Dry Phase Research Articles

Study on Stable Phase Equilibria of Quinary System LiBr–NaBr–KBr–MgBr2–H2O at 298.15 K

According to the composition characteristics of mineral elements in underground brine in the Sichuan basin of China, the complete phase equilibria and phase diagram of the quinary system LiBr–NaBr–KBr–MgBr2–H2O were studied at 298.15 K. Using the experimentally determined solubilities and equilibrium solids, the spatial stereo phase diagram of the quinary system, the dry base projection phase diagrams of the saturated surfaces of the four salts MgBr2·6H2O, KBr, LiBr·2H2O, and NaBr·2H2O, and the corresponding water content diagrams were plotted, respectively. The experimental results show that at 298.15 K, in addition to the four original components, the anhydrous salt NaBr and the double salt KBr·MgBr2·6H2O are formed. The phase diagram of the quinary system at 298.15 K contains 10 univariate curves, three invariant points, and six equilibrium solid-phase crystallization regions (KBr crystallization region, NaBr crystallization region, NaBr·2H2O crystallization region, MgBr2·6H2O crystallization region, LiBr·2H2O crystallization region, KBr·MgBr2·6H2O crystallization region). When MgBr2·6H2O or KBr is saturated, LiBr has a strong salting-out effect on KBr, NaBr, or MgBr2 and NaBr, while when LiBr·2H2O is saturated, MgBr2 has a salting-out effect on KBr and NaBr. All four saturated projection surfaces have MgBr2·6H2O, and NaBr is generated. These phase equilibrium data can provide a theoretical basis to guide underground brine mining and extract useful components.

Climate-controlled sensitivity of lake sediments to record earthquake-related mass wasting in tropical Lake Towuti during the past 40 kyr

Located at the triple junction of the Pacific, Eurasian and Sunda plates, the Island of Sulawesi in Indonesia is one of the most tectonically active places on Earth. This is highlighted by the recurrence of devastating earthquakes such as the 2018 Mw 7.5 earthquake that damaged the city of Palu and caused several thousand fatalities in central Sulawesi. The majority of large-magnitude earthquakes on Sulawesi are related to stress release along major strike-slip faults such as the Palu-Koro Fault and its southern extensions, the Matano and Lawanopo Faults. To date, information on the frequency and magnitude of past major events on these faults is limited to instrumental records and historical sources restricted to the last century, whereas information from natural archives is completely lacking. Lake-sediment records can fill this gap, but a detailed assessment of the various factors that influence the sensitivity of sediment successions to past earthquakes is required to evaluate their suitability. Lake Towuti, situated in Eastern Sulawesi, is known for its paleoclimate record and also promises to be a key site to generate a paleoseismology record for Sulawesi. The lake lies close to the highly active Matano and Lawanopo strike-slip faults and thereby is an ideal archive for past earthquakes that have occurred in the surrounding area. Here we combine high-resolution chirp seismic data with lithostratigraphic and petrophysical data of sediment piston cores to assess the recurrence of seismically generated mass-transport and turbidite deposits. Three major seismic-stratigraphic units are distinguished in the upper ∼10 m of the sediment succession and linked to differences in the frequency of mass-wasting during the past 60 kyrs. The evidence of a more turbidite-prone period between 12 and 40 ka is roughly coincident with a dry phase and associated lake-level lowstand during the last glacial period at Lake Towuti. Hence, we suggest that climate strongly influences the sensitivity of slopes to fail during seismic shaking in this tropical setting as a consequence of lowstand-forced sediment redeposition from the shelves onto the slopes and into the basins. As climate significantly impacts the sensitivity of the lacustrine sediments to record earthquake-related mass wasting deposits, we suggest that the frequency of mass-transport deposits can additionally be employed as a quantitative indicator for past changes in hydroclimate in these tropical settings.

Quantifying the impacts of a proposed hydraulic dam on groundwater flow behaviors and its eco-environmental implications in the large Poyang Lake-floodplain system

Dam-induced hydrological alterations and eco-environmental impacts have significant implications, however, these concern issues in large floodplain systems are less well understood. The present study shows a first attempt to adopt a quasi-three-dimensional groundwater flow modeling FEFLOW (Finite Element subsurface FLOW system) to investigate the influences of a proposed hydraulic dam on groundwater dynamics in the largest floodplain lake of the Yangtze River basin (Poyang Lake, China). The FEFLOW model was successfully constructed and has the ability to represent the hydrodynamics of floodplain groundwater flow. Model simulations indicate that, in general, the dam is likely to increase the groundwater levels across the floodplain during different hydrological phases. The responses of floodplain groundwater levels to the dam during the dry and recession phases are stronger (∼2–3 m) than the rising and flooding phases (<2 m). Under the natural condition, the floodplain groundwater may recharge the lake during the dry and recession phases, and discharge the lake during the rising and flooding phases. However, the dam regulation may alter the natural recharge-discharge patterns, forming a generally gaining condition of the floodplain groundwater. The proposed dam is most likely to reduce the groundwater flow velocity (∼<1 m/d) relative to the natural condition (up to 2 m/d) during different hydrological phases, and it may also alter the floodplain groundwater flow direction during the dry and recession phases. Additionally, the floodplain groundwater system is mainly characterized by losing state (−4.5 × 106 m3/yr) under the natural condition, while the dam-induced groundwater system exhibits an overall gaining state (9.8 × 106 m3/yr). The current research findings contribute to future water resources assessment and management by providing a foundation for assessing associated eco-environmental changes of the large lake-floodplain system.

Forest ecology and fire history of the mixed conifer forest belt in the Italian Alps from Late Roman fires to the 20th century under cultural and climate pressure

We reconstructed vegetation, fire and watershed history during the Late Roman-Early Middle Ages and in the last three centuries in a mixed conifer forest forming the middle mountain elevational belt in the inner Alpine region, analyzing co-registered micro-botanical data, charcoal particles, sediment lithology, nutrients, and modern pollen deposition from a high-resolution peat record in Valmalenco (Italian Alps). During Late Roman Age the site hosted a dump mixed conifer forest dominated by Picea abies and Abies alba on peaty forest soil, locally affected by fires which also triggered episodes of hillslope denudation. Fire frequency increases during Early Middle Ages dry and warm phases, favoring Alnus viridis and Larix, while Abies alba and Alnus glutinosa type maintained a main role in the pre- and post-fire. Specifically, Abies alba, nowadays eradicated from the Valmalenco watershed, withstood the local regime of low intensity surface fires for more than a millennium, from the Late Roman throughout the Early Middle Ages. Larix, Alnus viridis and Fraxinus excelsior abundance in modern vegetation is ascribed to effects of intensified disturbance in the Early Modern Age, and to further woodland thickening triggered by fire suppression and abandonment after the Second World War.

THE MASS ACCUMULATION OF POTATO POTATOES DEPENDS ON EXTRA-ROOT NUTRITION OF PLANTS WITH MICROFERTILIZERS IN THE CONDITIONS OF THE WESTERN FOREST-STEPPE OF UKRAINE

Goal. To determine the effect of foliar fertilizing with microfertilizers on the mass accumulation of potato tubers in the conditions of the Western Forest-Steppe of Ukraine. Methods. Analysis, synthesis, generalization, laboratory and field experiment. The results. It is established that the highest indices were obtained from the use of micronutrient Reakom – a variety of Dar and Crystaloneone special – a variety of Alladin. Thus, in the Aladin variety from the introduction of microfiber Crystaloneone special with a norm of 2,50 kg/ha, the average weight of tubers in the bushes in the budding phase was obtained – 318 g, in the phase of drying of the peduncle – 624 g, the Dar variety – the most effective rate of application among the studied variants the established norm of Reakom – 4,50 kg/ha, while the average weight of tubers in the budding phase was 309 g, the beginning of the drying of the peduncle – 683 g, respectively. The most effective rate for introducing potato plants is the following: Reakom – 4,50 kg/ha, Crystalonelone special – 2,50 kg/ha, and Rozasol – 3,00 kg/ha in the budding phase and the beginning of the disappearance of the peduncle. Conclusions. Indigenous fertilization with microfertilizers (Reakom, Crystalone special and Rozasol), influenced growth processes. At the same time, they were more intense compared with the control (without plant treatment) and maintained until the drying of the peduncle. All this contributed to the growth of the tubers weight and increased the yield and quality of products

Convection and Clouds under Different Planetary Gravities Simulated by a Small-domain Cloud-resolving Model

In this study, we employ a cloud-resolving model to investigate how gravity influences convection and clouds in a small-domain (96 × 96 km) radiative–convective equilibrium. Our experiments are performed with a horizontal grid spacing of 1 km, which can resolve large (>1 km2) convective cells. We find that under a given stellar flux, sea surface temperature increases with decreasing gravity. This is because a lower-gravity planet has larger water vapor content and more clouds, resulting in a larger clear-sky greenhouse effect and a stronger cloud warming effect in the small domain. By increasing stellar flux under different gravity values, we find that the convection shifts from a quasi-steady state to an oscillatory state. In the oscillatory state, there are convection cycles with a period of several days, comprised of a short wet phase with intense surface precipitation and a dry phase with no surface precipitation. When convection shifts to the oscillatory state, the water vapor content and high-level cloud fraction increase substantially, resulting in rapid warming. After the transition to the oscillatory state, the cloud net positive radiative effect decreases with increasing stellar flux, which indicates a stabilizing climate effect. In the quasi-steady state, the atmospheric absorption features of CO2 are more detectable on lower-gravity planets because of their larger atmospheric heights. While in the oscillatory state, the high-level clouds mute almost all of the absorption features, making the atmospheric components hard to characterize.

Material extrusion of highly-loaded silicon nitride aqueous inks for solid infilled structures

The material extrusion technique of direct ink writing (DIW) has garnered recent interest for the ability to create near-net shapes using polymer and/or ceramic based inks using low-cost commercially-available equipment. While most foundational work in the field has shown promise for single-walled structures, the nature of the circular cross-section of extruded ink has led to the reported issue of interfilament voids when multi-walled structures are attempted. In addition, particularly for ceramic-loaded aqueous inks, multi-walled structures have proven difficult to dry post-processing without cracking or void formation. In this study, DIW was used to produce bulk infilled samples of silicon nitride (Si3N4), a high-temperature ceramic of interest for various high-temperature aerospace, automotive, and structural applications. Here, an ink feedstock was developed and modified from an aqueous-based Si3N4 suspension previously developed for room-temperature injection molding. Tailoring the rheological properties for DIW to exhibit low yield stresses (< 100 Pa), and low equilibrium storage moduli (<1000) resulted in little to no interstitial void defects which are common with the infilled aligned print pattern. A drying analysis varying humidity and sample size revealed that bulk infilled samples required a controlled humidity around 90% for the initial drying phase to produce defect free samples. Through careful control of the ink rheology and drying kinetics, mechanical test bars were sintered to high density (∼95%) with four-point flexural strengths greater than 500 MPa (in-line with other reported values for similar sintering conditions). There was no discernable effect of nozzle size (i.e. 1.2 mm or 0.6 mm) on resulting flexural strength, indicating strong interfilament welding. In fact, X-ray CT analysis of fractured mechanical test bars revealed microstructures with minimal large pores (i.e > 100 µm) and no pore channels observed between printed filaments, common issues reported in other works on solid infilled DIW.

The Combined Influence of the Madden–Julian Oscillation and El Niño–Southern Oscillation on Australian Rainfall

Abstract This study first re-examines the impact of the Madden–Julian oscillation (MJO) on weekly rainfall probabilities and wind anomalies across Australia, motivated by the need for a contemporary understanding of the MJO’s influence on Australian rainfall, whether this has changed from a previous assessment published in 2009. With an extra 15 years of observations, we show that the strong impact of MJO phases 5 and 6 on northern Australia’s austral summer rainfall has weakened by around 5% over Australia’s Top End. In addition, austral spring has seen a weakening of the suppressed rainfall teleconnection with MJO phases 2 and 3 over southeast Australia. The weakened relationships make it a little harder to use the MJO to explain rainfall variations over northern Australia in summer and southeast Australia in spring in the current climate. The study’s second motivation is to further document the combined influence of El Niño–Southern Oscillation (ENSO) and the MJO on rainfall. In summer during El Niño, as compared with La Niña or neutral ENSO conditions, there are stronger reductions in rainfall probabilities over northern Australia associated with the dry MJO phases 8, 1, and 2, but the significantly increased rainfall probabilities in MJO phases 5 and 6 remain much the same. Indeed, the MJO dominates over ENSO in its influence on weekly rainfall probabilities in the north in summer. In contrast, ENSO tends to dominate across subtropical and southern Australia in spring. The updated probability maps are an important resource for estimating the intraseasonal influence of the MJO and ENSO on Australian rainfall. Significance Statement Accompanying forecasts of multiweek rainfall, the Australian Bureau of Meteorology provide average condition maps showing the long-term relationship between the Madden–Julian oscillation (MJO) and Australian weekly rainfall. Motivated by discussions with northern Australian beef producers, we updated the maps using high-resolution data and found that in the austral summer, the association between the MJO and northern rainfall has weakened in the past 15 years. Despite this, the MJO still dominates over El Niño–Southern Oscillation (ENSO) as a driver of changes in week-to-week rainfall over northern Australia in summer, although ENSO dominates farther south in spring. This study gives users an improved understanding of what to expect in terms of upcoming weekly weather when interpreting rainfall and MJO predictions.

Accelerated corrosion test and field test of steel and zinc coupons at buffer areas and cross passages in a mass rapid transit tunnel

ABSTRACT A study has been conducted to measure the distribution of temperature, relative humidity and corrosivity due to uniform corrosion along the Mass Rapid Transit (MRT) North East Line (NEL) tunnel in Singapore. The corrosion rates of carbon steel 1010 and zinc coupons at the buffer areas of ten stations and five cross passages along the NEL were monitored over a period of one year. The median temperatures were between 31 and 36°C while the median relative humidity varied between 43 and 53%. At all exposure sites, the values of relative humidity corresponding to the 75th percentile values were below 60%, with very few data points registering above 80%. The cross passages showed a lower degree of fluctuations in the temperature and relative humidity compared to the buffer areas. The corrosivity levels showed some differences between exposure sites, but their values were generally low and could be categorised as C1 according to the ISO 9223:2012 categorisation. A set of procedures for an accelerated laboratory test to approximate the corrosion in the tunnel was also studied. The test procedures involved the exposure to a salt fog containing 0.12% Na2SO4 + 0.05% NaCl, followed by a drying phase and subsequent exposure to a constant temperature of 40°C and a constant relative humidity of 60%. It was found that after exposure for 80 h, the accelerated tests were able to generate the degree of corrosion observed in the most severe conditions in the field.

Late Holocene fire and precipitation history of the Kashmir Himalaya: Inferences from black carbon in lake sediments

Throughout the human history, fire, climate, and human advancement had a very complicated relationship. Scientists have explored this relationship using different proxies such as black carbon, polycyclic aromatic hydrocarbons, and charcoal. In this study, black carbon (BC) concentrations and its isotopic compositions (δ13CBC) in a sediment core from the Wular Lake, Kashmir (India) were measured to understand the interactions of fire and human development in the Kashmir Himalaya during the late Holocene. As revealed through radiocarbon dating, the sediment core covered the time span from 3752 to 306 Cal years BP. Two major climate phases in the region were identified based on the relationship between mean annual precipitation and δ13CBC. The first phase, from 3752 to 1500 Cal year BP, was characterised by low mean annual precipitation (dry climate), which transitioned into a wetter phase with higher mean annual precipitation after 1500 Cal year BP until 306 Cal year BP. Within the dry phase, a phase of extreme dryness and minimum precipitation around ∼2500 Cal years BP was observed. The variability in BC concentrations in the sediments revealed dynamic fire history in the Kashmir Himalaya with occurrences of high fire events around 3000 Cal years BP, which gradually declined until 1500 Cal year BP then increase again. Our results, in combination with available studies from the region, suggested that forest fires in the Kashmir Himalaya were dominantly human-driven than due to large scale climate change.

Influence of Temperature during Freeze-Drying Process on the Viability of Bifidobacterium longum BB68S

Maintaining optimum temperature during freeze-drying is crucial to ensuring the viability of strains. In this study, we evaluated the effect of pre-freezing, sublimation and desorption temperatures on the viability of Bifidobacterium longum BB68S (BB68S). Moreover, we examined the water content, water activity, enzyme activities, and scanning electron microscope of BB68S to explore mechanisms underpinning the effect of temperature on viability. Our analyses revealed the highest survival rates of BB68S collected after pre-freezing and sublimation drying at -40 °C (94.9 ± 2.2%) and -10 °C (65.4 ± 3.8%), respectively. Additionally, response surface methodology demonstrated that the optimum conditions for freeze-drying of BB68S were pre-freezing temperature at -45.52 °C and sublimation temperature at -6.58 °C, and the verification test showed that survival rates of BB68S could reach 69.2 ± 3.8%. Most of the vitality loss occurred during the sublimation drying phase. Further studies showed that different sublimation temperatures affected water content and activity, β-galactosidase, lactate dehydrogenase, Na+-K+-ATP and Ca2+-Mg2+-ATP activities. In conclusion, the temperature during freeze-drying, especially sublimation temperature, is a key factor affecting the survival rate of BB68S, and the vitality loss during freeze-drying process might be due to compromised cell membrane integrity and permeability.

Smart Powder Processing for Excellent Advanced Materials and Its Applications

To create advanced materials with minimal energy consumption and environmental impacts, a green and sustainable powder processing technology is essential. The authors have developed this technique based on powder grinding technology. In this paper, the authors will explain the recent progress of the smart powder processing, and its applications. Firstly, particle bonding process, and novel one-pot processing methods to synthesize nanoparticles, to create nanostructured composite granules and to form nano-porous films on substrates in dry phase will be discussed. Their applications on the advanced material fabrications contributing to the sustainable economy will also be explained. Then, the use of grinding technology in wet processing to synthesize nanoparticles and control their morphology will be explained. Smart powder processing can be a foundation to move forward material development technologies and create many more high-quality advanced materials in the future.

Understanding the Impact of Microstructures on Reconstitution and Drying Kinetics of Lyophilized Cake Using X-ray Microscopy and Image-Based Simulation

The drying time of lyophilization and resultant cake microstructure are dependent on each other as water and solvent leave a lyophilized cake. The drying rate affects the size, distribution, and tortuosity of the pores as these macropores evolve during the primary drying phase, which in return impact the further removal of water and solvent from the cake throughout the drying period. This interplay results in a microstructure that determines the reconstitution time for a given formulation. The current study employs advanced X-ray Microscopy (XRM) coupled with mathematical models to correlate the microstructure with the drying kinetics and the reconstitution time. The normalized diffusion coefficients, derived from the reconstructed 3D microstructure of the cake, correlate with the solid content of the pre-lyophilization solution and agree with the mass transfer coefficients from a semi-empirical drying model built with lyophilization process data. Specifically, a solution with less solid content leads to a lyophilized cake with larger pores, thinner walls, and a greater pore volume compared to a solution with more solid content. Consequently, models from the microstructure and drying experiments reveals faster mass transfer independently. While the mass transfer models from the cake structure and the lyophilization process data accurately represents the drying kinetics, both models are inadequate to describe the reconstitution process due to the significant impact from formulation ingredients that alter the mass transfer mechanism via solubility and wettability. In summary, X-ray microscopy imaging and mathematical models are powerful tools that provide insights into the lyophilization process from a new angle.

БИОИНДИКАЦИОННЫЕ ПРИЗНАКИ АТМОСФЕРНЫХ АНОМАЛИЙ В РАЗРЕЗАХ ТОРФЯНИКОВ НА ВОСТОЧНОМ МАКРОСКЛОНЕ СИХОТЭ-АЛИНЯ В ПОЗДНЕМ ГОЛОЦЕНЕ

Studies of peat stratigraphy in the upper reaches of the Milogradovka River made it possible to restore changes in humidity as a source of moisture in the middle Sikhote-Alin over the last 3400 years. High-resolution reconstructions were based on the data from biostratigraphic analyses (botanical and diatom); the ash content of peat was also studied. Radiocarbon dating of the events was performed using an age-depth model. In the upper part of the section, the B-Tm cryptotephra of the Baitoushan caldera-forming volcano was found, which was identified by the volcanic glass chemical composition. Prolonged rains are assumed to cause a massive landslide with the formation of a dam and a shallow reservoir turning the river valley into a swamp. Bioindicators of changes in humidity in the river valley and the occurrence of floods were identified. Events were correlated with the data for the main watershed of the Sikhote-Alin, mountainous plateaus, lakes on the slopes of the ancient Solontsovsky volcano and the eastern Primorye coast. The peat section in the valley is shown to record in more detail the hydrological changes associated with the nature of cyclogenesis. A relationship was revealed between paleoevents and anomalies of large-scale atmospheric circulation. Long dry phases occurred during global cooling and were accompanied by aridization in East Asia, caused by a decrease in the intensity of the East Asian summer monsoon. Studies show that floods occurred in the summer to autumn season even in dry phases. The phases of flooding were associated with the activation of the summer monsoon, as well as more intense cyclogenesis. The most complex climate rhythm was established for the last 1340 years.

An ultramicroporous multi-walled metal–organic framework for efficient C2H2/CO2 separation under humid conditions

An infinite multi-walled ultramicroporous MOF has been designed and prepared from a classical H3TATB linker and In(iii) ions, exhibiting good C2H2/CO2 separation performance in both dry and humid gas phases.

Developing the Adapted Scale of Microphenological Phases for the Controlled Sprouting of Grain Crops

As a result of the research and in view of the methodological approach to the controlled sprouting of grain crops, the term “sprouted grain” adapted to the conditions of controlled sprouting has been proposed. A unified scale of microphenological phases for controlled sprouting of different types of grain crops treated with low doses of gamma radiation has been developed. In order to take the reading for the quiescence state of the grains of the “Ekaterina” soft spring wheat and the “Remembrance of Chepelev” spring barley of 2019-2021 harvest years zoned in the Ural region, the treatment with low doses of ionizing gamma radiation (5Gy, 10Gy, and 15Gy) has been carried out. In the developed scale of microphenological phases for germination of grain crops, the dry grain phase has been introduced and the technological features of the sprouting and its effectiveness have been given. In the second phase of the sprouting, intense water absorption is observed in all groups of samples. Bioactivation of grain crops effects the increase in germination energy—up to 92-93% when treated with a dose of 10Gy. The germination rate of the 1st seed is on average 2-3 days. Low-dose gamma radiation of grains is distinguished by its industrial applicability when sprouted grains are used as an independent product or as a raw material component.

Citizen science data validates aerial imagery to track the ‘rise and fall’ of woody vegetation through extremes of climate

Context Ground truthing remotely sensed imagery for detecting changes in wetland vegetation can be time-consuming and costly for monitoring. Harnessing the resources of citizen scientists (CS) using mobile devices has been under utilised in Australia. Aims The project aimed to test the feasibility and practicality of using CS to collect data using mobile devices to ground truth remotely sensed imagery. Methods Using high-resolution aerial imagery, we detected the establishment of woody vegetation over a 20-year dry phase from 2000 to 2020 in Thirlmere Lakes National Park, NSW, Australia. To ground truth these woody species, we engaged with a local community group using a customised, freely available mobile device application. Key results During the dry event of 2020, CS documented well-established woody species, such as Melaleuca linariifolia (flax-leaved paperbark), amongst the Lepironia articulata grey rush. With the La Niña wet events in early 2020–22 and subsequent higher water levels, the CS documented the survival of M. linariifolia but the dieback of eucalypts, and other woody species. Conclusions Observations at higher temporal frequencies by CS using mobile devices, augmented with researchers’ observations, proved to be a valuable, quality-controlled method to ground truth high-resolution aerial imagery. Implications This case study showed that monitoring the phenology of vegetation in a peat wetland can be supplemented by the inclusion of a CS programme. This under-utilised resource can increase coverage and frequency of data observations, lower costs as well as create community awareness, capability and engagement in scientific research.

Intermittent Rivers as a Challenge for Freshwater Ecosystems Quality Evaluation: A Study Case in the Ribeira de Silveirinhos, Portugal

Intermittent rivers and streams are aquatic ecosystems that lose hydrological connectivity during drought periods. Anthropogenic pressures combined with climate change accelerate the spatial and temporal intermittency of these ecosystems, promoting alterations in ecology and ecosystem functions. This study aimed to assess the ecological status of Ribeira de Silveirinhos, located in the municipalities of Valongo and Gondomar (north of Portugal), using the metrics described in the Water Framework Directive. Thus, five sampling sites were selected along Ribeira de Silveirinhos. Sampling was done in three different periods, spring of 2019 and 2020, and autumn of 2019. At each site, physical and chemical water parameters were measured, and the benthic macroinvertebrates community was characterized. Physical and chemical parameters showed low pH values at upstream sites (where the dry phase occurs and is surrounded by Eucalyptus monoculture) and high concentrations of phosphorus at the downstream sites (subjected to several anthropogenic activities, iron waters, and agriculture). The macroinvertebrate community revealed low values of specific abundance and richness, especially during the dry period. Sensitive taxa (Ephemeroptera, Plecoptera, and Trichoptera) were negatively correlated with flow intermittency. Results showed that Ribeira de Silveirinhos is classified between “poor” and “moderate” in terms of ecological status. Intermittent streams are undervalued, so their protection is at risk. Thus, it is important to consider the specific ecological functioning of these ecosystems and to adjust the planning and management models in order to guarantee ecological quality and conservation processes.

Colonisation of terrestrial vegetation in an intermittent river: Diversity responses to seasonal drying

AbstractIntermittent rivers are dynamic ecosystems that experience a predictable or unpredictable loss of surface water and are characterised by changing lotic, lentic (ponding) and dry habitats. Plant communities colonising dry channels during the desiccation stage can be diverse, abundant and differ in their tolerances to water availability and habitat conditions. This study examines the colonisation of terrestrial vegetation in two intermittent rivers in the United Kingdom, and whether terrestrial plant taxonomic richness and functional diversity increase during the dry phase. Six reaches were surveyed for terrestrial plants during the dry phase over a standard 100 m length every month from April to October 2021. We found the channel and bank taxonomic richness increased with drying duration. Functional traits of vegetation height, clonality, clonality richness and Ellenberg's value of light moisture also increased with stream desiccation. Bed sediment conditions (the proportion of sand and gravel) and the 12‐month antecedent percentage of zero flow days were the key drivers of plant community composition. We believe plant propagules from the riparian zone and channel vegetation on topographic high points in the channel aided plant colonisation of the riverbed once flow ceased. Past research may have underestimated the biodiversity value of intermittent rivers by failing to include the ecological importance of plants during the dry phase. Information on plant diversity of the dry phase is important to determine the overall biodiversity of intermittent rivers for their long‐term conservation and management.

Hydrogeotechnical Predictive Approach for Rockfall Mountain Hazard Using Elastic Modulus and Peak Shear Stress at Soil–Rock Interface in Dry and Wet Phases at KKH Pakistan

Predicting the susceptibility of rockfall mountain hazards for block-in-matrix soils is challenging for critical steep cuts. This research illustrates a hydrogeotechnical approach for the prediction of rockfall triggering by performing laboratory tests on low-cohesive-matrix soil collected from steep slopes with 85° to 88° angles at the Tatta Pani site, Karakorum Highway (KKH), and then real-scale moisture-induced rockfall was conducted on site for the validation of laboratory data. Laboratory data of forty quick direct shear tests on samples collected from the field depicted a 3-fold drop in peak shear stress (PS) at the soil–soil interface and a 9.3-fold drop at the soil–rock interface by varying the moisture content from 1% (taken as dry phase) to a critical laboratory moisture content (MC)LC of 21% (taken as wet phase). Similarly, a drop in the elastic modulus (ES) was observed to be 5.7-fold at the soil–soil interface and 10-fold at the soil–rock interface for a variation of moisture content from 1 % to 21% for the matrix with a permeability (k) range of 3 × 10−4 to 5.6 × 10−4 m/s, which depicts the criticality of moisture content for the rockfall phenomenon. The critical moisture content evaluated in laboratory is validated by an innovative field-inundation method for thirty-two moisture-induced real-scale forced rockfall cases, which showed the rock-block triggering at field dry density (γd)f and the critical field moisture content (MC)FC of the matrix ranging from 1.78 g/cm3 to 1.92 g/cm3, and 1.3% to 25.4%, respectively. Hydrogeotechnical relations, i.e., MC versus PS and ES, at the soil–rock interface are developed for the prediction of rockfall triggering. The proposed correlations may be helpful in the prediction of rockfall hazards by using expected rainfall in the field for disaster warning and landslide disaster prevention at ecological geotechnical engineering projects. The results revealed that the critical (MC)FC and (MC)LC are within 20%, depicting a good confidence level of the outcomes of this research.