Seasonal Changes In Air Temperature Research Articles

Unraveling the Role of Vegetation CO2 Physiological Forcing on Climate Zone Shifts in China

AbstractIncreasing atmospheric CO2 causes substantial spatial and seasonal changes in air temperature and precipitation through its radiative (RAD) and vegetation physiological (PHY) effects. However, it remains poorly understood on how these two effects impact the integrated climate zone shifts over China. Here, we disentangle the RAD and PHY effects on the shifts of Köppen‐Geiger climate zones from pre‐industrial to 4 × CO2 in China using nine Earth system models. We find that climate zone changes over approximately 56.1% of China, and PHY contributes 15.2% of such changes at 4 × CO2. PHY shifts regional climate to warmer and wetter classifications, shrinking (−42.8%) the arid zone distributions and promoting (26.8%) the tropical zone northward extensions. Our findings highlight the critical role of vegetation in reshaping the overall climate zone distributions, yet introduce potential risk to climate mitigation and adaptation.

A Systematic Review and Meta-Analysis of Free Triiodothyronine (FT3) Levels in Humans Depending on Seasonal Air Temperature Changes: Is the Variation in FT3 Levels Related to Nonshivering Thermogenesis?

Thyroid hormones play a crucial role in regulating normal development, growth, and metabolic function. However, the controversy surrounding seasonal changes in free triiodothyronine (FT3) levels remains unresolved. Therefore, the aim of this study was to conduct a systematic review and meta-analysis of variations in FT3 levels in relation to seasonal air temperatures in the context of current knowledge about its role in nonshivering thermogenesis. Ten eligible articles with a total of 336,755 participants were included in the meta-analysis. The studies were categorized into two groups based on the air temperature: "Cold winter", where the winter temperature fell below 0 °C, and "Warm winter", where the winter temperature was above 0 °C. The analysis revealed that in cold regions, FT3 levels decreased in winter compared to summer (I2 = 57%, p < 0.001), whereas in warm regions, FT3 levels increased during winter (I2 = 28%, p < 0.001). These findings suggest that seasonal variations in FT3 levels are likely to be influenced by the winter temperature. Considering the important role of the FT3 in the nonshivering thermogenesis process, we assume that this observed pattern is probably related to the differences in use of thyroid hormones in the brown adipose tissue during adaptive thermogenesis, which may depend on intensity of cold exposure.

PATHOGENETIC ASPECTS OF THE INFLUENCE OF SEASONALITY ON THE HEALTH OF PATIENTS WITH CHRONIC PATHOLOGY OF THE CARDIOVASCULAR SYSTEM: LITERATURE REVIEW

Purpose. To summarize and systematize the literature data on the pathogenetic aspects of the influence of seasonality on the health status of patients with chronic pathology of the cardiovascular system.&#x0D; Materials and methods. To analyze the literature, materials from the PubMed and PubMed Central resources of the US National Library of Medicine, Google Scholar, Elsevier Clinical Key and Elsevier Science Direct, as well as in the Russian RSCI database were used. The sample consisted of scientific papers devoted to the pathogenetic aspects of the influence of various meteorological factors on the course of cardiovascular pathology.&#x0D; Results. The generalized results of clinical and experimental studies presented in this review indicate both direct and indirect effects on the state of the cardiovascular system of seasonal changes in air temperature, atmospheric pressure, solar radiation, air humidity and geomagnetic indicators.&#x0D; Conclusion. Meteorological factors have a pronounced effect on the course of cardiovascular diseases both through direct mechanisms of influence, and through the inclusion in the pathogenesis of these diseases and the aggravation of existing risk factors. The pathogenetic mechanisms of the influence of weather factors on the state of the cardiovascular system are important for understanding the application points that can be influenced and improved by primary and secondary prevention of cardiovascular pathology.

Modeling seasonal vegetation phenology from hydroclimatic drivers for contrasting plant functional groups within drylands of the Southwestern USA

In dryland ecosystems, vegetation within different plant functional groups exhibits distinct seasonal phenologies that are affected by the prevailing hydroclimatic forcing. The seasonal variability of precipitation, atmospheric evaporative demand, and streamflow influences root-zone water availability to plants in water-limited environments. Increasing interannual variations in climate forcing of the local water balance and uncertainty regarding climate change projections have raised the potential for phenological shifts and changes to vegetation dynamics. This poses significant risks to plant functional types across large areas, especially in drylands and within riparian ecosystems. Due to the complex interactions between climate, water availability, and seasonal plant water use, the timing and amplitude of phenological responses to specific hydroclimate forcing cannot be determined a priori, thus limiting efforts to dynamically predict vegetation greenness under future climate change. Here, we analyze two decades (1994–2021) of remote sensing data (soil adjusted vegetation index (SAVI)) as well as contemporaneous hydroclimate data (precipitation, potential evapotranspiration, depth to groundwater, and air temperature), to identify and quantify the key hydroclimatic controls on the timing and amplitude of seasonal greenness. We focus on key phenological events across four different plant functional groups occupying distinct locations and rooting depths in dryland SE Arizona: semi-arid grasses and shrubs, xeric riparian terrace and hydric riparian floodplain trees. We find that key phenological events such as spring and summer greenness peaks in grass and shrubs are strongly driven by contributions from antecedent spring and monsoonal precipitation, respectively. Meanwhile seasonal canopy greenness in floodplain and terrace vegetation showed strong response to groundwater depth as well as antecedent available precipitation (aaP = P − PET) throughout reaches of perennial and intermediate streamflow permanence. The timings of spring green-up and autumn senescence were driven by seasonal changes in air temperature for all plant functional groups. Based on these findings, we develop and test a simple, empirical phenology model, that predicts the timing and amplitude of greenness based on hydroclimate forcing. We demonstrate the feasibility of the model by exploring simple, plausible climate change scenarios, which may inform our understanding of phenological shifts in dryland plant communities and may ultimately improve our predictive capability of investigating and predicting climate-phenology interactions in the future.

Precipitation trends (1958–2021) on Ammassalik island, south-east Greenland

Along with Arctic warming, climate models project a strong increase in Arctic precipitation in the 21st century as well as an increase in the ratio of liquid to total precipitation. In the precipitation-rich region of south-east Greenland, precipitation changes could locally have significant impacts on runoff. However, climate data are sparse in this remote region. This study focuses on improving our understanding of the past precipitation changes on Ammassalik island in south-east Greenland between 1958 and 2021. To assess past changes in air temperature at 2-meter and precipitation, output from a regional polar climate model (RACMO2.3p2) is evaluated with measurements from automatic weather stations in Tasiilaq and on Mittivakkat glacier. In addition, RACMO2.3p2 is used to assess past seasonal changes in air temperature at 2-meter, precipitation amount, precipitation phase and the altitude of the rain/snow boundary. We find that the climate model accurately represents the monthly average observed air temperature at 2-meter. While total precipitation is overestimated, interannual variability of precipitation is properly captured. We report a significant increase of summer temperature at 2-meter of +0.3°C/decade (p&amp;lt;0.01) at Mittivakkat glacier and +0.2°C/decade (p&amp;lt;0.01) in Tasiilaq in 1958–2021. For the subperiod 1990–2019, the trend in annual averages of temperature at 2-meter in Tasiilaq (+0.8°C/decade, p=0.02) corresponds well to known temperature trends on the Greenland Ice Sheet within the same period. On Mittivakkat glacier a significant trend is not detected within this subperiod (+0.2°C/decade, p=0.25). The modelled liquid precipitation ratio on Ammassalik island increased in all summer months (1958–2015) by +2.0/+1.9/+1.8%/decade in June/July/August respectively. In July and August, these trends were stronger at higher elevations. No statistical evidence is found for trends in other seasons. We also identify monthly increases in the altitude of the rain-to-snow boundary (+25/+23/+20 m/decade in July/August/September respectively).

Climate induced changes in streamflow and water temperature in basins across the Atlantic Coast of the United States: An opportunity for nature-based regional management

Study regionWatersheds of the Atlantic Coast of the United States (ACUS) spanning a latitudinal range of 30.8°N – 46.5°N Study focusThis study assessed climate-induced changes (CMIP5-RCP 8.5) in projected streamflow and water temperature estimates from individual SWAT watershed models across the ACUS territory by mid and end of the century. Seasonal and spatial trends as well as relationships between hydroclimatologic variables were analyzed to identify opportunities for regional implementation of water management strategies. New hydrological insights for the regionChanges in hydroclimatologic variables suggest spatial trends clearly differentiated by seasons. Northern and central watersheds are projected to experience the most dramatic changes in winter, summer, and spring streamflows (67 %, −25 %, and −24 %, respectively) and summer water temperature (6.2 °C), while southern watersheds presented the largest streamflow increase in fall (35 %), and water temperature changes greater than 3 °C for all seasons. These similarities and contrasts between ACUS watersheds’ hydrologic responses provide an opportunity for regional management of climate induced impacts on water resources. Mitigation strategies such as regional conservation of forests and wetlands can alleviate water scarcity and extreme flow events occurring across the ACUS under the assumed emissions scenario. Results suggest that changes in seasonal air temperature and water temperature may be linearly related in watersheds at lower elevations with no snow influence; while streamflow, precipitation, and air temperature changes have complex non-linear relationships.

Research of the environmental temperature influence on the horizontal displacements of the Dnieper hydroelectric station dam (according to GNSS measurements)

Abstract The paper studies the relationship between the ambient temperature change and the horizontal displacements on control points of the Dnieper Hydroelectric Station dam from 2016 to 2020. A specially developed software product analyzed the GNSS time series of measurements pre-processed by the GeoMoS system to determine the parameters of seasonal displacements and their relationship with seasonal changes in air temperature. The research established that the influence of ambient temperature in the absence of significant changes in the water level in the upper reservoir determines the cyclicity of dam deformations. It is established that the projections of velocity vectors of reference points in the ETRF-2014 system for the studied period do not exceed the absolute value of 3 mm/month. The directions of the horizontal displacement vectors in the first half of each year are opposite to the directions recorded in the second half. In the first half of the year, the dam’s body shifts towards the reservoir, while in the second half year period, it shifts-backwards. According to the three-year GNSS monitoring of the Dnieper Hydroelectric Station dam, the amplitude of semi-annual horizontal oscillations of the control points relative to the dam axis is from -9.5 to +8 mm. In winter and summer, the horizontal displacements increase from the edges of the dam to its central part, and the amplitudes of the horizontal displacements move vice versa. The obtained data establish a linear analytical relationship between the average temperature and the horizontal displacements of the GNSS control points.

ГЕОДИНАМІКА

The goal. Identify the relationship between seasonal temperature changes and vertical and horizontal displacements of GNSS control points based on data obtained by the automated monitoring system of the Dnipro HPP dam in the period from 2016 to 2020. Input data. The research used data of uninterrupted GNSS measurements obtained at 16 points of the Dnipro HPP dam from mid-2016 to mid-2020. Method. A specially developed software product analyzes the GNSS time series of measurements pre-processed by the GeoMoS system to determine the parameters of seasonal displacements and their relationship with seasonal changes in air temperature. The GNSS time series analysis. Based on the conducted research, the influence of environmental temperature has a decisive effect on the cyclicity of dam deformations. This applies to both horizontal and vertical displacements but in the absence of significant changes in the water level in the upper reservoir. Values of extreme displacements increase closer to the middle of the dam and decrease at the edges. This tendency is observed every year in the study period. According to the three-year GNSS dam monitoring, the amplitude of semi-annual horizontal oscillations of the control points relative to the dam axis is in the range of 15-18 mm. Almost all vectors of horizontal displacements are perpendicular to the axis of the arcuate dam. In the first half of the year, the vectors of horizontal displacements aim to widen the dam, and in the second half of the year - at compressing the dam. The analysis of the data represents that almost every year, extreme deviations, both horizontal and vertical, occur in February and August. Temperature extremes occur faster than excessive GNSS displacements. For the dam of the Dnipro HPP, the extreme horizontal displacements lag on average by 37 days, and the vertical ones - by 32 days from the extreme temperatures. The deformations of the dam are related to the concrete structure temperature, which changes with a certain delay relative to the air temperature. The magnitudes of extreme displacements and the epoch of their manifestation depend on the dam's design and its technical parameters. For each dam, these extreme displacements and the periods of their representation will be different. Accordingly, monitoring these displacements and their changes over time is one of the criteria for assessing the general condition of the dam. Scientific novelty and practical significance. The regularities of the connection between the change of temperature and the displacements of the GNSS points, revealed during the research, can be used for the further study of data processing and analysis of the hydraulic structures monitoring.

Borehole Diameter Controls Thermal‐Induced Convection and Evaporation From a Shallow Water Table

AbstractUnderstanding air exchange via boreholes, shafts, and wells is important for Earth and environmental sciences because of their potential role for increased evaporation and greenhouse gas emissions. Here, we investigated the effect of atmospheric temperature variability on air transport via a borehole as a function of its diameter. Field experiment included five boreholes with diameters ranging from 0.10 to 0.38 m and a depth of 3 m with an artificial water table at −2.7 m. Temperature was recorded in each borehole at 1‐min intervals for 1 year. Diurnal and seasonal air temperature changes triggered thermal instability, mainly during winter nights, which initiated thermal‐induced convection within the boreholes. The thermal‐induced convection penetrated deeper into the borehole as the diameter increased, doubling the water table evaporation rate for the largest borehole relative to the smallest. Borehole diameter plays an important role in controlling air exchange rates between the subsurface and the atmosphere.

Monitoring of permafrost degradation along the Bei’an-Heihe Expressway in China

We performed a regional geological survey in discontinuous permafrost (PF) area along the Bei’an to Heihe Expressway between September 2009 and October 2016 to investigate the state and change of PF in northeast China. Underground resistivity changes were periodically detected along the foot of the subgrade and soil temperatures were monitored under the road foundation. We combined local meteorological and average annual air temperature data to analyze changes in PF thickness. The climate data show that the average annual temperature has gradually increased in the study area since 1980, rising to 0 °C around 1990, and the frost number has decreased to less than 0.5 since 1988. The soil temperature results show that the PF temperature in this section is higher than − 1 °C and is in a high-temperature PF zone affected by changes in seasonal air temperature. The PF under the left foot of the subgrade (LPF) and under the road central separation zone of the road (CPF) both show a decreased PF table, increased PF base, and severe PF degradation. Owing to different cover thicknesses, as well as differences in heat transfer between frozen and unfrozen soil, the base of LPF degraded faster than its table, to CPF the opposite is true. Underground resistivity measurements to verify the accuracy of the PF degradation results. The ground temperature monitoring data and climate data show good consistency. Comprehensive analysis results show that PF in the study area is in a strong degradation stage and will soon disappear.

ОСОБЕННОСТИ РАСПРОСТРАНЕНИЯ РАДИОВОЛН УВЧ ДИАПАЗОНА В ПРИЗЕМНОМ И ПРИВО́ДНОМ ТРОПОСФЕРНОМ ВОЛНОВОДЕ

The article considers examples of ultra-long propagation of UHF radio waves in mobile cellular communication systems. The phenomena are mainly observed in the Astrakhan region in the spring-summer period (May-June) and are presumably associated with sharp seasonal changes of air temperature followed by rains. The effect of temperature inversion results in changing the refraction index in the surface layer and, as a result, in changing the wave direction as the effect of superrefraction in the surface atmospheric layer. The properties of radio waves in their propagation in the land and sea-water surface waveguide are investigated. The values of the heights of land and sea-water surface tropospheric waveguides for cellular communication systems of different ranges are obtained. The features of existing of tropospheric land and sea-water surface tropospheric waveguides are described. The need to use their properties in the mobile communication systems design is stated.

Temporal variations in soil CO2 efflux in an alpine meadow site on the Qinghai–Tibetan Plateau

AbstractTemporal variations in soil CO2 efflux and its direct links to soil microbial biomass and environmental factors in high‐elevation regions are poorly understood. In this study, I investigated the variations in soil CO2 efflux over time and their relationships to soil organic matter, soil microbial biomass and environmental factors in an alpine meadow site on the Qinghai–Tibetan Plateau. The results showed notable monthly to seasonal changes in soil CO2 efflux in alpine meadows. The soil CO2 efflux was lower overall from January to May and from October to December than from June to September (p &lt; 0.05); on a seasonal basis, the soil CO2 efflux was lower during the spring, autumn and winter than during the summer (p &lt; 0.05). In addition, linear regression analysis showed that the temporal variations in soil CO2 efflux over the whole year decreased with soil microbial biomass carbon content (p &lt; 0.05). Soil CO2 efflux was also positively related to air temperature and snow cover depth (p &lt; 0.05). Multiregression and principal component regression analyses indicated that temporal variations in soil CO2 efflux were mainly caused by monthly and seasonal changes in air temperature and soil microbial biomass.

Field evaluation of the impact of environmental conditions on concrete moisture-related shrinkage and coefficient of thermal expansion

This study evaluates the impact of the environmental conditions on the moisture-related shrinkage and the coefficient of thermal expansion (CTE) of concrete. The evaluations are based on the strain measured in a series of unrestrained shrinkage prisms during fifteen months. The prisms included four concrete mixtures containing either portland cement or calcium sulfoaluminate cement. The prisms were fabricated in the field and left outdoors so that they were subjected to natural rainfall, sun radiation, and daily and seasonal changes in air temperature and relative humidity (RH). A strain model was used to divide the deformation measured in the prisms into its thermal and moisture-related components. By doing so, the evolution of concrete moisture-related shrinkage and CTE during the fifteen-month period was back-calculated. A strong correlation (R2 = 0.998) existed between the maximum moisture-related shrinkage that was back-calculated in the outdoor prisms and the ultimate moisture-related shrinkage measured in the laboratory under constant temperature and 50 percent air RH. Because of drying, concrete CTE reached values that were up to 50 percent higher than the CTE determined in the laboratory under saturated conditions. Concrete moisture-related shrinkage and CTE systematically decreased after the rainfall events, except when the concrete was already saturated. Rainfalls, rather than air RH, controlled the re-wetting of the concrete in the field.

Influence of inter-annual environmental variability on chrysophyte cyst assemblages: insight from a 2-years sediment trap study in lakes from northern Poland

&lt;p&gt;Quantitative paleonvironmental studies using transfer functions are developed from training sets. However, changes in some variables (&lt;em&gt;e.g&lt;/em&gt;., climatic) can be difficult to identify from short-term monitoring (&lt;em&gt;e.g.,&lt;/em&gt; less than one year). Here, we present the study of the chrysophyte cyst assemblages from sediment traps deployed during two consecutive years (November 2011-November 2013) in 14 lakes from Northern Poland. The studied lakes are distributed along a W-E climatological gradient, with very different physical, chemical and morphological characteristics, and land-uses. Field surveys were carried out to recover the sediment trap material during autumn, along with the measurement of several environmental variables (nutrients, major water ions, conductivity, pH, dissolved oxygen and chlorophyll&lt;em&gt;-a&lt;/em&gt;). During the study, one year experienced mild seasonal changes in air temperature (November 2011-November 2012; TS1), typical of oceanic climate, while the other year was characterized by colder winter and spring (November 2012-November 2013; TS2), and higher summer temperatures, more characteristic of continental climate. Other environmental variables (&lt;em&gt;e.g&lt;/em&gt;., nutrients) did not show great changes between both years. Multivariate statistical analyses (RDA and DCA) were performed on individual TS1 and TS2 datasets. Water chemistry and nutrients (pH, TN and TP) explained the largest portion of the variance of the chrysophyte data for the individual years. However, analyses of the combined TS1 and TS2 datasets show that strong changes between summer and autumn (warm period, ice-free period with thermal stratification) and winter and spring (cold period, ice-cover period) play the most important role in the inter-annual variability in the chrysophyte assemblages. We show how inter-annual sampling maximizes ecological gradients of interest, particularly in regions with large environmental diversity, and low climatic variability. This methodology could help to identify distinct seasonal and inter-annual changes of biological communities to improve its application in paleoclimate studies.&lt;/p&gt;

Base flow-driven shifts in tropical stream temperature regimes across a mean annual rainfall gradient

Climate change is expected to affect air temperature and watershed hydrology, but the degree to which these concurrent changes affect stream temperature is not well documented in the tropics. How stream temperature varies over time under changing hydrologic conditions is difficult to isolate from seasonal changes in air temperature. Groundwater and bank storage contributions to stream flow (i.e., base flow) buffer water temperatures against seasonal and daily fluctuations in solar radiation and air temperature while rainfall-driven runoff produces flooding events which also influence stream temperature. We used a space-for-time substitution to examine how shifts in base flow and runoff alter thermal regimes in streams by analyzing hydrological and temperature data collected from similar elevations (400-510 m above sea level) across a 3500 mm mean annual rainfall gradient on Hawai‘i Island. Sub-daily water temperature and streamflow gathered for three years were analyzed for daily, monthly, and seasonal trends and compared to air temperature measured at multiple elevations. Results indicate that decreases in median base flow increased mean, maximum and minimum water temperatures as well as daily temperature range. Monthly and daily trends in stream temperature among watersheds were more pronounced than air temperature, driven by differences in groundwater inputs and runoff. Stream temperature was strongly negatively correlated to base flow during the dry season but not during the wet season due to frequent wet season runoff events contributing to total flow. In addition to projected increases in global air temperature, climate driven shifts in rainfall and runoff are likely to affect stream flow and groundwater recharge, with concurrent influences on base flow resulting in shifts in water temperature that are likely to affect aquatic ecosystems. This article is protected by copyright. All rights reserved.

Environmental Studies on the Aqaba Gulf Coastal Waters during 2011-2013

In order to assess the quality of the Aqaba Gulf coastal waters for the sustainable use and development, and consequently for the national income, four field campaigns were annually carried out during the period from 2011-2013 to monitor hydrographic variables, i.e. temperature, salinity, pH, etc., nutrients, some heavy metals, i.e. iron, lead, copper, cadmium, chromium, etc. in addition to petroleum hydrocarbons. Except for the area of Sharm El-Sheikh Harbor, the results for the density, composition, and distributions of beach litter cleared out that the Egyptian shoreline of the Aqaba Gulf is relatively not affected by man-made litter. The area of Sharm El-Sheikh Harbor was subjected to many factors which undoubtedly affected the rate of man-made litter ac-cumulation, especially, oil contamination (oil and old or new tar) which is a good es-timator of levels of oil contamination and an effective means of evaluating the poten-tial threat of oil on coastal resources. The results of the present study cleared out also that water temperature followed seasonal changes in air temperature. Aqaba Gulf water is characterized by its high salinity and the presence of well oxygenated waters. Minor changes in the distribution of pH, BOD, DOM and COD, revealed limited effects of human impacts. Low levels of Chl-a and TSM concentrations and high transparency revealed also negligible effects for human impacts. Significantly higher sea water temperatures, TSM, DO, BOD, DOM, COD, NH4, NO2, PO4 and TP were observed in summer season compared to their corresponding values in winter season. On contrast, higher values of chlorophyll-a, NO2, TN, and SiO4 were observed in winter compared to summer season. Based on the mean annual values, Aqaba Gulf coastal waters are classified as oligotrophic to mesotrophic state. The concentrations of dissolved inorganic nitrogen forms followed the following order: NH4= NO3＞NO2. In general, the majority of TN in winter was in the form of organic-N (96.3%) compared to 91.7% in summer season. On the meantime, TP exhibited more or less comparable organic-P percentage in summer (86.2%) and winter (81.2%) seasons. Moreover, the DIN/DIP ratio showed relatively higher values in winter season (14.2:1) compared to summer season (12.4:1). This indicates high nitrogen concentrations in comparison with that of phosphorous in winter; yet it reflects the generally lower nutrient levels present in the coastal waters of the Aqaba Gulf due to the lack of significant nutrient input or oceanic upwelling. Concentrations of heavy metals were relatively low signifying that Aqaba Gulf Coastal waters are not yet seriously threatened in spite of the rapid recreational and human developments that are considered a challenge to the safety and viability of Aqaba Gulf marine environment. Furthermore, concentrations of petroleum hydrocarbons were significantly higher in summer than in winter that are mainly attributed to the increase in the levels of oil pollution that most probably re-sulted from the increase in accidental, deliberate or operational discharges and spills of oil from ships. In general, the maximum concentration was much lower than the harmful concentrations reported for seawater. A stepwise multiple linear regression, analysis of variance (ANOVA), and principle component analysis (PCA) were applied.

Evaluation of the Quality for the Egyptian Red Sea Coastal Waters during 2011-2013

To assess the quality of the Egyptian Red Sea coastal waters for the sustainable use and development, due to its importance for the national income, four field campaigns were annually carried out during the period from 2011-2013 to investigate the hydrography, nutrient salts, heavy metals and petroleum hydrocarbons. Except for the area of Bir Shalatein, the results of beach litter cleared out that the shoreline of the studied area is not affected by man-made litter. No sewage could be observed. The results of the present study showed that water temperature followed seasonal changes in air temperature. Red Sea water is more saline than adjacent Arabian Sea. DO revealed high values and presence of well oxygenated waters. Minor changes in the distribution of pH, BOD, DOM and COD, revealed that limited effects of human impacts and depend mainly on the dynamics of its water as well as on the geographical location. Low Chl-a and TSM concentrations and high transparency revealed that also the effect of human impacts is almost negligible. Significantly higher sea water temperatures, TSM, pH, DO, BOD, DOM, and COD were observed in summer season compared to their corresponding values in winter season. Dissolved inorganic nitrogen concentrations were quite low because there is little nutrient input from soil, agriculture and pollution on land. Based on the annual mean values, the pattern concentrations of dissolved inorganic nitrogen forms followed the order: NO3 > NH4 > NO2. The Red Sea coastal waters are classified as oligotrophic to mesotrophic state. A remarkable increase of PO4 concentration was observed in the middle Red Sea stations due to huge amounts of effluents enriched with phosphate from the main shipping and industry of Phosphate Companies. SiO4 displayed a large variability due to the supply of SiO4, which flows in the Red Sea through the strait of Bab El-Mandab, biological consumption, organic matter decomposition and the partial dissolution of quartz particle transported to the sea from the surrounding desert during sand storms. Concentrations of ammonia, phosphorus, total nitrogen, and total phosphorus were significantly higher in summer compared to their corresponding values in winter. In general, the majority of TN and TP in winter were in the form of organic-N (91.3%) and organic P (96.8%). The mean DIN/DIP ratio revealed high nitrogen concentrations in comparison with that of phosphorous and the surface coastal waters of the Red Sea are principally, P-limited for phytoplankton growth with higher values in winter season compared to summer season. Concentrations of heavy metals were quite low most probably due the absence of major local impacts of any land-based sources and/or any major negative impacts of coastal tourism. Regional variations were almost negligible and except for Mn, Cd, and Hg insignificant seasonal variations were observed. The present study revealed concentrations for metals in the acceptable levels. Furthermore, concentrations of petroleum hydrocarbons were significantly higher in winter than in summer which is mainly attributed to the increase in the rate of evaporation for petroleum hydrocarbons in summer. In general, the maximum concentration was much lower than the harmful concentrations reported for seawater. Correlation coefficients as well as principle component analysis (PCA) were applied.

A pilot study of the effects of environmental and physiological stress on the conjunctival bacteria of college student contact wearers

The influence of environmental and physiological stress on conjunctival bacteria of the eye during soft contact lens wear is incompletely understood. A five week case control study was conducted during the second half of the Fall 2011 semester on the campus of the University of West Alabama to assess the impact of environmental and physiological stress on the conjunctival bacteria of contact lens wearers. Weekly stress survey scores and bacterial colonies from conjunctival swab samples were recovered from eight undergraduate students representing males, females, contact wearers, and non-contact wearers. The most common bacteria recovered were Ornithinibacillus bavariensis, Staphylococcus equorum, and Micrococcus luteus. No positive correlations were observed between stress scores and bacterial counts in the subjects. Changes in bacterial counts correlated with seasonal changes in air temperature and precipitation, suggesting that conjunctival bacteria respond strongly to environmental changes.

In-situ monitoring of settlement at different layers under embankments in permafrost regions on the Qinghai–Tibet Plateau

Ground temperature and settlement at different soil layers are monitored at four typical sections of the Qinghai–Tibet Highway (QTH) and one section of a newly built test road (NBTR) in Beilu River basin, for the purpose of extensive investigation on the rather complicated mechanism of embankment settlement owing to several physical and mechanical processes (i.e., settlement sources) taking place in different soil layers in permafrost regions. Combining the ground temperature with borehole drilling exploration, thawing temperatures of the permafrost layers in the five sections are determined, and then characteristics of permafrost degradation are analyzed. Three types of sections are summarized to clarify different settlement sources in different soil layers. On these bases, characteristics of embankment settlement under different geological conditions are analyzed; the influence of the seasonal changes of air temperature on embankment settlement is discussed; since the two sections, one on QTH and the other on NBTR, are both located in Beilu River basin, they are compared with respect to the variation of the main settlement source in the process of permafrost degradation. The results help to understand the mechanism of embankment settlement.

Assessment of regional climate model simulation estimates over the northeast United States

Given the coarse scales of coupled atmosphere‐ocean global climate models, regional climate models (RCMs) are increasingly relied upon for studies at scales appropriate for many impacts studies. We use outputs from an ensemble of RCMs participating in the North American Regional Climate Change Assessment Program (NARCCAP) to investigate potential changes in seasonal air temperature and precipitation between present (1971–2000) and future (2041–2070) time periods across the northeast United States. The models show a consistent modest cold bias each season and are wetter than observations in winter, spring, and summer. Agreement in spatial variability and pattern correlation is good for air temperature and marginal for precipitation. Two methods were used to evaluate robustness of the mid 21st century change projections; one which estimates model reliability to generate multimodel means and assess uncertainty and a second which depicts multimodel projections by separating lack of climate change signal from lack of model agreement. For air temperature we find changes of 2–3°C are outside the level of internal natural variability and significant at all northeast grid cells. Signals of precipitation increases in winter are significant region wide. Regionally averaged precipitation changes for spring, summer, and autumn are within the level of natural variability. This study raises confidence in mid 21st century temperature projections across the northeast United States and illustrates the value in comprehensive assessments of regional climate model projections over time and space scales where natural variability may obscure signals of anthropogenically forced changes.