Seasonal Humidity Variations Research Articles

RECONHECENDO TOCAS FÓSSEIS DA ESTIVAÇÃO DE PEIXES PULMONADOS (SARCOPTERYGII, DIPNOI): ICNOTAXONOMIA E PALEOAMBIENTE

Recognizing lungfish (Sarcopterygii, Dipnoi) estivation burrows: ichnotaxonomy and paleoenvironment. Lungfishes first appeared on Earth around 350 million years ago in freshwater environments from Gondwana, since when they suffered harsh adaptations through the geological time, among which, the aestivation capability. Such a behavior keeps preserved in the geological record along the eras and the fossil burrows own a high potential for environmental inferences. From so much we developed this work aiming to (i) gather the records once published on this theme, (ii) to discuss the adopted standard by the authors for interpreting the burrows and their burrowers, and (iii) to discuss the paleoenvironmental significance of the lungfish burrows presenting a model of its probable occurrence in the landscape context. For such a purpose, we made the literature review searching for terms related to the theme, in different basis and pages of scientific journals. We have found 35 articles reporting new occurrences of lungfish burrows, besides uncertain or refuted records, according to ichnotaxonomical parameters. A large proportion of the papers inform about sedimentary facies and paleoenvironmental conditions. Essentially, the records occur in areas of shallow rivers and lakes of a semiarid to subtropical climate, with seasonal humidity variations, but also in coastal environments. Still, from the presented publications, we consider lungfish aestivation burrows to be safe paleoenvironmental indicators. Keywords: lungfish; aestivation; ichnofossils; ichnotaxonomy; floodplains; semiarid.

Durability and mechanical long-term performance of reclaimed asphalt pavement stabilized by alkali-activation

The application of alkali-activated industrial by-products for the stabilization of reclaimed asphalt pavement (RAP), can become a sustainable solution to reduce the carbon footprint of road construction and maintenance activities. Furthermore, this approach can also reduce the increasing depletion of natural resources. Thus, the durability and long-term mechanical performance of RAP stabilized with alkali-activated fly ash were assessed in this study. The alkaline activator was a solution composed of sodium hydroxide and sodium silicate. To this extent, unconfined compressive strength (UCS) and durability tests were conducted in this research. The proposed alkali-activated binder significantly increased the UCS of RAP mixtures, with long-term (365 days) results reaching values up to 32 MPa; fulfilling the strength requirements for cement-stabilized soil mixtures and even stable inorganic binder materials for road base and sub-base layers of pavements. These results indicate that when stabilized with an alkali-activated fly ash binder, RAP presents several applications for road engineering; even when subjected to seasonal variations in humidity and temperature, as shown by the durability tests.

A 30,000-km journey by Apus apus pekinensis tracks arid lands between northern China and south-western Africa

BackgroundAs a widely distributed and aerial migratory bird, the Common Swift (Apus apus) flies over a wide geographic range in Eurasia and Africa during migration. Although some studies have revealed the migration routes and phenology of European populations, A. a. apus (from hereon the nominate apus), the route used by its East Asian counterpart A. a. pekinensis (from hereon pekinensis) remained a mystery.MethodsUsing light level geolocators, we studied the migration of adult pekinensis breeding in Beijing from 2014 to 2018, and analysed full annual tracks obtained from 25 individuals. In addition, we used the mean monthly precipitation to assess the seasonal variations in humidity for the distribution ranges of the nominate apus and pekinensis. This environmental variable is considered to be critically relevant to their migratory phenology and food resource abundance.ResultsOur results show that the swifts perform a round-trip journey of ca 30,000 km each year, representing a detour of 26% in autumn and 15% in spring compared to the shortest route between the breeding site in Beijing and wintering areas in semi-arid south-western Africa. Compared to the nominate apus, pekinensis experiences drier conditions for longer periods of time. Remarkably, individuals from our study population tracked arid habitat along the entire migration corridor leading from a breeding site in Beijing to at least central Africa. In Africa, they explored more arid habitats during non-breeding than the nominate apus.ConclusionsThe migration route followed by pekinensis breeding in Beijing might suggest an adaptation to semi-arid habitat and dry climatic zones during non-breeding periods, and provides a piece of correlative evidence indicating the historical range expansion of the subspecies. This study highlights that the Common Swift may prove invaluable as a model species for studies of migration route formation and population divergence.

Nanopore characterization of mine roof shales by SANS, nitrogen adsorption, and mercury intrusion: Impact on water adsorption/retention behavior

Moisture-induced reduction in the strength of shales is one of the primary mechanisms of roof degradation affecting the stability and safety of underground coal mines. The underlying mechanisms of nanoscale matrix-water interactions remains unclear. Thus, an improved understanding of the nanopore structure, and dependent water adsorption and retention behavior of shale is key in defining strength degradation due to seasonal variations in humidity and temperature in underground coal mines. We use small-angle neutron scattering (SANS), low-pressure N2 adsorption (LPNA), and high-pressure mercury intrusion porosimetry (MIP) to characterize the nanopore structure of a fireclay (7F) and four coal mine roof shales (6R, 5A, 6F, H6) from the Illinois basin. The results show that overall distributions of pore volume obtained from SANS, LPNA and MIP techniques agree well between methods and over a wide range of pore size from ~1 nm to ~100 nm. Mercury porosities for the five ordered (7F, 6R, 5A, 6F, H6) samples (7.3%, 7.8%, 8.3%, 12.3%, 4.6%) are higher than the respective N2 porosities (5.0%, 6.3%, 3.8%, 8.2%, 2.5%), as attributed to the dilation of mesopores and compression of the grain skeleton induced by high pressure intrusion of mercury. The SANS porosities for samples 7F, 6R, 5A, 6F (4.0%, 6.2%, 4.1%, 8.8%) are in good agreement with their N2 porosities. Among all tested samples, H6 shale exhibits a relatively high SANS porosity (8.0%) but the lowest N2 (2.5%) and mercury porosities (4.6%). This is attributed to the interlayer micro-pore spaces within montmorillonite, which is detected by SANS but not by the two fluid penetration methods due to the inaccessibility of N2 molecules and mercury. Based on LPNA, larger micropores (1.5–2 nm) and mesopores (2–50 nm) predominantly contribute to the total porosity (~77.8%–87.6%) for the five tested samples.The water adsorption isotherms are measured by dynamic vapor sorption (DVS) and water retention curves are calculated based on the characterized pore size distribution (PSD) by LPNA and MIP techniques. Pore structures of the five studied samples evidently exert a strong influence on their water adsorption and retention behaviors. Water adsorption capacity correlates positively with total porosity/specific surface area (SSA), with a large proportion of micro/meso-pores resulting in the strong water retention capacity with matric suction reaching ~100–150 MPa for liquid saturation < 3%. Among the studied fireclay/shales, samples with higher retention capacity tend to adsorb more water. Thus, nanopore structure and its impact on water adsorption and retention behavior exert the key controls on shale-water interaction and its implication on strength reduction of roof shales in underground coal mines.

Solar Cells: Overcoming the Ambient Manufacturability‐Scalability‐Performance Bottleneck in Colloidal Quantum Dot Photovoltaics (Adv. Mater. 35/2018)

The low-cost fabrication of colloidal-quantum-dot (CQD) solar cells in ambient air remains elusive in many parts of the world due to high humidity. In article number 1801661, Aram Amassian and co-workers demonstrate a simple oxygen-doping step that enables ambient manufacturing, irrespective of seasonal humidity variations, to obtain solar cells with power conversion efficiency > 10% by blade-coating in air at industrially viable speeds. Cover by Heno Hwang, scientific illustrator, KAUST.

Overcoming the Ambient Manufacturability-Scalability-Performance Bottleneck in Colloidal Quantum Dot Photovoltaics.

Colloidal quantum dot (CQD) solar cells have risen rapidly in performance; however, their low-cost fabrication under realistic ambient conditions remains elusive. This study uncovers that humid environments curtail the power conversion efficiency (PCE) of solar cells by preventing the needed oxygen doping of the hole transporter during ambient fabrication. A simple oxygen-doping step enabling ambient manufacturing irrespective of seasonal humidity variations is devised. Solar cells with PCE > 10% are printed under high humidity at industrially viable speeds. The devices use a tiny fraction of the ink typically needed and are air stable over a year. The humidity-resilient fabrication of efficient CQD solar cells breaks a long-standing compromise, which should accelerate commercialization.

Investigating the differences between receptor and dispersion modeling for concentration prediction and health risk assessment of volatile organic compounds from petrochemical industrial complexes

Receptor and dispersion models both provide important information to help understand the emissions of volatile organic compounds (VOCs) and develop effective management strategies. In this study, differences between the predicted concentrations of two models and the associated impacts on the estimated health risks due to different theories behind two models were investigated. Two petrochemical industrial complexes in Kaohsiung city of southern Taiwan were selected as the sites for this comparison. Although the study compares the approaches by applying the methods to this specific area, the results are expected to be adopted for other areas or industries. Ninety-nine VOC concentrations at eight monitoring sites were analyzed, with the effects of diurnal temperature and seasonal humidity variations being considered. The Chemical Mass Balance (CMB) receptor model was used for source apportionment, while the Industrial Source Complex (ISC) dispersion model was used to predict the VOC concentrations at receptor sites. In the results of receptor modeling, 54% ± 11% and 49% ± 20% of the monitored concentrations were contributed by process emissions in two complexes, whereas the numbers increased to 78% ± 41% and 64% ± 44% in the results of dispersion modeling. Significant differences were observed between two model predictions (p < 0.05). The receptor model was more reproducible given the smaller variances of its results. The effect of seasonal humidity variation on two model predictions was not negligible. Similar findings were observed given that the cancer and non-cancer risks estimated by the receptor model were lower but more reproducible. The adverse health risks estimated by the dispersion model exceeded and were 75.3%–132.4% of the values estimated by using the monitored data, whereas the percentages were lowered to the range from 27.4% to 53.8% when the prediction was performed by using the receptor model. As the results of different models could be significantly different and affect the final health risk assessment, it is important to carefully choose an appropriate model for prediction and to evaluate by monitoring to avoid providing false information for appropriate management.

Multivariate analysis of effects of diurnal temperature and seasonal humidity variations by tropical savanna climate on the emissions of anthropogenic volatile organic compounds

Volatile organic compounds (VOCs), particularly those from anthropogenic sources, have been of substantial concern. In this study, the influences of diurnal temperature and seasonal humidity variations by tropical savanna climate on the distributions of VOCs from stationary industrial sources were investigated by analyzing the concentrations during the daytime and nighttime in the dry and wet seasons and assessing the results by principal component analysis (PCA) and cluster analysis. Kaohsiung City in Southern Taiwan, known for its severe VOC pollution, was chosen as the location to be examined. In the results, the VOC concentrations were lower during the daytime and in the wet season, possibly attributed to the stronger photochemical reactions and increasing inhibition of VOC emissions and transports by elevating humidity levels. Certain compounds became appreciably more important at higher humidity, as these compounds were saturated hydrocarbons with relatively low molecular weights. The influence of diurnal temperature variation on VOC distribution behaviors seemed to be less important than and interacted with that of seasonal humidity variation. Heavier aromatic hydrocarbons with more complex structures and some aliphatic compounds were found to be the main species accounting for the maximum variances of the data observed at high humidity, and the distinct grouping of compounds implied a pronounced inherent characteristic of each cluster in the observed VOC distributions. Under the influence of diurnal temperature variation, selected VOCs that may have stronger photochemical resistances and/or longer lifetimes in the atmosphere were clustered with each other in the cluster analysis, whereas the other groups might consist of compounds with different levels of vulnerability to sunlight or high temperatures. These findings prove the complications in the current knowledge regarding the VOC contaminations and providing insight for managing the adverse impacts of the anthropogenic VOCs on the environment and public health.

Measurement of H2O Broadening of O2 A-Band Transitions and Implications for Atmospheric Remote Sensing

We present laboratory measurements of H(2)O-broadened (16)O(2) A-band (b(1)Σ(g)(+) ← X(3)Σ(g)(-)(0,0)) absorption spectra acquired with a laser-based photoacoustic spectroscopy method. This absorption band is widely used in a variety of high-precision atmospheric remote sensing applications. We report H(2)O broadening parameters for six of the strongest transitions in this band, and we show that these measured values are nominally 1.5-2 times greater than the corresponding air-broadening parameters. Simulations of atmospheric transmission spectra in the O(2) A-band that incorporate our measured H(2)O broadening parameters indicate that H(2)O present at concentrations typically found in the Earth's atmosphere can influence the column-integrated transmission relative to the dry air case. Further, because of spatial and seasonal variations in humidity, failure to account for the enhanced H(2)O pressure broadening effects can lead to concomitant biases in atmospheric O(2) A-band retrievals of quantities such as surface pressure and path length in greenhouse gas retrievals.

Titan's Tropical Storms in an Evolving Atmosphere

The Huygens probe landed in a damp lake bed fed by fluvial channels, indicative of past rainfall. Such washes, interspersed with vast dunes, are typical of Titan's tropical landscape. Yet, Cassini-Huygens measurements reveal a highly stable tropical atmosphere devoid of deep convective storms, and the formation of washes in dune fields is not understood. Here we examine the effects of seasonal variations in humidity, surface heating, and dynamical forcing on the stability of Titan's troposphere. We find that during the probe landing, the middle troposphere was weakly unstable to convection, consistent with the tenuous cloud detected at 21 km. Yet the tropical atmosphere, at any season, is too stable to produce deep convective storms. Convection in the tropics remains weak and confined to altitudes below ~30 km, unless the humidity is increased below 9 km altitude. Solar heating is insufficient to significantly humidify the tropical atmosphere. The large polar lakes are seasonably stable, and the methane column abundance measured by Huygens typical of the tropical atmosphere. Our study indicates the presence of distinct polar and equatorial climates. It also suggests that fluvial features in the tropics do not result from recent seasonal rainstorms, and thereby supports other origins such as geological seepage, cryovolcanism, or a wetter climate in the past.

Annual cycles of tropospheric water vapor

To understand better the annual cycles of atmospheric humidity, radiosonde data were used to create climatologies of temperature, dew point, relative humidity, and precipitable water in the lower troposphere for 56 locations around the world for the period 1973–1990. On the basis of the annual ranges of relative humidity at the surface and at the 850, 700, and 500 mbar levels and the ratio of the annual maximum to minimum surface to 500‐mbar precipitable water, we have defined five humidity regimes: (1) middle‐ and high‐latitude continental, (2) middle‐ and high‐latitude oceanic, (3) midlatitude monsoon, (4) tropical oceanic, and (5) tropical monsoon. For each regime we describe the annual cycles of temperature and humidity variables and discuss phase relationships among them. Relative humidity ranges are small in the first two regimes, where precipitable water and temperature vary in phase. Relative humidity ranges in the other three regimes are moderate to large, and in the tropics the annual march of horizontal moisture advection and vertical convection, not temperature, controls seasonal humidity variations. These results suggest that the assumption of constant relative humidity made in some climate models is not always justified and that precipitable water is not a strong function of temperature in the tropics.

Accelerated physical stability testing and long-term predictions of changes in the crushing strength of tablets stored in blister packages

A physical model is presented which permits the amount of sorbed moisture and the crushing strength of compressed tablets stored in blister packages to be predicted based on a knowledge of: (1) tablet moisture sensitivity; (2) package moisture permeability; and (3) relative humidity storage conditions. The tendency of tablets to sorb water can be characterized in approximately one week by storing unprotected tablets at several relative humidities. This information, in combination with package moisture permeability data, permits changes in tablet crushing strength and sorbed moisture to be made under a variety of storage and packaging conditions. These predictions are useful in establishing long-term stability testing protocols. They are also useful in predicting what tablets stored in blister packages might reasonably be expected to experience in the market place where short-term and long-term oscillating conditions are likely to occur. Theoretical predictions based on the physical model indicate that, in general, tablets stored in relatively permeable blister packaging materials will be protected from large, short-term humidity fluctuations of several hours or days. Long-term fluctuations due to monthly and seasonal variations in humidity will be important. Tablets stored in relatively permeable blister packages at relative humidities representative of marketplace conditions can be expected to experience humidities varying between 30% and 70% while less permeable packages will show less variation. This suggests that oscillating unprotected tablets between 30% and 70% relative humidity every 2–3 days for a 2–3-week period may produce changes similar to those observed for tablets stored in marketed blister packages. Tablets tested using these conditions showed changes in crushing strength similar to those packaged in blister packages and used in a 3-year field study. The theoretical predictions and experimental results emphasize the importance of matching the dosage formulation characteristics to the package material and testing conditions. In this way, a more rational selection of packaging material and testing protocols can be made.

Museum display cases and the exchange of water vapour

AbstractEnvironmental monitoring data, experimental measurements and computer modelling have been employed to investigate the system of local humidity control at the Sainsbury Centre for Visual Arts. Experiments to determine therate of display case leakage suggested diffusion was the main control for gas transport, and water vapour was transferred with a half-life of 1·75 days. Three parameters, exchange rate constant, half-life and residence time are used to describe gas transfer to and from cases. Equations are provided for calculating the slope of the sorption isotherms of various sorbents in order to assess their effectiveness at desired relatIve humidities. Computer modelling demonstrated that the sorbent's chief function is to buffer seasonal humidity variations; it was shown that a well-sealed case damps out the more rapid diurnal fluctuations. Modelling is also used to illustrate the benefit of minimizing case leakage and increasing the mass of sorbent to extend hygrometric half-time.