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Variation in canopy water content (CWC) that can be detected from microwave remote sensing of vegetation optical depth (VOD) has been proposed as an important measure of vegetation water stress. However, the contribution of leaf surface water (LWs ), arising from dew formation and rainfall interception, to CWC is largely unknown, particularly in tropical forests and other high-humidity ecosystems. We compared VOD data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and CWC predicted by a plant hydrodynamics model at four tropical sites in Brazil spanning a rainfall gradient. We assessed how LWs influenced the relationship between VOD and CWC. The analysis indicates that while CWC is strongly correlated with VOD (R2 = 0.62 across all sites), LWs accounts for 61-76% of the diurnal variation in CWC despite being < 10% of CWC. Ignoring LWs weakens the near-linear relationship between CWC and VOD and reduces the consistency in diurnal variation. The contribution of LWs to CWC variation, however, decreases at longer, seasonal to inter-annual, time scales. Our results demonstrate that diurnal patterns of dew formation and rainfall interception can be an important driver of diurnal variation in CWC and VOD over tropical ecosystems and therefore should be accounted for when inferring plant diurnal water stress from VOD measurements.

Investigating plant morphological traits can provide insights into plant drought tolerance. To date, many papers have focused on plant hydraulic responses to drought during dehydration, but atmospheric water absorption by trichomes to mitigate drought stress by influencing leaf hydraulics in plant species that inhabit arid environments has been largely ignored. The experiment in this study was designed to assess how dew absorbed by leaf trichomes helps Caragana korshinskii withstand drought. The results showed that under a drought stress and dew (DS & D) treatment, C. korshinskii displayed a strong capacity to absorb dew with trichomes; exhibited slow decreases in leaf water potential (Ψleaf ), leaf hydraulic conductivity (Kleaf ), and gas exchange; experienced 50% Kleaf and gas exchange losses at lower relative soil water content levels than plants treated with drought stress and no dew (DS & ND); and experienced 50% Kleaf loss (Kleaf P50 ) at similar Ψleaf levels as DS & ND plants. Its congener C. sinica, which does not have leaf trichomes, displayed little ability to absorb dew under drought stress and did not show any remarkable improvement in the above parameters under the DS & D treatment. Our results indicated that leaf trichomes are important epidermal dew-uptake structures that assist in partially sustaining the leaf hydraulic assimilation system, mitigate the adverse effects of drought stress and contribute to the distribution of C. korshinskii in arid environments.

1. Manipulative experiments typically show a decrease in dryland biocrust cover and altered species composition under climate change. Biocrust‐forming lichens, such as the globally distributed Diploschistes diacapsis, are particularly affected and show a decrease in cover with simulated climate change. However, the underlying mechanisms are not fully understood, and long‐term interacting effects of different drivers are largely unknown due to the short‐term nature of the experimental studies conducted so far. 2. We addressed this gap and successfully parameterised a process‐based model for D. diacapsis to quantify how changing atmospheric CO2, temperature, rainfall amount and relative humidity affect its photosynthetic activity and cover. We also mimicked a long‐term manipulative climate change experiment to understand the mechanisms underlying observed patterns in the field. 3. The model reproduced observed experimental findings: warming reduced lichen cover, whereas less rainfall had no effect on lichen performance. This warming effect was caused by the associated decrease in relative humidity and non‐rainfall water inputs, which are major water sources for biocrust‐forming lichens. Warming alone, however, increased cover because higher temperatures promoted photosynthesis during early morning hours with high lichen activity. When combined, climate variables showed non‐additive effects on lichen cover, and effects of increased CO2 levelled off with decreasing levels of relative humidity. 4. Synthesis. Our results show that a decrease in relative humidity, rather than an increase in temperature, may be the key factor for the survival of the lichen D. diacapsis under climate change and that effects of increased CO2 levels might be offset by a reduction in non‐rainfall water inputs in the future. Because of a global trend towards warmer and drier air and the widespread global distribution of D. diacapsis, this will affect lichen‐dominated dryland biocrust communities and their role in regulating ecosystem functions worldwide. This research was supported by the Collaborative Research Centre 973 (www.sfb973.de) of the German Research Foundation (DFG) and by the European Research Council (grant agreement no. 647038 (BIODESERT)). P. Porada appreciates funding by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—408092731. F.T. Maestre acknowledges support from Generalitat Valenciana (CIDEGENT/2018/041) and the Alexander Von Humboldt Foundation. J. Raggio acknowledges the ERA-Net BiodivERsA program as Soil Crust InterNational (SCIN) and The Spanish Ministerio de Economía y Competitividad (MINECO) project numbers PRI-PIMBDV-2011-0874 and CRYPTOCOVER, CTM2015-64728-C21-R.

Fil: Hirsch Jofre, Matias Eberardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tandil. Instituto Superior de Ingenieria del Software. Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto Superior de Ingenieria del Software; Argentina

Foliar uptake of dew is likely an important mechanism of water acquisition for plants from tropical dry environments. However, there is still limited experimental evidence describing the anatomical pathways involved in this process and the effects of this water subsidy on the maintenance of gas exchange and leaf lifespan of species from seasonally dry tropical vegetation such as the Brazilian caatinga. We performed scanning electron, bright-field and confocal microscopic analyses and used apoplastic tracers to examine the foliar water uptake (FWU) routes in four woody species with different foliar phenology and widely distributed in the caatinga. Leaves of plants subjected to water stress were exposed to dew simulation to evaluate the effects of the FWU on leaf water potentials, gas exchange and leaf lifespan. All species absorbed water through their leaf cuticles and/or peltate trichomes but FWU capacity differed among species. Leaf wetting by dew increased leaf lifespan duration up to 36 days compared to plants in the drought treatment. A positive effect on leaf gas exchange and new leaf production was only observed in the anisohydric and evergreen species. We showed that leaf wetting by dew is relevant for the physiology and leaf lifespan of plants from seasonally dry tropical vegetation, especially for evergreen species.

Adoption of dicamba tolerant soybeans [Glycine max (L.) Merr.] accompanied by postemergence applications of dicamba resulted in off‐target movement and damage to nearby crops. The underlying cause, in some cases, has been attributed to weather‐related phenomena such as temperature inversions, which are often accompanied by the formation of dew. The objective of this controlled study was to determine if the formation of simulated dew on soybean leaves treated with dicamba led to increased short‐term dicamba volatility. Over a 48‐h period after the application of dicamba, dicamba volatility concentrations quantified in air samples increased by 20% when soybeans were exposed to simulated dew for 3 h compared with soybeans that were not exposed to dew. Concentrations of volatilized dicamba were elevated in the first (0–24 h) and second (24–48 h) 24‐h period after initiating collection of air samples. Dew may alter the stability of dicamba, ultimately contributing to increased off‐target movement.

Summary To extend the reach of cloud computing, the concept of edge computing and dew computing is introduced to execute various Internet of things (IoT) application with minimized delay in real ti...

With the help of satellite data and numerical geographical information system (GIS) methods, the total capacity of dew volume on the entire territory of the Republic of Serbia was estimated. Multicriteria GIS analysis and satellite detections with the support of methods such as kriging and semi-kriging gave satisfactory results in the present research. After the download of satellite data, they were compared with meteorological data for precipitation, evaporation and air temperature. A very precise grid in 1 × 1 degreesof longitude and latitude was created. The average estimated dew potential for the territory of Serbia is 20–40 mm per yearfor the south of the country, 15 mm per yearfor the north, 30–50 mm per yearfor the central region and 20–30 mm per yearfor the east. In most drought regions, it is < 10 mm per year per m. Counties with the largest dew capacity (between 15,200 and 20,000 L) include Borski, Nišavski and Jablanicki in the eastern part of the country, as well as Zlatiborski, Raški and Pecki in the western and southern parts, respectively. On the other hand, counties with the lowest dew capacity (2,000–3,000 L) encompass northern parts of Serbia (Sremski, Severno-Banatski, Srednje-Banatski, Južno-Banatski, Severno-Backi and Zapadno-Backi). The possibility for dew use is particularly strong during the spring. The estimated total capacity of the dew potential for Serbia is 1.5 × 107 L. By comparing the obtained data for Serbia, it is concluded that the amount of this type of water resource is not large, but enough for use in agricultural and other economic sectors.

BACKGROUND: In the present study, the rate of dermal transfer of pesticides to agricultural workers occurring via contact with sprayed hard surfaces was investigated. Cotton gloves were used as dosimeters to collect residues from hard surfaces contaminated by pesticides in greenhouses. Dosimeters, either dry or moistened, were in contact with wood, metal and plastic surfaces that had previously been sprayed. The experimental approach applied mimicked typical hand contact. Moistened cotton gloves were used to simulate hand moisture from dew/condensation or rainfall. The effect of total duration of contact on the final hand exposure via transfer was investigated. RESULTS: The higher duration contact tested (50 s) resulted in higher transfer rates for metal and plastic surfaces; no such effect was noted in the case of the wood surface. The pesticide amount transferred from the metal and plastic surfaces to wet gloves was greater than that transferred to dry gloves. Such a trend was not observed for the wood surface. Transfer rates varied from 0.46 to 77.62% and from 0.17 to 16.90% for wet and dry samples, respectively. CONCLUSION: The current study has generated new data to quantify the proportion of pesticide deposits dislodged from three different non-crop surfaces when in contact with dry or wet gloves. © 2018 Crown copyright. Pest Management Science © 2018 Society of Chemical Industry. © 2018 Crown copyright. Pest Management Science © 2018 Society of Chemical Industry

Peat soils shrink and become very hydrophobic when dried. Both properties may cause inaccuracies when applying laboratory methods for soil hydraulic properties that have been developed and tested for mineral soils. This study aimed to compare different methods for the determination of the water retention of peat soils near permanent wilting point (pF 3.5 to 4.2). Three common methods were tested: two pressure apparatus (ceramic plate [Soilmoisture] vs. membrane [eijkelkamp]) and a dew-point potentiameter (WP4C, Decagon Devices, Inc.), which is based on the equilibrium of soil water potential with air humidity. We used both field-moist peat samples and samples that had been rewetted after oven-drying. We found that there was no systematic difference between the two pressure apparatus. Low moisture variability among replicates and dew-point potentiameter measurements that indicated a drainage to pF 4.2 support the use of pressure apparatus for the determination of water retention near permanent wilting point. Despite a rewetting time of 2 wk including periodic mixing, rewetted oven-dried samples showed lower soil moistures at pF 3.5 and 4.2 than field-moist ones. This severe and long-lasting hysteresis effect was strongest for less decomposed peat samples. Thus, field-moist samples should be used. This makes the classical dew-point potentiameter measurement protocol, which is based on defined water additions to oven-dried samples, unsuitable for peat samples.

Summary 1.Decomposition of organic matter in semiarid ecosystems is a key component of the terrestrial carbon (C) cycle. The well-known inaccuracies in predicting litter decay in water-limited regions were lessened by considering solar radiation as an abiotic decay driver of photodegradation. Moreover, exposure to high solar irradiance in dry periods often led to massive facilitation of litter decay in subsequent wet periods (“photoacceleration”), though in many studies this effect was absent. 2.Recently, water vapor and dew were identified as modulators enabling substantial microbial degradation during rainless periods. Here we asked, (i) if the activity of microorganisms modifies litter traits, such as litter quality and microbial community in dry periods, consequently altering the loss of litter mass and nitrogen (N) in wet periods, and (ii) whether it can co-occur with photoacceleration. 3.By successively introducing litter to the field at the beginning and the end of the dry season, we found that microbial activity during the dry season affected litter mass and N loss during the wet season. Low microbial activity in the dry season led to inhibition of mass loss in the wet season, while high microbial activity led to facilitation of mass loss. Microbial activity during the dry season also caused strong inhibition of N loss from litter during the wet season, likely by enhancing the dry-season N loss. A microclimate manipulation experiment using radiation filters showed that microbial activity and exposure to solar radiation jointly modified the litter during the dry season and affected subsequent decay in the wet season. 4.Knowledge of biotic and abiotic modifications of litter during dry periods and their implication for wet periods enhances our understanding of litter decay in semiarid regions. Furthermore, it can improve biogeochemical model predictions of C and N cycling in drylands and in the many regions that are projected to experience a drier climate during the coming decades. This article is protected by copyright. All rights reserved.

The seasonally-dry climate of Northern California imposes significant water stress on ecosystems and water resources during the dry summer months. Frequently during summer, the only water inputs occur as non-rainfall water, in the form of fog and dew. However, due to spatially heterogeneous fog interaction within a watershed, estimating fog water fluxes to understand watershed-scale hydrologic effects remains challenging. In this study, we characterized the role of coastal fog, a dominant feature of Northern Californian coastal ecosystems, in a San Francisco Peninsula watershed. To monitor fog occurrence, intensity, and spatial extent, we focused on the mechanisms through which fog can affect the water balance: throughfall following canopy interception of fog, soil moisture, streamflow, and meteorological variables. A stratified sampling design was used to capture the watershed's spatial heterogeneities in relation to fog events. We developed a novel spatial averaging scheme to upscale local observations of throughfall inputs and evapotranspiration suppression and make watershed-scale estimates of fog water fluxes. Inputs from fog water throughfall (10–30 mm/year) and fog suppression of evapotranspiration (125 mm/year) reduced dry season water deficits by 25% at watershed scales. Evapotranspiration suppression was much more important for this reduction in water deficit than were direct inputs of fog water. The new upscaling scheme was analyzed to explore the sensitivity of its results to the methodology (data type and interpolation method) employed. This evaluation suggests that our combination of sensors and remote sensing allows an improved incorporation of spatially-averaged fog fluxes into the water balance than traditional interpolation approaches.

High-resolution large-eddy simulations (LESs) are used to investigate the effect of turbulence as well as the interaction between atmosphere and soil on the life cycle of nocturnal radiation fog. The first part of the article focuses on the validation of the LES model system for simulating radiation fog against measurement data from the meteorological super-site in Cabauw (Netherlands). Differences found in the fog life cycle, depth, and liquid water content between LES and observations can, as in former studies, be largely ascribed to the presence of local advection processes in the observational data and uncertainty in the measurement data used to initialise the model. Moreover it is found that the choice of the droplet number concentration within the cloud microphysical representation has a high impact on the liquid water content within the fog layer, but a rather small effect on its life cycle. In the second part of the article, a set of LES runs is analysed with idealised initial conditions in order to study the effect of turbulent mixing as well as the initial state of the soil on the development of radiation fog. As expected, the results show that turbulent mixing has a strong impact on the time of fog formation, which is complicated by the interaction with both radiative cooling and water vapour removal by dew deposition. Furthermore, it is found that the near-surface soil temperature plays a key role for the exact time of fog formation, whereas near-surface soil moisture is decisive for the lifting and dissipation time of the fog layer.

Precipitation is usually the primary source of water for the hydrological cycle in a semi-arid area. However, dew occurs frequently and affects water circulation dramatically in the west of Jilin Province in China. Measurements of the amount of dew formed and precipitation were carried out from July 2012 to October 2013 in the Momoge Natural Reserve. The results indicated that moisture from primary precipitation in the summer originated from the East Asian Monsoon and was affected by the atmospheric circulation in the middle and high latitudes of Eurasia in the winter. The dew amount was approximately 19.44 mm (approximately 5% of the total rainfall amount), consisting of the evapotranspiration in the local area and atmospheric moisture. Dew also supplies nutrients to the local vegetation. The maximum contribution of total nitrogen (TN), total phosphorus (TP) and potassium (K) in unit corn area could reach 288.60 mg/m2, 27.46 mg/m2 and 291.63 mg/m2 in half a month, respectively. The wind speed, relative humidity and lowest temperature were the primary factors that dramatically affected dew formation and amount. As an additional source of fresh water, dew not only had a positive impact on the ecosystem in arid and semi-arid zones but also played an important role in the local water cycle and other ecological processes. This research has important implications for water circulation and land use management.

The arid and semi-arid drylands of the world are increasingly recognized for their role in the terrestrial net carbon dioxide (CO) uptake, which depends largely on plant litter decomposition and the subsequent release of CO back to the atmosphere. Observed decomposition rates in drylands are higher than predictions by biogeochemical models, which are traditionally based on microbial (biotic) degradation enabled by precipitation as the main mechanism of litter decomposition. Consequently, recent research in drylands has focused on abiotic mechanisms, mainly photochemical and thermal degradation, but they only partly explain litter decomposition under dry conditions, suggesting the operation of an additional mechanism. Here we show that in the absence of precipitation, absorption of dew and water vapor by litter in the field enables microbial degradation at night. By experimentally manipulating solar irradiance and nighttime air humidity, we estimated that most of the litter CO efflux and decay occurring in the dry season was due to nighttime microbial degradation, with considerable additional contributions from photochemical and thermal degradation during the daytime. In a complementary study, at three sites across the Mediterranean Basin, litter CO efflux was largely explained by litter moisture driving microbial degradation and ultraviolet radiation driving photodegradation. We further observed mutual enhancement of microbial activity and photodegradation at a daily scale. Identifying the interplay of decay mechanisms enhances our understanding of carbon turnover in drylands, which should improve the predictions of the long-term trend of global carbon sequestration., This research project was financially supported by ... and the Spanish Ministry of Economy and Competitiveness (project CGL2011-24748/PHOTODEG).

Spatial variability in lithobiont-induced weathering patterns on desert rocks is aspect-dependent. While differences between the northern and southern aspects have been extensively studied, little is known concerning the differences between east-facing (EF) and west-facing (WF) aspects in deserts, including the Negev Desert. Whereas cobbles on both slopes are inhabited by endolithic lichens, epilithic lichens, which render the bedrock a smooth appearance, and free-living cyanobacteria, which give the bedrock a rugged microrelief, predominate on WF and EF bedrock, respectively. Following previous research that regarded dew as the principal factor that determines lithobiont distribution, measurements of radiation, temperature, wind and dew were carried out during 2008–2009 in the Negev Desert. The data indicated that albeit slightly higher midday surface temperatures that characterize WF surfaces (cobbles and bedrock), nocturnal temperatures on these surfaces were significantly lower, therefore facilitating higher dew condensation. High amounts of dew result from the relatively rapid drop in temperatures (14:00–20:00) due to the afternoon northwesterly sea-breeze wind (with a cooling rate of the WF bedrock being 52.9% higher than on EF bedrock, 2.6 °C h−1 in comparison to only 1.7 °C h−1), and facilitate the growth of high-chlorophyll dew-fed (and rain-fed) epilithic lichens, which may act as bio-protectors on WF bedrock. Lack of condensation on EF bedrock results in turn in the growth of rain-fed free-living cyanobacteria, responsible for high rock dissolution and subsequently for a rugged microrelief. By affecting the nocturnal bedrock temperatures, wind acts as a cooling agent, impacting in turn the amount of dew, and subsequently lithobiont composition and weathering patterns in the Negev Desert. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The cup plant (Silphium perfoliatum L.) is discussed as an alternative energy crop for biogas production in Germany due to its ecological benefits over continuously grown maize. Moreover, a certain drought tolerance is assumed because of its intensive root growth and the dew water collection by the leaf cups, formed by fused leaf pairs. Therefore, the aim of this study was to estimate evapotranspiration (ET), water-use efficiency (WUE) and the relevance of the leaf cups for the cup plant's water balance in a 2-year field experiment. Parallel investigations were conducted for the two reference crops maize (high WUE) and lucerne-grass (deep and intensive rooting) under rainfed and irrigated conditions. Root system performance was assessed by measuring water depletion at various soil depths. Transpiration-use efficiency (TUE) was estimated using a model approach. Averaged over the 2 years, drought-related above-ground dry matter reduction was higher for the cup plant (33 %) than for the maize (18 %) and lucerne-grass (14 %). The WUE of the cup plant (33 kg ha−1 mm−1) was significantly lower than for maize (50 kg ha−1 mm−1). The cup plant had a lower water uptake capacity than lucerne-grass. Cup plant dry matter yields as high as those of maize will only be attainable at sites that are well supplied with water, be it through a large soil water reserve, groundwater connection, high rainfall or supplemental irrigation.

Summary Environmental research often faces two major hurdles: (i) fluctuating spatial and temporal conditions and consequently large variability in the organisms' abundance and performance, and (ii) complex, costly logistics involved in field experiments. Measurements of physiological parameters or molecular analyses often represent single shot experiments. To study desiccation acclimation of filamentous cyanobacteria, the founders and main primary producers in desert biological soil crusts (BSC), we constructed an environmental chamber that can reproducibly and accurately simulate ambient conditions and measure microorganism performance. We show that recovery from desiccation of BSC cyanobacteria and Leptolyngbya ohadii isolated thereof are strongly affected by dehydration rate following morning dew. This effect is most pronounced in cells exposed to high light and temperature in the dry phase. Simultaneous measurements of water content, gas exchange and fluorescence were performed during dehydration. Photosynthetic performance measured by fluorescence begins declining when light intensity reaches values above 100 μmol photons m−2 s−1, even in fully hydrated cells. In contrast, photosynthetic rates measured using O2 evolution and CO2 uptake increased during rising irradiance to the point where the water content declined below ∼ 50%. Thus, fluorescence cannot serve as a reliable measure of photosynthesis in desert cyanobacteria. The effects of drying on gas exchange are discussed.

When transporting CO2 for sequestration, it is important to know the water dew point in order to avoid condensation that can lead to corrosion. A flow apparatus to measure the water content at saturation in a compressed gas has been constructed. A saturator humidifies the flowing gas by equilibrating it with liquid water. Then, a gravimetric hygrometer measures the water mole fraction of the humid gas. Dew-point data for H2O in CO2 on six isotherms between 10 and 80 °C at pressures from 0.5 to 5 MPa are reported. The uncertainties in water content at the dew point (expanded uncertainty with coverage factor k = 2) are on average 0.3%, significantly smaller than in any previous work. The data have been analyzed to extract the interaction second virial coefficient; the values are consistent with the theoretical estimates of Wheatley and Harvey but have a much smaller uncertainty. Published 2015 American Institute of Chemical Engineers AIChE J, 2015 © 2015 American Institute of Chemical Engineers AIChE J, 61: 2913–2925, 2015

Different peatland mosses have varying strategies for water storage and capillary rise mechanisms depending on their particular hydrophysical properties and preferred water sources. To understand these strategies, the retention and redistribution of water from various sources in Sphagnum, feather and Tomenthypnum moss communities were addressed through investigation of the sensitivity of moss moisture dynamics to environmental variables, field surveys and a drought stress experiment. Feather mosses preferred habitats well above the water table, and their relatively low volumetric water content (θ) increased only with precipitation events. The relatively high residual θ (0·22) of Sphagnum capitula helped the moss type maintain conditions suitable for photosynthesis over a range of water table conditions. Tomenthypnum mosses occurred over a broader range of water table positions than Sphagnum or feather mosses because of their ability to use both capillary rise and atmospheric water for growth. While Tomenthypnum had relatively low near-surface θ (~0·10), evaporative losses were sustained by both small nocturnal additions by condensation of vapour and upward capillary rise. An intermediate layer of partially decomposed mosses supported contact with the underlying peat and helped transport sufficient water to the Tomenthypnum moss surface. However, Tomenthypnum θ and productivity changes were more sensitive to rainfall additions as the uppermost portion of moss shoots can easily desiccate under typical evaporative demand. As a result, nocturnal sources of atmospheric water from dew (~0·15mm per night) and distillation (~0·10mm per night) provided temporary relief from desiccation for potentially important early morning photosynthesis and helped drive evaporation and capillary rise. Copyright © 2015 John Wiley & Sons, Ltd.

Mercury is a common contaminant in natural gas and partially follows carbon dioxide through amine separation during natural gas processing. In this study, we used simple volumetric analyses, the simulator TOUGH2/EOS7C, and dew-point calculations to investigate the potential impacts on injectivity of trace amounts of mercury in a carbon dioxide stream injected for geologic carbon dioxide sequestration. For mercury concentrations up to 190 ppbV (∼1.6 mg/stdm3 CO2), the total volumetric pore-space plugging that could occur around the wellbore due to complete condensation of mercury, or due to complete precipitation of mercury as cinnabar, results in a very small porosity change. Evaporative concentration of aqueous mercury by water evaporation into carbon dioxide is unlikely because the volatility of mercury into the carbon dioxide stream is higher than that of water. Dew-point calculations suggest that mercury concentrations of about 2000 ppbV are needed for mercury condensation to occur. Our analyses suggest that for mercury concentrations of a few hundred ppbV, the impacts on injectivity of mercury deposition by condensation or precipitation as cinnabar are negligible.

There is various evidence that the presence of condensed water, e.g. dew, improves plant water relations. Because particularly plants in drier environments are expected to benefit from atmospheric water, it may be assumed that special adaptations promoting exploitation of dew water evolved in these habitats. Surface characteristics affect dewfall and retention of dew water. Leaf surface characteristics such as hairs (trichomes), which are often present in plants of arid environments, may therefore play a substantial role in dew harvesting. In this study, it is analysed to what extent (1) the presence of hygrophilic aerosoles promotes dewfall by reducing vapour saturation pressure (‘early condensation’), (2) dew water can be stored within a dense trichome layer, (3) the presence of dew water increases humidity directly above the leaf surface, thereby reducing water loss from the leaf interior by decreasing the water potential gradient between leaf interior and exterior, and (4) dew evaporation reduces transpiration further by evaporative cooling. A physical framework is provided in this contribution that shows that these processes are in fact possible under natural conditions. Copyright © 2014 John Wiley & Sons, Ltd.

This chapter focuses on the effects of the troposphere on radiowave propagation, starting with a definition of the troposphere as a natural layered air medium consisting of different gaseous, liquid, and crystal structures. It then discusses the effects of hydrometeors on radio propagation in the troposphere. Some well‐known hydrometeors are rain, fog, snow, clouds, hail, dew, rime, glaze, blowing snow, and blowing spray. Next, the chapter considers the main characteristics and parameters of atmospheric turbulence and discusses the tropospheric scintillations, as well as the effects of multiple scattering due to the irregular structure of the troposphere. Finally, it presents the link budget design for tropospheric communication links.

Summary High-pressure processing (HPP) is known to modify the functional properties of the proteins by changing its structure that can lead to protein denaturation, aggregation or gelation, depending on the protein system and the applied pressure. The potential to modify functional properties of protein and their products using HPP has been explored widely in last decade. In this study, the effect of HPP on the degree of trypsin hydrolysis (DTH) and antioxidant activity (AA) of egg white protein (EWP) and freeze-dried egg white powder (DEW) was evaluated. EWP and DEW were subjected to trypsin hydrolysis for up to 120 min, with and without HP treatments [pressure level (350–550 MPa) and treatment time (5–15 min)]. HP treatment caused substantial increase in DTH of EWP and DEW, increasing it from 2.78% (EWP control) and 2.20% (DEW control) to 11.3% (HP-treated EWP) and 8.41% (HP-treated DEW), respectively. HP treatment also had an emphatic effect on AA of EWP (concentration 10% w/v) with AA increasing from 9.34% for control EWP to 19.0% after 5-min HP treatment at 350 MPa and 25.00% after the same treatment at 550 MPa. Overall, HPP caused an increase in DTH and AA of EWP and DEW over the control. SDS-PAGE and differential scanning calorimetric studies confirmed the effect of HP on the hydrolysis of egg proteins.

The water balance of a certain soil profile in a certain time interval is subjected to changes of soil water content within the respective profile, and fluxes at its upper and lower boundary. Weighing lysimeters are valuable instruments for water-balance studies. Typically, mass changes—thus, changes of soil profile water content—are detected by a weighing system, while seepage water outflow is measured by a tipping bucket, and precipitation data originate from a rain gauge. Hence, evapotranspiration as unknown component can be determined by solving a simple water-balance equation. However, using separately measured precipitation data may cause implausible (negative) evapotranspiration. In this study, change of soil profile water content, seepage water, precipitation, and evapotranspiration were determined directly from 10-min lysimeter data from 2011. Precipitation measured with the lysimeter was in total 20% greater than rain-gauge values. Even dew formation was measured and considered as water-balance component; however, its total amount was rather low. Evapotranspiration calculated on daily and hourly base indicated a sound correlation with measured data, but measured values were considerably smaller. Both calculated and measured dew amount were of the same magnitude. Comparison of lysimeter evapotranspiration with daily calculations (neglecting dew) and hourly computation (considering dew) delivered similar results. Generally, the utilized lysimeter facility and the specific data management provided sound water-balance components with high accuracy and temporal resolution, respectively.

Dew, as a supplementary water source, may have an important ecological role in arid and semi-arid regions. During August and September of 2007 and 2008, measurements were taken to investigate the dew accumulation and evaporation patterns in the very early morning hours, in three different habitats (dunetop, footslope, and interdune lowland) of a fixed sand dune in Northwest China. Dew quantities were measured using the cloth-plate method. The results indicated that there was a positive correlation between dew amounts and relative humidity, but a negative correlation between dew amounts and mean temperature. Clear mornings were characterized by higher dew amounts and longer dew duration, whereas less dew was recorded during cloudy and especially windy mornings. Dew continued to condense even after sunrise, although a shorter warming time after dawn is also of vital importance in dew formation. The higher average maximum dew quantities (0.06mm) and longer average dew duration (2.3h) occurred in the interdune lowland; the lower and shorter average dew amounts (0.048mm) and duration (1.9h) were obtained at the dune top. The footslope habitat exhibited intermediate values. Clearly, the differences in dew deposition can be partially attributed to the distinguishing characteristics of the microhabitats. The present study highlighted the impacts of these characteristics on near-ground dew condensation accumulation and evaporation in a fixed sand dune and may facilitate evaluation of the role of dew in arid and semi-arid environments. Copyright (c) 2012 John Wiley & Sons, Ltd.

The green peach aphid, Myzus persicae (Sulzer), feeds consistently and regularly throughout all stages of nymphs and adult. That is, honey dew production, which indicates a state of feeding, occurs at regular intervals within a given stage, and moving, which interrupts feeding, tends to occur rarely. We used these behaviors to test whether sound stimuli acted as a stress in this species. We conducted the playback experiment in which acoustic stimuli with a combination of five frequencies (100, 500, 1000, 5000, and 10000 Hz) and three intensity levels (66, 78, 90 dB SPL) were presented to all stages of aphids. Under all acoustic stimuli, honey dew production occurred less often, and moving occurred more often and for longer. The results of two-way multivariate analysis of variance showed that the stimulus frequency was a significant factor for variation in aphid behaviors in the playback experiment. However, there was no intensity effect on the aphid’s behavior. Based on the electrical penetration graph experiment, aphid feeding stopped frequently and lasted only for short durations under acoustic stimuli. The results of both experiments demonstrated that the acoustic stimuli were effective in inducing feeding suppression in this species. Thus, the acoustic stimuli may be a stressor in the green peach aphid. Furthermore, the behavioral bioassay employed in this study may be used to assess the effect of various stressors on aphids.

Investigations were conducted to determine the pollution levels of air condensate and rain samples using the enhanced chemiluminescence (ECL) reaction. Air condensate samples were initially collected from roadside sites, non-roadside sites, smoking-exposed sites and non-smoking-exposed sites using an automatic dew collector. Rainwater was also collected throughout the sampling period. Samples were subsequently analysed using the ECL reaction, and pollution levels (Eclox Units) were calculated. Air condensate samples collected from roadside- and smoking-exposed sites generally had higher pollution levels than those from non-roadside- and non-smoking-exposed sites. Samples from both smoking-exposed and traffic-exposed sites generally had higher pollution levels than rainwater. Finally, in samples collected from roadside-exposed sites and rainwater, the main polluting constituents were determined to be cationic/anionic components. In samples collected from smoking-exposed sites, the main polluting constituents were determined to be organic components.

Summary •Additional water supplied by dew formation is an important resource for microbes, plants and animals in precipitation-limited habitats, but has received little attention in tropical forests until now. •We evaluated the micro-environmental conditions of tree stem surfaces and their epiphytic organisms in a neotropical forest, and present evidence for a novel mechanism of diurnal dew formation on these surfaces until midday that has physiological implications for corticolous epiphytes such as lichens. •In the understorey of a lowland forest in French Guiana, heat storage of stems during the day and delayed radiative loss during the night decreased stem surface temperatures by 6°C in comparison to the dew-point temperature of ambient air. This measured phenomenon induced modelled totals of diurnal dew formation between 0.29 and 0.69 mm d−1 on the surface of the bark and the lichens until early afternoon. •Crustose lichens substantially benefit from this dew formation, because it prolongs photosynthetic activity. This previously unrecognized mechanism of midday dew formation contributes to the water supply of most corticolous organisms, and may be a general feature in forest habitats world-wide.

Summary Sprouts have become an important part of the diet because of their nutritive value and low-calorie content. The effect of radiation processing (1 and 2 kGy dose) on minimally processed dew gram and chick pea sprouts with respect to different quality parameters was studied over a storage period of 16 days at 8 � C. Radiation treatment and storage period did not have any significant effect on the sensory as well as nutritional qualities of irradiated dew gram and chick pea sprout. No significant change (P > 0.05) was observed in the colour and firmness of irradiated sprouts as compared to control samples. However, radiation processing resulted in significant reduction in aerobic plate counts (APC), coliform counts (CC), yeast and mould count (YMC) and staphylococci counts (SC). Radiation processing of dew gram and chick pea sprouts at 1 and 2 kGy extends the shelf life without affecting sensory and nutritional qualities.

The higher flammability of tropical savanna, compared with forest, plays a critical role in mediating vegetation-environment feedbacks, alternate stable states, and ultimately, the distribution of these two biomes. Multiple factors contribute to this difference in flammability, including microclimate, fuel amount and fuel type. To understand this transition in flammability, we studied fuel characteristics and microclimate across eight savanna–forest boundaries in south-central Brazil. At each boundary, the environment was monitored for one week with automated measurements of near-surface wind speed, air temperature, relative humidity and presence of dew. Manual measurements were performed to quantify fuel amounts and fuel moisture. These data were used to parameterize the fire behaviour model BehavePlus5 in order to simulate fire behaviour over the savanna–forest boundary. There were strong gradients across the boundary in all variables with the exception of total fuel load. During the day, savannas had higher wind speed and air temperature, and lower relative humidity and fuel moisture than forests. Although fuel loads were similar in savanna and forest, savanna was characterized by lower fuel bulk density, largely because of the presence of grasses. Based on these measurements, the fire behaviour model predicted savanna fires to be faster, more intense, and with greater flame lengths, relative to forest. A sensitivity analysis indicated that the primary cause of these differences was the low fuel bulk density characteristic of grassy fuels, with lesser contributions from wind speed, fuel moisture and total fuel load. These results indicate that the dominance of grassy fuels is the primary cause of the high flammability of savanna.

• Vascular epiphytes have developed distinct lifeforms to maximize water uptake and storage, particularly when delivered as pulses of precipitation, dewfall or fog. The seasonally dry forest of Chamela, Mexico, has a community of epiphytic bromeliads with Crassulacean acid metabolism showing diverse morphologies and stratification within the canopy. We hypothesize that niche differentiation may be related to the capacity to use fog and dew effectively to perform photosynthesis and to maintain water status. • Four Tillandsia species with either 'tank' or 'atmospheric' lifeforms were studied using seasonal field data and glasshouse experimentation, and compared on the basis of water use, leaf water δ(18) O, photosynthetic and morphological traits. • The atmospheric species, Tillandsia eistetteri, with narrow leaves and the lowest succulence, was restricted to the upper canopy, but displayed the widest range of physiological responses to pulses of precipitation and fog, and was a fog-catching 'nebulophyte'. The other atmospheric species, Tillandsia intermedia, was highly succulent, restricted to the lower canopy and with a narrower range of physiological responses. Both upper canopy tank species relied on tank water and stomatal closure to avoid desiccation. • Niche differentiation was related to capacity for water storage, dependence on fog or dewfall and physiological plasticity.

Trace gas fluxes exhibit extensive spatial and temporal variability that is dependent on a number of factors, including meteorology, ambient concentration, and emission source size. Previous studies have found that agricultural fertilization contributes to higher fluxes of certain gases. The magnitude of trace gas fluxes over unfertilized crops is still uncertain. In the present study, deposition of ammonia (NH), nitric acid (HNO), and sulfur dioxide (SO) was measured over unfertilized soybean using the flux-gradient technique. The eddy diffusivity was estimated from eddy covariance measurements of temperature fluxes, resulting in K of 0.64 ± 0.30 m s. Flux means and standard deviations were -0.14 ± 0.13, -0.22 ± 0.19, and -0.38 ± 0.54 μg m s for NH, HNO, and SO, respectively. Low concentrations of NH and HNO increased the relative uncertainties in the deposition velocities estimated from measured fluxes. This contributed to dissimilarities between deposition velocities estimated from the resistance analogy and deposition velocities estimated from fluxes. However, wet canopy conditions during the study may have led to an underestimation of deposition by the resistance analogy because the resistance method does not accurately describe the enhanced deposition rates that occur after dew formation. Quantification of vegetation characteristics, such as leaf wetness and apoplast chemistry, would be beneficial in future studies to more accurately determine stomatal resistance and its influence on fluxes.

Two kinds of retted Canadian linseed flax fibers, dewretted (F1) and enzyme-retted flax fibers (F2) were characterized in detail for their applications in composites, such as retting degree, thermal stability, tensile strength, and interfacial behavior in polypropylene (PP) matrix. It’s clear from Scanning Electron Micrograph that the aspect ratio of F2 was much higher than that of F1 in the light of their separated elementary fibers in most cases. Instead, the elementary fibers of F1 remained tightly bundled into technical fiber wrapping with more non-cellulose portions. This reflected its lower retting degree and resulted in its lower thermal stability. Single fiber tensile test and single fiber pull-out test were used to evaluate the fiber tensile properties and fiber/PP interfacial shear strength, respectively. Better retting degree and fewer damages on F2 endowed F2 better tensile property. Consequently, higher aspect ratio, retting degree, and tensile strength proved F2 to be a kind of better reinforcing material than F1 for composites. POLYM. ENG. SCI., 52:165–171, 2012. 2011 published by Society of Plastics Engineers*

Dew formation, a common meteorological phenomenon, is expected to intensify in the future. Dew can influence the H2 18 O and HDO isotopic compositions of leaf water (dL), but the phenomenon has been neglected in many experimental and modelling studies. In this study, the dew effect on dL was investigated with a dark plant chamber in which dew formation was introduced. The H2 18 O and HDO compositions of water vapour, dew water and leaf water of five species were measured for up to 48 h of dew exposure. Our results show that the exchanges of H2 18 O and HDO in leaf water with the air continued in the darkness when the net H2 16 O flux was zero. Our estimates of the leaf conductance using the isotopic mass balance method ranged from 0.035 to 0.087 mol m -2 s -1 , in broad agreement of the night-time stomatal conductance reported in the literature. In our experiments, the conductance of the C4 species was 0.04 0.01 mol m -2 s -1 and that of the C3 plants was 0.10 0.04 mol m -2 s -1 .At the end of 16 h dew exposure, 72 (17) and 94 (11)% of the leaf water came from dew according to the 18 O and D tracer, respectively.

Experiments were conducted under controlled conditions to quantify the effects of temperature, water regime and irrigation system on the release of Mycosphaerella nawae ascospores from leaf litter in Spanish persimmon orchards. The effect of temperature on ascospore release was best described by a Gompertz model. The end of the lag phase of ascospore release occurred at 9·75°C, and the end of the exponential phase at 15·75°C. Few ascospores were discharged from dry leaves wetted with 0·1 or 0·5 mm water, but significant amounts were recovered with 1–50 mm water. About half of the total ascospores were released after three wetting and drying cycles, but 32 cycles were necessary for a complete discharge. No significant difference in ascospore release was detected when the leaf litter was wetted by flood and drip irrigation. However, considering the proportion of soil area wetted in both systems, inoculum release was significantly reduced by drip irrigation. The potential of drip irrigation as a cultural control measure should be investigated.

We evaluated the effect of moisture period on foliar disease development by Phytophthora ramorum on 2- to 3-year-old northern red oak (Quercus rubra) and chestnut oak (Q. prinus). We also determined the propensity of P. ramorum to form sporangia and chlamydospores on these two host species. Leaves were dip-inoculated with ca. 5000 sporangia/ml of P. ramorum isolate Pr-6 and incubated at 100% relative humidity in dew chambers in darkness for up to 6 days. Several plants were removed each day to a greenhouse, and foliar infection was evaluated on day 7. Sporangia were collected over a 7-day period from diseased foliage in a mist tent. A significant relationship between moisture period and disease incidence was found for both tree species. Chestnut oak exhibited significantly greater disease incidence and severity compared with northern red oak. However, sporulation levels were larger in northern red oak over the 7-day period of sporangia collection, and northern red oak also produced significantly greater numbers of sporangia per square centimetre of lesion area compared with chestnut oak. Chlamydospore production in diseased leaves sampled 1 month following moist incubation was also significantly greater for northern red oak compared with chestnut oak. Knowledge of P. ramorum sporulation capacity in relation to disease incidence and severity on Eastern US oak species will help determine the potential for epidemic development should the pathogen become established in this region.