Water Conductivity Research Articles

Thermal Transport and Thermal Polarization of Water in the Supercooled Regime.

The behavior of water in the deep supercooled regime has attracted significant interest, motivated by the hypothesis of the second critical point of water. Previous studies indicated the existence of a water anomaly, characterized by a minimum in the thermal conductivity of water. Here, we employ nonequilibrium molecular dynamics computer simulation and the TIP4P/2005 water force field to investigate the thermal conductivity of supercooled water targeting four different isobars, 1, 200, 700, and 1200 bar. We demonstrate using NEMD simulations the existence of minima in thermal conductivity associated with the maximum isothermal compressibility and the minimum speed of sound in water, hence establishing a firm connection with the second critical point of liquid water. Moreover, we demonstrate that thermal gradients polarize supercooled water with a thermal polarization coefficient of several mV/K. We explain the thermal polarization effect using a theoretical formulation introduced recently that connects the thermal polarization effect to the isobaric thermal expansion coefficient.

COSMARIUM TAXICHONDRIFORME EICHLER & GUTWINSKI 1895 – THE FOURTH RECORD OF A RARE DESMID (ZYGNEMATOPHYCEAE, STREPTOPHYTA) IN CHERNIHIV POLESIE

Purpose. Adding new distribution and microphotographs of a rare taxon of the genus Cosmarium found in a small pond in Chernihiv Polesie. Review of the history of this taxon study in Ukraine and its taxonomy, infraspecific taxa characters are compared discussed. Methodology. The new locality of C. taxichondriforme is situated at the border of the landscape reserve of national significance "Zamglai" that is one of the largest eutrophic swamps in the Chernihiv Polesie. During the field research of the Zamglai bog complex, algal samples were collected from a small pond (2000 м2) situated along the road to Hrybova Rudnia village from route E95, at the distance of 1,8 km village and 0.8 km from the route. The samples were fixed with 4 % formalin for further study in laboratory conditions; pH and electrical conductivity of water were measured with a portable pH and conductivity meter. Microscopic examination of the samples was carried out using a light microscope equipped with a camera for taking microphotos. Identification manuals and monographs of the leading Ukrainian (Palamar-Mordvintseva, 1986, 2005) and European desmidiologists (Lenzenweger, 1999) were used for species identification. The iconotype provided in the original description of the newly recorded taxon (Eichler &Gutwiński, 1895) was used. Scientific novelty. The fourth record in the Ukrainian desmidioflora and a new locality in Chernihiv Polesie of a rare taxon from the genus Cosmarium is documented. Previously it was discovered 26 years ago (Palamar-Mordvitseva & Shindanovina, 1998) in Soseske bog nearby Olyshivka village Chernihiv rayon and oblast. This is the first publication of Ukrainian cells microphotographs. Conclusions. All records of this taxon in Ukraine are in Chernihiv Polesie. We hope this publication will provide good illustrative and informative basis for further findings of C. taxichondriforme in other regions of Ukraine. Sampling small water bodies should not be neglected.

Tissue-specific accumulation of PIP aquaporins of a particular heteromeric composition is part of the maize response to mycorrhiza and drought

The systemic coordination of accumulation of plasma membrane aquaporins (PIP) was investigated in this study in relation to mycorrhized maize response to a rapid development of severe drought followed by rewatering. In non-mycorrhizal roots, drought led to a drop in PIP abundance, followed by a transient increase under rewatering, whereas leaves showed an opposite pattern. In contrast, mycorrhiza contributed to maintenance of high and stable levels of PIPs in both plant organs after an initial increase, prolonged over the irrigation period. Isoelectric focusing electrophoresis resolved up to 13 aquaporin complexes with highly reproducible pl positions across leaf and root samples, symbiotic and non-symbiotic, stressed or not. Mass spectrometry recognized in leaves and roots a different ratio of PIP1 and PIP2 subunits within 2D spots that accumulated the most. Regardless of symbiotic status, drought regulation of aquaporins in roots was manifested as the prevalence of complexes that comprise almost exclusively PIP2 monomers. In contrast, the leaf response involved enrichment in PIP1s. PIP1s are thought to enhance water transport, facilitate CO2 diffusion but also affect stomatal movements. These features, together with elevated aquaporin levels, might explain a stress tolerance mechanism observed in mycorrhizal plants, resulting in faster recovery of stomatal water conductance and CO2 assimilation rate after drought.

Gaps in predicting water quality impacts of unbound air-cooled blast furnace slag utilized for roadway construction

Air-cooled blast furnace slag (ACBFS) is often used as road construction aggregate. Several incidences of adverse environmental effects have been reported in Indiana where unbound slag has been used. The aggregates that caused issues in the field had been previously approved for use by passing State of Indiana standard slag leaching procedures. The study goal was to test several hypotheses posed to the Indiana Department of Transportation and authors by the industry about slag leaching, and to better understand water quality impacts. Ten slags from two suppliers underwent leaching procedures adopted by two U.S. states, but additional test procedures and material and leachate chemical characterization were also conducted to better interpret results. Aggregates varied in size and age (24 h to 2 years old). Like prior literature reports, the chemical composition among the slag samples was similar. However, water quality impacts observed at the bench-scale in this study differed substantially across the slags. Results were consistent with those previously reported at Indiana field sites, but not with literature reported results from standardized leaching tests (i.e., TCLP, percolation, etc.). In the present study, no relationship was found between slag age and leachate composition. Leachate pH, conductivity, and color levels exceeded thresholds of regulatory and aquatic toxicity significance. For one slag, leachate pH reached 12.9, but the effluent was colorless. During both stagnation and rinsing tests, aqueous chloride, sulfate, and zinc concentrations sometimes exceeded regulatory water quality and aquatic toxicity levels. Repeated rinsing of the slag resulted in water conductivity and sulfate concentration differences. To better understand and predict the impacts of unbound ACBFS, additional fundamental studies and field investigations are recommended. Unbound ACBFS is not recommended for use near environmentally sensitive areas, drinking water sources, habituated areas, and where it may have water contact (i.e., waterways, wetlands, reservoirs, and groundwater).

Improved properties of glass vials for primary packaging with atomic layer deposition

Novel pharmaceuticals and drug delivery devices may require better performance from the packaging material e.g., in terms of extractables and leachables, and unwanted interactions. To address this, we applied atomic layer deposition (ALD) to build nanometer-range SiO2, ZrO2 and Al2O3-TiO2 films on primary packaging glass. Controlled modification of the surface also enabled creation of functionality without affecting visual appearance of the material. ALD-coated Type I borosilicate vials were compared to uncoated ones, and tailored functionality was presented by appropriate measurements. The tested ALD coatings formed a barrier on glass against extractables and leachables, from the vial and the coating alike. A good ALD coating prevents any leakage into the stored drug product. Hydrolytic resistance results improved by 85–92 %, and these results correlated well with straightforward water conductivity measurements. Opposite to uncoated borosilicate glass vials, no extracted elements could be detected from the extracts of the coated vials with stable ALD films. Improved surface integrity was observed with electron microscopy as well. ALD films increased hydrophilicity of the surface and tuning the ALD film thickness and composition allowed precise blocking of UV light wavelengths, without affecting transparency. As a conclusion, ALD is a versatile method to create barrier and functional films on primary packaging materials.

Prevention of bacterial adhesion in water conduction systems using vanillin-functionalized grates

Pathogenic microorganisms can adhere to the surfaces of water conducting systems, finally resulting in biofilm structures. Considering the importance of the adhesion capability of cells and the biofilm formation in these surfaces, their inhibition by using naturally occurring antimicrobial compounds can be a potential alternative or complement to water chlorination. This work aimed to study the antiadhesive capability of vanillin-functionalized stainless-steel surfaces against bacteria present in low-pressure water distribution network. Stainless-steel surfaces were pretreated (by sanding or polishing) and activated, allowing the covalent anchoring of vanillin to the stainless-steel. Characterization of functionalized surfaces, by macroscopic, microscopic, and elemental analysis confirmed the efficiency of the vanillin anchoring protocol. Subsequently, in vitro antiadhesive capability assays were performed with Staphylococcus epidermidis as a model microorganism to assess the antiadhesiveness capacity of the functionalized surfaces. This assay allowed the confirmation of the capacity of vanillin-functionalized surfaces to prevent the adhesion of S. epidermidis to the stainless-steel surfaces. Finally, grates were functionalized and placed in low-pressure water conduction pipes in the city of Valencia, Spain. After placement, samples of the biofilm adhered to the grates were taken at certain times and analyzed through metagenomic analysis. The results showed statistically significant differences in both the amount and type of bacterial strains adhered to vanillin-functionalized and non-functionalized grates. These findings demonstrated for the first time the potential application of vanillin-functionalized stainless-steel surfaces in water conduction systems to avoid the adhesive ability of bacteria, preventing their contamination and/or biofilm formation.

Dynamics of soil water, temperature, and salt and their coupled effects in Haloxylon ammodendron forests of different ages in an arid desert oasis ecotone

Study regionThe study region is a typical desert oasis ecotone of the Hexi Corridor, Northwest China. Study focusBased on four years of in situ observational data of soil water, temperature, and electrical conductivity obtained from three Haloxylon ammodendron (H. ammodendron) forests (20, 30 and 50 years) in a typical desert oasis ecotone (DOE) of the Hexi Corridor, in this study, the mechanisms of change and coupled effects of water, heat, and salt in frozen desert soils along a long-term shrub plantation in a typical desert oasis ecotone are presented. New hydrological insights for the regionThis study revealed that changes in soil water, heat, and salt and their coupling effects were completely different between shallow (0–80 cm) and deep (160–200 cm) depths. At 0–80 cm, soil water gradually decreased in the 50-year-old H. ammodendron plot, but soil salt first increased in the 30-year plot and then decreased in the 50-year plot. When the freezing process occurred in the 0–80 cm depth interval, the soil water and salt contents decreased nonlinearly with the absolute value of the soil temperature (|T|), following a power function and logarithmic function, respectively. For the thawing process in the 0–80 cm depth interval, soil water and salt increased with increasing temperature, and there was a significant linear relationship between soil water and salt (P<0.01). In the 160–200 cm layer, soil water and salt significantly increased after 30–50 years during the growing season.

Aquaporin-3a Dysfunction Impairs Osmoadaptation in Post-Activated Marine Fish Spermatozoa.

Spermatozoon volume regulation is an essential determinant of male fertility competence in mammals and oviparous fishes. In mammals, aquaporin water channels (AQP3, -7 and -8) have been suggested to play a role in spermatozoon cell volume regulatory responses in the hypotonic female oviduct. In contrast, the ejaculated spermatozoa of marine teleosts, such as the gilthead seabream (Sparus aurata), experience a high hypertonic shock in seawater, initially resulting in an Aqp1aa-mediated water efflux, cell shrinkage and the activation of motility. Further regulatory recovery of cell volume in post-activated spermatozoa is mediated by Aqp4a in cooperation with the Trpv4 Ca2+ channel and other ion channels and transporters. Using a paralog-specific antibody, here, we show that seabream spermatozoa also express the aquaglyceroporin AQP3 ortholog Aqp3a, which is highly accumulated in the mid posterior region of the spermatozoon flagella, in a similar pattern to that described in mouse and human sperm. To investigate the role of Aqp3a in seabream sperm motility, we used a recently developed AQP3 antagonist (DFP00173), as well as the seabream Aqp3a-specific antibody (α-SaAqp3a), both of which specifically inhibit Aqp3a-mediated water conductance when the channel was heterologously expressed in Xenopus laevis oocytes. Inhibition with either DFP00173 or α-SaAqp3a did not affect sperm motility activation but did impair the spermatozoon motion kinetics at 30 s post activation in a dose-dependent manner. Interestingly, in close resemblance to the phenotypes of AQP3-deficient murine sperm, electron microscopy image analysis revealed that both Aqp3a inhibitors induce abnormal sperm tail morphologies, including swelling and angulation of the tail, with complete coiling of the flagella in some cases. These findings suggest a conserved role of Aqp3a as an osmosensor that regulates cell volume in fish spermatozoa under a high hypertonic stress, thereby controlling the efflux of water and/or solutes in the post-activated spermatozoon.

Water Thermal Conductivity in Nanoscale and Its Effect on Dropwise Condensation Heat Transfer

The present study employs equilibrium molecular dynamics simulation based on the Green-Kubo approach to investigate the thermal conductivity of liquid water at the nanoscale. Specifically, the discussion centers around the influence of the size and surface wettability of two-dimensional nanochannels on the confined water thermal conductivity. The simulation results reveal a significant impact of nanochannel size on the thermal conductivity of confined water, with a decrease in channel spacing leading to a reduction in thermal conductivity below its bulk value. However, the thermal conductivity of water confined within a surface is not influenced by the water surface wettability. Additionally, the study investigates the influence of water thermal conductivity on droplet formation. The results indicate that incorporating changes in droplet thermal conductivity during the nucleation process can partially address the issue of overestimating the heat transfer coefficient for dropwise condensation.

Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries.

Microplastic pollution has raised significant concerns among scientific communities and society in recent years due to its increase and lesser-known effects on the environment. To improve the knowledge of microplastic pollution in freshwater, we investigated microplastics in Anzali Wetland, a Ramsar site in northern Iran, as well as its nine main entering rivers. The extracted microplastics were characterized via visual identification, SEM-EDX, and μ-Raman methods. Microplastics (size range: 50-5000 μm) were found in all water and sediment samples with concentration of fibrous particles as well as polypropylene and polyethylene polymers. The mean concentration of microplastics in bottom sediment and surface water samples of the wetland was 301 ± 222 particles∙kg-1 d.w. and 235 ± 115 particles∙m-3 (0.23 particles∙L-1), respectively. The microplastic concentration in the central and eastern parts of the wetland was higher than in other areas; however, the mean concentrations revealed homogeneity across the wetland area. Water properties (dissolved oxygen, pH, temperature, electrical conductivity, and salinity in water) did not affect the concentration of microplastic particles, though correlational analysis revealed a strong positive association between microplastic quantity and turbidity. There was a significant positive relationship between microplastic concentration and the percentage of clay in sediment samples. The quantity of microplastics in river water was higher than in wetland water, but the difference between the results was not significant. However, the quantity of microplastics in the river's littoral sediment was higher than in the bottom sediment of the wetland where the difference between the results was significant. Microplastic ecological risk assessment showed high potential ecological risk. The findings underscore the importance of effective management strategies and the implementation of policies to mitigate the negative impact of MP pollution on ecosystems and human health.

Effect of priming guava seeds with H2O2 on seedling production under salt stress

Guava is one of the most economically important fruit crops grown in the Northeast region of Brazil. This region is characterized by a high concentration of salts in the water sources used for irrigation, necessitating the development of strategies to minimize the harmful effects of salt stress on production systems. The objective of this study was to analyze the effect of priming guava seeds with H2O2 on seedling production under salt stress. The experiment was conducted in a greenhouse at the Center for Agri-food Science and Technology at the Federal University of Campina Grande, located in Pombal, PB, Brazil. A randomized complete block experimental design was employed, involving a 5 × 3 factorial arrangement represented by five levels of electrical conductivity of irrigation water (ECw: 0.3, 1.1, 1.9, 2.7, and 3.5 dS m-1) and three concentrations of hydrogen peroxide (H2O2: 0, 25, and 50 µM). Four replications were used, with five plants per plot. Salinity in the water starting from 0.3 dS m-1 reduced growth, relative water content, photosynthetic pigments, dry biomass, and Dickson’s quality index, and increased the water saturation deficit in ‘Paluma’ guava seedlings 110 days after sowing. Hydrogen peroxide at a concentration of 25 µM increased the emergence speed index of seedlings, although its application at a concentration of up to 50 µM did not alleviate the adverse impacts of salt stress on ‘Paluma’ guava seedlings under an electrical conductivity of irrigation water of 3.5 dS m-1.

Effect of hydrogen peroxide application on physiology, production, and post-harvest quality of mini watermelon under salt stress

It is extremely important to identify an alternative capable of minimizing the effects of salt stress on plants. In this context, the objective of this study was to evaluate the physiology, growth, production, and post-harvest quality of mini watermelon as a function of irrigation water salinity and hydrogen peroxide. The experiment was conducted in pots adapted as drainage lysimeters under greenhouse conditions, using a randomized block design in a 5 × 4 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water – ECw (0.3 – control, 1.0, 1.7, 2.4, and 3.1 dS m−1) and four concentrations of hydrogen peroxide – H2O2 (0, 20, 40, and 60 μM), with three replicates. The results obtained in the present study indicate that Sugar Baby mini watermelon is sensitive to saline stress, with its physiology, production, and fruit quality negatively affected by irrigation with water of electrical conductivity above 0.3 dS m−1. However, foliar application of hydrogen peroxide at a concentration of 20 µM partially reduces the harmful effects of saline stress, especially for plants irrigated with ECw of 0.3 dS m−1.

Thermal regime of High Arctic tundra ponds, Nanuit Itillinga (Polar Bear Pass), Nunavut, Canada

Abstract. This study evaluates the seasonal and inter-seasonal temperature regime of small tundra ponds ubiquitous to an extensive, low-gradient wetland in the Canadian High Arctic. Pond temperatures can modify evaporation and ground thaw rates, impact losses of greenhouse gases, and control the timing and emergence of insects and larvae critical for migratory-bird feeding habits. We focus our study on thaw ponds with a range of hydrologic linkages and sizes across Nanuit Itillinga, formerly known as Polar Bear Pass (PBP), Bathurst Island, and compare their thermal signals to other Arctic ponds. Pond temperatures and water levels were evaluated using temperature and water level loggers and verified by regular manual measurements. Other environmental data collected included microclimate, frost table depths, and water conductivity. Our results show that there is much variability in pond thermal regimes over seasons, years, and space. Cumulative relative pond temperatures were similar across years, with ponds normally reaching 10–15 °C for short to longer periods, except in 2013, which experienced a cold summer season during which pond temperatures never exceeded 5 °C. Pond frost tables and water conductivities respond to variable substrate conditions and pond thermal patterns. This study contributes to the ongoing discussion on climate warming and its impact on Arctic landscapes.

Electrical conductivity profiling for rapid contamination assessment in unsaturated zones: A case study of an MSW landfill

This study investigates the potential of using bulk soil electrical conductivity (ECbulk) to predict pore water conductivity (ECpw) for assessing the contamination in the unsaturated zone of an old municipal solid waste (MSW) landfill. ECbulk, ECpw, and water content were evaluated with depth at an old MSW landfill in Bhalswa, Delhi, using the Hydraulic Profiling Tool (HPT) and a dual tube soil sampling system. This data was also supplemented by a cone penetration test (CPTu) for high-resolution soil type identification. The correlation of ECbulk with ECpw was primarily influenced by volumetric water content and mineral conductivity with the latter being negligible at this site due to the high conductivity of the leachate. A reasonable linear correlation between normalized EC (ECbulk/ECpw) was observed with volumetric water content, except at low water contents. ECbulk and ECpw profiles with depth indicated attenuation of contaminants in clay layers, while sand layers exhibited constant profile with depth. ECpw was contributed by macro ions generally found in the leachate, including Na+, Mg2+, K+, Ca2+, NH4+, Cl−, SO42−, and HCO3−, as demonstrated by a strong correlation with their cumulative ionic strength. The results indicate that ECbulk profile can be used as a rapid semi-quantitative method for assessing contaminant migration in the unsaturated soil zone, supporting the remediation or control strategies at old landfills.

Liana attachment to supports leads to profound changes in xylem anatomy and transcriptional profile of cambium and differentiating xylem.

Wood serves crucial functions in plants, yet our understanding of the mechanisms governing the composition, arrangement, and dimensions of its cells remains limited. The abrupt transition from nonlianescent to lianescent xylem in lianas represents an excellent model to address the underlying mechanisms, although consistent triggering factors for this process remain uncertain. In this study we examined how physical support attachment impacts the development of lianescent xylem in Bignonia magnifica (Bignoniaceae), employing a comprehensive approach integrating detailed anatomical analysis with gene expression profiling of cambium and differentiating xylem. Our findings demonstrate that attachment to physical supports triggers the formation of lianescent xylem, leading to increased vessel size, broader vessel distribution, reduced fibre content, and higher potential specific water conductivity than nonlianescent xylem. These shifts in wood anatomy coincide with the downregulation of genes associated with cell division and cell wall biosynthesis, and the upregulation of transcription factors, defense/cell death, and hormone-responsive genes in the lianescent xylem. Our findings provide insights into the regulation of xylem differentiation, driven by response to environmental stimuli. Additionally, they shed light on the mechanisms underlying the adaptation of lianas to climbing.

Modeling and Research on Railway Balise Transmission System for Underwater Debris

The balise transmission system (BTS) is essential for train position sensing and safe operation. Transmission loss is a key parameter particularly required for the evaluation of systems. The eddy current loss (ECL), caused by the conductivity of debris, affects the transmission performance of the BTS when the balise is immersed in water. This study proposes an effective modeling for the BTS using S-parameters. Utilizing the electromagnetic coupling analysis in the near-field region, we derived an equivalent circuit with the frequency and conductivity of water taken into consideration. The S21 can be predicted accurately by using the proposed equivalent circuit. For validation, a BTS system was implemented and measured to compare with theoretically calculated results and electromagnetic simulation results in the main lobe zone. The measurement results, simulation, and calculation were in good agreement. Moreover, the modeling was used to predict the I/O characteristics of the balise. The power of the balise uplink FSK signal was measured in the water debris and found to be approximately 0.62 dB less than in air. These findings aligned well with theoretical predictions.

Geometrical effective medium model of electric conduction of partially saturated clays

The current existing researches were discussed to assess the advantages and limitations of existing empirical and theoretical models for direct conductivity (DC) prediction. Prior research has demonstrated that an effective medium model may not accurately reflect the actual situation due to the presence of two types of water (bound water and bulk water) in clay-rich materials. Furthermore, the existing models can not satisfy the prediction of electrical conductivity of metal ions adsorbed clay or unsaturated clay. To address this issue, a new Effective Medium Double Water (EMDW) model was proposed based on multiple scattering techniques, which encompasses soil particles, surface-bound water layers, and bulk water and was established by controlled soil types and degrees of saturation. The novel EMDW model includes the Coherent Potential Approximation (CPA), which has consistently demonstrated superior agreement with experimental data when compared to other approximation models. Moreover, the binomial expansion approximation was utilized to simplify the formula and facilitate its use. The developed conductivity model was validated with data from other researchers. In comparison to other well-established conductivity models, the proposed EMDW model has clear physical meaning and can accurately compute matrix conductivity utilizing modified coated particle conductivity and saturation conductivity. The findings suggest that matrix conductivity in clay materials is significantly correlated with electrical-physical parameters, such as porosity, degree of saturation, shape of each discontinuous phase, and conductivity of surface-bound water and bulk water. Consequently, the new EMDW model is a theoretically grounded, physically meaningful, and easy-to-use model for conductivity prediction in clay materials.

Measurements of Soil Water Potential and Conductivity based on a Simple Evaporation Experiment using a Hydraulic Property Analyzer.

The measurement of soil hydraulic properties is critical in understanding the physical components of soil health as well as integrated knowledge of soil systems under various management practices. Collecting reliable data is imperative for informing decisions that affect agriculture and the environment. The simple evaporation experiment described here uses instrumentation in a laboratory setting to analyze soil samples collected in the field. The soil water tension of the sample is measured by the instrument, and tension data is modeled by software to return soil hydraulic properties. This method can be utilized to measure soil water retention and hydraulic conductivity and give insight into differences in treatments or environmental dynamics over time. Initial establishment requires a user, but data acquisition is automated with the instrument. Soil hydraulic properties are not easily measured with traditional experiments, and this protocol offers a simple and optimal alternative. Interpretation of results and options for extending the data range are discussed.

Assessing methane emissions and soil carbon stocks in the Camargue coastal wetlands: Management implications for climate change regulation

Coastal wetlands are crucial in climate change regulation due to their capacity to act as either sinks or sources of carbon, resulting from the balance between greenhouse gas (GHG) emissions, mainly methane (CH4), and soil carbon sequestration. Despite the paramount role of wetlands in climate regulation few studies investigate both aspects. The Camargue is one of the largest wetlands in Europe, yet the ways in which environmental and anthropic factors drive carbon dynamics remain poorly studied. We examined GHG emissions and soil organic carbon (SOC) stocks and accumulation rates in twelve representative wetlands, including two rice fields, to gain insights into the carbon dynamics and how it is influenced by hydrology and salinity. Mean CH4 rates ranged between – 87.0 and 131.0 mg m−2 h−1and the main drivers were water conductivity and redox, water table depth and soil temperature. High emission rates were restricted to freshwater conditions during summer flooding periods whereas they were low in wetlands subjected to summer drought and water conductivity higher than 10 mS cm−1. Nitrous oxide emissions were low, ranging from – 0.5 to 0.9 mg N2O m−2 h−1. The SOC stocks in the upper meter ranged from 17 to 90 Mg OC ha−1. Our research highlights the critical role of low-saline wetlands in carbon budgeting which potentially are large sources of CH4 but also contain the largest SOC stocks in the Camargue. Natural hydroperiods, involving summer drought, can maintain them as carbon sinks, but altered hydrology can transform them into sources. Artificial freshwater supply during summer leads to substantial CH4 emissions, offsetting their SOC accumulation rates. In conclusion, we advocate for readjusting the altered hydrology in marshes and for the search of management compromises to ensure the compatibility of economic and leisure activities with the preservation of the inherent climate-regulating capacity of coastal wetlands.

Active protein ubiquitination regulates xylem vessel functionality.

Xylem vessels function in the long-distance conduction of water in land plants. The NAC transcription factor VASCULAR-RELATED NAC-DOMAIN7 (VND7) is a master regulator of xylem vessel cell differentiation in Arabidopsis (Arabidopsis thaliana). We previously isolated suppressor of ectopic xylem vessel cell differentiation induced by VND7 (seiv) mutants. Here, we report that the responsible genes for seiv3, seiv4, seiv6, and seiv9 are protein ubiquitination-related genes encoding PLANT U-BOX46 (PUB46), an uncharacterized F-BOX protein (FBX), PUB36, and UBIQUITIN-SPECIFIC PROTEASE1 (UBP1), respectively. We also found decreased expression of genes downstream of VND7 and abnormal xylem transport activity in the seiv mutants. Upon VND7 induction, ubiquitination levels from 492 and 180 protein groups were upregulated and downregulated, respectively. VND7 induction resulted in the ubiquitination of proteins for cell wall biosynthesis and protein transport, whereas such active protein ubiquitination did not occur in the seiv mutants. We detected the ubiquitination of three lysine residues in VND7: K94, K105, and K260. Substituting K94 with arginine significantly decreased the transactivation activity of VND7, suggesting that the ubiquitination of K94 is crucial for regulating VND7 activity. Our findings highlight the crucial roles of target protein ubiquitination in regulating xylem vessel activity.