Frequency Distribution Curves Research Articles

Distribution of 210Po activity and soil texture in agricultural soil.

The assessment of 210Po in agricultural soil matrices in different regions of Kerala and Karnataka was studied. The wet ash method was used to find the activity concentration of 210Po. The alpha activity was counted using a silver-activated zinc sulfide counter of 30% efficiency, and the activity was calculated. The average concentration of 210Po activity in soil samples ranged from 0.09 to 20.52Bqkg-1, with an average value of 4.47Bqkg-1. The soil texture was measured using the International Pipette method. Using the IBM Statistical Package of Social Science Software, the frequency distribution curve of 210Po is plotted and found to be lognormal. The data of 210Po are highly skewed, and the Kurtosis has a significant positive value. The 210Po activity concentrations are substantially within the World Health Organization's recommended limits.

Rainfall analysis and deriving design storm for hydrological modelling of Koyna dam catchment area in Maharashtra state of India

Rainfall is a key hydro meteorological variable. Climate change is disrupting the hydrological cycle and altering the usual cycle of rainfall, which frequently results in long-lasting storms with significant rainfall. A first step in hydrologic design of project is to determine the design storm or rainfall events to be used. For deriving design storm, researchers concluded that instead of using generalized readily available curves or maps, it is better to estimate design storm based on site specific historical rainfall data. The objective of the study is to analyze the rainfall data in the koyna watershed area in order to evaluate the design storm, which will be further used as an input data for HEC-HMS event based hydrological modelling of flood peak attenuation of design storm flow at koyna dam during extreme rainfall event.In this study, 40 years (1982–2021) of rainfall data from 8 rain gauge stations in Koyna Dam Catchment area is used initially for performing trend analysis through statistical and graphical techniques and then for Isopluvial analysis. The Sen's slope test and the Mann-Kendall test are the statistical techniques employed, and Innovative Trend Analysis is the graphical technique used. IDF approach is used for deriving design storm, and using Gumbel's frequency distribution method Isohyetal maps, IDF tables and curves are prepared for 2,10,25,50,75 and 100 year return periods and 6,12,24,48 and 96 h durations. Results obtained from statistical and graphical trend analysis of annual rainfall series are consistent. No statistically significant trend in annual rainfall series is observed, however there is rising and falling trend was observed in annual as well as monthly rainfall series.From the results of design storm study, the design storm hyetograph of 10 years return period and 96 h duration is selected, which gives the rainfall intensity of 10.88 mm/h for the koyna catchment. There are various dams nearby koyna catchment, The Isohyet maps, IDF curves and table output available from this study can be more reliably used during planning and design of hydraulic structure for other areas near by koyna catchment.

Skeletal muscle preservation in arctic ground squirrels during hibernation season

Reduced skeletal loading leads to muscle atrophy in humans and most mammals. By contrast, hibernating mammals demonstrate limited loss of skeletal muscle mass and strength by the end of winter after being physically inactive for several months. The present study objective was to establish potential underlying processes for the lack of muscle loss during the hibernation season of arctic ground squirrels (AGS). Our hypothesis was that early in the the hibernation season, protective mechanisms of AGS are not yet mobilized and muscles show signs of atrophy, while compensatory processes for preventing muscle loss appear at a later time point. Quadriceps muscles of juvenile male AGS were collected shortly before hibernation, and on 2, 6, 10-12 and 16-22 weeks during hibernation. Pre-hibernating animals were used as controls. Fiber cross-sectional area (CSA) and fiber type composition were determined with immunohistochemistry. Amount of total RNA, ribosomal RNA content and expression levels of genes involved in 2 pathways of protein degradation, ubiquitination and autophagy, were analyzed by real-time PCR, to evaluate molecular mechanisms of muscle maintenance. One-Way ANOVA was used to statistically analyze the group differences. We found that CSA was not different between the groups (P > 0.05). CSA frequency distribution curves did not reveal any shift to a smaller or larger size range. No difference was detected in myofiber composition between the hibernation groups compared to the control. Total RNA and ribosomal RNA content were not significantly different between the groups during hibernation. Muscle atrophy marker FBXO32 (Atrogin-1, MAFBX) and autophagy related genes MAP1LC3A and BECN1 did not show different level of expression between the groups. Only another muscle atrophy marker TRIM63 (MURF-1, Iris Ring Finger Protein) was significantly over-expressed at the time point of 2 weeks of hibernation. These results indicate that throughout the hibernation season, AGS preserve muscle fiber CSA showing limited signs of muscle atrophy only during the first weeks of hibernation, and yet-to-be determined processes exist to suppress protein degradation in AGS muscles during hibernation. The work was supported by Center of Biomedical Research Excellence under grant number [P20GM130443]. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hydrogeological structures of karst features using hydrographs in an underground river basin formed in a peak cluster depression, southwest China

Understanding of the hydrological behaviors in different karst features is crucial for evaluating the hydrological storage and transfer functions of a karst system. In this study, the Maocun karst underground river system, characterized by typical karst features, was selected as the research area in the southwest region of China. The main objectives of this research are to analyze the hydrogeological structure characteristics of each karst feature and assess water storage capacity in different aquifer media. Frequency distribution curve (FDC) of electrical conductivity (EC) values revealed that recharge sources in the five karst features differed and varied according to the amount of precipitation. All hydrographs of water levels in five karst features were divided into three periods due to the presence of triple aquifer media in the basin. The spatial structure of each feature was interpreted by analyzing the variation characteristics of recession exponential coefficients (λ). Additionally, the ratios of fissure water, fracture water, and conduit water sources were calculated based on the recession curves of water levels. Results showed that fast water flow had the highest proportion in the relatively open subsystem located upstream, while fracture water flow had the lowest proportion. The slow water flow was the main pattern of water storage in the basin. Values of EC in water decreased with a well-connected spatial structure and high hydraulic conductivity. There were significant differences in the values of EC among conduit water, fracture water, and matrix water. These values were calculated using mathematical relationships between EC and water level hydrographs. The results indicated that the EC values in matrix water exceeded 200 μS/cm, while EC values in conduit water/channel water were below 100 μS/cm. Finally, hydrogeological conceptual models were constructed for five karst features based on the depletion characteristics of the aquifer media during each recession period. These characteristics were interpreted using variation curves of EC and hydrographs of water levels. These findings not only elucidated the characteristics of hydrogeological structures in multiple karst features, but also had significant implications for the assessment of karst water sources.

Estuarine environmental flow assessment based on the flow-ecological health index relation model: a case study in Yangtze River Estuary, China.

Environmental flow (e-flow) is the water demand of one given ecosystem, which can become the flow regulation target for protection and restoration of river or estuarine ecosystems. In this study, an e-flow assessment based on the flow-ecological health index (EHI) relation model was conducted to improve ecosystem health of the Yangtze River Estuary (YRE). Monitoring data of hydrology, biology, and water environment in the last decades were used for the model establishment. For the description of the YRE ecosystem, an EHI system was developed by cumulative frequency distribution curves and adaption of national standards. After preprocessing original flow values into proportional flow values, the generalized additive model and Monte Carlo random sampling were used for the establishment of the flow-EHI relation model. From the model calculation, the e-flow assessment results were that, in proportional flow values, the suitable flow range was 1.05-1.35, and the optimum flow range was 1.15-1.25 (flows in Yangtze River Datong Station). For flow regulation in two crucial periods, flows of 42,630-65,545 m3/s or over 14,675 m3/s are needed for the suitable flow of YRE in summer (June-August) or January, respectively. An adaptive management framework of ecological health-based estuarine e-flow assessment for YRE was contrived due to the limitation of current established model when facing the extreme drought in summer, 2022. The methodology and framework in this study are expected to provide valuable management and data support for the sustainable development of estuarine ecosystems and to bring inspiration for further studies at even continental or global levels.

Evaluation of succulent plants Echeveria elegans as a biomonitor of heavy metals and radionuclides

This work evaluates the use of Echeveria elegans as a biomonitor of metals and radionuclides, using semi-urban soils as a study area. The study area is exposed to various trace elements of concern for various social groups in nearby localities. The quantification of metals and radionuclides was performed by X-ray fluorescence spectrometry and gamma spectrometry, respectively. Cumulative frequency distribution curves, descriptive statistics, and multivariate analysis were used to estimate the local geochemical baseline and identify geochemical and anthropogenic patterns of metals and radionuclides from topsoil and E. elegans. The evaluation of contaminants and the contribution of possible exposure routes (topsoil and atmospheric deposition) was performed with the enrichment factor (EF) and the relative concentration factor (CFR). The results suggest that the plant does not present significant physical stress due to the environmental conditions to which it was exposed. Likewise, it can bioaccumulate heavy metals from natural and anthropogenic sources. The quantification of radionuclides in the plant is below the detection limits, indicating a low bioavailability and transfer factor. The CFR and EF results showed that the plant accumulates metals from the topsoil and atmospheric deposition. The bioaccumulation mechanism would be related to the functioning of Crassulaceae Acid Metabolism (CAM). In topsoil, the organic acids of the plant would modify the solubility of the metals present in an insoluble form in the soil, acting as ligands and, subsequently, following the transport route of these metabolites. In atmospheric deposition, the metals deposited in the leaves would be incorporated into the plant through the opening of the stomata because of the capture of CO2 (at night, day, or during environmental stress) by the CAM. Overall, the evidence showed that the succulent can be used as a biomonitor of heavy metals. However, additional studies are required to determine its usefulness as a radionuclide biomonitor.

Effect of iron nanoparticles on chromium adsorption in aqueous solution using magnetic biochar: A site energy distribution analysis

The effects of adding green-synthesized magnetic iron-containing nanoparticles (GSMFe) onto biochar in aqueous solution for the adsorptive removal of hexavalent chromium [Cr(VI)] were investigated in this study. Nanocomposites, denoted as green synthesis magnetic biochar (GSMB), were created using a green synthesis technique with white tea residue to introduce GSMFe into biochar. Six adsorbents, varying in GSMFe content, were tested for their effectiveness in eliminating Cr(VI), a globally significant hazardous heavy metal. The results demonstrated that incorporating GSMFe into biochar led to significant improvements in adsorption capacity and saturation magnetization. With an increasing amount of GSMFe, the maximum adsorption capacity increased from 2.47 mg/g (EWTWB) to 9.11 mg/g (GSMB4). The highest saturation magnetization was achieved at 13.4 Am2/kg at GSMB4. Similarly, surface areas rose up to 72.9 m2/g at GSMB3 but declined thereafter due to GSMFe aggregation and pore blockage. Sorption behavior for Cr(VI) was assessed using five isotherm models, with the Redlich-Peterson model showing the best fit. The analysis of approximate site energy distribution (SED) indicates that the incorporation of GSMFe enhances the frequency of the entire range of sorption energy sites, while the biochar matrix contributes to a slight increase in medium sorption energy sites within the GSMFe. Among the GSMBs, the difference were more pronounced at low-energy sites than at high-energy sites. At higher energy sites (27,500–40,000 J/mol), sorption site frequencies remained similar, regardless of GSMFe content and associated physicochemical properties. For sorption energy site values exceeding 17,500 J/mol (Cr(VI) concentration below 50 mg/L), GSMB2 is regarded as a more practical choice due to its relatively large area under the frequency distribution curve and commendable cost-effectiveness.

Monitoring buprenorphine in patients on medication-assisted treatment.

Buprenorphine is used for medication-assisted treatment of opioid dependence. Monitoring of medication adherence involves testing of urine or oral fluid for the drug or its metabolite. Quantitative results using liquid chromatography tandem mass spectrometer testing defined the excretion pattern of the drug and its metabolites. Frequency distribution curves of buprenorphine and norbuprenorphine describe the expected drug concentrations of patients on this medication. Urine and oral fluid drug testing can be used to monitor adherence in this population.

Age estimation and boulder population analysis of the West crater at Apollo 11 landing site using Orbiter High Resolution Camera on board Chandrayaan-2 mission

Orbiter High Resolution Camera (OHRC) on-board Chandrayaan-2 had acquired a high-resolution image (∼0.26 m) covering Apollo 11 landing site, showing the Lander Module (LM) along with other small-scale features, such as boulders, etc. In the east of Apollo 11 LM lies the West crater, which has a rich population of boulders spread around it. We studied this boulder distribution around the West crater to estimate the age of the West crater and to understand the aspects related to the impact cratering and space weathering through the analysis of boulder distribution. For this, we identified and mapped >8500 boulders around the West crater using the OHRC image, out of which 6466 boulders (>∼1 m in size) lying within 1–5 crater radius were used for further analysis. For estimating the age of the West crater, we applied various methods based on crater morphology, boulder distributions and Diviner Rock Abundance. The age was estimated to be in the range of 80 Ma to 120 Ma with the most probable age close to 100 Ma, the same as that expected from the cosmic ray exposure dating. Boulder distribution around the West crater was found to be highly anisotropic with majority of boulders lying in the eastern to north-eastern direction, suggesting an impact at very low angle. Relationship between crater size and largest boulder size also pointed towards primary origin of the West crater. The Height (H) to Diameter (D) ratio is estimated to be ∼0.25 considering all the boulders with diameter ≤ 4m, going up to 0.38 with comparatively poor correlation for boulders with diameter > 4m. The H/D ratio from Apollo mission photos for boulders around Apollo 11 LM is found to be approximately double that of the corresponding measurements from the OHRC image. We also fit a Power law and the Weibull distribution to the cumulative Boulder Size Frequency Distribution (BSFD) curve with Maximum Likelihood (ML) method and Kolmogrov-Smirnoff (KS) statistics. Both fit well with R2 of 0.999, but varying minimum diameter (dKS) of 1.85 m and 1.64 m, respectively. The good fit by Power-law with high slope value (b = 4.61) describes the fragmentation due to the West crater forming impact as complex. However, the higher diameter tail was better explained by the Weibull fit implying sequential fragmentation of boulders with time.

Coastal sediment heavy metal(loid) pollution under multifaceted anthropogenic stress: Insights based on geochemical baselines and source-related risks

Contamination and risk assessments generally ignore the potential bias in results caused by the variation of background values at different spatial scales due to the spatial heterogeneity of sediments. This study aims to perform quantitative source-ecological risk assessment via establishing geochemical baselines values (GBVs) of heavy metal(loid)s (HMs) in Daya Bay, China. Cumulative frequency distribution (CFD) curves determined the GBVs of 12.44 (Cu), 30.88 (Pb), 69.89 (Zn), 0.06 (Cd), 47.85 (Cr), 6.80 (As), and 0.056 mg kg−1 (Hg), which were comparable to the background values of Guangdong Province surface soils, and implied a potential terrestrial origin of the coastal sediments. Principal component analysis (PCA) and positive matrix factorization (PMF) identified three sources (F1: natural processes; F2: anthropogenic impacts; F3: specific sources) with contributions of 51.7%, 29.2%, and 19.1%, respectively. The source-specific risk assessment revealed an ecological risk contribution potential of 73.8% for the mixed anthropogenic sources (F2 + F3) and only 26.2% for natural processes. Cd and Hg were the priority management of metallic elements, occupying 63.5% and 72.5% of the contribution weights of F2 and F3, respectively, which showed multi-level pollution potentials and ecological risk levels. The spatial distribution patterns demonstrated the hotspot features of HM pollution, and priority concerns should be given to the management of marine traffic and industrial point source pollution in Daya Bay. The results of the study provide a scientific approach and perspective for pollution treatment and risk management in the coastal environment.

Research on the purification enhancement of ecological ponds: Integrating water cycle optimization and plants layout

The hydrodynamic conditions of ponds are generally poor, which seriously affects the long–term water quality guarantee. In this research, the numerical simulation method was used to establish an integrated model of hydrodynamics and water quality for the simulation of the plant purification effect in ponds. Based on the flushing time using the tracer method, the purification rate of plants was introduced to consider the purification effect of plants on water quality. In–situ monitoring was carried out at the Luxihe pond in Chengdu, and the model parameters such as the purification rate of typical plants were calibrated. The degradation coefficient of NH3–N in the non–vegetated area was 0.014 d−1 in August and 0.010 d−1 in November. In areas with vegetation, the purification rate of NH3–N was 0.10–0.20 g/(m2·d) in August and 0.06–0.12 g/(m2·d) in November. The comparison of the results in August and November showed that due to the higher temperature in August, the plant growth effect was better, and the degradation rate of pollutants and the purification rate of pollutants by plants were higher.The flushing time distribution of the proposed Baihedao pond under the conditions of terrain reconstruction, water replenishment, and plant layout was simulated, and the frequency distribution curve of flushing time was used to evaluate the results. Terrain reconstruction and water replenishment can significantly improve the water exchange capacity of ponds. The reasonable planting of plants can reduce the variability of the water exchange capacity. Based on this combined with the purification effect of plants on NH3–N, the layout plan of Canna, Cattails, and Thalia in ponds was proposed.

Spatial and temporal variation of nearshore significant wave height in the Three Gorges Reservoir, China

The study of wave characteristic changes is critical for understanding the role of wave erosion in the shoreline erosion of reservoirs and its subsequent impact on environmental pollution. This study utilizes RBRvirtuoso D-wave-pressure-based wave gauges to make in situ observations of the nearshore significant wave height (SWH) in the Three Gorges Reservoir. The differential and impact factors affecting the SWH under varying water levels, in the main and tributary streams, and shoreline sections are analyzed. This research also investigates the alteration of the frequency distribution of the SWH. The findings indicate that the average SWH increases as the water level increases, reaching 1.2 cm, 1.5 cm, and 1.9 cm for water levels of 150 m, 165 m, and 175 m, respectively, with a SWH frequency distribution curve that becomes increasingly smooth. The average SWH in the mainstream is 2.9 times larger than that in the tributaries, with the former having a smoother frequency distribution curve. The average SWHs in different shoreline sections are inconsistent at the same water level, with the Badong (downstream) section near the Three Gorges Dam exhibiting a significantly higher average SWH than the Zhongxian (midstream) section further from the dam. When shipping activities intensify, there is often a marked increase in the magnitude of the SWH. The SWH in narrower reservoir sections is significantly greater than that in wider sections, with average measurements of 2.2 cm and 1.4 cm, respectively. Fluctuations of the water level, shipping activities, and other factors in the Three Gorges Reservoir have a significant impact on the alteration of the nearshore SWH, and changes in the SWH from low to high water levels may result in changes in both the spatial and temporal patterns of shoreline erosion. These alterations can, in turn, affect sediment and nutrient transport, potentially exacerbating environmental pollution issues.

Evaluation of indoor 222Rn and 220Rn concentrations in Dakshina Kannada, Karnataka, India

Naturally occurring radioactive gases which tend to build up (radon and thoron) in indoor environs can cause deleterious health effects including the development of lung cancer. The present study aims to measure 222Rn and 220Rn levels in dwellings in different seasons in the environs of Dakshina Kannada region of India. The 222Rn and 220Rn concentrations were measured in the monsoon, autumn, winter, and summer seasons using Solid State Nuclear Track Detector (SSNTD, LR-115 type II) films fixed in single-entry pinhole cylindrical twin-cup dosimeters. The higher 222Rn levels in indoors were observed during winter with an average concentration of 38.8Bqm-3 and lower during summer with an average of 14.1Bqm-3. The average indoor thoron concentration was also highest in winter with an average value of 25.5Bqm-3 and lowest in summer with 8.8Bqm-3. The annual inhalation dose ranged from 0.44 to 1.06mSvyear-1 with a mean value of 0.66mSvyear-1. The annual effective dose varied from 1.03 to 2.57mSvyear-1 with an average value of 1.59mSvyear-1. The assessed values have been contrasted with the limit suggested by the UNSCEAR and the ICRP and were found to be within the permissible level. The normality of frequency distribution curves of 222Rn and 220Rn concentrations was assessed by the Kolmogorov-Smirnov test.

Geographic distribution of arsenic contamination in the Himalayan Rivers flowing through Pakistan: Implications for its natural source and effects of anthropogenic activities

Arsenic (As) in natural hydrological systems is known as a worldwide major environmental concern. A geochemical and sedimentological study was done to ascertain the origin and geographical distribution of As in surface water and fluvial sediment collected from the floodplains/basins of the River Indus and its four major tributaries that drain through the northern Pakistan. The hydrogeochemical compositions of all five rivers were similar with calcium (Ca2+) and bicarbonate (HCO3−) being the dominating ions. The concentration of As ranged from 0.62–24.05 μg/L (average 3.7 ± 3.5 μg/L, n = 61) in river water, 2.3–23.4 mg/kg (average 5.7 ± 3.9 mg/kg) in suspended sediment, and 2.0–13 mg/kg (average 4.13 ± 2.3 mg/kg) in fluvial sediment. Various approaches were used, including mineralogical, sequential extraction, geochemical, and statistical analyses to investigate the distribution, behavior, and potential sources of As in the sediment. The effect of geological factors on the distribution of As was also studied. No noticeable changes in the relative abundance of minerals were observed in the sediment at different locations along the river. Both mineralogical and statistical analyses showed that silicate minerals like muscovite, biotite, and chloride are the main As reservoir while oxides minerals like hematite and magnetite, which are minor components in the sediment are second largest As carrier. A geochemical baseline, using the normalization and cumulative frequency distribution curves was constructed for As. The estimated mean human contribution of As was 3.4% in the Indus River, 1.9% in the Jhelum River, 13.7% in the Chenab River, 17.5% in the Ravi River and 5.4% in the Sutlej River, indicating relatively higher effects of anthropogenic activity along the Chenab River and Ravi River. The almost negligible effects of anthropogenic activities were additionally confirmed through the pollution assessment parameters estimated from the geo-enrichment, contamination factors, and accumulation index analyses. The current data suggest that As transported by the Indus River and its major tributaries is accumulated in the sediment and is potentially incorporated in the sedimentary aquifers situated along the Indus Basin and surrounding areas. Based on the current study, it is concluded that the source of As is dominantly geogenic whereas the role of anthropogenic activities is considered negligible except along the Ravi River which showed relatively a higher percentage (17.5%) of human or industrial contribution.

Particle size composition characteristics of weathered debris from grey–green slate under the action of freeze–thaw and dry–wet cycles

The material basis for soil formation is rock weathering debris. Understanding the particle size composition characteristics of rock weathering debris and its impacts is important for improving the soil structure of dry farmland in the central dry zone of Ningxia,China. In this study, the particle sizes of weathered debris collected from grey–green slate after indoor simulations of freeze–thaw and dry–wet cycles tests were examined. The results were as follows: (1) Under 16 treatments, the weathering debris of grey–green slate contained about 10% or less very fine sand and coarse silt, while clay, fine silt, and fine sand were the most abundant sizes (at least 60% of the total). (2) Under each treatment, the average particle size of the grey–green slate weathered debris was 5.52Ф (silt grade). The overall skewness was high, but the symmetry was poor. The particle size frequency distribution curve had many broad peaks or multiple peaks. (3) The fractal dimension was associated with very fine silt but had a strong negative correlation with fine sand and medium-coarse sand. The results indicate that fractal dimension can reflect the grain size characteristics of weathered debris. The mineral element content of the grey–green slate somewhat affected the fractal dimension, and it positively correlated with environmental electrical conductivity (EC) and element-leaching amount; it negatively correlated with particle size, temperature, and pH. According to the findings, the fractal dimension can accurately represent the particle size distribution of weathered debris. The generation of grey–green slate weathering debris should be considered in the formation and development of local soil.

Arsenic (v) Adsorption by Using Synthesized Iron Oxide Nanoparticles (Fe2O3-NPs) and Aluminum Oxide Nanoparticles (Al2O3-NPs)

Arsenic, is one of the most harmful elements to humans, health of chronic diseases, and continuously causing a threat to the world. Arsenic is found in combined form in rocks under the earth's surface and when it dissolves, it contaminates groundwater. In the current research study synthesized iron oxide nanoparticles (Fe2O3-NPs) and aluminum oxide nanoparticles (Al2O3-NPs) for the removal of arsenic (As) (˅) from an aqueous medium and characterized the synthesized material by different analytical techniques such as FT-IR spectroscopy and XRD spectroscopy. The results show successful synthesis of Fe2O3-NPs and Al2O3-NPs. Furthermore, the synthesized material was used as an adsorbent for extraction of as (V) from water. The effect of different parameters such as pH, temperature, contact time, and adsorbent dose on the adsorption process was investigated. The adsorption efficiency was determined by Fe2O3-NPs at about 20 mg/g and Al2O3-NPs at 19.5 mg/g. The quantitative removal of as (V) from industrial water required a minimum amount (0.2 g) of Fe2O3-NPs and Al2O3-NPs. various kinetic and isotherms were investigated in the current study. The result showed that the obtained data for Fe2O3-NPs was more fitted to Pseudo second order kinetic and Freundlich equation, while for Al2O3-NPs the data was more fitted to Pseudo second order kinetic and Elovich model equation, which confirms the interaction among as (V) and adsorbents. Thermodynamic parameters were also investigated which shows the process is spontaneous and endothermic. This model was used to estimate the site energy distribution for each adsorbent. Thermodynamic parameters were also investigated which shows the non-spontaneous and endothermic nature of the adsorbent. According to the results of the analysis of the approximate site energy distribution, adding Fe2O3 and Al2O3-NPs to arsenic decreased the area under the frequency distribution curve of the sorption site energies, which in turn decreased the number of sorption sites that were open to arsenic. This might be explained by the hydrophobic interaction between synthesized materials and arsenic being reduced due to the blocking of the Fe2O3 and Al2O3-NPs hydrophobic surface.

Enrichment of High Arsenic Groundwater Controlled by Hydrogeochemical and Physical Processes in the Hetao Basin, China.

Based on 447 samples collected from a shallow aquifer (depths from 0 to 150 m) in the Hetao Basin, Northern China, an integrated hydrogeochemical approach was used in this study to conceptualize the enrichment of high arsenic groundwater in the Hetao Basin. An unconventional method of distinguishing hydrogeochemical and physical processes from a dataset was tested by investigating the cumulative frequency distribution of ionic ratios expressed on a probability scale. By applying cumulative frequency distribution curves to characterize the distribution of ionic ratios throughout the Hetao Basin, hydrogeochemical indicators were obtained that distinguish the series of hydrogeochemical processes that govern groundwater composition. All hydrogeochemical processes can basically be classified as recharge intensity of groundwater, evaporation concentration intensity, and reductive degree controlling the spatial distribution of arsenic. By considering the three processes, we found that the concentration of arsenic was more than 10 μg/L when the (HCO3-+CO32-)/SO42- ratio was over 4.1 (strong reductive area). As the evaporation concentration intensity increased, the median value of arsenic increased from 10.74 to 382.7 μg/L in the median reductive area and rapidly increased from 89.11 to 461.45 μg/L in the strong reductive area. As the river recharge intensity increased (with the intensity index increasing from 0 to 5), the median value of arsenic dropped from 40.2 to 6.8 μg/L in the median reductive area and decreased more markedly from 219.85 to 23.73 μg/L in the strong reductive area. The results provide a new insight into the mechanism of As enrichment in groundwater.

Dependence of natural radioactivity on physico-chemical parameters of soils in Belagavi region of Karnataka, India

The radiation level, radionuclide distribution, and dependence of radioactivity on physico-chemical parameters of soils have been studied in Belagavi region of Karnataka, India. The gamma dose rates in air were measured using a portable survey metre, and the activity in soils was measured using NaI (Tl)-based gamma ray spectrometer. The measured absorbed dose rate in air ranges from 54 to 77 nGy h−1 with a mean value of 58 nGy h−1. The 40K activity in soil was found to vary from 97.9 to 378.5 Bq kg−1 with an average of 214.2 Bq kg−1. The 226Ra activity varied from 15.3 to 68.8 Bq kg−1 with an average value of 30.5 Bq kg−1 and the activity of 232Th varied from 12.3 to 65.4 Bq kg−1 with an average value of 27.96 Bq kg−1. The activity of 226Ra and 232Th were found to be higher than the world average value in some locations of the study area. A good positive correlation was observed between the activity concentration of radionuclides and physico-chemical parameters of soil. A good positive correlation was observed between the activity of 226Ra and 232Th with clay with a correlation coefficient of r = 0.609 and 0.591, respectively. The frequency distribution curve of 226Ra, 232Th, and 40K are lognormal in nature. The application of cluster analysis and principal component analysis were carried out using IBM SPSS software for better understanding of dynamics of soil matrix and the dependence of soil radioactivity on the physico-chemical parameters of the soil.

Assessment of natural radioactivity and its dependence on clay minerals of the soil of Dakshina Kannada district, South India

ABSTRACT The current study is the first in-depth investigation into the natural radioactivity in soils and assessment of associated radiological risks to the population in Dakshina Kannada district of southern India. The specific activity of natural radionuclides was determined by NaI(Tl) gamma spectroscopy. The trace minerals found in the soil were detected by FTIR spectroscopy and their relative distribution is quantified by calculating the extinction coefficient. The specific activity of 226Ra, 232Th, and 40K range from 9.73 ± 0.7 to 59.97 ± 1.9 Bq kg−1 with a mean of 26.47 ± 1.2 Bq kg−1, 15.88 ± 0.8 to 78.8 5 ± 2.1 Bq kg−1 with a mean of 35.45 ± 1.2 Bq kg−1 and 147.06 ± 3.4 to 535.92 ± 6.7 Bq kg−1 with a mean of 403.11 ± 5.5 Bq kg−1, respectively. The normality of frequency distribution curves of radionuclide concentrations was confirmed by the Kolmogorov–Smirnov test. The estimated hazard indices were found to be within acceptable levels. Higher levels of 226Ra, 232Th and 40K in soils were detected in certain parts of Dakshina Kannada, which was linked to the mineralogy of the region. The specific activity of radionuclides was discovered to be dependent on the minerals kaolinite and calcite. The extinction coefficients of Kaolinite, Calcite, and Quartz in soil ranged from 33.11 to 63.98, 29.63 to 111.24, and 84.47 to 115.83, respectively.

Physiological Mechanisms and Significance of Intracranial B Waves.

ObjectiveRecently published studies have described slow spontaneous cerebral blood flow (CBF) and cerebrospinal fluid (CSF) oscillations measured by magnetic resonance imaging (MRI) as potential drivers of brain glymphatic flow, with a similar frequency as intracranial B-waves. Aiming to establish the relationship between these waveforms, we performed additional analysis of frequency and waveform parameters, of our previously published transcranial Doppler (TCD) and intracranial pressure (ICP) recordings of intracranial B waves, to compare to published MRI frequency measurements of CBF and CSF slow oscillations.Patients and MethodsWe analyzed digital recordings of B waves in 29 patients with head injury, including middle cerebral artery (MCA) flow velocity (FV), ICP, end tidal CO2, and arterial blood pressure (ABP). A subset of these recordings demonstrated high B wave activity and was further analyzed for parameters including frequency, interaction, and waveform distribution curve features. These measures were compared to published similar measurements of spontaneous CBF and CSF fluctuations evaluated using MRI.ResultsIn patients with at least 10% amplitude B wave activity, the MCA blood flow velocity oscillations comprising the B waves, had a maximum amplitude at 0.0245 Hz, and time derivative a maximum amplitude at 0.035 Hz. The frequency range of the B waves was between 0.6–2.3 cycles per min (0.011-0.038 Hz), which is in the same range as MRI measured CBF slow oscillations, reported in human volunteers. Waveform asymmetry in MCA velocity and ICP cycles during B waves, was also similar to published MRI measured CBF slow oscillations. Cross-correlation analysis showed equivalent time derivatives of FV vs. ICP in B waves, compared to MRI measured CBF slow oscillations vs. CSF flow fluctuations.ConclusionsThe TCD and ICP recordings of intracranial B waves show a similar frequency range as CBF and CSF flow oscillations measured using MRI, and share other unique morphological wave features. These findings strongly suggest a common physiological mechanism underlying the two classes of phenomena. The slow blood flow and volume oscillations causing intracranial B waves appear to be part of a cascade that may provide a significant driving force for compartmentalized CSF movement and facilitate glymphatic flow.