Factors Influencing the Persistence of Salmonella Infantis in Broiler Litter During Composting and Stabilization Processes and Following Soil Incorporation
. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021
Broiler litter (BL), a by-product of broiler meat production, is frequently contaminated with Salmonella and other zoonotic pathogens. To ensure the safety of crop production chains and limit pathogen spread in the environment, a pre-treatment is desired before further agricultural utilization. The objective of this study was to characterize the effect of physico-chemical properties on Salmonella persistence in BL during composting and stabilization and following soil incorporation, toward optimization of the inactivation process. Thirty-six combinations of temperature (30, 40, 50, and 60 degrees C), water content (40, 55, and 70%; w/w), and initial pH (6, 7, and 8.5) were employed in static lab vessels to study the persistence of Salmonella enterica serovar Infantis (S. Infantis; a multidrug-resistant strain) during incubation of artificially-inoculated BL. The effect of aeration was investigated in a composting simulator, with controlled heating and flow conditions. Temperature was found to be the main factor significantly influencing Salmonella decay rates, while water content and initial pH had a secondary level of influence with significant effects mainly at 30 and 40 degrees C. Controlled simulations showed faster decay of Salmonella under anaerobic conditions at mesophilic temperatures (<45 degrees C) and no effect of NH3 emissions. Re-wetting the BL at mesophilic temperatures resulted in Salmonella burst, and led to a higher tolerance of the pathogen at increased temperatures. Based on the decay rates measured under all temperature, water content, and pH conditions, it was estimated that the time required to achieve a 7 log(10) reduction in Salmonella concentration, ranges between 13.7-27.2, 6.5-15.6, 1.2-4.7, and 1.3-1.5 days for 30, 40, 50, and 60 degrees C, respectively. Inactivation of BL indigenous microbial population by autoclaving or addition of antibiotics to which the S. Infantis is resistant, resulted in augmentation of Salmonella multiplication. This suggests the presence of microbial antagonists in the BL, which inhibit the growth of the pathogen. Finally, Salmonella persisted over 90 days at 30 degrees C in a Vertisol soil amended with inoculated BL, presumably due to reduced antagonistic activity compared to the BL alone. These findings are valuable for risk assessments and the formulation of guidelines for safe utilization of BL in agriculture.
Physical and chemical indicators of transformations of poultry carcass parts and broiler litter during short term thermophilic composting
. WASTE MANAGEMENT 2021
Short-term on-site composting of poultry carcasses and broiler litter (BL) is considered as a feasible technology for pathogen elimination during events of mass mortality in poultry houses. However, factors related to mass losses and physical transformation of the poultry carcass, and associated emissions of volatile organic compounds (VOCs) and odors, have not been thoroughly evaluated. This study aims to characterize the degradation of separated carcass parts co-composted with BL and the associated air emissions during 30 days of enclosed composting at 50 degrees C with constant aeration. The study was carried out in lab-scale simulators using five mixtures containing feathers, rib bones, skins, breast muscles, and hearts and livers, prepared at a 1:2 volumetric ratio (carcass:BL). Dry mass losses reached 59.5, 41.1, 60.8 and 103.5% (based on weight) or 48.4, 29.6, 49.7, and 94.8% (based on CO2-C and NH3-N emissions), for rib bones, skins, breast muscles, and hearts and livers, respectively. Visually, most of the carcass parts were degraded, and the typical carcass odor had disappeared by the end of the 30 days. Out of 24 VOCs, dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) contributed 80.7-88.3% of the total VOC flux, considering the partial contribution of each part to the emissions involved with the whole carcass. DMDS, DMTS, benzaldehyde, methanethiol, pentanoic acid, and NH3, contributed 90.5-97.9% of the odor activity values during composting. DMDS/DMTS ratio is suggested as a potential biomarker of stabilization and readiness of the compost for transportation toward further treatment or safe burial. (C) 2020 Elsevier Ltd. All rights reserved.
High-integrity human intervention in ecosystems: Tracking self-organization modes
. PLOS COMPUTATIONAL BIOLOGY 2021
Author summary Human intervention in ecosystems is motivated by various functional needs, such as provisioning ecosystem services, but often has unexpected detrimental outcomes. A major question in ecology is how to manage human intervention so as to achieve its goal without impairing ecosystem function. The main idea pursued here is the need to identify the inherent response ways of ecosystems to disturbances, and use them as road maps for conducting interventions. This approach is demonstrated mathematically using two contexts, grazing management and vegetation restoration, and compared to remote sensing data for the latter. Among the surprising insights obtained is the beneficial effect of grazing, in terms of resilience to droughts, that can be achieved by managing it non-uniformly in space. Humans play major roles in shaping and transforming the ecology of Earth. Unlike natural drivers of ecosystem change, which are erratic and unpredictable, human intervention in ecosystems generally involves planning and management, but often results in detrimental outcomes. Using model studies and aerial-image analysis, we argue that the design of a successful human intervention form calls for the identification of the self-organization modes that drive ecosystem change, and for studying their dynamics. We demonstrate this approach with two examples: grazing management in drought-prone ecosystems, and rehabilitation of degraded vegetation by water harvesting. We show that grazing can increase the resilience to droughts, rather than imposing an additional stress, if managed in a spatially non-uniform manner, and that fragmental restoration along contour bunds is more resilient than the common practice of continuous restoration in vegetation stripes. We conclude by discussing the need for additional studies of self-organization modes and their dynamics.
Comparison of adsorption behaviors of selected endocrine-disrupting compounds in soil
. JOURNAL OF ENVIRONMENTAL QUALITY 2021
Bisphenol-A (BPA), 17 alpha-ethinylestradiol (EE2), and 4-nonylphenol (4NP) are endocrine-disrupting chemicals (EDCs) that are useful models for studying the potential fate and transport of EDCs in soil and water environments. Two alluvial soils with contrasting physicochemical properties were used as adsorbents for this study. The Zook soil material had more organic matter and clay than the sandy loam Hanlon soil material. Batch equilibrium experiments were performed to generate adsorption isotherms, to determine the adsorption parameters, and to assess desorption hysteresis. Adsorption of BPA to both soils followed an L-type isotherm, and 4NP adsorbed to both Hanlon and Zook soils exhibited S-shape isotherms. EE2 adsorbed to the Zook soil also followed an S-shaped isotherm, but EE2 adsorbed to the Hanlon soil showed an H-type isotherm. Overall, the Sips model fit the data well, with standard errors of prediction generally <= 6%. The adsorption affinity (K-LF) values were highest for 4NP, and BPA had the lowest hysteresis indices. The data suggest that BPA was most likely adsorbed by soil organic matter via hydrogen bonding involving its two phenolic groups. In contrast, isotherm shape, model affinity indices, lack of desorption, and molecular-scale characteristics led us to infer that 4NP was adsorbed largely by the retention of molecular clusters, perhaps in clay nanopores. Finally, the adsorption of EE2 exhibited different isotherm shapes for the two soils as well as intermediate affinity and desorption indices, suggesting that EE2 molecules could be retained both by soil organic matter and by clay.
Forecasting fire risk with machine learning and dynamic information derived from satellite vegetation index time-series
. SCIENCE OF THE TOTAL ENVIRONMENT 2021
Fire risk mapping - mapping the probability of fire occurrence and spread - is essential for pre-fire management as well as for efficient firefighting efforts. Most fire risk maps are generated using static information on variables such as topography, vegetation density, and fuel instantaneous wetness. Satellites are often used to provide such information. However, long-term vegetation dynamics and the cumulative dryness status of the woody vegetation, which may affect fire occurrence and spread, are rarely considered in fire risk mapping. Here, we investigate the impact of two satellite-derived metrics that represent long-term vegetation status and dynamics on fire risk mapping - the long-term mean normalized difference vegetation index (NDVI) of the woody vegetation (NDVIW) and its trend (NDVIT). NDVIW represents the mean woody density at the grid cell, while NDVIT is the 5-year trend of the woody NDVI representing the long-term dryness status of the vegetation. To produce these metrics, we decompose Lime-series of satellite-derived NDVI following a method adjusted for Mediterranean woodlands and forests. We tested whether these metrics improve fire risk mapping using three machine learning (ML) algorithms (Logistic Regression, Random Forest, and XGBoost). We chose the 2007 wildfires in Greece for the analysis. Our results indicate that XGBoost, which accounts for variable interactions and non-linear effects, was the ML model that produced the best results. NDVIW improved the model performance, while NDVIT was significant only when NDVIW was high. This NDVIW-NDVIT interaction means that the long-term dryness effect is meaningful only in places of dense woody vegetation. The proposed method can produce more accurate fire risk maps than conventional methods and can supply important dynamic information that may be used in fire behavior models. (C) 2020 Published by Elsevier B.V.
Pepper Plants Leaf Spectral Reflectance Changes as a Result of Root Rot Damage
. REMOTE SENSING 2021
Symptoms of root stress are hard to detect using non-invasive tools. This study reveals proof of concept for vegetation indices' ability, usually used to sense canopy status, to detect root stress, and performance status. Pepper plants were grown under controlled greenhouse conditions under different potassium and salinity treatments. The plants' spectral reflectance was measured on the last day of the experiment when more than half of the plants were already naturally infected by root disease. Vegetation indices were calculated for testing the capability to distinguish between healthy and root-damaged plants using spectral measurements. While no visible symptoms were observed in the leaves, the vegetation indices and red-edge position showed clear differences between the healthy and the root-infected plants. These results were achieved after a growth period of 32 days, indicating the ability to monitor root damage at an early growing stage using leaf spectral reflectance.
Worldwide continuous gap-filled MODIS land surface temperature dataset
. SCIENTIFIC DATA 2021
Satellite land surface temperature (LST) is vital for climatological and environmental studies. However, LST datasets are not continuous in time and space mainly due to cloud cover. Here we combine LST with Climate Forecast System Version 2 (CFSv2) modeled temperatures to derive a continuous gap filled global LST dataset at a spatial resolution of 1 km. Temporal Fourier analysis is used to derive the seasonality (climatology) on a pixel-by-pixel basis, for LST and CFSv2 temperatures. Gaps are filled by adding the CFSv2 temperature anomaly to climatological LST. The accuracy is evaluated in nine regions across the globe using cloud-free LST (mean values: R-2 = 0.93, Root Mean Square Error (RMSE) = 2.7 degrees C, Mean Absolute Error (MAE) = 2.1 degrees C). The provided dataset contains day, night, and daily mean LST for the Eastern Mediterranean. We provide a Google Earth Engine code and a web app that generates gap filled LST in any part of the world, alongside a pixel-based evaluation of the data in terms of MAE, RMSE and Pearson's r.
Pharmaceuticals in edible crops irrigated with reclaimed wastewater: Evidence from a large survey in Israel
. JOURNAL OF HAZARDOUS MATERIALS 2021
Pharmaceuticals and other contaminants of emerging concern (CECs) are continuously introduced into the agroecosystem via reclaimed wastewater irrigation, a common agricultural practice in water-scarce regions. Although reclaimed wastewater irrigated crops are sold and consumed, only limited information is available on the occurrence of pharmaceuticals and other CECs in edible produce. Here, we report data on CECs in irrigation water, soils, and crops collected from 445 commercial fields irrigated with reclaimed wastewater in Israel. The following produce were analyzed: leafy greens, carrot, potato, tomato, orange, tangerine, avocado, and banana. Pharmaceuticals and CECs were found in quantifiable levels in all irrigation water, soils, and plants (>99.6%). Leafy greens exhibited the largest number and the highest concentration of pharmaceuticals. Within the same crop, contamination levels varied due to wastewater source and quality of treatment, and soil characteristics. Anticonvulsants (carbamazepine, lamotrigine, and gabapentin) were the most dominant therapeutic group found in the reclaimed wastewater-soil-plant continuum. Antimicrobials were detected in similar to 85% of the water and soil samples, however they exhibited low detection frequencies and concentrations in produce. Irrigation with reclaimed wastewater should be limited to crops where the risk for pharmaceutical transfer to the food chain is minimal.
Soil oxygen and water dynamics underlying hypoxic conditions in the root-zone of avocado irrigated with treated wastewater in clay soil
. SOIL & TILLAGE RESEARCH 2021
Alternative water sources for agriculture are in high demand in a world with diminishing fresh water (FW) availability. Treated wastewater (TWW) offers a reliable alternative, but increasing evidence is pointing to damage to TWW irrigated orchards planted in clay soils related to soil hypoxia. The mechanisms responsible for this hypoxia have not been extensively studied to date. The aim of this study was to elucidate meaningful insights into the mechanisms responsible for the hypoxia in TWW irrigated orchards planted in clay soils using a novel approach whereby parameters describing the soil oxygen and water temporal dynamics are analyzed. To that end, soil oxygen and soil water tension (SWT) measurements from a two year field experiment comparing TWW to FW irrigation in an avocado orchard planted in a clay soil (60 % clay) were used. The deterioration in oxygen levels occurred as the irrigation season progressed, and the oxygen availability decreased with depth (10-35 cm depth). During August-September, when the lowest oxygen concentrations were measured, the water content at which oxygen supply matched oxygen consumption at 35-cm depth did not differ between treatments (similar to 50 mbar), but the TWW irrigated soil experienced similar to 47 % more time at wetter conditions. Lower oxygen decline rates were observed in the TWW irrigated plots which countered the previous concept that TWW leads to increased soil oxygen consumption. The findings point towards the rate of soil drying as the prime cause of differences - TWW irrigated plots dried in a rate which is nearly 4-times smaller than that in FW irrigated plots during the dark and light hours, reflecting slower drainage and water uptake respectively. It is suggested that soil hypoxia induced by the low soil drainage in TWW irrigated clay soils impairs tree water uptake, which further hinders the soil oxygen levels. Based on these results management tools are suggested to allow sustainable irrigation with TWW in the future. Furthermore, the work demonstrates how analysis of parameters describing the oxygen hourly changes can be utilized to gain mechanistic insights unto processes affecting the oxygen regime in the soil.
Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity - a modeling framework
. HYDROLOGY AND EARTH SYSTEM SCIENCES 2021
Declining soil-saturated hydraulic conductivity (K-s) as a result of saline and sodic irrigation water is a major cause of soil degradation. While it is understood that the mechanisms that lead to degradation can cause irreversible changes in K-s, existing models do not account for hysteresis between the degradation and rehabilitation processes. We develop the first model for the effect of saline and sodic water on K-s that explicitly includes hysteresis. As such, the idea that a soil's history of degradation and rehabilitation determines its future K-s lies at the center of this model. By means of a ``weight'' function, the model accounts for soil-specific differences, such as clay content. The weight function also determines the form of the hysteresis curves, which are not restricted to a single shape, as in some existing models for irreversible soil processes. The concept of the weight function is used to develop a reversibility index, which allows for the quantitative comparison of different soils and their susceptibility to irreversible degradation. We discuss the experimental setup required to find a soil's weight function and show how the weight function determines the degree to which K-s is reversible for a given soil. We demonstrate the feasibility of this procedure by presenting experimental results show-casing the presence of hysteresis in soil K-s and using these results to calculate a weight function. Past experiments and models on the decline of K-s due to salinity and sodicity focus on degradation alone, ignoring any characterization of the degree to which declines in K-s are reversible. Our model and experimental results emphasize the need to measure ``reversal curves'', which are obtained from rehabilitation measurements following mild declines in K-s. The developed model has the potential to significantly improve our ability to assess the risk of soil degradation by allowing for the consideration of how the accumulation of small degradation events can cause significant land degradation.
Interplay of stress responses to carbamazepine treatment, whitefly infestation and virus infection in tomato plants
. PLANT STRESS 2021
Reclaimed wastewater is increasingly used to irrigate agriculture crops. We have previously shown that carbamazepine (CBZ), an anticonvulsant human medication, not entirely discarded during wastewater purification, induces a stress response in tomatoes grown with roots bathing in CBZ-containing water. Induction of stress-related osmoprotectants (sugars, amino acids, proteins) was conspicuous in CBZ-treated seedlings. Here, tomato seedlings were grown in pots watered with increasing concentrations of CBZ. Soluble sugars effectively reacted to CBZ in both leaves and roots. However, the induction of stress-related amino acids and proteins was relevant in roots, but insignificant in leaves. Therefore, roots may be the site where CBZ stress is exerted. Moreover, roots may protect the whole plant from the pharmaceutical. Tomato crops endure biotic stresses, caused by whitefly (Bemisia tabaci) infestation and by the tomato yellow leaf curl begomovirus (TYLCV) they vector. The interplay between CBZ, TYLCV infection and B. tabaci was studied in tomato. Whiteflies preferred CBZ-treated plantlets than control plants, which may be due to increased amount of sugars in leaves. The increased amount of viruliferous whiteflies on CBZ-treated plants is expected to be accompanied by a rise in virus amounts. In fact, CBZ caused a reduction of TYLCV amounts. CBZ-dependent activation of autophagy degradation may explain this decrease in virus amounts. TYLCV infection mitigates the activation of stress markers associated with CBZ treatment. Altogether, CBZ in the water used to irrigate tomatoes grown in pots causes a relatively weak plant stress response, but is definitively sensed by insect and by virus.
Root Exudates Alters Nutrient Transport in Soil
. WATER RESOURCES RESEARCH 2021
Root exudates alter the rhizosphere's physical properties, but the impact that these changes have on solute transport is unknown. In this study, we tested the effects of chia mucilage and wheat root exudates (WREs) on the transport of iodide and potassium in saturated or unsaturated soil. Saturated solute breakthrough experiments, conducted in loamy sand soil or coarser textured quartz sand, revealed that increasing the exudate concentration in soil resulted in non-equilibrium solute transport. This behavior was demonstrated by an initial solute breakthrough after fewer pore volumes (PVs) and the arrival of the peak solute concentration after greater PVs in soil mixed with exudates compared to soil without exudates. These patterns were more pronounced for the coarser textured quartz sand than for the loamy sand soil, and in soil mixed with mucilage than in soil mixed WREs. Parameter fits to these breakthrough curves with a mobile-immobile transport model indicated the fraction of immobile water increased as the concentration of exudates increased. For example, in quartz sand the estimated immobile fraction increased from 0 without exudates to 0.75 at a mucilage concentration of 0.2%. The solutes' breakthrough under unsaturated conditions was also altered by the exudates, demonstrated by a smaller volume of water extracted from soil mixed with exudates, compared to soil without exudates, before the arrival of the peak solute concentration. The results indicate that exudates alter the rhizosphere's transport properties; we hypothesize that this is due to exudates creating low-conducting flow paths that result in a physical non-equilibrium solute transport.
Water infiltration into subcritical water-repellent soils with time-dependent contact angle
. JOURNAL OF HYDROLOGY 2021
Soil water repellency, defined as the situation in which the affinity of soils to water is reduced, has been reported for many natural and agricultural soils worldwide. Soil water repellency has significant impacts on hydrology and geomorphology. It has been widely observed that the contact angle (CA) of a sessile water drop placed on a single-layer surface of water-repellent soil particles decreases in an exponential manner with time. This time-dependent CA has a substantial effect on flow in water-repellent soils. However, mathematical models aimed at modeling water flow in water-repellent soils disregard the time-dependent CA's effect. The current study aims to correct this omission. Using capillary rise of water with a time-dependent CA in a capillary tube, a model for water infiltration into subcritical water-repellent soils (CA < 90 degrees) was developed. This model was successfully verified by performing infiltration experiments into (packed) coated glass beads. The CA at the wetting front during infiltration decreased exponentially to equilibrium, and the time to equilibrium was similar to that measured for a reference single layer of coated glass beads. Simulations for subcritical water-repellent soils with time-dependent CA yielded an infiltration rate that is either increasing with time (noted as concave) or initially increases and afterward decreases (noted as a concave-convex pattern).
Abiotic Transformation of Lamotrigine by Redox-Active Mineral and Phenolic Compounds
. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021
The anticonvulsant drug lamotrigine is a recalcitrant environmental pollutant. It was detected in drinking water, surface water, reclaimed wastewater, arable soils, and even in edible crops. In this work, we studied the mechanisms of lamotrigine transformation by a common redox soil mineral, birnessite, in a single-solute system and in bisolute systems with vanillic acid or o-methoxyphenol. In the single-solute system, 28% of lamotrigine was transformed and 14 transformation products (TPs) were identified. Based on a detailed analysis of the TPs, we suggested that lamotrigine is transformed mainly by oxidation, addition, and dechlorination reactions. In the bisolute systems, the redox-active phenolic compounds enhanced the elimination and transformation of lamotrigine. Vanillic acid was more efficient, generating 92% transformation of lamotrigine (58 TPs were identified), whereas o-methoxyphenol induced 48% transformation (35 TPs were identified). In the bisolute system with phenolic compounds, lamotrigine has possibly been transformed mainly via addition reactions with phenolic compounds and their oxidation products (protocatechuic acid, quinone, and oligomers). Thus, masses of the formed TPs were elevated as compared to the parent compound. The current study demonstrates the important role of redox-active minerals and naturally occurring phenolic compounds in abiotic removal and transformation of a recalcitrant environmental pollutant.
Applications of Chemically Modified Clay Minerals and Clays to Water Purification and Slow Release Formulations of Herbicides
. MINERALS 2021
This review deals with modification of montmorillonite and other clay-minerals and clays by interacting them with organic cations, for producing slow release formulations of herbicides, and efficient removal of pollutants from water by filtration. Elaboration is on incorporating initially the organic cations in micelles and liposomes, then producing complexes denoted micelle- or liposome-clay nano-particles. The material characteristics (XRD, Freeze-fracture electron microscopy, adsorption) of the micelle- or liposome-clay complexes are different from those of a complex of the same composition (organo-clay), which is formed by interaction of monomers of the surfactant with the clay-mineral, or clay. The resulting complexes have a large surface area per weight; they include large hydrophobic parts and (in many cases) have excess of a positive charge. The organo-clays formed by preadsorbing organic cations with long alkyl chains were also addressed for adsorption and slow release of herbicides. Another examined approach includes ``adsorptive'' clays modified by small quaternary cations, in which the adsorbed organic cation may open the clay layers, and consequently yield a high exposure of the siloxane surface for adsorption of organic compounds. Small scale and field experiments demonstrated that slow release formulations of herbicides prepared by the new complexes enabled reduced contamination of ground water due to leaching, and exhibited enhanced herbicidal activity. Pollutants removed efficiently from water by the new complexes include (i) hydrophobic and anionic organic molecules, such as herbicides, dissolved organic matter; pharmaceuticals, such as antibiotics and non-steroidal drugs; (ii) inorganic anions, e.g., perchlorate and (iii) microorganisms, such as bacteria, including cyanobacteria (and their toxins). Model calculations of adsorption and kinetics of filtration, and estimation of capacities accompany the survey of results and their discussion.
Modeling and Experimental Study of the Effect of Pore Water Velocity on the Spectral Induced Polarization Signature in Porous Media
. WATER RESOURCES RESEARCH 2021
Induced polarization (IP) is increasingly applied for hydrological, environmental and agricultural purposes. Interpretation of IP data is based on understanding the relationship between the IP signature and the porous media property of interest. Mechanistic models on the IP phenomenon rely on the Poisson-Nernst-Plank equations, where diffusion and electromigration fluxes are the driving forces of charge transport and are directly related to IP. However, to our knowledge, the impact of advection flux on IP was not investigated experimentally and was not considered in any IP model. In this work, we measured the spectral IP (SIP) signature of porous media under varying flow conditions, in addition to developing and solving a model for SIP signature of porous media, which takes flow into consideration. The experimental and the model results demonstrate that as bulk velocity increases, polarization and relaxation time decrease. Using a numerical model, we established that fluid flow near the particle deforms the electrical double layer (EDL) structure, accounting for the observed reduction in polarization. We found a qualitative agreement between the model and the measurements. Still, the model overestimates the impact of flow rate on SIP signature, which we explain in terms of the flow boundary conditions. Overall, our results demonstrate the sensitivity of the SIP signature to fluid flow, highlighting the need to consider fluid velocity in the interpretation of the SIP signature of porous media, and opening an exciting new direction for noninvasive measurements of fluid flow at the EDL scale.
Modeling Plant Roots Spectral Induced Polarization Signature
. GEOPHYSICAL RESEARCH LETTERS 2021
Monitoring the growth, architecture, and function of plant roots is of great interest. One promising noninvasive geoelectrical monitoring approach is spectral induced polarization (SIP). However, the roots' SIP signature is underexplored, not well understood, and a mechanistic model has not been proposed. Here, we developed a mechanistic model for SIP's response of roots, which is based on the Poisson-Nernst-Planck equation. The modeling results suggest that the magnitude of root polarization is linearly related to the root's external surface area and that the polarization length scale is the root's diameter. We suggest that injecting a current to the plant's stem results in higher polarization associated with the root-cells' total surface area. In this case, the polarization length scale is the cell diameter. Overall, we quantified the link between the root's dimensions and their electrical signature, which may inspire SIP application for root phenotyping.
Plant pharmacology: Insights into in-planta kinetic and dynamic processes of xenobiotics
. CRITICAL REVIEWS IN ENVIRONMENTAL SCIENCE AND TECHNOLOGY 2021
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.
Remediating the Adverse Effects of Treated Wastewater Irrigation by Repeated On-Surface Surfactant Application
. WATER RESOURCES RESEARCH 2021
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.
Removal of geosmin and 2-methylisoborneol from aquaculture water by novel, alginate-based carriers: Performance and metagenomic analysis
. JOURNAL OF WATER PROCESS ENGINEERING 2021
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.