Kaolin Film Increases Gas Exchange Parameters of Coffee Seedlings During Transference From Nursery to Full Sunlight

Increases in water use efficiency (WUE) and the reduction of negative impacts of high temperatures associated with high solar radiation are being achieved with the application of fine particle film of calcined and purified kaolin (KF) on the leaves and fruits of various plant species. KF was applied on young Coffea arabica and Coffea canephora plants before their transition from nursery to full sunlight during autumn and summer. The effects of KF were evaluated through the responses of leaf temperature (T_leaf), net CO₂ assimilation rate (A), stomatal conductance (g _s), transpiration (E), WUE, crop water stress index (CWSI), index of relative stomatal conductance (I_g), initial fluorescence (F₀), and photosynthetic index (PI) in the first 2-3 weeks after the plant transitions to the full sun. All measurements were performed at midday. In Coffea plants, KF decreased the T_leaf up to 6.7°C/5.6°C and reduced the CWSI. The plants that were not protected with KF showed lower A, g _s, E, and I_g than those protected with KF. C. canephora plants protected with KF achieved higher WUE compared with those not protected by 11.23% in autumn and 95.58% in summer. In both Coffea sp., KF application reduced F₀, indicating reduced physical dissociation of the PSII reaction centers from the light-harvesting system, which was supported with increased PI. The use of KF can be recommended as a management strategy in the transition of Coffea seedlings from the nursery shade to the full sunlight, to protect leaves against the excessive solar radiation and high temperatures, especially in C. canephora during the summer.

A Wireless Sensor Network Deployment for Soil Moisture Monitoring in Precision Agriculture

The use of precision agriculture is becoming more and more necessary to provide food for the world’s growing population, as well as to reduce environmental impact and enhance the usage of limited natural resources. One of the main drawbacks that hinder the use of precision agriculture is the cost of technological immersion in the sector. For farmers, it is necessary to provide low-cost and robust systems as well as reliability. Toward this end, this paper presents a wireless sensor network of low-cost sensor nodes for soil moisture that can help farmers optimize the irrigation processes in precision agriculture. Each wireless node is composed of four soil moisture sensors that are able to measure the moisture at different depths. Each sensor is composed of two coils wound onto a plastic pipe. The sensor operation is based on mutual induction between coils that allow monitoring the percentage of water content in the soil. Several prototypes with different features have been tested. The prototype that has offered better results has a winding ratio of 1:2 with 15 and 30 spires working at 93 kHz. We also have developed a specific communication protocol to improve the performance of the whole system. Finally, the wireless network was tested, in a real, cultivated plot of citrus trees, in terms of coverage and received signal strength indicator (RSSI) to check losses due to vegetation.

Water Management Alters Cadmium Isotope Fractionation between Shoots and Nodes/Leaves in a Soil-Rice System

The drainage of rice soils increases Cd solubility and results in high Cd concentrations in rice grains. However, plant Cd uptake is limited by sorption to iron plaques, and Cd redistribution in the plant is regulated by the nodes. To better understand the interplay of Cd uptake and redistribution in rice under drained and flooded conditions, we determined stable Cd isotope ratios and the expression of genes coding transporters that can transport Cd into the plant cells in a pot experiment. In soil, both water management practices showed similar patterns of isotope variation: the soil solution was enriched in heavy isotopes, and the root Fe plaque was enriched in light isotopes. In rice, the leaves were heavier (Δ^114/110Cd_leaf-shoot = 0.17 to 0.96‰) and the nodes were moderately lighter (Δ^114/110Cd_node-shoot = -0.26 to 0.00‰) relative to the shoots under flooded conditions, indicating preferential retention of light isotopes in nodes and export of heavy isotopes toward leaves. This is generally reversed under drained conditions (Δ^114/110Cd_leaf-shoot = -0.25 to -0.04‰, Δ^114/110Cd_node-shoot = 0.10 to 0.19‰). The drained treatment resulted in significantly higher expression of OsHMA2 and OsLCT1 (phloem loading) but lower expression of OsHMA3 (vacuolar sequestration) in nodes and flag leaves relative to the flooded treatment. It appeared that OsHMA2 and OsLCT1 might preferentially transport isotopically heavier Cd, and the excess Cd was purposefully retranslocated via the phloem under drained conditions when the vacuoles could not retain more Cd. Cd in seeds was isotopically heavier than that in stems under both water management practices, indicating that heavy isotopes were preferentially transferred toward seeds via the phloem, leaving light isotopes retained in stems. These findings demonstrate that the Fe plaque preferentially adsorbs and occludes light Cd isotopes on the root surface, and distinct water management practices alter the gene expression of key transporters in the nodes, which corresponds to a change in isotope fractionation between shoots and nodes/leaves.

Monthly river temperature trends across the US confound annual changes

Climate variations and human modifications of the water cycle continue to alter the Earth's surface water and energy exchanges. It is therefore critical to ascertain how these changes impact water quality and aquatic ecosystem habitat metrics such as river temperatures. Though river temperature trend analyses exist in the literature, studies on seasonal trends in river temperatures across large spatial extents, e.g. the contiguous United States (US), are limited. As we show through both annual and monthly trend analyses for 20 year (n = 138 sites) and 40 year (n = 40 sites) periods, annual temperature trends across the US mask extensive monthly variability. While most sites exhibited annual warming trends, these annual trends obscured sub-annual cooling trends at many sites. Monthly trend anomalies were spatially organized, with persistent regional patterns at both reference and human-impacted sites. The largest warming and cooling anomalies happened at human impacted sites and during summer months. Though our analysis points to coherence in trends as well as the overall impact of human activity in driving these patterns, we did not investigate the impact of river temperature observation accuracy on reported trends, an area needed for future work. Overall, these patterns emphasize the need to consider sub-annual behavior when managing the ecological impacts of river temperature throughout lotic networks.

Recent Insights on Catalyst Layers for Anion Exchange Membrane Fuel Cells

Anion exchange membrane fuel cells (AEMFCs) performance have significantly improved in the last decade (>1 W cm-2 ), and is now comparable with that of proton exchange membrane fuel cells (PEMFCs). At high current densities, issues in the catalyst layer (CL, composed of catalyst and ionomer), like oxygen transfer, water balance, and microstructural evolution, play important roles in the performance. In addition, CLs for AEMFCs have different requirements than for PEMFCs, such as chemical/physical stability, reaction mechanism, and mass transfer, because of different conductive media and pH environment. The anion exchange ionomer (AEI), which is the soluble or dispersed analogue of the anion exchange membrane (AEM), is required for hydroxide transport in the CL and is normally handled separately with the electrocatalyst during the electrode fabrication process. The importance of the AEI-catalyst interface in maximizing the utilization of electrocatalyst and fuel/oxygen transfer process must be carefully investigated. This review briefly covers new concepts in the complex AEMFC catalyst layer, before a detailed discussion on advances in CLs based on the design of AEIs and electrocatalysts. The importance of the structure-function relationship is highlighted with the aim of directing the further development of CLs for high-performance AEMFC.

Comprehensive review of water management and wastewater treatment in food processing industries in the framework of water-food-environment nexus

Food processing is among the greatest water-consuming industries with a significant role in the implementation of sustainable development goals. Water-consuming industries such as food processing have become a threat to limited freshwater resources, and numerous attempts are being carried out in order to develop and apply novel approaches for water management in these industries. Studies have shown the positive impact of the new methods of process integration (e.g., water pinch, mathematical optimization, etc.) in maximizing water reuse and recycle. Applying these methods in food processing industries not only significantly supported water consumption minimization but also contributed to environmental protection by reducing wastewater generation. The methods can also increase the productivity of these industries and direct them to sustainable production. This interconnection led to a new subcategory in nexus studies known as water-food-environment nexus. The nexus assures sustainable food production with minimum freshwater consumption and minimizes the environmental destructions caused by untreated wastewater discharge. The aim of this study was to provide a thorough review of water-food-environment nexus application in food processing industries and explore the nexus from different aspects. The current study explored the process of food industries in different sectors regarding water consumption and wastewater generation, both qualitatively and quantitatively. The most recent wastewater treatment methods carried out in different food processing sectors were also reviewed. This review provided a comprehensive literature for choosing the optimum scenario of water and wastewater management in food processing industries.

Machine Learning in Agriculture: A Comprehensive Updated Review

The digital transformation of agriculture has evolved various aspects of management into artificial intelligent systems for the sake of making value from the ever-increasing data originated from numerous sources. A subset of artificial intelligence, namely machine learning, has a considerable potential to handle numerous challenges in the establishment of knowledge-based farming systems. The present study aims at shedding light on machine learning in agriculture by thoroughly reviewing the recent scholarly literature based on keywords' combinations of "machine learning" along with "crop management", "water management", "soil management", and "livestock management", and in accordance with PRISMA guidelines. Only journal papers were considered eligible that were published within 2018-2020. The results indicated that this topic pertains to different disciplines that favour convergence research at the international level. Furthermore, crop management was observed to be at the centre of attention. A plethora of machine learning algorithms were used, with those belonging to Artificial Neural Networks being more efficient. In addition, maize and wheat as well as cattle and sheep were the most investigated crops and animals, respectively. Finally, a variety of sensors, attached on satellites and unmanned ground and aerial vehicles, have been utilized as a means of getting reliable input data for the data analyses. It is anticipated that this study will constitute a beneficial guide to all stakeholders towards enhancing awareness of the potential advantages of using machine learning in agriculture and contributing to a more systematic research on this topic.

Assessment of Irrigation Water Use Efficiency in Citrus Orchards Using AHP

Irrigation water use efficiency, the small size of the orchards, and part-time farmers are major issues for Spanish citriculture. How should irrigation water use efficiency be assessed? Does irrigation water use efficiency improve when increasing the size of the orchards? Are full-time farmers more efficient in irrigation water use than part-time ones? To address these three questions, we propose to apply a new multicriteria approach based on the analytic hierarchy process (AHP) technique and the participation of a group of experts. A new synthetic irrigation efficiency index (IEI) was proposed and tested using data from an irrigation community (IC) and a cooperative of farmers in the East of Spain. The results showed that the size of the orchards had no relation with the IEI scoring but full-time farmers tended to have better IEI scores and, thus, were more efficient. These results were obtained from a sample of 24 orchards of oranges, navelina variety, growing in a very similar environment, and agronomical characteristics. The proposed methodology can be a useful benchmarking tool for improving the irrigation water management in other ICs taking into account the issues related to farm data sharing recorded during the case study.

[Effects of Water Management on Cadmium Accumulation by Rice (Oryza sativa L.) Growing in Typical Paddy Soil]

In order to explore the effects of water management on the Cd accumulation of rice in paddy soils with different parent materials, a pot experiment with three paddy soils with different parent materials from Hunan Province (granite sandy soil, plate shale soil, and purple sandy shale soil) with different water management treatments ［flooding and alternate wetting and drying (AWD)］ was performed. The soil pH, DTPA-Cd, Fe plaque in the rice roots, and heavy metal concentration in the rice were determined. The results showed that the soil pH of the three paddy soils under the flooding treatment was increased by 0.17-1.33 units. During the filling and maturity periods, compared with that under AWD, the DTPA-Cd concentration in the three paddy soils was reduced by 14.39%-36.56% under the flooding treatment, but the DTPA-Fe concentration was increased by 35.35%-347.25%. In the three growth stages, the Cd and Mn concentrations in the Fe plaque (except for DCB-Fe) were in the order of tillering stage < filling stage < mature stage. Compared with that under AWD, the brown rice Cd concentration in the three soils was reduced by 57.84%-93.79% under flooding treatment. The Cd accumulation in rice was reduced under flooding treatment by reducing the DTPA-Cd via increasing the soil pH and DTPA-Fe and by decreasing the formation of Fe plaque. According to the results of the correlation and SEM analysis, the soil pH and DCB-Cd were the main factors affecting the Cd accumulation in rice grains, although the changes in the DTPA-Cd and DTPA-Fe also impacted the Cd in rice grains. In summary, our study demonstrated that water management had a significant impact on the Cd content in rice, and there were significant differences among the three paddy soils with different parent materials. In conclusion, the Cd content in rice grains was affected by the soil parent material, soil physicochemical properties, and Fe plaque on the surface of the rice roots. The granite sandy soil and plate shale soil with different water management treatments had significant impacts on the contents of heavy metals in rice. Continuous flooding is a valuable strategy for improving soil acidity and alkalinity and minimizing soil available Cd, but the soil parent materials must be considered.

[Characteristics of Paddy Soil Organic Carbon Mineralization and Influencing Factors Under Different Water Conditions and Microbial Biomass Levels]

Paddy soil often undergoes frequent dry-wet alternation. The change in water status not only affects the physical and chemical properties of the soil, but also changes the structure and diversity of the soil microbial communities, which in turn determines the rate of soil organic carbon mineralization. However, the effects of different water conditions and soil microbial biomass levels on the process of soil organic carbon mineralization and its mechanisms are still unclear. Therefore, this study took typical subtropical paddy soil as the research object, applied a laboratory incubation experiment with two water treatments of dry-wet and continuous flooding, and reduced the soil microbial biomass through chloroform fumigation, thereby obtaining high and low soil microbial biomass carbon contents, to elucidate the influencing mechanisms of microbial biomass and water conditions on organic carbon mineralization in paddy soil. The results showed that during the first 30 d of incubation, the dry-wet treatment was in a non-flooded stage and its cumulative CO₂ emissions were significantly lower than those of the continuous flooded treatment. After 30 d, the dry-wet treatment entered the flooded stage. The difference in the cumulative CO₂ emissions of the soils with a high microbial biomass carbon content between the dry-wet and continuous flooding treatments gradually decreased, and there was no significant difference on day 78. In the soil with a low microbial biomass carbon content, the cumulative CO₂ emissions of the dry-wet treatment on day 78 was still significantly lower than that of the continuous flooded treatment. The soils with a low microbial biomass carbon content showed a faster CO₂ emission rate at the beginning of the incubation period (first 20 d), which was 1.1-6.1 times greater than that of the high microbial biomass carbon soils owing to their high soil dissolved organic carbon (DOC) content, and the CO₂ emission rate then gradually decreased until it was below that of the soil with a high microbial biomass carbon content. The soil organic carbon mineralization rate became stable later in the incubation period (days 45-78). The stable mineralization rate of the high microbial biomass carbon soil was 20%-30% higher than that of the low microbial biomass carbon soil. The multiple regression analysis results showed that the decrease in the soil DOC content (ΔDOC) and the increase in the Fe²⁺ content (ΔFe²⁺) significantly affected the change in cumulative CO₂ emissions (ΔCO₂) under continuous flooding conditions, but had no effect on ΔCO₂ during the flooding stage of the dry-wet treatment. The correlation analysis showed that the daily CO₂ emission rate of soils with high microbial biomass carbon was significantly positively correlated with glucosidase activity under dry-wet treatment and significantly negatively correlated with acetylglucosaminidase (NAG) and peroxidase activities under continuous flooding treatment. In the low microbial biomass carbon soils, the daily CO₂ emission rate of the continuous flooding treatment was negatively correlated with the NAG activity, but showed no correlation with enzyme activities under dry-wet management. In summary, the cumulative CO₂ emissions of dry-wet treatment were lower than those of continuous flooding treatment, and the difference was significant in soils with low microbial biomass carbon. The size of the soil microbial biomass determined the level of the stable soil organic carbon mineralization rate. The amount of soluble organic carbon and iron reduction affected the soil CO₂ emissions under continuous flooding conditions, and the soil water conditions affected the daily CO₂ emission rate and its key influencing enzymes. This study provides data and theoretical support for the carbon cycle and carbon sequestration potential in paddy soil.

A Method for Spatial Quantification of Water in Microporous Layers of Polymer Electrolyte Fuel Cells by X-ray Tomographic Microscopy

A microporous layer (MPL) is typically added to the gas diffusion layer of polymer electrolyte fuel cells (PEFCs) to promote cell performance and water management. The transport mechanism of the water through the MPL is, however, not well understood due to its small pores (20-500 nm). Here, we demonstrate that polychromatic X-ray tomographic microscopy (XTM) can be used to determine the porosity and the spatial distribution of water in nanoporous materials and can quantitatively map the liquid water saturation of MPLs. The presented technique requires no a priori knowledge of the composition of the MPL and has a field of view on the millimeter scale, which is orders of magnitude larger than conventional electron microscopy techniques for nanoscale materials. The available field of view is compatible with existing operando cells for X-ray tomography, paving the way for the analysis of water transport in MPLs during operation.

A Trilaminar-Catalytic Layered MEA Structure for a Passive Micro-Direct Methanol Fuel Cell

A membrane electrode assembly (MEA) with a novel trilaminar-catalytic layered structure was designed and fabricated for a micro-direct methanol fuel cell (μ-DMFC). The trilaminar-catalytic layer comprises three porous layers. The medial layer has a lower porosity than the inner and outer layers. The simulation results predicted a lower water content and a higher oxygen concentration in the trilaminar-catalytic layer. The novel trilaminar-catalytic layer enhanced the back diffusion of water from the cathode to the anode, which reduces methanol crossover and improves oxygen mass transportation. The electrochemical results of the half-cell test indicate that the novel MEA has a greatly increased cathode polarization and a slightly increased anode polarization. Thus, this novel μ-DMFC structure has a higher power density and a longer discharging time, and hence may be used in portable systems.

[Effects of Water Management and Silicon Application on Iron Plaque Formation and Uptake of Arsenic and Cadmium by Rice]

To explore the effects of water management and silicon application on the bioavailability of soil arsenic (As) and cadmium (Cd), and the accumulation of As and Cd in rice, pot experiments were carried out using As/Cd co-contaminated paddy soil from a field in Kaiyang County, Guizhou Province. The experimental treatments had the following five water application modes with and without silicon addition:flooding during the entire growth period (T1); flooding for three weeks (0-105 d) after transplanting with wet irrigation (moisture content 50%-60%) during other growth periods (T2); flooding for three weeks before heading (0-65d), three weeks after heading (84-105d), and wet irrigation during other growth periods (T3); flooding from heading to three weeks after heading (84-105d) and wet irrigation during the other growth periods (T4); and wet irrigation during the entire growth period (T5). The results showed that compared with flooding and wet irrigation, flooding combined with wet irrigation was more conducive to the formation of iron plaque (DCB-Fe) on the surfaces of roots. As and Cd content increased with an increasing of content of DCB-Fe. Silicon application increased soil pH and the content of DCB-As but decreased available As and Cd in the soil and, with the exception of the flooding treatment, the DCB-Fe/Cd content. The shorter the flooding time, the higher the accumulation of Cd and the lower the accumulation of As in each part of the rice. Silicon application increased the biomass of rice but decrease the Cd content of roots, stems, leaves, and grain by 4.23%-31.06%, 11.41%-52.90%, 1.74%-35.73%, and 19.25%-39.76%, respectively. Silicon application also decreased the As content of roots, stems, leaves, and grain by 1.47%-52.60%, 6.12%-63.02%, 2.97%-28.41%, and 16.33%-61.23%, respectively. Among the five modes of water application tested, silicon application combined with the T3 mode achieved the highest rice biomass and lowest rice As and Cd contents. Therefore, it is suggested that selecting water management and silicon application regimes according to the level of As/Cd pollution can effectively decrease the bioavailability of As/Cd in the soil, thereby reducing the accumulation of As/Cd in rice.

Gas Diffusion Layers with Deterministic Structure for High Performance Polymer Electrolyte Fuel Cells

Hydrogen-fed polymer electrolyte fuel cells (PEFCs) are promising electrochemical energy converters and a key technology for sustainable mobility and coupling energy sectors. Under operating conditions, water is produced by the oxygen reduction reaction. The gas diffusion layer (GDL) materials, interfacing the reaction sites and gas feed channels, play a key role in the water management. When water condenses in the GDL pore structure, the gas transport to the cathode catalyst layer is deteriorated, thus limiting the cell performance. State-of-the-art GDL materials are stochastic, porous media based on carbon fibers, where water and gas are transported on random, tortuous paths through the pore network. In this work, a novel approach based on a material with a deterministic structure, with a two-layered fabric, is presented. This material, with just one pore throat in the transport path, facilitates water transport and increases the effective diffusivity for gas transport through its open structure. Furthermore, the regular pattern opens up a wide range of tuning opportunities. The presented results demonstrate the improved water management, on the basis of X-ray tomographic image data, and superior cell performance of this novel class of materials, able to be adapted to the local channel geometry.

Polystyrene-Based Hydroxide-Ion-Conducting Ionomer: Binder Characteristics and Performance in Anion-Exchange Membrane Fuel Cells

Polystyrene-based polymers with variable molecular weights are prepared by radical polymerization of styrene. Polystyrene is grafted with bromo-alkyl chains of different lengths through Friedel-Crafts acylation and quaternized to afford a series of hydroxide-ion-conducting ionomers for the catalyst binder for the membrane electrode assembly in anion-exchange membrane fuel cells (AEMFCs). Structural analyses reveal that the molecular weight of the polystyrene backbone ranges from 10,000 to 63,000 g mol^-1, while the ion exchange capacity of quaternary-ammonium-group-bearing ionomers ranges from 1.44 to 1.74 mmol g^-1. The performance of AEMFCs constructed using the prepared electrode ionomers is affected by several ionomer properties, and a maximal power density of 407 mW cm^-2 and a durability exceeding that of a reference cell with a commercially available ionomer are achieved under optimal conditions. Thus, the developed approach is concluded to be well suited for the fabrication of next-generation electrode ionomers for high-performance AEMFCs.

[Effect of Water Management on Rice Growth and Rhizosphere Priming Effect in Paddy Soils]

The rhizosphere priming effect (RPE) caused by carbon inputs from crop rhizodeposits plays a key role in regulating the carbon emission flux and carbon balance of farmland soils. Due to frequent alternations between dry and wet conditions, CO₂ and CH₄ emissions and the RPE in paddy field ecosystems are significantly different to those of other ecosystems. Therefore, it is of great significance to determine the direction and intensity of the rice RPE under alternations of dry and wet to limit greenhouse gas emissions. In this study, using a ¹³C-CO₂ continuous labeling method combined with a pot-based experiment, the response of rice growth and the RPE under alternating dry and wet and continuous flooding conditions was examined. The results showed that, compared with the continuous flooding treatment, the alternating dry and wet treatments significantly increased aboveground and root biomass and the root-to-root ratio, and also increased soil microbial biomass. Under continuous flooding conditions, fluxes of ¹³CO₂ and ¹³CH₄ increased with rice growth from 10.2 μg·(kg·h)^-1 and 2.8 μg·(kg·h)^-1 (63 d) to 16.0 μg·(kg·h)^-1 and 3.2 μg·(kg·h)^-1 (75 d), respectively. During the 12-day drying process, the emissions of ¹³CO₂ and ¹³CH₄ derived from rhizosphere deposited C decreased by 57.5% and 88.1%. Under continuous flooding conditions, the RPE for CO₂ and CH₄ were positive and increased with the growth of rice. Under the alternating dry and wet treatment, after 12 days of drying, the RPE for CO₂ and CH₄ was reduced from 0.29 mg·(kg·h)^-1 and 12.3 μg·(kg·h)^-1 (63 d) to -0.39 mg·(kg·h)^-1 and 0.07 μg·(kg·h)^-1 (75 d). Thus, alternating wet and dry treatment can effectively promote rice growth and reduce the cumulative emissions of CH₄. Therefore, adopting appropriate field water management is of great significance for increasing rice yields and mitigating greenhouse gas emissions.

Performance Studies of Proton Exchange Membrane Fuel Cells with Different Flow Field Designs - Review

Proton Exchange Membrane Fuel Cell (PEMFC) is majorly used for power generation without producing any emission. In PEMFC, the water generated in the cathode heavily affects the performance of fuel cell which needs better water management. The flow channel designs, dimensions, shape and size of the rib/channel, effective area of the flow channel and material properties are considered for better water management and performance enhancement of the PEMFC in addition to the inlet reactant's mass flow rate, flow directions, relative humidity, pressure and temperature. With the purpose of increasing the output energy of the fuel cell, many flow field designs are being developed continuously. In this paper, the performance of various conventional, modified, hybrid and new flow field designs of the PEMFC is studied in detail. Further the effects of channel tapering, channel bending, landing to channels width ratios, channel cross-sections and insertion of baffles/blockages/pin-fins/inserts are reviewed. The power density of the flow field designs, the physical parameters like active area, dimensions of channel/rib, number of channels; and the operating parameters like temperature and pressure are also tabulated.

Accumulation of Silicon and Changes in Water Balance under Drought Stress in Brassica napus var. napus L

The aim of this study was to investigate the accumulation of silicon in oilseed rape and to characterize the changes in chosen water balance parameters in response to drought. The following parameters were estimated: water content, osmotic and water potential, evapotranspiration, stomatal conductance and abscisic acid level under optimal and drought conditions. It was shown that oilseed rape plants accumulate silicon after its supplementation to the soil, both in the case of silicon alone and silicon together with iron. It was revealed that silicon (without iron) helps maintain constant water content under optimal conditions. While no silicon influence on osmotic regulation was observed, a transpiration decrease was detected under optimal conditions after silicon application. Under drought, a reduction in stomatal conductance was observed, but it was similar for all plants. The decrease in leaf water content under drought was accompanied by a significant increase in abscisic acid content in leaves of control plants and those treated with silicon together with iron. To sum up, under certain conditions, silicon is accumulated even in non-accumulator species, such as oilseed rape, and presumably improves water uptake under drought stress.

Water management improvement in PEM fuel cells via addition of PDMS or APTES polymers to the catalyst layer

Water management is one of the obstacles in the development and commercialization of proton exchange membrane fuel cells (PEMFCs). Sufficient humidification of the membrane directly affects the PEM fuel cell performance. Therefore, 2 different hydrophobic polymers, polydimethylsiloxane (PDMS) and (3-Aminopropyl) triethoxysilane (APTES), were tested at different percentages (5, 10, and 20 wt.%) in the catalyst layer. The solution was loaded onto the surface of a 25 BC gas diffusion layer (GDL) via the spraying method. The performance of the obtained fuel cells was compared with the performance of the commercial catalyst. Characterizations of each surface, including different amounts of PDMS and APTES, were performed via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses. Molecular bond characterization was examined via Fourier transform infrared spectroscopy (FTIR) analysis and surface hydrophobicity was measured via contact angle measurements. The performance of the fuel cells was evaluated at the PEM fuel cell test station and the 2 hydrophobic polymers were compared. Surfaces containing APTES were found to be more hydrophobic. Fuel cells with PDMS performed better when compared to those with APTES. Fuel cells with 5wt.% APTES with a current density of 321.31 mA/cm ² and power density of 0.191 W/cm ² , and 10wt.% PDMS with a current density of 344.52 mA/cm ² and power density of 0.205 W/cm ² were the best performing fuel cells at 0.6V.

[Combined Effect of Weathered Coal Based Amendments and Soil Water Management on Methylmercury Accumulation in Paddy Soil and Rice Grains]

A pot experiment and field experiment were designed to study the changes in the grain methyl mercury content in paddy soil and rice yield by sowing soil amendments that contained weathered coal, CaCO₃, and Na₂SeO₃ as the main raw materials, combined with water management in a paddy field (80% field capacity after the heading and flowering periods). The results showed that:① In pot experiment, the content of methylmercury in rice rhizosphere soil decreased by 86.6% and the content of methylmercury in the rice grains decreased by 65.2% compared with that of the control. In field experiment, the content of methylmercury in rice rhizosphere soil decreased by 77.4% and the content of methylmercury in rice grains decreased by 60.6% upon adding the amendment+water management compared with that of CK. ② The soil pH increased by more than 0.3 in the pot experiment and 0.2 in the field experiment compared with that of the control. Furthermore, rice yield and plant biomass did not decrease in the two parts of the experiment. It can be inferred that the soil amendment and agronomic regulation measures (water management) used in this study have the advantages of quick effects, convenient use, and remarkable control effects and without secondary pollution. More, they can effectively reduce the risk of rice methylmercury exposure.

Scaling Up Studies on PEMFC Using a Modified Serpentine Flow Field Incorporating Porous Sponge Inserts to Observe Water Molecules

Flooding of the cathode flow channel is a major hindrance in achieving maximum performance from Proton Exchange Membrane Fuel Cells (PEMFC) during the scaling up process. Water accumulated between the interface region of Gas Diffusion Layer (GDL) and rib of the cathode flow field can be removed by the use of Porous Sponge Inserts (PSI) on the ribs. In the present work, the experimental investigations are carried out on PEMFC for the various reaction areas, namely 25, 50 and 100 cm². Stoichiometry value of 2 is maintained for all experiments to avoid variations in power density obtained due to differences in fuel utilization. The experiments include two flow fields, namely Serpentine Flow Field (SFF) and Modified Serpentine with Staggered provisions of 4 mm PSI (4 mm × 2 mm × 2 mm) Flow Field (MSSFF). The peak power densities obtained on MSSFF are 0.420 W/cm², 0.298 W/cm² and 0.232 W/cm² compared to SFF which yields 0.242 W/cm², 0.213 W/cm² and 0.171 W/cm² for reaction areas of 25, 50 and 100 cm² respectively. Further, the reliability of experimental results is verified for SFF and MSSFF on 25 cm² PEMFC by using Electrochemical Impedance Spectroscopy (EIS). The use of 4 mm PSI is found to improve the performance of PEMFC through the better water management.

A Methodology for Classifying Root Causes of Outbreaks of Legionnaires' Disease: Deficiencies in Environmental Control and Water Management

We piloted a methodology for collecting and interpreting root cause—or environmental deficiency (ED)—information from Legionnaires’ disease (LD) outbreak investigation reports. The methodology included a classification framework to assess common failures observed in the implementation of water management programs (WMPs). We reviewed reports from fourteen CDC-led investigations between 1 January 2015 and 21 June 2019 to identify EDs associated with outbreaks of LD. We developed an abstraction guide to standardize data collection from outbreak reports and define relevant parameters. We categorized each ED according to three criteria: ED type, WMP-deficiency type, and source of deficiency. We calculated the prevalence of EDs among facilities and explored differences between facilities with and without WMPs. A majority of EDs identified (81%) were classified as process failures. Facilities with WMPs (n = 8) had lower prevalence of EDs attributed to plumbed devices (9.1%) and infrastructure design (0%) than facilities without WMPs (n = 6; 33.3% and 24.2%, respectively). About three quarters (72%) of LD cases and 81% of the fatalities in our sample originated at facilities without a WMP. This report highlights the importance of WMPs in preventing and mitigating outbreaks of LD. Building water system process management is a primary obstacle toward limiting the root causes of LD outbreaks. Greater emphasis on the documentation, verification, validation, and continuous program review steps will be important in maximizing the effectiveness of WMPs.

Response of Plant Rhizosphere Microenvironment to Water Management in Soil- and Substrate-Based Controlled Environment Agriculture (CEA) Systems: A Review

As natural agroecology deteriorates, controlled environment agriculture (CEA) systems become the backup support for coping with future resource consumption and potential food crises. Compared with natural agroecology, most of the environmental parameters of the CEA system rely on manual management. Such a system is dependent and fragile and prone to degradation, which includes harmful bacteria proliferation and productivity decline. Proper water management is significant for constructing a stabilized rhizosphere microenvironment. It has been proved that water is an efficient tool for changing the availability of nutrients, plant physiological processes, and microbial communities within. However, for CEA issues, relevant research is lacking at present. The article reviews the interactive mechanism between water management and rhizosphere microenvironments from the perspectives of physicochemical properties, physiological processes, and microbiology in CEA systems. We presented a synthesis of relevant research on water-root-microbes interplay, which aimed to provide detailed references to the conceptualization, research, diagnosis, and troubleshooting for CEA systems, and attempted to give suggestions for the construction of a high-tech artificial agricultural ecology.

Applied use of alternate stable state modeling in restoration ecology

The concept of alternate stable states is important in ecological theory and models, but the application and implementation of these models have the potential to make significant future advances in the field of patterned landscapes. The bistable ridge and slough landscape is a central feature of Everglades restoration and provides an important opportunity to test stable state theory with multistate transition models. We used these models to estimate environmental parameters associated with state changes (water depths, edaphic factors, etc.) and develop a quantitative method to measure resilience and stability. The multistate model indicates that long-term, local hydrology (15-yr mean maximums and 15-yr mean amplitude) and edaphic factors control the local scale shifts between ridge and slough states. We show that multistate models can provide hydrologic envelopes for managers, produce a tool to help assess future water management scenarios, and address issues of sustainability, resilience, and restoration for any bistable system.

Multiplexed Passive Optical Fiber Sensor Networks for Water Level Monitoring: A Review

Water management is a critical mission required to protect the water resources that is essential in diverse industrial applications. Amongst a variety of parameters such as level (or depth), temperature, conductivity, turbidity, and pH, the water level is the most fundamental one that needs to be monitored on a real-time basis for securing the water management system. This paper presents an overview of water level monitoring technologies based on optical fiber sensor (OFS) networks. Firstly, we introduce and compare the passive distributed and quasi-distributed (discrete) sensor networks with the recent achievements summarized. The performance (i.e., sensing range and resolution) of the OFS networks can be enhanced through diverse multiplexing techniques based on wavelength, time, coherence, space, etc. Especially, the dense wavelength division multiplexing (DWDM)-based sensor network provides remote sensing (where its reach can be extended to >40 km) with high scalability in terms of the channel number that determines the spatial resolution. We review the operation principle and characteristics of the DWDM-based OFS network with full theoretical and experimental analysis being provided. Furthermore, the key system functions and considerations (such as the link protection from physical damages, self-referencing, management of sensing units, and so on) are discussed that could be a guideline on the design process of the passive OFS network.

Identifying groundwater end members by spatio-temporal isotopic and hydrogeochemical records

Intensive groundwater use has altered the local hydrological cycle within the Bajío Guanajuatense, Mexico. To improve the knowledge of this hydrogeological system and support water management in the area, groundwater end members were identified using multivariate statistical analysis. Pumped groundwater is composed of two well-mixed end members: (a) recent recharge, affected by a reuse cycle through irrigation where nitrate and chloride evolve and reach levels of 368 mg/L and greater than 100 mg/L, respectively, and (b) deep old groundwater. Mixing estimations show that most wells extract at least 70% of deep groundwater, and some of them extract more than 94%, posing a development and groundwater sustainability conundrum in the area.

Improving Net Photosynthetic Rate and Rooting Depth of Grapevines Through a Novel Irrigation Strategy in a Semi-Arid Climate

Direct root-zone irrigation (DRZ) is a novel subsurface irrigation strategy initially tested in vineyards for economizing water and securing grape production in arid regions with unstable climatic patterns. However, studies are lacking on the responses of grapevine leaf carbon assimilation and deep rooting patterns to the novel irrigation strategy, which are essential for optimizing grapevine growth and alleviating extreme water stress during periods of heat and drought. Thus, a two-year field study was conducted in a commercial vineyard of Cabernet Sauvignon (Vitis vinifera L.) under a semi-arid climate in Washington, USA to compare the differences in leaf gas exchange and root distribution along the 0-160 cm soil profile, combined with measurements of specific leaf area and total carbon and nitrogen content in leaves and shoots to compare DRZ and traditional surface drip irrigation (SD) under three watering regimes. Compared to SD, significantly higher rates of net CO₂ assimilation, stomatal conductance and transpiration in leaves, which positively correlated to midday stem water potential, were found in grapevines irrigated through DRZ in both years. Meanwhile, DRZ reduced total root number by 50-60% and root length density (RLD) by 30-40% in the upper 60 cm soil at high (0.75-0.80 crop evapotranspiration) and moderate (0.60-0.65 crop evapotranspiration) irrigation rates, but no significant differences were found at low (0.45-0.50 crop evapotranspiration) irrigation rate between DRZ and SD. Higher root number and RLD were detected under DRZ within 60-160 cm soil depths, accompanied by a decreased ratio of total carbon to nitrogen content in leaves with slightly increased specific leaf area. Decreased rainfall and increased temperature in 2018 possibly amplified the positive effects of DRZ. Our study indicates that grapevines under DRZ could develop deeper roots for water uptake, which helps ameliorate water stress and improve the photosynthetic rate as well as enhance grapevine adaptation to semi-arid climates.

An Integrated IoT Architecture for Smart Metering Using Next Generation Sensor for Water Management Based on LoRaWAN Technology: A Pilot Study

This pilot study focuses on the design, implementation, optimization and verification of a novel solution of smart measuring of water consumption and crisis detection leading to a smart water management platform. The system implemented consists of a modular IoT platform based on a PCB (Printed Circuit Board) design using the M2.COM standard, a LoraWAN modem and a LoraWAN gateway based on the Raspberry Pi platform. The prototype is modular, low-cost, low-power, low-complex and it fully reflects the requirements of strategic technological concepts of Smart City and Industry 4.0, i.e., data integration, interoperability, (I)IoT, etc. The study was produced in cooperation with M.I.S Protivanov and VODARENSKA AKCIOVA SPOLECNOST, a.s. (industry partners distributing drinking water in the Olomouc and South-Moravian regions) to depict the current situation in the Czech Republic, characterized by extreme weather fluctuations and increasingly frequent periods of drought. These drinking water distributors are also constantly placing new demands on these smart solutions. These requirements include, above all, reliability of data transmission, modularity and, last but not least, low cost. However, smart water management (water consumption, distribution, system identification, equipment maintenance, etc.) is becoming an important topic worldwide. The functionality of the system was first verified in laboratory conditions and, then, in real operation. The study also includes checking signal propagation in the municipal area of the village of Zdarna, where the radius of the proposed measuring system was tested. A laboratory test with simulation of water leakage is also part of this work. Subsequently, the system was tested in a residential unit by means of water leakage detection using the MNF method (minimum night flow); the detection success rate was 95%.

[Effects of Different Treatments with Water Management Combined with Leaf Spraying Silicon Fertilizer on Cd Accumulation in Rice]

A field experiment involving eight treatments with water management combined with leaf spraying silicon fertilizer was conducted in a paddy field heavily contaminated with Cd (2.83 mg·kg^-1) to study the effects of these treatments on rice growth and Cd accumulation in different rice tissues. The results showed that:① the treatments had no significant effects on rice plant height or number of tillers, but increased the biomass of brown rice by 1.7% to 25.0%. Among the eight treatments, that of water flooding during the rice maturation period plus leaf spraying silicon fertilizer (CY) resulted in the highest amount of brown rice yield. ② The treatment of conventional water management plus leaf spraying silicon fertilizer (Si) had no significant effect on the exchangeable Cd content and TCLP extractable Cd content in soil, whereas the other treatments reduced the exchangeable Cd content by 7.8%-42.6% and the TCLP extractable Cd content by 20.0%-40.8%. ③ The Si treatment could reduce the Cd content in various rice tissues, with an overall decrease of 19.0% in brown rice. The other treatments significantly reduced the Cd content in various rice tissues. The treatment of moisture during the rice maturation period plus leaf spraying silicon fertilizer (CS) resulted in the highest reduction in the Cd content in brown rice (44.0%), and was followed by the treatments of batch-type water flooding during the entire rice growth period plus leaf spraying silicon fertilizer (JX; 36.4%), and moisture during the rice pustulation period plus leaf spraying silicon fertilizer (GS; 31.8%). ④ For paddy-fields that are contaminated with Cd to medium and heavy levels, the CS and JX treatments are recommended to manage rice production in order to significantly reduce the Cd content of brown rice whilst having little effect on the rice yield.

[Effects of Water Management on Soil Properties and Cd Behavior of Typical Paddy Soils]

To explore the effects of water management mode on Cd environmental behavior in different parent-material-developed paddy soils, two parent-material-developed paddy soils (yellow clayey soil and granitic sandy soil) under three exogenous Cd levels (0.5, 2.0, and 5.0 mg·kg^-1) with different water management modes (long-term flooding, moistening irrigation, and wet-dry rotation) were cultured in this study. The soil redox potential (Eh value), pH value, Cd concentration in soil solution, and Cd fractionation were also determined. The results showed that water management mode had different effects on the pH and Eh values of soils developed from different parent materials. The change rates of soil pH value were as follows:long-term flooding:-2.61% (yellow clayey soil), 2.25% (granitic sandy soil); alternation of dry and wet:-1.96% (yellow clayey soil); 0.52% (granitic sandy soil); wet irrigation:-4.08% (yellow clayey soil) and -0.52% (granitic sandy soil). The Eh value of the soils was negatively correlated with the pH value. The influence pattern of water management model on Cd mass concentration of soil solutions in two parent-material soils was consistent. The Cd mass concentration of soil solutions in granitic sandy soil was higher than that in yellow clayey soil. The mean values of Cd concentration were 1.03 μg·L^-1 for yellow clayey soil and 1.07 μg·L^-1 for granitic sandy soil. Water management mode had no significant effect on the proportions of organic bound Cd or Fe-Mn bound Cd in two different parent-material-developed soils. The long-term flooding mode promoted the transformation of exogenous Cd to residual Cd, and this promotion in yellow clayey soil was higher than that in granitic sandy soil. In conclusion, during the process of regulating soil Cd bioavailability through water management, the role of soil parent materials needs to be considered.

Enhanced Water Management in PEMFCs: Perforated Catalyst Layer and Microporous Layers

An experimental in situ study was performed to investigate the effects of the catalyst layer (CL) and cathode microporous layer (MPL_c ) perforation on the water management and performance of polymer electrolyte membrane fuel cells (PEMFCs). Polymeric pore formers were utilized to produce perforated CL and MPL structures. High-resolution neutron tomography was employed to visualize the liquid water content and distribution within different components of the cell under channel and land regions. The results revealed that at humid conditions, the perforated layers enhanced the liquid water transport under the channel regions. Moreover, at high current densities, the performance was improved for the cells with perforated layers compared to a baseline cell with non-perforated layers, owing to reduced mass transport losses.

A Review of Environment Effects on Nitrate Accumulation in Leafy Vegetables Grown in Controlled Environments

Excessive accumulation of nitrates in vegetables is a common issue that poses a potential threat to human health. The absorption, translocation, and assimilation of nitrates in vegetables are tightly regulated by the interaction of internal cues (expression of related genes and enzyme activities) and external environmental factors. In addition to global food security, food nutritional quality is recognized as being of strategic importance by most governments and other agencies. Therefore, the identification and development of sustainable, innovative, and inexpensive approaches for increasing vegetable production and concomitantly reducing nitrate concentration are extremely important. Under controlled environmental conditions, optimal fertilizer/nutrient element management and environmental regulation play vital roles in producing vegetables with low nitrate content. In this review, we present some of the recent findings concerning the effects of environmental factors (e.g., light, temperature, and CO2) and fertilizer/nutrient solution management strategies on nitrate reduction in vegetables grown under controlled environments and discuss the possible molecular mechanisms. We also highlight several perspectives for future research to optimize the yield and nutrition quality of leafy vegetables grown in controlled environments.

Multi-Faceted Environmental Analysis to Improve the Quality of Anthropogenic Water Reservoirs (Paprocany Reservoir Case Study)

Maintaining good condition of dam reservoirs in urban areas seems increasingly important due to their valuable role in mitigating the effects of global warming. The aim of this study is to analyze possibilities to improve water quality and ecosystem condition of the Paprocany dam reservoir (highly urbanized area of southern Poland) using current data of the water parameters, historical sources, and DPSIR (Driver–Pressure–State–Impact–Response) and 3D modeling concerning human activity and the global warming effects. In its history Paprocany reservoir overcame numerous hydrotechnical changes influencing its present functioning. Also, its current state is significantly influenced by saline water from the coal mine (5 g L⁻¹ of chlorides and sulphates) and biogenic elements in recreational area (about 70 mg L⁻¹ of chlorate and to 1.9 mg L⁻¹ Kjeldahl nitrogen) and in sediments (222.66 Mg of Kjeldahl nitrogen, 45.65 Mg of P, and 1.03 Mg of assimilable phosphorus). Concluding, the best solutions to improve the Paprocany reservoir water quality comprise: increasing alimentation with water and shortening the water exchange time, restoration of the 19th century water treatment plant, and wetlands and reed bed area revitalization. The study also proved the applicability of mathematical models in planning of the actions and anticipating their efficiency.

Water Management for Construction: Evidence for Risk Characterization in Community and Healthcare Settings: A Systematic Review

Construction activities are a known risk contributing to the growth and spread of waterborne pathogens in building water systems. The purpose of the study is to integrate evidence for categorizing construction activity risk factors contributing to waterborne disease in community and healthcare settings, establish severity of such risk factors and identify knowledge gaps. Using a systematic review, the inclusion criteria were: 1) studies with disease cases suspected to be associated with construction activities and waterborne pathogens, and 2) active construction work described in a community or healthcare setting. Each construction activity risk factor was correlated across all studies with the number of disease cases and deaths to establish risk severity. The eligibility review and quantitative synthesis yielded 31 studies for inclusion (community, n = 7 and healthcare, n = 24). From 1965 to 2016, a total of 894 disease cases inclusive of 112 deaths were associated with nine construction activity risk factors and waterborne pathogens. The present study findings support the need for building owners, water management teams and public health professionals to address construction activity risk factors and the analysis of current knowledge deficiencies within the scope of an ongoing water management program. The impact of construction activities on waterborne disease is preventable and should no longer be considered incidental nor accidental.

Integrating the Water Planetary Boundary With Water Management From Local to Global Scales

The planetary boundaries framework defines the "safe operating space for humanity" represented by nine global processes that can destabilize the Earth System if perturbed. The water planetary boundary attempts to provide a global limit to anthropogenic water cycle modifications, but it has been challenging to translate and apply it to the regional and local scales at which water problems and management typically occur. We develop a cross-scale approach by which the water planetary boundary could guide sustainable water management and governance at subglobal contexts defined by physical features (e.g., watershed or aquifer), political borders (e.g., city, nation, or group of nations), or commercial entities (e.g., corporation, trade group, or financial institution). The application of the water planetary boundary at these subglobal contexts occurs via two approaches: (i) calculating fair shares, in which local water cycle modifications are compared to that context's allocation of the global safe operating space, taking into account biophysical, socioeconomic, and ethical considerations; and (ii) defining a local safe operating space, in which interactions between water stores and Earth System components are used to define local boundaries required for sustaining the local water system in stable conditions, which we demonstrate with a case study of the Cienaga Grande de Santa Marta wetlands in Colombia. By harmonizing these two approaches, the water planetary boundary can ensure that water cycle modifications remain within both local and global boundaries and complement existing water management and governance approaches.

Water Quality as a Predictor of Legionella Positivity of Building Water Systems

Testing drinking water systems for the presence of Legionella colonization is a proactive approach to assess and reduce the risk of Legionnaires’ disease. Previous studies suggest that there may be a link between Legionella positivity in the hot water return line or certain water quality parameters (temperature, free chlorine residual, etc.) with distal site Legionella positivity. It has been suggested that these measurements could be used as a surrogate for testing for Legionella in building water systems. We evaluated the relationship between hot water return line Legionella positivity and other water quality parameters and Legionella colonization in premise plumbing systems by testing 269 samples from domestic cold and hot water samples in 28 buildings. The hot water return line Legionella positivity and distal site positivity only demonstrated a 77.8% concordance rate. Hot water return line Legionella positivity compared to distal site positivity had a sensitivity of 55% and a specificity of 96%. There was poor correlation and a low positive predictive value between the hot water return line and distal outlet positivity. There was no correlation between Legionella distal site positivity and total bacteria (heterotrophic plate count), pH, free chlorine, calcium, magnesium, zinc, manganese, copper, temperature, total organic carbon, or incoming cold-water chlorine concentration. These findings suggest that hot water return line Legionella positivity and other water quality parameters are not predictive of distal site positivity and should not be used alone to determine the building’s Legionella colonization rate and effectiveness of water management programs.

Constructing a Cathode Catalyst Layer of a Passive Direct Methanol Fuel Cell with Highly Hydrophilic Carbon Aerogel for Improved Water Management

Nitrogen-doped porous carbon materials show excellent water adsorption ability by forming strong hydrogen bonding between water molecules and the doped atoms. When these porous carbon materials are used to construct a water management layer (WML) of a passive direct methanol fuel cell (DMFC), high water concentration and hydraulic pressure formed inside the cathode catalyst layer would facilitate the water recovery from cathode to anode. In this paper, a highly hydrophilic nitrogen-doped carbon aerogel was synthesized by the carbonization of hydrogel precursors composed of resorcinol, formaldehyde, and graphene oxide under ammonia, and it was used for the first time to construct the WML for liquid-feed and vapor-feed passive DMFCs. The results show that the WML significantly improves the output performance of the liquid-feed DMFC by enhancing the water recovery, which is characterized and proved by the smaller cathode polarization, the slightly increased anode polarization, and a released cathode water flooding situation. A new method was also proposed to study the in situ methanol crossover of DMFCs, which confirmed that the methanol crossover during the discharge was reduced by the WML. As for the vapor-feed DMFCs, the WML reduces both the cathode and anode polarizations significantly, which increases the output performance greatly. This study opens a new window for the design and optimization of the membrane assembly electrode of DMFCs.

Water Source Preferences and Water Quality Perceptions among Women in the Eastern Region, Ghana: A Grounded Theory Study

Residents in the Eastern Region, Ghana with access to improved water sources (e.g., boreholes and covered wells) often choose to collect water from unimproved sources (e.g., rivers and uncovered wells). To assess why, we conducted two field studies to coincide with Ghana’s rainy and dry seasons. During the rainy season, we conducted semi-structured in-depth interviews among a convenience sample of 26 women in four rural communities (including one woman in the dry season). We asked each participant about their attitudes and perceptions of water sources. During the dry season, we observed four women for ≤4 days each to provide context for water collection and water source choice. We used a grounded theory approach considering the multiple household water sources and uses approach to identify three themes informing water source choice: collection of and access to water, water quality perception, and the dynamic interaction of these. Women selected water sources based on multiple factors, including season, accessibility, religious/spiritual messaging, community messaging (e.g., health risks), and ease-of-use (e.g., physical burden). Gender and power dynamics created structural barriers that affected the use of unimproved water sources. A larger role for women in water management and supply decision-making could advance population health goals.

Membrane/Electrode Interface Design for Effective Water Management in Alkaline Membrane Fuel Cells

The recent development of ultrathin anion exchange membranes and optimization of their operating conditions have significantly enhanced the performance of alkaline-membrane fuel cells (AMFCs); however, the effects of the membrane/electrode interface structure on the AMFC performance have not been seriously investigated thus far. Herein, we report on a high-performance AMFC system with a membrane/electrode interface of novel design. Commercially available membranes are modified in the form of well-aligned line arrays of both the anode and cathode sides by means of a solvent-assisted molding technique and sandwich-like assembly of the membrane and polydimethylsiloxane molds. Upon incorporating the patterned membranes into a single-cell system, we observe a significantly enhanced performance of up to ∼35% compared with that of the reference membrane. The enlarged interface area and reduced membrane thickness from the line-patterned membrane/electrode interface result in improved water management, reduced ohmic resistance, and effective utilization of the catalyst. We believe that our findings can significantly contribute further advancements in AMFCs.

Effects of Cell Temperature and Reactant Humidification on Anion Exchange Membrane Fuel Cells

The performance of an anion exchange membrane fuel cell (AEMFC) under various operating conditions, including cell temperature and humidification of inlet gases, was systematically investigated in this study. The experimental results indicate that the power density of an AEMFC is susceptible to the cell temperature and inlet gas humidification. A high performance AEMFC can be achieved by elevating the cell operating temperature along with the optimization of the gas feed dew points at the anode and cathode. As excess inlet gas humidification at the anode is supplied, the flooding is less severe at a higher cell temperature because the water transport in the gas diffusion substrate by evaporation is more effective upon operation at a higher cell temperature. The cell performance is slightly affected when the humidification at the anode is inadequate, owing to dehydration of the membrane, especially at a higher cell temperature. Furthermore, the cell performance in conditions of under-humidification or over-humidification at the cathode is greatly reduced at the different cell temperatures tested due to the dehydration of the anion exchange membrane and the water shortage or oxygen mass transport limitations, respectively, for the oxygen reduction reaction. In addition, back diffusion could partly support the water demand at the cathode once a water concentration gradient between the anode and cathode is formed. These results, in which sophisticated water management was achieved, can provide useful information regarding the development of high-performance AEMFC systems.

Calibration of Granier-Type (TDP) Sap Flow Probes by a High Precision Electronic Potometer

Thermal dissipation probe (TDP) method (Granier, 1985) is widely used to estimate tree transpiration (i.e., the water evaporated from the leaves) because it is simple to build, easy to install, and relatively inexpensive. However, the universality of the original calibration has been questioned and, in many cases, proved to be inaccurate. Thus, when the TDP is used in a new species, specific tests should be carried out. Our aim was to propose a new method for improving the accuracy of TDP on trees in the field. Small hazelnut trees (diameter at breast height 5 cm) were used for the experiment. The response of TDP sensors was compared with a reference water uptake measured with an electronic potometer system provided with a high precision liquid flow meter. We equipped three stems where we measured the sap flow density, the sapwood area (by using fuchsine), the total tree water uptake (reference), and the main meteorological parameters during summer 2018. Results confirmed that the original Granier’s calibration underestimated the effective tree transpiration (relative error about −60%). We proposed a new equation for improving the measurement accuracy within an error of about 4%. The system proposed appeared an easier solution compared to potted trees and particularly suitable for orchards, thus contributing to improve the irrigation management worldwide.

Real-Time Continuous Surveillance of Temperature and Flow Events Presents a Novel Monitoring Approach for Hospital and Healthcare Water Distribution Systems

Within hospitals and healthcare facilities opportunistic premise plumbing pathogens (OPPPs) are a major and preventable cause of healthcare-acquired infections. This study presents a novel approach for monitoring building water quality using real-time surveillance of parameters measured at thermostatic mixing valves (TMVs) across a hospital water distribution system. Temperature was measured continuously in real-time at the outlet of 220 TMVs located across a hospital over a three-year period and analysis of this temperature data was used to identify flow events. This real-time temperature and flow information was then compared with microbial water quality. Water samples were collected randomly from faucets over the three-year period. These were tested for total heterotrophic bacteria, Legionella spp. and L. pneumophila. A statistically significant association with total heterotrophic bacteria concentrations and the number of flow events seven days prior (rs[865] = -0.188, p < 0.01) and three days prior to sampling (rs[865] = -0.151, p < 0.01) was observed, with decreased heterotrophic bacteria linked to increased flushing events. Only four samples were positive for Legionella and statistical associations could not be determined; however, the environmental conditions for these four samples were associated with higher heterotrophic counts. This study validated a simple and effective remote monitoring approach to identifying changes in water quality and flagging high risk situations in real-time. This provides a complementary surveillance strategy that overcomes the time delay associated with microbial culture results. Future research is needed to explore the use of this monitoring approach as an indicator for different opportunistic pathogens.

Co-Producing Interdisciplinary Knowledge and Action for Sustainable Water Governance: Lessons from the Development of a Water Resources Decision Support System in Pernambuco, Brazil

One of the most pressing global challenges for sustainable development is freshwater management. Sustainable water governance requires interdisciplinary knowledge about environmental and social processes as well as participatory strategies that bring scientists, managers, policymakers, and other stakeholders together to cooperatively produce knowledge and solutions, promote social learning, and build enduring institutional capacity. Cooperative production of knowledge and action is designed to enhance the likelihood that the findings, models, simulations, and decision support tools developed are scientifically credible, solutions-oriented, and relevant to management needs and stakeholders' perspectives. To explore how interdisciplinary science and sustainable water management can be co-developed in practice, the experiences of an international collaboration are drawn on to improve local capacity to manage existing and future water resources efficiently, sustainably, and equitably in the State of Pernambuco in northeastern Brazil. Systems are developed to model and simulate rainfall, reservoir management, and flood forecasting that allow users to create, save, and compare future scenarios. A web-enabled decision support system is also designed to integrate models to inform water management and climate adaptation. The challenges and lessons learned from this project, the transferability of this approach, and strategies for evaluating the impacts on management decisions and sustainability outcomes are discussed.

Limited potential of harvest index improvement to reduce methane emissions from rice paddies

Rice is a staple food for nearly half of the world's population, but rice paddies constitute a major source of anthropogenic CH₄ emissions. Root exudates from growing rice plants are an important substrate for methane-producing microorganisms. Therefore, breeding efforts optimizing rice plant photosynthate allocation to grains, i.e., increasing harvest index (HI), are widely expected to reduce CH₄ emissions with higher yield. Here we show, by combining a series of experiments, meta-analyses and an expert survey, that the potential of CH₄ mitigation from rice paddies through HI improvement is in fact small. Whereas HI improvement reduced CH₄ emissions under continuously flooded (CF) irrigation, it did not affect CH₄ emissions in systems with intermittent irrigation (II). We estimate that future plant breeding efforts aimed at HI improvement to the theoretical maximum value will reduce CH₄ emissions in CF systems by 4.4%. However, CF systems currently make up only a small fraction of the total rice growing area (i.e., 27% of the Chinese rice paddy area). Thus, to achieve substantial CH₄ mitigation from rice agriculture, alternative plant breeding strategies may be needed, along with alternative management.

Lost in translation: the German literature on freshwater salinization

Human activities have globally increased and altered the ion concentration of freshwater ecosystems. The proliferation of potash mines in Germany (especially intense in the early 1900s) constitutes a good example of it. The effluents and runoff coming from potash mines led to extreme salt concentrations (e.g. 72 g l^-1 of total salt content, approx. 149 mS cm^-1) in surrounding rivers and streams, causing ecosystem degradation (e.g. massive algal blooms and fish kills). This promoted scientific research that was mostly published in German, thereby being neglected by the wide scientific community. Here, the findings of the German literature on freshwater salinization are discussed in the light of current knowledge. German studies revealed that at similar ion concentrations potassium (K⁺) can be the most toxic ion to freshwater organisms, whereas calcium (Ca²⁺) could have a toxicity ameliorating effect. Also, they showed that salinization could lead to biodiversity loss, major shifts in the composition of aquatic communities (e.g. dominance of salt-tolerant algae, proliferation of invasive species) and alter organic matter processing. The biological degradation caused by freshwater salinization related to potash mining has important management implications, e.g. it could prevent many European rivers and streams from reaching the good ecological status demanded by the Water Framework Directive. Within this context, German publications show several examples of salinity thresholds and biological indices that could be useful to monitor and regulate salinization (i.e. developing legally enforced salinity and ion-specific standards). They also provide potential management techniques (i.e. brine collection and disposal) and some estimates of the economic costs of freshwater salinization. Overall, the German literature on freshwater salinization provides internationally relevant information that has rarely been cited by the English literature. We suggest that the global editorial and scientific community should take action to make important findings published in non-English literature more widely available.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Water Sustainability at the River Grande Basin, Brazil: An Approach Based on the Barometer of Sustainability

Water resources are fundamental for the social and economic development of a country and sustainability is the best approach to treat water-related problems. Therefore, sustainability studies of water resources are deemed urgent. Sustainability analysis methods should enable space-temporal monitoring, decision-making, and development of policies necessary for water governance. Furthermore, sustainability analysis methods should also integrate environment and socioeconomic variables into a single system. In this context, this study aimed to assess the water sustainability conditions of the River Grande Basin (BHRG), Brazil, before the implementation of the Integrated Water Resources Plan (IWRP), using the Barometer of Sustainability tool (BS). The River Grande basin was in an “almost unsustainable” condition and under high environmental stress. A significant imbalance between environmental and human well-being in the system was also observed. To achieve an acceptable sustainability condition, it is thus necessary to improve the environmental quality of the area. Among the priority thematic area, native vegetation recovery was the most urgent. Overall, the sustainability study based on the BS not only facilitates comprehension regarding environment and human interrelationships, but also provide references for policy formulations and water management.

[Lead Uptake and Accumulation in Rice (Oryza sativa L.) with Water Management and Selenite Fertilization]

Lead (Pb) accumulation in rice grains has been identified as a potential threat to human health. Our study investigated the effects of varied rates of selenite fertilization (0, 0.5 and 1.0 mg·kg^-1) on the dynamics of Pb in soil solutions, and its uptake and translocation by rice under different water management scenarios (aerobic and flooded) in pot experiments. Plants were harvested at seedling stage and at maturity to determine the Pb contents, and soil solutions were extracted during the growing season to monitor the Pb dynamics. Results showed that flooding the soil significantly increased Pb concentrations in DCB extracts and rice roots both at seedling stage and maturity. Root Pb contents in flooded treatments were 4.2-8.5 and 1.4-1.5 times higher than those under aerobic conditions at rice seedling stage and maturity. Flooding also decreased the percentage of Pb in rice shoots. The Pb content in soil solutions, rice seedlings, rice roots and stems at maturity were significantly decreased by selenite additions. Relative to the control treatment, selenite additions decreased the rice root Pb contents by 5.4%-24.3% and 2.7%-61.7% under flooding and aerobic conditions at seedling stage, respectively; while decreased Pb in rice root by 56.1%-64.1% and 53.8%-63.2% respectively, at maturity. No significant differences existed in grain Pb levels among the treatments. Results demonstrated that water management regimes and selenite additions affected Pb uptake by rice roots significantly, but had no significant influence on Pb accumulation in rice grains.

Machine Learning in Agriculture: A Review

Machine learning has emerged with big data technologies and high-performance computing to create new opportunities for data intensive science in the multi-disciplinary agri-technologies domain. In this paper, we present a comprehensive review of research dedicated to applications of machine learning in agricultural production systems. The works analyzed were categorized in (a) crop management, including applications on yield prediction, disease detection, weed detection crop quality, and species recognition; (b) livestock management, including applications on animal welfare and livestock production; (c) water management; and (d) soil management. The filtering and classification of the presented articles demonstrate how agriculture will benefit from machine learning technologies. By applying machine learning to sensor data, farm management systems are evolving into real time artificial intelligence enabled programs that provide rich recommendations and insights for farmer decision support and action.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems.