the amount of sea ice present. Sea ice extent plays an important role in reflecting sunlight back into space, regulating ocean and air temperatures, circulating ocean water, maintaining animal habitats. Similarly, sea ice concentration helps to determine the number of other important climate variables. In this paper, the sea ice data from different institutes were used to analyze the spatial and temporal variation of arctic sea ice concentration (SIC) and sea ice extent (SIE) over the 30-year period 1992-2021. During this period, the results shows that these two variables were increased in the arctic during 2021 due to the decrease of temperatures particularly near Chukchi, Kara, Beaufort, East Siberian and Greenland Seas.

Historical fluxes of metal and metalloids in an aquatic ecosystem affected by land-use change and mining activities in northwestern Mexico

Freshwater reservoirs are essential owing because of their ecological, economic, and social importance. They are particularly vulnerable to contamination, as of metal and metalloids, derived from anthropogenic activities like mining. The temporal variations in trace element concentrations (arsenic (As), mercury (Hg), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn)), enrichment, fluxes, and possible sources were evaluated by studying two sediment cores from the La Angostura (ANG) Reservoir (northwest Mexico), using 210Pb geochronology. The enrichment factors showed from null to minor enrichment for most elements, but moderate to severe enrichment of mercury (Hg). Most trace element concentrations had a detrital origin, and notable Hg concentration increases since the past decade were associated with severe drought periods, likely resulting from wildfires. The observed sediment concentrations of As and Hg can cause adverse effects on biota in the ecosystem since they are above the probable effect level (PEL). Development of strategies for metal attenuation in this reservoir is recommended and metals should be controlled until specific ecotoxicological studies are performed.

Tissue Oxygenation Around Capillaries: Effects of Hematocrit and Arteriole Oxygen Condition.

Oxygen transfer in the microvasculature is a complex phenomenon that involves multiple physical and chemical processes and multiple media. Hematocrit, the volume fraction of red blood cells (RBCs) in blood, has direct influences on the blood flow as well as the oxygen supply in the microcirculation. On the one hand, a higher hematocrit means that more RBCs present in capillaries, and thus, more oxygen is available at the source end. On the other hand, the flow resistance increases with hematocrit, and therefore, the RBC motion becomes slower, which in turn reduces the influx of oxygen-rich RBCs entering capillaries. Such double roles of hematocrit have not been investigated adequately. Moreover, the oxygen-hemoglobin dissociation rate depends on the oxygen tension and hemoglobin saturation of the cytoplasm inside RBCs, and the dissociation kinetics exhibits a nonlinear fashion at different oxygen tensions. To understand how these factors and mechanisms interplay in the oxygen transport process, computational modeling and simulations are favorite since we have a good control of the system parameters and also we can access to the detailed information during the transport process. In this study, we conduct numerical simulations for the blood flow and RBC deformation along a capillary and the oxygen transfer from RBCs to the surrounding tissue. Different values for the hematocrit, arteriole oxygen tension, tissue metabolism rate and hemoglobin concentration and affinity are considered, and the simulated spatial and temporal variations of oxygen concentration are analyzed in conjunction with the nonlinear oxygen-hemoglobin reaction kinetics. Our results show that there are two competing mechanisms for the tissue oxygenation response to a hematocrit increases: the favorite effect of the higher RBC density and the negative effect of the slower RBC motion. Moreover, in the low oxygen situations with RBC oxygen tension less than 50mmHg at capillary inlet, the reduced RBC velocity effect dominates, resulting in a decrease in tissue oxygenation at higher hematocrit. On the opposite, for RBC oxygen tension higher than 50mmHg when entering the capillary, a higher hematocrit is beneficial to the tissue oxygenation. More interestingly, the pivoting arteriole oxygen tension at which the two competing mechanisms switch dominance on tissue oxygenation becomes lower for higher oxygen-hemoglobin affinity and lower hemoglobin concentration. This observation has also been analyzed based on the oxygen supply from RBCs and the oxygen-hemoglobin reaction kinetics. The results and discussions presented in this article could be helpful for a better understanding of oxygen transport in microcirculation.

IRREGULARITIES THE RELATIONSHIP OF VARIATIONS IN THE VOLUME ACTIVITY OF RADON AND ATMOSPHERIC PRESSURE DURING SEISMIC ACTIVITY (ON THE EXAMPLE OF THE BAIKAL REGION)

A comparison was made of temporal variations in atmospheric pressure and soil radon concentration measured in loose sediments at three monitoring stations in the Baikal region for the period of manifestation of three fairly strong earthquakes – Bystrinsky (21.09.2020, K = 14.6), Kudarinsky (09.12.2020, K = 14.0) and Khubsugulsky (11.01.2021, K = 16.0). It has been established that the release of radon is controlled in the region by variations of atmospheric pressure. Irregularities of this dependence, first identified in the course of a formalized statistical analysis, occur for each of the studied seismic activations. They are connected with the process of preparing an earthquake, which opens up real opportunities for developing an emanation approach to medium-term forecasting.