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The Robert  H Smith Faculty
of Food, Agriculture and Environment
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Publications

2021
Malchi, T. ; Eyal, S. ; Czosnek, H. ; Shenker, M. ; Chefetz, B. . Plant Pharmacology: Insights Into In-Planta Kinetic And Dynamic Processes Of Xenobiotics. CRITICAL REVIEWS IN ENVIRONMENTAL SCIENCE AND TECHNOLOGY 2021.Abstract
The exposure of plants to pharmaceuticals via treated wastewater irrigation and biosolid application presents an important route of chronic exposure of crops to a wide variety of bioactive pollutants. This paper presents a novel approach which aims to improve our understanding of the interactions of bioactive pollutants with plants through the concept of plant pharmacology and two main sub-divisions: (i) plant pharmacokinetics which describes the fate of exogenous xenobiotics in the plant based on the processes of absorption, distribution, metabolism and accumulation (ADMA), processes that are analogous to pharmacokinetics in animals; and (ii) plant pharmacodynamics that proposes that exogenous xenobiotics interact with plant enzymes and biochemical pathways, establishing a relationship with pharmacological concepts and emphasizing the importance of exposure-response interactions. The concept of plant pharmacology and its two subdivisions provide a foundation for the development of in-depth knowledge regarding the fate of xenobiotics in plants and establishing plant pharmacokinetic-pharmacodynamic models that include both the ADMA processes and time-dependent response of the plant to these compounds. This concept provides a new perspective on pharmacovigilance, focusing on plant-xenobiotic compound interactions, and a conceptual framework for understanding the fate and interactions of these bioactive molecules in agricultural systems, to enable more accurate risks assessments of environmental and human health.
Ogunmokun, F. A. ; Wallach, R. . Remediating The Adverse Effects Of Treated Wastewater Irrigation By Repeated On-Surface Surfactant Application. WATER RESOURCES RESEARCH 2021, 57.Abstract
The use of treated wastewater (TWW) has gained recognition as an alternative source for freshwater irrigation, and is steadily expanding worldwide. Despite the benefits of freshwater conservation and nutrient richness, there is mounting evidence of TWW adverse effects on soil, yield, and the environment. Irrigation using TWW has resulted in soil water repellency, in which preferential flow pathways and uneven soil water and chemical distribution occur. These increase deep water percolation and chemical leaching, which can lead to soil and groundwater pollution. This study was conducted in a commercial citrus orchard grown on sandy-loam soil in central Israel and irrigated with TWW, with the aim of investigating the remediation of these adverse effects, by repeatedly spraying a nonionic surfactant on the soil surface. The surfactant application succeeded to turn the soil wettable, diminishing the preferential flow pathways, and rendering the soil water and dissolved chemicals uniformly distributed. The overall water content in the 0-40 cm layer increased, and deep percolation and chemical leaching substantially decreased. The grapefruit yield increase during the two-year study period increased the water use efficiency. Electrical resistance tomography scans executed during and after irrigation events for two subsequent years revealed that a ``soil memory'' phenomenon has been developed for water repellent soils, where water flow takes place through previously developed preferential flow pathways in such soils. This study demonstrates that recurrent surfactant application enables a continuous use of TWW, while eliminating most of its prejudicial effects.
Azaria, S. ; Nussinovitch, A. ; Nir, S. ; Mordechai, S. ; van Rijn, J. . Removal Of Geosmin And 2-Methylisoborneol From Aquaculture Water By Novel, Alginate-Based Carriers: Performance And Metagenomic Analysis. JOURNAL OF WATER PROCESS ENGINEERING 2021, 42.Abstract
Hydrophobic carriers were examined for geosmin and 2-methylisoborneol removal from water derived from an aquaculture system. A combination of adsorption and biodegradation was found to underlie the removal of the off-flavor compounds. Adsorption of these compounds by the carriers was unaffected by the presence of organic matter in the water to be treated. A model based on adsorption/desorption and first-order degradation kinetics provided an accurate prediction for experimentally determined 2-methylisoborneol removal rates. Steady removal of geosmin and 2-methylisoborneol as well as nitrate reduction were observed during long-term operation of the plug-flow reactors with water derived from an aquaculture facility. Metagenomic analysis of the microbial community on the carriers during long-term operation of the reactors revealed a predominance of denitrifying bacteria. It was found that geosmin and 2-methylisoborneol led to statistically significant changes in the abundances of 21 contigs that contained genes involved in terpene degradation. This study shows that at low ambient concentrations of geosmin and 2-methylisoborneol in nitrate and organic-rich water, such as found in aquaculture systems, their biodegradation can be accomplished by terpene-degrading denitrifiers that develop on hydrophobic carriers used for filtration of the contaminated water.
Shabtai, I. A. ; Lynch, L. M. ; Mishael, Y. G. . Designing Clay-Polymer Nanocomposite Sorbents For Water Treatment: A Review And Meta-Analysis Of The Past Decade. WATER RESEARCH 2021, 188.Abstract
{{Clay-polymer nanocomposites (CPNs) have been studied for two decades as sorbents for water pollutants, but their applicability remains limited. Our aim in this review is to present the latest progress in CPN research using a meta-analysis approach and identify key steps necessary to bridge the gap between basic research and CPN application. Based on results extracted from 99 research articles on CPNs and 8 review articles on other widely studies sorbents, CPNs had higher adsorption capacities for several inorganic and organic pollutant classes (including heavy metals, oxyanions, and dyes
Hochman, D. ; Dor, M. ; Mishael, Y. G. . Diverse Effects Of Wetting And Drying Cycles On Soil Aggregation: Implications On Pesticide Leaching. CHEMOSPHERE 2021, 263.Abstract
The important effect of soil wetting and drying cycle (WDC) on soil structure, and the consequent effect on pollutant fate is underexplored. We thoroughly investigated the changes in soil structure and in leaching of Alion (indaziflam) and Express (tribenuron methyl), pre and post WDC, from two clayey soils and two loamy soils under different land uses (uncultivated, field crops, and orchards). Soil stability was quantified by an aggregate durability index we recently developed. WDC did not affect the stability of the sandy-loam soils, as expected. However, for the sandy-clay-loam with high CaCO3 content aggregation was observed. For the clayey soils with similar CaCO3, aggregation and disaggregation were obtained, for a soil with relatively low and high SOM, respectively. The stability trends are reflected by the ratio between the contents of inorganic carbon and soil organic matter (SOM), CaCO3/SOM, normalized to the clay content. Aggregation was explained by CaCO3 cementation, while disaggregation was attributed to high clay content and to alterations in SOM conformation post WDC. These opposite trends, obtained for the two clayey soils, were confirmed by analyzing changes in soil packing employing X-ray tomography (micro-CT). Our results clearly demonstrated that soil aggregation and disaggregation, induced by a WDC, suppresses and enhances herbicide mobility, respectively. However, the effect of WDC on herbicide leaching was not noticeable for Alion upon its high adsorption to a clayey soil, indicating that herbicide physical-chemical properties may dominate. Finally, WDC induces micron-scale changes in aggregate structure, which have a notable effect on pollutant mobility and fate in the environment. (C) 2020 Elsevier Ltd. All rights reserved.
Zusman, O. B. ; Perez, A. ; Mishael, Y. G. . Multi-Site Nanocomposite Sorbent For Simultaneous Removal Of Diverse Micropollutants From Treated Wastewater. APPLIED CLAY SCIENCE 2021, 215.Abstract
Despite the advantages of maximizing treated wastewater (TWW) reuse, this practice brought upon the presence of micropollutants in edible plants, animals, and even humans, since many micropollutants are not completely removed by conventional treatment plants. Clay polymer nanocomposites (CPNs) have been proposed and widely studied in recent years as a promising sorbent for micropollutant removal. However, most of these studies report the development of a single CPN for the removal of specific micropollutants in batch experiments, usually from synthetic water, and do not compare to the removal by commercial sorbents. Here, we thoroughly investigated the adsorption mechanism of three chemically-diverse micropollutants; cationic, anionic, and non-ionic (metoprolol, diclofenac, and lamotrigine, respectively) from TWW by a CPN with a `loopy' polymer configuration. The results suggest that both cation and anion exchange sites coexist on the CPN, and therefore anionic and cationic micropollutants adsorb simultaneously, and they do not compromise the adsorption of each other. The adsorption of the non-ionic micropollutant enhanced in the presence of the charged micropollutants due to a synergistic effect. These adsorption trends were also obtained for micropollutant filtration by CPN columns. Finally, we demonstrated the simultaneous filtration of effluent organic matter and an array of micropollutants from TWW by the CPN columns and compared it to the filtration by granular activated carbon (GAC). A costeffective comparison indicates that the filtration by the CPN column is more efficient (ng pollutants/ sorbent cost) than by the GAC column.
Chaudhary, N. ; Bonfil, D. J. ; Tas, E. . Physiological And Yield Responses Of Spring Wheat Cultivars Under Realistic And Acute Levels Of Ozone. Atmosphere 2021, 12. Publisher's VersionAbstract
Tropospheric ozone (O3) is widely recognized as the cause of substantial yield and quality reduction in crops. Most of the previous studies focused on the exposure of wheat cultivars to elevated O3 levels. Our main objectives were to: (i) investigate the consistency of wheat cultivars’ physiological responses across two different realistic O3 levels; and (ii) compare these physiological responses with those under short acute O3 exposure. Three commercially available hard spring wheat cultivars bred under semiarid and Eastern Mediterranean conditions were exposed to two different O3 levels during two consecutive seasons (2016–2018)—36 and 71 ppbv 7 h mean O3 mixing ratios in open-top chambers. The results were compared to those following short acute O3 exposure (102.8 ppbv, 7 h mean for 10 days) in a greenhouse. Non-stomatal responses were significantly more pronounced than stomatal responses in all cultivars under different levels of O3. The specific cultivar was observed as the most O3-tolerant under all experiments. The fact that the same cultivar was found remarkably tolerant to the local semiarid ambient conditions according to other studies and to O3 exposure based on the present study supports a link between cultivar resistance to drought conditions and O3.
Xue, B. ; Helman, D. ; Wang, G. ; Xu, C. - Y. ; Xiao, J. ; Liu, T. ; Wang, L. ; Li, X. ; Duan, L. ; Lei, H. . The Low Hydrologic Resilience Of Asian Water Tower Basins To Adverse Climatic Changes. 2021, 155, 103996. Publisher's VersionAbstract
Climate change has a significant impact on the runoff of basins in cold, dry areas. The quantification of regional ecohydrological responses to climate change such as warming and drought is essential for establishing proper water resource management schemes. We propose a simple and novel method based on the Budyko framework to evaluate the hydrologic resilience of 16 basins that conform the Asian Water Tower in the Tibetan Plateau (TP). Our method defines two metrics within the Budyko domain – tolerance (ψ) and plasticity (φ) – that characterize the hydrologic resilience of a basin. Based on an ecohydrological point of view, a basin is considered hydrologically resilient if ψ and φ are both greater than 1 or its φ is negative and ψ is greater than 1. Our results show that ψ varies between 0.27 and 0.74, with an average value of 0.45 and φ varies between 2 and 16.33, with an average value of 6.90, for 14 out of the 16 basins. Only two basins – Taohe and Datonghe – had negative φ (-11.67 and -8.11, respectively) and ψ greater than 1 (2.26 and 19.58, respectively), suggesting that these two are the only basins with a hydrologic resilience to climatic warming/drying in the TP. Within the non-resilient basins, we found vegetation to play a key role in the level of tolerance and plasticity indicating that basins with a larger vegetation cover display a lower capability to adapt to adverse climatic changes. Following these results, we call for afforestation efforts to be carefully considered in cold, dry areas. The proposed method and conclusions drawn by this study may help predict the hydrologic responses to future adverse climatic conditions.
Saadon, T. ; Lazarovitch, N. ; Jerszurki, D. ; Tas, E. . Predicting Net Radiation In Naturally Ventilated Greenhouses Based On Outside Global Solar Radiation For Reference Evapotranspiration Estimation. Agricultural Water Management 2021, 257, 107102. Publisher's VersionAbstract
A reliable prediction of net radiation (Rn) inside naturally ventilated greenhouses is critical for accurate evapotranspiration evaluation and thus for water saving, considering that previous studies have indicated that evapotranspiration in such relatively decoupled greenhouses is predominantly controlled by greenhouse Rn (Rn-GH). We hypothesized here that Rn-GH in naturally ventilated greenhouses can be accurately predicted using global solar radiation in the vicinity of the greenhouse (Rs-out) as the only measured parameter, together with the calculated position of the sun, defined by the solar elevation angle and solar azimuth. To test this hypothesis, we performed experiments in two adjacent greenhouses in the Southern Negev, Israel (30.96° N, 34.69° E) under arid climate. In one of the greenhouses, tomato was grown during winter 2017–2018, while in the other, melon was grown during winter and spring 2018–2019. Our analyses demonstrated that Rn-GH can be accurately predicted (r2 = 0.982) using Rs-out as the only measured parameter, while the global solar radiation inside the greenhouse (Rs-GH), and the ratio between Rn-GH and Rs-GH are predominantly dependent on solar elevation angle and solar azimuth, as well as the greenhouse structure and cloud cover. This paper shows that the impact of these properties on the association between Rs-out and Rn-GH can be accurately resolved using multivariate regression by the k-nearest neighbors approach. This suggests that computerized modeling of the greenhouse structure and light transmission can potentially enable precise evaluation of Rn-GH and therefore also reference evapotranspiration in naturally ventilated greenhouses, using Rs-out as the only measured parameter. A calculation-based factor for the cloud effect on Rs-out transmittance into the greenhouse significantly improved the Rn-GH prediction under cloudy conditions.
Jerszurki, D. ; Saadon, T. ; Zhen, J. ; Agam, N. ; Tas, E. ; Rachmilevitch, S. ; Lazarovitch, N. . Vertical Microclimate Heterogeneity And Dew Formation In Semi-Closed And Naturally Ventilated Tomato Greenhouses. Scientia Horticulturae 2021, 288, 110271. Publisher's VersionAbstract
The extent of the vertical microclimate heterogeneity inside a greenhouse is mostly unknown, and it can strongly affect plant production and yield quality. Tomato crop was grown in a semi-closed greenhouse equipped with horizontal ventilation and sidewall curtains, which were only opened depending on microclimate conditions; and a naturally ventilated greenhouse equipped with sidewalls curtains that were kept open. Both greenhouses had a 1,000-m2 area and a net size of 50-mesh, and were located in an arid climate zone in Israel. Vertical profiles of CO2 concentration, actual vapor pressure, air, leaf and soil temperature, net CO2 assimilation rates, stomatal conductance, and total fruit yield, fresh mass, and quality were monitored in both greenhouses for 13 days, in January 2018; CO2 concentration, actual vapor pressure, and air and soil temperature were additionally monitored in the semi-closed greenhouse for seven days in December 2016, when the ventilation was inoperative, and in December 2017, with ventilation. The vertical air temperature gradient, along with the colder microclimate inside the naturally ventilated greenhouse, led to a lack of plant uniformity and yield loss. Closing the side curtains in the fanned semi-closed greenhouse had a beneficial effect on yield, however, with mixed results for quality, due to the higher air temperature and lower carbon dioxide levels at the upper canopy. Horizontal air circulation in the semi-closed greenhouse increased transpiration and assimilation, and increased dew occurrence at night, but did not reduce the vertical heterogeneity. Significant vertical gradients affect plant physiology, and closing the curtains in winter cultivation in semi-arid/arid climates has the potential to improve fruit yield and quality. However, it must be coupled with proper air circulation and, preferably, with CO2 enrichment, or careful management of natural ventilation through side curtains, in order to maximize CO2 replenishment while minimizing heat losses.
Klausner, Z. ; Ben-Efraim, M. ; Arav, Y. ; Tas, E. ; Fattal, E. . The Micrometeorology Of The Haifa Bay Area And Mount Carmel During The Summer. Atmosphere 2021, 12. Publisher's VersionAbstract
The Haifa bay area (HBA), which includes Mount Carmel and the Zevulun valley is the third largest metropolitan area in Israel. It is also a centre of heavy industry and an important transportation hub which serve as sources of local anthropogenic pollution. Such sources are associated with adverse health effects. In order to estimate the possible exposure of the inhabitants in such heterogeneous orographic area, a detailed atmospheric transport and dispersion modelling study is required, which in turn must take into account the local micrometeorology. The aim of this study is to conduct a spatio-temporal analysis of the flow field in the HBA in order to identify the common patterns of the average wind and characterize the statistical parameters of turbulence in this area, essential for detailed pollutants dispersion modelling. This study analyses data collected during four months of summer in a network of 16 weather stations which extend across Mount Carmel and the Zevulun valley. It was found that, during the evening and night time on Mount Carmel, different flow patterns may develop on each side, separated by the watershed line. When such conditions do not develop, as well as during the daytime, the wind field, both on Mount Carmel and the Zevulun valley is approximately homogenous. The analysis of the Monin–Obukhov similarity theory functions for the velocity standard deviations show a distinct difference between Mount Carmel and the Zevulun valley, as well as between strong and weak winds. This difference can be clearly seen also in the diurnal hourly distribution of atmospheric stabilities which exhibit higher proportions of unstable conditions in the Zevulun valley during day time and higher proportion of stable stratifications at the Mount Carmel during night-time.
Hendel, E. ; Bacher, H. ; Oksenberg, A. ; Walia, H. ; Schwartz, N. ; Peleg, Z. . Deciphering The Genetic Basis Of Wheat Seminal Root Anatomy Uncovers Ancestral Axial Conductance Alleles. Plant, Cell & EnvironmentPlant, Cell & EnvironmentPlant Cell Environ 2021, n/a. Publisher's VersionAbstract
ABSTRACT Root axial conductance which describes the ability of water to move through the xylem, contributes to the rate of water uptake from the soil throughout the whole plant lifecycle. Under the rainfed wheat agro-system, grain-filling is typically occurring during declining water availability (i.e. terminal drought). Therefore, preserving soil water moisture during grain filling could serve as a key adaptive trait. We hypothesized that lower wheat root axial conductance can promote higher yields under terminal drought. A segregating population derived from a cross between durum wheat and its direct progenitor wild emmer wheat was used to underpin the genetic basis of seminal root architectural and functional traits. We detected 75 QTL associated with seminal roots morphological, anatomical, and physiological traits, with several hotspots harboring co-localized QTL. We further validated the axial conductance and central metaxylem QTL using wild introgression lines. Field-based characterization of genotypes with contrasting axial conductance suggested the contribution of low axial conductance as a mechanism for water conservation during grain filling and consequent increase in grain size and yield. Our findings underscore the potential of harnessing wild alleles to reshape the wheat root system architecture and associated hydraulic properties for greater adaptability under changing climate. This article is protected by copyright. All rights reserved.
Weksler, S. ; Rozenstein, O. ; Haish, N. ; Moshelion, M. ; Wallach, R. ; Ben-Dor, E. . Detection Of Potassium Deficiency And Momentary Transpiration Rate Estimation At Early Growth Stages Using Proximal Hyperspectral Imaging And Extreme Gradient Boosting. Sensors 2021, 21. Publisher's VersionAbstract
Potassium is a macro element in plants that is typically supplied to crops in excess throughout the season to avoid a deficit leading to reduced crop yield. Transpiration rate is a momentary physiological attribute that is indicative of soil water content, the plant’s water requirements, and abiotic stress factors. In this study, two systems were combined to create a hyperspectral–physiological plant database for classification of potassium treatments (low, medium, and high) and estimation of momentary transpiration rate from hyperspectral images. PlantArray 3.0 was used to control fertigation, log ambient conditions, and calculate transpiration rates. In addition, a semi-automated platform carrying a hyperspectral camera was triggered every hour to capture images of a large array of pepper plants. The combined attributes and spectral information on an hourly basis were used to classify plants into their given potassium treatments (average accuracy = 80%) and to estimate transpiration rate  
2020
Osovsky, R. ; Cherf, S. ; Karagach, S. ; Aviram, L. ; Mishael, Y. G. . Decontamination Of Sarin In Water By Designed Oxime-Clay Composites. APPLIED CLAY SCIENCE 2020, 192.Abstract
The hydrolysis of the organophosphate nerve agent sarin (GB), is prone to rapid catalytic hydrolysis by oximes. In this study, an oxime-clay composite, based on the adsorption of 2-pyridinealdoxime (2-PAM) to montmorillonite (MMT), was designed as a delivery system of oxime for GB degradation in water. 2-PAM adsorption reached a plateau at similar to 0.5 mmol/g; however, the degree of 2-PAM desorption from composites in water (with and without GB) was not constant and increased with an increase in its initial added concentration. The composites were characterized by SEM, XRD, FTIR-ATR and TGA measurements. We suggest 2-PAM adsorbs in three modes; in a planar orientation while 1. intercalated or 2. directly adsorbed on the external surface, and 3. ``weakly adsorbed'', as a multilayer on the external surface. The removal of GB (40 mu g/ml) in the presence of MMT-PAM composites enhanced dramatically compared to its spontaneous hydrolysis in distilled-, tap- or buffered water e.g., from a half-life time of 2.5 h in tap-water to 0.3 h in a composite suspension (6.4 g clay/l). GB removal was attributed, not to adsorption, but rather to catalytic hydrolysis by released oxime, forming nontoxic compounds. The rate of GB removal was further enhanced by applying composites designed to release higher concentrations of 2-PAM.
Zusman, O. B. ; Kummel, M. L. ; De la Rosa, J. M. ; Mishael, Y. G. . Dissolved Organic Matter Adsorption From Surface Waters By Granular Composites Versus Granular Activated Carbon Columns: An Applicable Approach. WATER RESEARCH 2020, 181.Abstract
Many new sorbents have been introduced as an alternative for granular activated carbon (GAC), the most common sorbent for dissolved organic matter (DOM) removal. In the current study, we developed an applicable granular composite based on a flocculant commonly employed for drinking water treatment adsorbed to montmorillonite. DOM adsorption from surface waters, Lake Kinneret and Suwannee River, with low and high specific ultraviolet absorption (SUVA), respectively, by composite and GAC columns, was studied. Adsorption of DOM from Suwannee River was significantly higher by the composite column, in comparison to the GAC column, while an opposite trend was obtained for the adsorption of DOM from Lake Kinneret. In-situ regeneration of the columns with a brine solution was extremely efficient and inefficient for the composite and GAC columns, respectively. Adsorption, of both waters, postregeneration by the composite column was not compromised, while GAC effectiveness decreased. The opposite trend in DOM adsorption from Suwannee River and Lake Kinneret was explained by the different affinities of the sorbents towards various DOM molecules. Distinguishing between different DOM components adsorbed by GAC and the composite was supported by C-13 NMR and direct pyrolysisGC-MS measurements. Furthermore, we demonstrated that the kinetics and adsorption at the equilibrium of five organic molecules to the composite and GAC can be correlated to their chemical-physical properties. Indeed, combining the properties of both sorbents, by integrating them into a single column, yielded higher DOM removal than by the individual columns. Furthermore, since DOM removal by GAC and by the composite, increases, and decreases with temperature, respectively, the integrated column, mitigates the changes in removal, stabilizing the adsorption performance. Such an integrated filter may minimize additional seasonal and water quality fluctuations. (C) 2020 Elsevier Ltd. All rights reserved.
De Nobili, M. ; Bravo, C. ; Chen, Y. . The Spontaneous Secondary Synthesis Of Soil Organic Matter Components: A Critical Examination Of The Soil Continuum Model Theory. APPLIED SOIL ECOLOGY 2020, 154.Abstract
The Soil Continuum Model questions the occurrence of any independent natural process of secondary synthesis that generates compounds structurally distinct from plant or microbial metabolites. This review shows that a vast volume of interdisciplinary scientific evidence supports the formation of relevant non-pre-existing complex molecules exhibiting various types of structures. These molecules form during degradation and decay of biological cell components. The spontaneous abiotic and enzymatically catalysed reactions of components of organic residues and of their oxidative decomposition products suggested by state-of-the-art studies are indeed those proposed by most of the classical descriptions of humification. The review also highlights the chemically active role of pedofauna, explaining why the apparently harsh conditions of alkaline extraction of HS cannot be considered un-natural. Many insects and larvae feeding on foliage of plants with a high content of tannins have a midgut pH above 9. Albeit, reducing conditions are often maintained to avoid oxidation, peroxidases are active in the intestinal tract and pass on to feces. Polyphenols are then immediately enzymatically oxidized to their reactive quinone form, once feces are excreted and exposed to oxygen. Implications of our current knowledge on the reactivity of plant components in soil are discussed in relation with the present state of the art research on humic substances. Contrary to claims by the Soil Continuum Model theory, complimentary modern approaches need to be used to understand the complexity of soil organic matter.
Dor, M. ; Levi-Kalisman, Y. ; Day-Stirrat, R. J. ; Mishael, Y. G. ; Emmanuel, S. . Assembly Of Clay Mineral Platelets, Tactoids, And Aggregates: Effect Of Mineral Structure And Solution Salinity. JOURNAL OF COLLOID AND INTERFACE SCIENCE 2020, 566, 163-170.Abstract
Clay mineral properties, together with solution chemistry, control the assembly of clay platelets into hierarchical structures, including tactoids and aggregates. We studied the effect of salinity on the assembly of kaolinite, illite, and montmorillonite at three critical scales: platelet, tactoid, and aggregate, using cryogenic scanning electron microscopy (cryo-SEM), atomic force microscopy (AFM) and cryo-transmission EM (cryo-TEM), respectively. Cyro-SEM images coupled with original alignment analysis indicate that the degree of aggregate alignment in an ionized solution was significantly higher than in deionized water. Furthermore, upon increasing platelet-platelet bonding energy (montmorillonite > illite > kaolinite), tactoid size increased, packing was less ordered, and aggregate alignment decreased. AFM measurements showed that an increase in ionic-strength caused a decrease in the Young's modulus of the clays, indicating higher tactoid alignment, since, disordered structures, comprising various platelet orientations, are stiffer than highly-aligned structures. We successfully measured distances <1 nm, for both kaolinite and montmorillonite by cryo-TEM, directly demonstrating that increasing ionic-strength reduces platelet-platelet distances. The outcome of this study offers a new approach and methodology to study fundamental colloid-assembly which will trigger future studies investigating additional parameters affecting assembly such as, temperature, solution pH, natural organic matter, and anthropogenic activity. (C) 2020 Elsevier Inc. All rights reserved.
Grodek, T. ; Morin, E. ; Helman, D. ; Lensky, I. ; Dahan, O. ; Seely, M. ; Benito, G. ; Enzel, Y. . Eco-Hydrology And Geomorphology Of The Largest Floods Along The Hyperarid Kuiseb River, Namibia. JOURNAL OF HYDROLOGY 2020, 582.Abstract
Flood-fed aquifers along the sandy lower reach of the Kuiseb River sustain a 130-km-long green belt of lush oases across the hyperarid Namib desert. This oasis is a year-round source for water creating dense-tall woodland along the narrow corridor of the ephemeral river valley, which, in turn, supports human activity and fauna including during the long dry austral winters and multi-year droughts. Occasional floods, originating at the river's wetter headwaters, travel similar to 280 km downstream, before recharging these aquifers. We analyzed the flood-aquifer-vegetation dynamics at-a-site and along the river, determining the relative impact of floods with diverse magnitude and frequency on downstream reaches. We find that flood discharge that feeds the alluvial aquifers also affects vegetation dynamics along the river. The downstream aquifers are fed only by the largest floods that allow the infrequent germination of plants; mean annual recharge volume is too low to support the aquifers level. These short-term vegetation cycles of green-up and then fast senescence in-between floods are easily detected by satellite-derived vegetation index. This index identifies historical floods and their magnitudes in arid and hyperarid regions; specifically, it determines occurrences of large floods in headwater-fed, ephemeral Namib streams as well as in other hyperarid regions. Our study reveals the importance of flood properties on the oasis life cycle, emphasizing the impact of drought and wet years on the Namib's riparian vegetation.
Tolkin, S. ; Chen, Y. ; Tarchitzky, J. . Humic Acid, Dextran, And Valeric Acid Representing Macromolecules Similar To Compounds Prevailing In Treated Wastewater Induce Soil Hydrophobicity. JOURNAL OF SOILS AND SEDIMENTS 2020, 20, 3548-3556.Abstract
Purpose Organic compounds originating from treated wastewater and soil texture have been reported to be the dominant factors influencing soil hydrophobicity. It is the aim of this investigation to elaborate the role of humic acid, dextran, and valeric acid, representing dissolved organic matter, polysaccharides, and fatty acids, respectively, as well as imitating their activity in inducing soil sub-critical water repellency induced by treated wastewater irrigation. Materials and methods The relationships between three model compounds imitating fractions of dissolved organic matter commonly found in treated wastewater, soil texture in relation to water repellency, were investigated. Three types of organic molecules, five soil mixtures with different specific surface areas, and three different organic compounds, as well as a mixture of the three, were tested. Results and discussion After 14-15 of wetting and drying cycles, low levels (sub-critical hydrophobicity) of water repellency developed in all soil mixtures were subjected to applications of several solutions of organic compounds, in comparison with a freshwater control. The highest degree of water repellency was exhibited by the soil with the lowest clay content (lowest specific surface area) and it decreased with increasing clay content (increasing specific surface area). Conclusions The order of intensity of sub-critical water repellency levels induced by the organic compounds was consistent, yet independent of soil texture. However, soil texture exhibited large influence on soil hydrophobicity in response to the various organic chemicals. Humic acid, the closest in structure to organic matter prevailing in treated wastewater, exhibited the largest effect in inducing soil hydrophobicity.
Castan, S. ; Sigmund, G. ; Hueffer, T. ; Tepe, N. ; von der Kammer, F. ; Chefetz, B. ; Hofmann, T. . The Importance Of Aromaticity To Describe The Interactions Of Organic Matter With Carbonaceous Materials Depends On Molecular Weight And Sorbent Geometry. ENVIRONMENTAL SCIENCE-PROCESSES & IMPACTS 2020, 22, 1888-1897.Abstract
Dissolved organic matter (DOM) is ubiquitous in aquatic environments where it interacts with a variety of particles including carbonaceous materials (CMs). The complexity of both DOM and the CMs makes DOM-CM interactions difficult to predict. In this study we have identified the preferential sorption of specific DOM fractions as being dependent on their aromaticity and molecular weight, as well as on the surface properties of the CMs. This was achieved by conducting sorption batch experiments with three types of DOM (humic acid, Suwannee River natural organic matter, and a compost extract) and three types of CMs (graphite, carbon nanotubes, and biochar) with different geometries and surface complexities. The non-adsorbed DOM fraction was analyzed by size exclusion chromatography and preferentially sorbed molecular weight fractions were analyzed by UV/vis and fluorescence spectroscopy. All three sorbent types were found to preferentially sorb aromatic DOM fractions, but DOM fractionation depended on the particular combination of sorbent and sorbate characteristics. Single-walled carbon nanotubes only sorbed the smaller molecular weight fractions (<1 kDa). The sorption of smaller DOM fractions was not accompanied by a preference for less aromatic compounds, contrary to what was suggested in previous studies. While graphite preferentially sorbed the most aromatic DOM fraction (1-3 kDa), the structural heterogeneity of biochar resulted in reduced selectivity, sorbing all DOM > 1 kDa. The results explain the lack of correlation found in previous studies between the amount of aromatic carbon in a bulk DOM and its sorption coefficient. DOM sorption by CMs was generally controlled by DOM aromaticity but complex sorbent surfaces with high porosity, curvatures and functional groups strongly reduced the importance of aromaticity.