Carbamazepine and lamotrigine prescribed antiepileptic drugs are highly persistent in the environment and were detected in crops irrigated with reclaimed wastewater. This study reports pharmacokinetics of the two drugs and their metabolites in cucumber plants under hydroponic culture, testing their uptake, translocation, and transformation over 96 h in single and bisolute systems at varying pH. Ruling out root adsorption and transformations in the nutrient solution, we demonstrate that carbamazepine root uptake is largely affected by the concentration gradient across the membrane. Unlike carbamazepine, lamotrigine is adsorbed to the root and undergoes ion trapping in root cells thus its translocation to the shoots is limited. On the basis of that, carbamazepine uptake was not affected by the presence of lamotrigine, while lamotrigine uptake was enhanced in the presence of carbamazepine. Transformation of carbamazepine in the roots was slightly reduced in the presence of lamotrigine. Carbamazepine metabolism was far more pronounced in the shoots than in the roots, indicating that most of the metabolism occurs in the leaves, probably due to higher concentration and longer residence time. This study indicates that the uptake of small nonionic pharmaceuticals is passive and governed by diffusion across the root membrane.Carbamazepine and lamotrigine prescribed antiepileptic drugs are highly persistent in the environment and were detected in crops irrigated with reclaimed wastewater. This study reports pharmacokinetics of the two drugs and their metabolites in cucumber plants under hydroponic culture, testing their uptake, translocation, and transformation over 96 h in single and bisolute systems at varying pH. Ruling out root adsorption and transformations in the nutrient solution, we demonstrate that carbamazepine root uptake is largely affected by the concentration gradient across the membrane. Unlike carbamazepine, lamotrigine is adsorbed to the root and undergoes ion trapping in root cells thus its translocation to the shoots is limited. On the basis of that, carbamazepine uptake was not affected by the presence of lamotrigine, while lamotrigine uptake was enhanced in the presence of carbamazepine. Transformation of carbamazepine in the roots was slightly reduced in the presence of lamotrigine. Carbamazepine metabolism was far more pronounced in the shoots than in the roots, indicating that most of the metabolism occurs in the leaves, probably due to higher concentration and longer residence time. This study indicates that the uptake of small nonionic pharmaceuticals is passive and governed by diffusion across the root membrane.

The gram-negative bacterium Acidovorax citrulli causes bacterial fruit blotch (BFB) disease of cucurbits, which represents a serious threat to melon and watermelon production worldwide. To date, there are no efficient means to manage the disease, and reliable resistance sources for cucurbit germplasm are lacking. Mineral nutrition markedly affects plant diseases. Recently, we reported that disease severity on melon foliage and A. citrulli growth in the leaf tissue were significantly influenced by the form of nitrogen supply. In the present study, we investigated the influence of potassium nutrition on BFB severity and A. citrulli establishment in the foliage of melon plants. Fertilization with relatively low concentrations of potassium increased these variables compared with higher potassium concentrations. Since establishment of A. citrulli during the growing season is assumed to increase the incidence of fruit infection, the fact that mineral nutrition influences BFB incidence in the plant foliage is of particular importance.

Seminal roots constitute the initial wheat root system and provide the main route for water absorption during early stages of development. Seminal root number (SRN) varies among species. However, the mechanisms through which SRN is controlled and in turn contribute to environmental adaptation are poorly understood. Here, we show that SRN increased upon wheat domestication from 3 to 5 due to the activation of 2 root primordia that are suppressed in wild wheat, a trait controlled by loci expressed in the germinating embryo. Suppression of root primordia did not limit water uptake, indicating that 3 seminal roots is adequate to maintain growth during seedling development. The persistence of roots at their primordial state promoted seedling recovery from water stress through reactivation of suppressed primordia upon rehydration. Our findings suggest that under well-watered conditions, SRN is not a limiting factor, and excessive number of roots may be costly and maladaptive. Following water stress, lack of substantial root system suppresses growth and rapid recovery of the root system is essential for seedling recovery. This study underscores SRN as key adaptive trait that was reshaped upon domestication. The maintenance of roots at their primordial state during seedling development may be regarded as seedling protective mechanism against water stress.

Drip irrigation is a useful method for the application of low-quality water because it does not wet the foliage and limits the spread of contaminants. Nevertheless, when using water containing high levels of dissolved salts, drip irrigation may be insufficient for leaching and can lead to soil salinization. A new conceptual model was tested experimentally and numerically to examine if manipulation of the distribution of soils with different textures could promote the removal of salts from the root zone and increase leaching efficiency. The manipulated root zone consisted of a volume of coarse soil, located under a drip irrigation emitter, surrounded by finer texture soil. We hypothesized that the differences in hydraulic properties between the two soils and the capillary barrier developed at their interface would generate a one-directional flow path of the salty water from the location of irrigation to the fine soil. This would enforce salt accumulation beyond the root zone. The concept was tested in a series of lysimeter and Hele–Shaw chamber experiments, together with a two-dimensional flow model created in HYDRUS-2D. Results showed preferential salt accumulation beyond the coarse segment of the manipulated soil, providing a volume of leached soil sufficient to support a healthy root system. Under conditions of homogenous soil texture, a notable buildup of salinity was observed in the central root zone, whereas under the manipulated texture conditions, such salt buildup was not observed.

The greatest challenge of wastewater treatment is the removal of trace concentrations of persistent micropollutants in the presence of the high concentration of effluent organic matter (EfOM). Micropollutant removal by sorbents is a common practice, but sorbent employment is often limited because of fouling induced by EfOM and challenging sorbent regeneration. We directly addressed these two issues by designing regenerable dual-site composite sorbents based on polymerized β-cyclodextrin, modified with a cationic group (pCD+) and adsorbed to montmorillonite (pCD+-MMT). This dual-site composite was tailored to simultaneously target an emerging micropollutant, bisphenol A (BPA), through inclusion in β-cyclodextrin cavities and target anionic EfOM compounds, through electrostatic interactions. The removal of BPA from treated wastewater by the composite was not compromised despite the high removal of EfOM. The composites outperformed many recently reported sorbents. Differences in composite performance was discussed in terms of their structures, as characterized with TGA, XRD, BET and SEM. The simultaneous filtration of BPA and EfOM from wastewater by pCD+-MMT columns was demonstrated. Furthermore, successful in-column regeneration was obtained by selectively eluting EfOM and BPA, with brine and alkaline solutions, respectively. Finally, the composites removed trace concentrations of numerous high priority micropollutants from treated wastewater more efficiently than commercial activated carbon. This study highlights the potential to design novel dual-site composites as selective and regenerable sorbents for advanced wastewater treatment.The greatest challenge of wastewater treatment is the removal of trace concentrations of persistent micropollutants in the presence of the high concentration of effluent organic matter (EfOM). Micropollutant removal by sorbents is a common practice, but sorbent employment is often limited because of fouling induced by EfOM and challenging sorbent regeneration. We directly addressed these two issues by designing regenerable dual-site composite sorbents based on polymerized β-cyclodextrin, modified with a cationic group (pCD+) and adsorbed to montmorillonite (pCD+-MMT). This dual-site composite was tailored to simultaneously target an emerging micropollutant, bisphenol A (BPA), through inclusion in β-cyclodextrin cavities and target anionic EfOM compounds, through electrostatic interactions. The removal of BPA from treated wastewater by the composite was not compromised despite the high removal of EfOM. The composites outperformed many recently reported sorbents. Differences in composite performance was discussed in terms of their structures, as characterized with TGA, XRD, BET and SEM. The simultaneous filtration of BPA and EfOM from wastewater by pCD+-MMT columns was demonstrated. Furthermore, successful in-column regeneration was obtained by selectively eluting EfOM and BPA, with brine and alkaline solutions, respectively. Finally, the composites removed trace concentrations of numerous high priority micropollutants from treated wastewater more efficiently than commercial activated carbon. This study highlights the potential to design novel dual-site composites as selective and regenerable sorbents for advanced wastewater treatment.

ABSTRACTA novel, stimuli-responsive composite, based on poly(4-vinylpyridine) (PVP) brushes, end-grafted to montmorillonite clay (GPC), was designed as a regenerable sorbent for efficient removal of pollutants from water. We characterized the novel composite sorbent and its response to pH, employing Fourier transform infrared, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry analysis and zeta potential measurements. In comparison with conventional, electrostatically adsorbed PVP composites (APC), the GPC presented superior characteristics: higher polymer loading without polymer release, higher zeta potential and lower pH/charge dependency. These superior characteristics explained the significantly higher removal of organic and inorganic anionic pollutants by this composite, in comparison with the removal by APC and by many reported sorbents. For example, the filtration (20 pore volumes) of selenate by GPC, APC and a commercial resin column was complete (100%), negligible (0%) and reached 90% removal, respectively. At low?moderate pH, the grafted polymer undergoes protonation, promoting pollutant adsorption, whereas at high pH, the polymer deprotonates, promoting pollutant desorption. Indeed, ?in-column? regeneration of the GPC sorbents was achieved by increasing pH, and upon a second filtration cycle, no reduction in filter capacity was observed. These findings suggest the possible applicability of this stimuli-responsive sorbent for water treatment.

Water transports organic matter through soils, where mineral-organic associations form to retain dissolved organic matter (“DOM”), influencing terrestrial carbon cycling, nutrient availability for plant growth, and other soil organic matter functions. We combined Fourier transform ion cyclotron resonance mass spectrometry with novel data analysis techniques to examine the role of sorptive fractionation in the associations between Fe(III)-montmorillonite and DOM from composted biosolids (“anthropogenic DOM”). To examine the influence of DOM composition on sorption and sorptive fractionation, we used resin-based separation to produce DOM subsamples with different molecular compositions and chemical properties. A large proportion (45 to 64%) of the initial carbon in every DOM solution sorbed to the Fe(III)-montmorillonite. However, when the compositions of the initial solutions were compared to the sorbed organic matter, the computed changes in composition were lower (10 to 32%). In fact, non-selective sorption was more important than selective sorption in every sample, except for the hydrophilic neutral (HiN) fraction, where high nitrogen content and acidic conditions appeared to enhance sorptive fractionation. The results from this study demonstrate that the importance of sorptive fractionation varies with DOM composition and other factors, and that non-selective sorption can contribute substantially to the formation of mineral-organic associations.

Waterborne pathogens are a major health threat and must be eliminated to guarantee safe usage of water for potable purposes. For this purpose, a new carbon-based nanomaterial composed of single-walled carbon nanotubes (SWCNTs) and iron oxides was constructed for bacterial inactivation. Owing to its magnetic properties, the SWCNT–iron oxide nanocomposite may serve as a reusable antimicrobial agent. The nanocomposite material exhibited high antimicrobial activity against Escherichia coli. Successful reuse of the nanocomposite material was achieved by washing with calcium chloride and distilled water, which restored its performance for several successive cycles. To investigate the cytotoxicity mechanisms of the nanocomposite material, we exposed it to single-gene knockout mutant strains of E. coli. Mutants bearing shorter lipopolysaccharide (LPS) layers in the outer membrane (ΔrfaC and ΔrfaG) demonstrated an increased sensitivity in comparison to the wildtype strain, exemplified in enhanced removal by the nanocomposite material. This finding suggests that the LPS acts as a protective shield against the nanocomposite material. Inactivation of mutants impaired in specific oxidative stress defense mechanisms (ΔsodA, ΔkatG and ΔsoxS) emphasized that oxidative stress plays a significant role in the inactivation mechanism of the nanocomposite. This study sheds light on the mechanisms of bacterial inactivation by carbon-based nanomaterials and advances their potential implementation for water disinfection.

Cultivated land is a major source of pesticides, which are transported with the runoff water and eroded soil during rainfall events and pollute riverine and estuarine environments. Common ecotoxicological assessments of riverine systems are mainly based on water sampling and analysis of only the dissolved phase, and address a single pesticide's toxicological impact under laboratory conditions. A clear overview of mixtures of pesticides in the adsorbed and dissolved phases is missing, and therefore the full ecotoxicological impact is not fully addressed. The aim of this study was to characterize and quantify pesticide concentrations in both suspended sediment and dissolved phases, to provide a better understanding of pesticide-load dynamics during storm events in coastal streams in a Mediterranean climate. High-resolution sampling campaigns of seven flood events were conducted during two rainy seasons in Alexander stream, Israel. Samples of suspended sediments were separated from the solution and both media were analyzed separately for 250 pesticides. A total of 63 pesticides were detected; 18 and 16 pesticides were found solely in the suspended sediments and solution, respectively. Significant differences were observed among the pesticide groups: only 7% of herbicide, 20% of fungicide and 42% of insecticide load was transported with the suspended sediments. However, in both dissolved and adsorbed phases, a mix of pesticides was found which were graded from “mobile” to “non-mobile” with varied distribution coefficients. Diuron, and tebuconazole were frequently found in large quantities in both phases. Whereas insecticide and fungicide transport is likely governed by application time and method, the governing factor for herbicide load was the magnitude of the stream discharge. The results show a complex dynamic of pesticide load affected by excessive use of pesticides, which should be taken into consideration when designing projects to monitor riverine and estuarine water quality.

Knowledge of the physicochemical properties of ingestible silver nanoparticles (AgNPs) in the human gastrointestinal tract (GIT) is essential for assessing their bioavailability, bioactivity, and potential health risks. The gastrointestinal fate of AgNPs and silver ions from a commercial dietary supplement was therefore investigated using a simulated human GIT. In the mouth, no dissolution or aggregation of AgNPs occurred, which was attributed to the neutral pH and the formation of biomolecular corona, while the silver ions formed complexes with biomolecules (Ag-biomolecule). In the stomach, aggregation of AgNPs did not occur, but extensive dissolution was observed due to the low pH and the presence of Cl–. In the fed state (after meal), 72% AgNPs (by mass) dissolved, with 74% silver ions forming Ag-biomolecule and 26% forming AgCl. In the fasted state (before meal), 76% AgNPs dissolved, with 82% silver ions forming Ag-biomolecule and 18% forming AgCl. A biomolecular corona around AgNPs, comprised of mucin with multiple sulfhydryl groups, inhibited aggregation and dissolution of AgNPs. In the small intestine, no further dissolution or aggregation of AgNPs occurred, while the silver ions existed only as Ag-biomolecule. These results provide useful information for assessing the bioavailability of ingestible AgNPs and their subsequently potential health risks, and for the safe design and utilization of AgNPs in biomedical applications.Knowledge of the physicochemical properties of ingestible silver nanoparticles (AgNPs) in the human gastrointestinal tract (GIT) is essential for assessing their bioavailability, bioactivity, and potential health risks. The gastrointestinal fate of AgNPs and silver ions from a commercial dietary supplement was therefore investigated using a simulated human GIT. In the mouth, no dissolution or aggregation of AgNPs occurred, which was attributed to the neutral pH and the formation of biomolecular corona, while the silver ions formed complexes with biomolecules (Ag-biomolecule). In the stomach, aggregation of AgNPs did not occur, but extensive dissolution was observed due to the low pH and the presence of Cl–. In the fed state (after meal), 72% AgNPs (by mass) dissolved, with 74% silver ions forming Ag-biomolecule and 26% forming AgCl. In the fasted state (before meal), 76% AgNPs dissolved, with 82% silver ions forming Ag-biomolecule and 18% forming AgCl. A biomolecular corona around AgNPs, comprised of mucin with multiple sulfhydryl groups, inhibited aggregation and dissolution of AgNPs. In the small intestine, no further dissolution or aggregation of AgNPs occurred, while the silver ions existed only as Ag-biomolecule. These results provide useful information for assessing the bioavailability of ingestible AgNPs and their subsequently potential health risks, and for the safe design and utilization of AgNPs in biomedical applications.

Carbon-based nanomaterials have remarkable chemical and biological features. The introduction of supporting magnetic materials onto carbon-based nanoparticles has gained interest owing to their easy separation from heterogeneous systems. Herein, we report the synthesis of a novel composite comprised of single-walled carbon nanotubes, Fe3O4 and Ag nanoparticles with an aim to develop a bifunctional composite for water purification that maintains both high catalytic and antibacterial activities. The composite facilitated decomposition of nitrophenols and methyl orange in the presence of NaBH4 as the reducing agent – maintaining high activity (>90%) following three regeneration cycles. The composite’s catalytic activity was unaffected by the presence of dissolved organic matter (DOM) at an environmentally relevant concentration of 5 mg C L−1. DOM concentration of 50 mg C L−1 slightly decreased the reduction of p-nitrophenol, 2-methyl-p-nitrophenol, and methyl orange (by ∼14%, ∼11%, and ∼10% respectively) but significantly decreased that of o-nitrophenol (by 38%). The composite exhibited high antibacterial activity towards gram-negative and gram-positive bacteria even in the presence of DOM at an environmentally relevant concentration. However, the composite’s efficiency decreased with increase in DOM concentration. This study demonstrates dual catalytic and antibacterial activity of a novel Ag-Fe3O4-single walled carbon nanotube composite material in the absence and presence of DOM, and considers its potential implementation in water/wastewater treatment applications.

Abiotic mechanisms of oxytetracycline degradation by redox-active minerals, Fe(III)-saturated montmorillonite (Fe-SWy) and birnessite (δ-MnO2), were studied to better understand the environmental behavior of tetracycline antibiotics in aqueous systems. Kinetics of dissipation (adsorption, oxidation and formation of transformation products (TPs)), was investigated up to 7 days, and reaction mechanisms were elucidated based on identification of TPs by liquid chromatography mass spectrometry. Oxytetracycline was completely removed from solution by both minerals, however kinetics, TPs and mechanisms were distinct for each mineral. Oxytetracycline oxidation by δ-MnO2 occurred within minutes; 54 identified TPs were detected only in solution, most of them exhibited decreasing levels with time. In contrast, oxytetracycline was completely adsorbed by Fe-SWy, its degradation was slower, only 29 TPs were identified, among them 13 were surface-bound, and most of the TPs accumulated in the system with time. Oxytetracycline transformation by δ-MnO2 involved radicals, as was proven by electrochemical degradation. Reductive dissolution was observed for both minerals. X-ray photoelectron spectroscopy demonstrated accumulation of Fe(II) on Fe-SWy surface, whereas Mn(II) was primarily released from δ-MnO2 surface. Highly oxidized carbon species (i.e., newly formed TPs) were observed on the surface of both minerals interacting with oxytetracycline. This study demonstrates the impact of structure and reactivity of redox-active minerals on removal and decomposition of tetracycline antibiotics in aqueous systems.

Membrane fusion is a central biophysical and biochemical reaction in numerous biological processes. Exocytosis involves the fusion of the secretory vesicle membrane with the plasma membrane in diverse biological systems, including neurotransmitter release at the neuromuscular junction, histamine release from mast cells, chromaffin granule extrusion from adrenal medullary cells, trichocyst discharge in Paramecium, endotoxin-induced degranulation in Limulus amebocytes, and the cortical reaction in sea urchin eggs.1-4 The first stage in the formation of an endocytotic vesicle is the fusion of apposed regions of the invaginated plasma membrane. Later in the endocytotic pathway, endosomes and phagosomes fuse with lysosomes. Receptor recycling back to the plasma membrane proceeds through pinching off of receptor-containing vesicles from the compartment of uncoupling of receptor and ligand. Transport of newly synthesized membrane or secretory proteins from the endoplasmic reticulum to the Golgi apparatus, within the cis, medial and trans regions of the Golgi is thought to be mediated by transport vesicles that bud off from one compartment and fuse with another.5-7. © 1995 by Taylor & Francis.

Cyanobacteria and their toxins present potential hazard to consumers of water from lakes, reservoirs and rivers, thus their removal via water treatment is essential. The capacity of nano-composites of Octadecyltrimethyl-ammonium (ODTMA) complexed with clay to remove cyanobacterial and their toxins from laboratory cultures and from lake water, was evaluated. Column filters packed with micelles of ODTMA complexed with bentonite and granulated were shown to significantly reduce the number of cyanobacteria cells or filaments and their corresponding toxins from laboratory cultures. Fluorescence measurements demonstrated that cyanobacteria cells lost their metabolic activity (photosynthesis) upon exposure to the micelle (ODTMA)–bentonite complex, or ODTMA monomers. The complex efficiently removed cyanobacteria toxins with an exceptional high removal rate of microcystins. The effectiveness of the complex in elimination of cyanobacteria was further demonstrated with lake water containing cyanobacteria and other phytoplankton species. These results and model calculations suggest that filters packed with granulated composites can secure the safety of drinking water in case of a temporary bloom event of toxic cyanobacteria. © 2017 Elsevier Ltd