Total Solute Research Articles

Chemical and physical characteristics of wheat root mucilage influenced by Serendipita indica symbiosis: a comparison among four cultivars.

Although there is evidence to suggest that the endophytic fungus Serendipita indica plays a crucial role in enhancing plant tolerance against biotic/abiotic stressors, less is known about the impacts of this symbiosis association on root mucilage chemical composition and its physical functions. The mucilage of inoculated and non-inoculated seedlings of four wheat cultivars (i.e., Roshan, Ghods, Kavir and Pishtaz) were extracted using an aeroponic method. Total solute concentration (TCm), carbon content (Cmucilage), electrical conductivity (EC), pH, fatty acids, surface tension (σm), and viscosity (ηm) of mucilage were measured. Ghods and Kavir had the highest and lowest root colonization percents, respectively. Saturated fatty acids, including palmitic and stearic acids, were dominant over unsaturated fatty acids in wheat root mucilage. However, their compositions were significantly different among wheat cultivars. S. indica colonization, especially for Ghods, increased the TCm, Cmucilage, and palmitic acid. Moreover, root mucilage of S. indica-inoculated Ghods had lower σm and greater ηm. An increased amount of powerful surfactants like palmitic acid in the mucilage of S. indica inoculated treatments led to lower σm and greater ηm. Such studies provide further support for the idea that plant-released mucilage plays a major role in modifying the physical environment of the rhizosphere. This knowledge toward truly understanding the rhizosphere can be potentially used for improving the rhizosphere soil quality and increasing crop growth and yield.

Assessing porosity limit in freeze‐cast sintered lithium titanate (Li4Ti5O12) materials

AbstractThis study aims to assess the lower limit of porosity that can be achieved in freeze‐cast sintered lithium titanate (LTO) materials while maintaining the characteristic pore directionality. LTO materials were fabricated with solid loading varying in the range of 30–37 vol.%. Sucrose and cationic dispersant were used to vary viscosity and total solute concentration in the aqueous LTO suspensions. Two series of suspension compositions were selected for freeze‐casting. In one series, aqueous suspensions were prepared by mixing deionized (DI) water, sucrose, and LTO powder, while in the other series, aqueous suspensions were prepared by mixing DI water, sucrose, cationic dispersant (1‐hexadecyl)trimethylammonium bromide (CTAB), and LTO powder. With increasing solid loading from 30 to 37 vol.%, porosity in the sintered materials decreased from about 50 to 36 vol.%. LTO materials fabricated from suspensions containing sucrose exhibited well‐developed characteristic freeze‐cast microstructure. Unexpectedly, LTO materials fabricated from suspensions containing sucrose and dispersant exhibited cellular pore morphology irrespective of the solid loading. Sample height had an impact on microstructure evolution in the transition zone and zone length. With the increasing solid loading from 30 to 37 vol.%, the compressive strength of sintered LTO materials having the characteristic freeze‐cast microstructure increased from about 110 to 240 MPa.

Improvement of the quality of garlic bulbs with long light treatment using LED light

AbstractGarlic is one type of vegetable that is strategically developed. Its need increases every year as the main spice of cuisine in Indonesia and a functional food that is beneficial to human health. Improvements in cultivation technology need to increase productivity, among other things, by increasing the length of lighting with white LED lights. This study evaluates the quality of garlic bulbs produced using white LED lights. The research was conducted in the experimental garden of the Indonesian Vegetable Research Institute (IVEGRI) in Lembang at an altitude of 1200 meters above sea level in March–October 2021. Varieties used are Tawangmangu Baru. The lighting duration consists of 4 treatments: 3 hours, 5 hours, 7 hours, and control (without lighting). The addition of lighting by LED lights begins at 18.00. The remote controller sets the length of lighting. Lighting was given to all experimental plants in the field. Garlic bulbs from the harvest were observed, including diameter, texture, moisture content, ash content, TSS (Total Soluble Solute), and VRS (Volatile Reducing Substance) content. The design carried out is a group random design. The data obtained were analyzed for variance (ANOVA) using SPSS software and further tested with Duncan’s Multiple Distance Test at a 95% confidence level. The results showed that the long lighting treatment significantly affected tuber weight, texture, ash content, and TSS. In three hours, lighting treatments, the weight of the bulb was significantly than the control (without lighting). TSS content in the five hours lighting treatment were higher than in other treatments.

Microphase Separation and Gelation through Polymerization-Induced Self-Assembly Using Star Polyethylene Glycols.

Polymerization-induced self-assembly (PISA) during the synthesis of diblock copolymers has garnered considerable interest; however, architectures beyond diblock copolymers have scarcely been explored. Here, we studied PISA using 4- and 8-arm star polyethylene glycol (PEG), as well as 2-arm (linear) PEG, wherein each terminus of PEG was functionalized with a chain-transfer agent, holding a constant molar mass for each arm. Styrene was polymerized from each PEG terminus through reversible addition-fragmentation chain-transfer (RAFT) polymerization in an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6]), with a total solute concentration of 40 wt %. While the styrene monomer is soluble in [BMIM][PF6], polystyrene is not; thus, self-assembly and cross-linking (gelation) occur. Structural analysis by small-angle X-ray scattering revealed that a relatively ordered microphase-separated structure for PISA was observed. Two-arm PEG-PS formed hexagonally packed cylinders, whereas 4- and 8-arm PEG-PS exhibited hexagonal close-packed spheres and disordered spheres. The dynamics, studied by oscillatory rheology, were also influenced by the number of arms; the 4-arm star block copolymers showed the highest plateau modulus. This study demonstrates that the topology is an important factor in controlling the microphase-separated structure and mechanical properties when preparing gels through PISA.

Parametric Control via the Algebraic Expression of Lotus-Type Pore Shapes in Metals

Lotus-type porous metals, characterized by low densities, large surface areas, and directional properties, are contemporarily utilized as lightweight, catalytic, and energy-damping materials; heat sinks; etc. In this study, the effects of dimensionless working parameters on the morphology of lotus-type pores in metals during unidirectional solidification were extensively investigated via general algebraic expressions. The independent dimensionless parameters include metallurgical, transport, and geometrical parameters such as Sieverts’ law constant, a partition coefficient, the solidification rate, a mass transfer coefficient, the imposed mole fraction of a solute gas, the total pressure at the top free surface, hydrostatic pressure, a solute transport parameter, inter-pore spacing, and initial contact angle. This model accounts for transient gas pressure in the pore, affected by the solute transfer, gas, capillary, and hydrostatic pressures, and Sieverts’ laws at the bubble cap and top free surface. Solute transport across the cap accounts for solute convection at the cap and the amount of solute rejected by the solidification front into the pore. The shape of lotus-type pores can be described using a proposed fifth-degree polynomial approximation, which captures the major portions between the initial contact angle and the maximum radius at a contact angle of 90 degrees, obtained by conserving the total solute content in the system. The proposed polynomial approximation, along with its working parameters, offers profound insights into the formation and shape of lotus-type pores in metals. It systematically provides deep insights into mechanisms that may not be easily revealed with experimental studies. The prediction of a lotus-type pore shape is thus algebraically achieved in good agreement with the available experimental data and previous analytical results.

Qualitative Analysis of Seawater Quality on Bulan Island in Batam

In line with the increase in population and socio-economic development activities, various problems arise in marine ecosystems in coastal areas where waste is disposed of or as a result of weathering ships passing by in the waters. This can cause pollution and reduce the quality of seawater physically, chemically, and biologically, and it can damage the balance of the ecosystem. These physicochemical factors include temperature, pH, total solute (TDS), lead (Pb), iron (Fe), magnesium (Mg), sodium (Na), zinc (Zn), nickel (Ni), and copper (Cu). This study aims to help qualitatively improve seawater quality in the Bulan Island region's waters. The research method for the physical parameters of odor, color, and taste used organoleptic methods, while the chemical parameters for pH used a pH meter, TDS used a TDS meter, and contacted metals using a qualitative method. The results of the research are based on the parameters of smell, taste, and color of the Indonesian Ministry of Health standards, while the highest temperature is found in the middle of the sea, namely (31.7 oC). The highest pH parameter was found in the water at Sagulung Port (7.9) and the lowest at seawater (7.5), while the highest TDS value was found in seawater at Sagulung Port (209 ppm) and the lowest at Pulau Bulan Port. (108 ppm), from the results of the pH and TDS tests the three samples still met the standards of the Indonesian Ministry of Health. The metal quality test found that the seawater of Pulau Bulan Port, mid-ocean sea air, and sea air at Sagulung Port identified the presence of Lead (Pb) and Zink (Zn) metals.

Synthesis of ZnO and ZnO/Ag fine particles by plasma-assisted inkjet processing

Zinc oxide (ZnO) and its composite particles with controlled sizes, shapes, compositions, and physical and chemical properties are required for a wide variety of applications. In this study, we report a simple method for synthesising ZnO and ZnO/Ag composite particles via atmospheric-pressure plasma processing using inkjet droplets. Depending on the initial solution concentration, ZnO particles containing voids, with average sizes ranging from submicrons to several microns can be synthesised. Energy dispersive x-ray spectroscopy measurements of the synthesised ZnO/Ag particles suggest that the molar ratio of Ag to Zn in the initial solution was retained in the synthesised particles. A high surface-enhanced Raman scattering effect was observed in the particles synthesised from the solution with an Ag molar ratio of 50% to the total solute. The proposed method enables the synthesis of ZnO particles of various sizes, microstructures, compositions and optical properties with relatively narrow size distributions.

Experimental and Theoretical Rotational Diffusion Studies of 7DM4M1M1,8, N-2(1H)-one and 7A4T2H1B-2-one in Series of Alcohol Solvents: Stoke's-Einstein-Debye and Alavi-Waldeck Models.

Rotational diffusion studies of two solutes 7-(dimethylamino)-4-methoxy-1-methyl-1,8-naphthyridin-2(1H)-one (7DM4M1M1,8, N-2(1H)-one) and 7-amino-4-(trifluoromethyl)-2H-1-benzopyran-2-one (7A4T2H1B-2-one) having equal volumes but different chemical natures are studied in series of alcohol solvents at 303K using steady-state methods. HOMO-LUMO, Electron density, Molecular electrostatic potential (MEP), etc., are obtained from computational calculations using Gaussian 09 software. Rotational reorientation times of 7DM4M1M1,8, N-2(1H)-one solute molecule is found to be less than 7A4T2H1B-2-one solute molecule indicates it rotates slowly in chosen solvents. Stoke's-Einstein-Debye (SED) model with stick boundary conditions for the 7A4T2H1B-2-one solute molecule is modeled to describe mechanical friction. Polar solutes along with mechanical friction also experience dielectric friction. Both these frictions being non-separable, the Alavi-Waldeck (AW) model is studied for dielectric friction contribution to the total friction solute experiences in solvents. AW model effectively explains the observed dielectric friction in alcohol solvents.

Mapping elemental solutes at sub-picogram levels during aqueous corrosion of Al alloys using diffusive gradients in thin films (DGT) with LA-ICP-MS

A novel approach using diffusive gradients in thin films (DGT) with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for two-dimensional mapping of elemental solute release at sub-picogram levels during aqueous corrosion of Al alloys is presented. Evaluation of different DGT gels with mixed micro-sized binding phases (polyacrylamide-Chelex-Metsorb, polyurethane (PU)-Chelex-Metsorb, PU-Chelex-Zr(OH)4) demonstrated the superior performance of PU gels due to their tear-proof handling, low shrinkage, and compliance with green chemistry. DGT devices containing PU-Chelex-Zr(OH)4 gels, which have not been characterized for Al sampling before, showed quantitative uptake of Al, Zn, and Cu solutes over time (t = 4–48 h) with higher Al capacity (ΓDGT = 6.25 µg cm−2) than different gels. Application of PU-Chelex-Zr(OH)4 gels on a high-strength Al-Cu alloy (Al2219) exposed to NaCl (w = 1.5%, pH = 4.5, T = 21 °C) for 15 min in a novel piston-type configuration revealed reproducible patterns of Al and Zn co-solubilization with a spatial expansion ranging between 50 and 1000 µm. This observation, together with complementary solid-state data from secondary electron microscopy with energy-dispersive X-ray spectroscopy, showed the presence of localized pitting corrosion at the material surface. Detection limits for total solute masses of Al, Zn, and Cu were ≤0.72 pg, ≤8.38 pg, and ≤0.12 pg, respectively, for an area of 0.01 mm2, demonstrating the method’s unique capability to localize and quantify corrosion processes at ultra-trace levels and high resolution. Our study advances the assessment of Al alloy degradation in aqueous environments, supporting the design of corrosion-resistant materials for fostering technological safety and sustainability.Graphical

Solute fluxes in headwater catchments with contrasting anthropogenic impact

Understanding the response of headwater catchments to increasing anthropogenic influences is one of the key issues in hydrological and geomorphological research. Two headwater catchments with contrasting human impacts on the environment were chosen to determine changes in surface water chemistry and solute fluxes. In one catchment, 22 % of the forest area was cleared in 2013 and in the other, 75 % of the arable lands was converted to grassland and forest in the last 25 years. Atmospheric input and solute mass balance were analysed using homogeneity Pettitt test. It seems that in both areas, a very important factor affecting solute fluxes was most likely changes, or lack thereof, in soil erosion. In the partially clear-cut catchment, a small clear-cut area and adequate protection of the soil cover had little effect on the stream water chemistry, and the total solute mass balance remained unchanged during the study period. In this catchment, the more pronounced effect on solute fluxes was using de-icing salts in winter, which contributed to a 62 % increase in total solute flux (mainly by supplying Na+ and Cl−, but also Ca2+, Mg2+ and K+). In a catchment with a decrease in arable lands, there was a 55 % decrease in total solute mass balance (including mass balance of Ca2+, Mg2+, Na+, K+, NH4+, SO4−, NO3−, Cl−) in the stream likely associated with a decrease in soil erosion and fertilization. In both catchments there was a decrease in total monthly atmospheric input (especially in input of NH4+, SO4− and NO3−) of 53 % and 21 %, respectively, over the study period. To summarize, the road salting has increased the amount of transported solutes in the stream and deteriorated surface water chemistry, while the reduction of arable land area has reduced the amount of transported solutes in the stream and improved surface water quality.

Grafting of Tomato (Solanum Lycopersicum L.) onto Potato (Solanum tuberosum L.): Harvesting Double Crops from a Single Plant

Rapid Urbanization and industrialization have been overtaking land for food production at the global level. Further, climate change has necessitated the modification of the existing food production system to adapt the changing environmental situations. Grafting is a rapid and economical solution to improving the yield in Solanaceous vegetables. In this study, the effects of grafting tomato (cv. Garv) on potato (cv. Desiree) rootstock were evaluated for yield of tomato and potato in comparison to non-grafted tomato and non-grafted potato plants. The results showed that the yield of tomato was significantly higher in non-grafted tomato (11.05 t/ha) and tomato grafted on potato with decapitation of potato shoots (4.07 t/ha) compared to that of tomato grafted on potato without decapitation of potato shoots (0.94 t/ha). On the other hand, the yields of non-grafted potato (1.44 t/ha) and tomato grafted on potato without decapitation of potato shoots (1.00 t/ha) were statistically higher than that of tomato grafted on potato with the decapitation of potato shoots. There were no statistical differences between the treatments for dry matter content and Total Soluble Solutes (TSS) of tomato and potato. The yield of tomato of the grafted pomato was negatively correlated to the yield of potato rootstock, but it was not statistically different. The data from this study suggest grafting of tomato on potato with decapitation of potato shoots is recommended for obtaining higher yield of grafted tomato and without decapitation of potato shoots for higher yield of potato from grafted plants.

Terrestrial Trentepohlia sp. (Ulvophyceae) from alpine and coastal collection sites show strong desiccation tolerance and broad light and temperature adaptation.

For the present study, we collected the Ulvophyceae species Trentepohlia aurea from limestone rock near Berchtesgaden, Germany, and the closely related taxa T. umbrina from Tilia cordata tree bark and T. jolithus from concrete wall both in Rostock, Germany. Freshly sampled material stained with Auramine O, DIOC6, and FM 1-43 showed an intact physiological status. Cell walls were depicted with calcofluor white and Carbotrace. When subjected to three repeated and controlled cycles of desiccation over silica gel (~ 10% relative humidity) followed by rehydration, T. aurea recovered about 50% of the initial photosynthetic yield of photosystem II (YII). In contrast, T. umbrina and T. jolithus recovered to 100% of the initial YII. HPLC and GC analysis of compatible solutes found highest proportions of erythritol in T. umbrina and mannitol/arabitol in T. jolithus. The lowest total compatible solute concentrations were detected in T. aurea, while the C/N ratio was highest in this species, indicative of nitrogen limitation. The prominent orange to red coloration of all Trentepohlia was due to extremely high carotenoid to Chl a ratio (15.9 in T. jolithus, 7.8 in T. aurea, and 6.6. in T. umbrina). Photosynthetic oxygen production was positive up to ~ 1500µmol photons m-2s-1 with the highest Pmax and alpha values in T. aurea. All strains showed a broad temperature tolerance with optima for gross photosynthesis between 20 and 35°C. The presented data suggest that all investigated Trentepohlia species are well adapted to their terrestrial lifestyle on exposed to sunlight on a vertical substrate with little water holding capacity. Nevertheless, the three Trentepohlia species differed concerning their desiccation tolerance and compatible solute concentrations. The lower compatible solute contents in T. aurea explain the incomplete recovery of YII after rehydration.

“Wrecking the rocks”: Continental weathering by groundwater

Abstract Groundwater solute mass flux discharged from the continents to the oceans is between 56% and 63% of particulate sediment transport mass flux. Herein we utilized newly developed continental geospatial groundwater concentration estimates that were multiplied by groundwater volumetric recharge flux to provide a continental-scale discharge mass flux to the oceans of 7.3 Pg DS/yr (petagrams dissolved solutes per year). This mass flux was evaluated from six continental ecosystems: direct ocean discharge (0.28 Pg DS/yr), endorheic basins (0.59 Pg DS/yr), cold-wet exorheic basins (0.55 Pg DS/yr), cold-dry exorheic basins (1.1 Pg DS/yr), warm-dry exorheic basins (0.82 Pg DS/yr), and warm-wet exorheic basins (4.0 Pg DS/yr), thus providing insight into the role of rainfall and temperature on continental weathering and denudation. A new, robust molar silicate/carbonate ratio of 0.42 was calculated for weathering of continental rocks, which is important in the Urey model of climate change. We estimate that rock weathering accounts for ~50% of the total solute mass flux discharged from the continents, the remainder being from externally derived marine aerosols and organic-derived bicarbonate.

Capturing unmodelled phenomena: A hybrid approach for the prediction of the transport through ceramic membranes in organic solvent nanofiltration

Organic Solvent Nanofiltration (OSN) is widely recognized as an interesting substitute to the thermal-based separation processes traditionally used in many industries. However, its industrial implementation has been hampered by the relatively poor understanding of the complex phenomena that drive its performance. Consequently, various model formulations have been proposed in the past with various degrees of success. Unfortunately, it seems that mechanistic methodologies tend to suffer from the mentioned lack of fundamental understanding, while data-driven approaches are typically bound to have very large data requirements and their predictions are often difficult to interpret and hard to extrapolate. Accordingly, this work presents a hybrid modelling methodology focused on OSN with ceramic membranes and aimed at the engineering practice. In this approach, a mechanistic component is married with a data-driven algorithm with the objective of obtaining accurate predictions that remain interpretable and bounded by the physics of the system. Two model architectures (parallel and serial) were formulated and subsequently tested with an experimental dataset. Both options were found to offer improved predictions of total flux and solute rejection in comparison with the widely used solution-diffusion framework. The models were found to produce accurate out-of-sample predictions and it was possible to obtain a picture of the influence of the effects driving model predictions. Additionally, adequate estimations of systems in which affinity interactions are dominant were obtained. This positions the hybrid methodology presented here as a promising alternative for the prediction of the performance of OSN.

Why is the film model fundamentally wrong but still able to correlate the experimental data in membrane processes?

The film model that predicts a logarithmic dependence of permeate velocity on feed solute concentration in membrane separation processes is fundamentally wrong because the primary mass balance equation in the model is inapplicable to the total solute. Based on mass balance relationships on the retained solute, The permeate velocity in crossflow membrane separation processes can be rigorously shown to be a cube root function of the retained solute concentration. Furthermore, the reported good fitness of the film model to the experimental permeate velocities can be shown just to be a delusion of curve fitting mainly due to the adjustable parameters in the model.

Composition, Distribution, and Attribution of Hydrochemistry in Drainage Systems in the North of Tianshan Mountains, China

The characteristics and sources of the hydrochemical composition of natural water are mainly influenced and limited at the basin scale by what factors, this has become a focal issue of environmental change in the middle latitude areas and even globally. In this study, three large drainage systems (Junggar, Yili, and Erlqis) in the north of the Tianshan Mountains were selected to study the hydrochemistry of different river basins and understand the relevant causes and attributions of different water bodies in arid environments in the Central Asian Orogenic Belt (CAOB). Natural water samples from the three drainage systems and their hydrochemical data, combined with literature data of the north and south Tianshan Mountains and surrounding areas, were systematically collected and comprehensively compared with other higher, middle, and low latitude watersheds with different climate conditions. The results show that the total dissolved solid concentrations in the CAOB drainage systems are generally higher than those of rivers in Chinese monsoon and humid regions, and also higher than the world average level. The relative concentrations of different ions are similar to those of rivers in the monsoon region of eastern China and most rivers in the world dominated by carbonate weathering. The ionic compositions of surface water bodies from different sub-basins in the study area are distributed near the Ca apex in the piper diagram, while those of phreatic and confined groundwater samples tend to the Na apex. The compositional differences in the anions are not like those in the cations, rarely distinguishable for these different water types. In a sub-drainage basin scale from I to VIII sub-basins in the study area, major ion concentrations and distributions in these basins are evidently heterogeneous. Almost all the cation and anion concentrations span > 1 order of magnitude, especially sodium and chlorine; however, the calcium and alkalinity concentrations and distributions are relatively homogeneous for some basins in the Junggar and Yili drainage systems. The relative homogeneity between anions and the relative heterogeneity between cations can be recognized in the ion chemistry of natural water samples between different types, indicating that the composition and distribution of cations in water is more conducive than those of anions to identifying the differences and commonalities between different regions. Atmospheric precipitation plays a key role on the hydrogeochemical process in the north of the Tianshan Mountains, and the elevation differentiation of chemical weathering and ion concentrations are closely related to it. The positive correlation between total solute flux and runoff cannot be explained by the dilution effect, indicating that hydroclimatic factors such as runoff and aridity have a strong effect in limiting the hydrochemistry of natural water bodies in the study area.

#4377 IMPACT OF TOLVAPTAN ON 24H-URINE VOLUME AND OSMOLALITY DURING THE UP-DOSING PHASE IN ADPKD PATIENTS: A SINGLE-CENTER STUDY

Abstract Background and Aims ADPKD is the most prevalent genetic kidney disease. Tolvaptan is the first proven disease-modifying therapy, but is associated with aquaretic side effects, frequently leading to treatment discontinuation. Therefore, identifying factors, which can ameliorate the aquaretic side effects and facilitate therapy is crucial. Previous data reported 24h-osmolar excretion in urine or GFR as the main determinants of urine volume on tolvaptan but included only few patients. This study's objective was to prospectively examine the 24-hour urine volume and urine osmolality during the up-dosing phase of tolvaptan in a cohort with a moderate sample size and different subgroups in order to identify modifiable and non-modifiable factors for urine volume increase. Finally, quality of life (QoL) during tolvaptan treatment was investigated in relation to urine volume since these data are scarce thus far and provide crucial insights into the therapy burden. Method Analysis of 24-h urine collection at baseline and at least once on tolvaptan was carried out for 75 patients (complete cohort). For 35 patients (longitudinal cohort) urine collections were available for baseline and all three tolvaptan doses (45/15 mg, 60/30 mg and 90/30 mg). All patients are participants of the German AD(H)PKD registry. Sodium, protein and potassium intake were calculated from excretion in 24h-urine and QoL was assessed by the Short Form-12 (SF-12) questionnaire. Statistical analyses were computed using R statistical software. A p-value of < 0.05 was regarded as significant. Results The mean age of the patients in the complete cohort was 41.3 ± 10.7 (range 18-64 years) with a mean eGFR of 67.3 ± 27.2 ml/min/1.73m2 and was similar to the longitudinal cohort with a mean age of 41.8 ± 10.1 (23-64 years) and eGFR of 69.4 ± 27.5ml/min/1.73m2. A significant increase (p< 0.0001) in 24-h urine volume (138%) occurred only immediately after therapy initiation with no further significant increase during updosing in the complete and longitudinal cohort. In line with this 24h-urine osmolality decreased (57%) significantly (p< 0.0001) only after beginning of treatment and remained almost unchanged after updosing. Total solutes, protein and sodium intake showed non-significant changes across all doses. There were no significant differences in urine volume between gender, age classes (<45 vs. ≥45 years), or Mayo class when examining the various subgroups. Considering modifiable factors, 24h-urine volume was positively correlated with eGFR on tolvaptan reaching significance on 45/15 mg (p = 0.013) and 90/30 mg (p = 0.027). Patients <45 years and patients with an eGFR ≥ 60 ml/min/1.73m2 experienced a significantly higher relative urine volume increase at the beginning (p = 0.0332 vs. ≥45 years and p = 0.0097 vs eGFR < 60 ml/min/1.73m2) in the complete cohort. In multivariable linear regression analyses containing modifiable and non-modifiable covariates only sodium intake had a significant impact in tolvaptan-naive patients (p = 0.0064), while on tolvaptan age (p = 0.0008) and weight (p = 0.0190) became significant together with sodium intake (p = 0.0008) and potassium intake (p = 0.0040). Across the three tolvaptan doses no significant differences between the number of patients reaching pre-defined osmolality goals (< 250 mosmol/kg for spontaneous urine and < 150 mosmol/kg for 24h-urine) could be detected. Before and after tolvaptan treatment, neither the mental nor physical QoL changed significantly. Conclusion Our study showed that the significant rise in urine volume occurs immediately after therapy initiation with only minor and non-significant increases upon further updosing. Urine osmolality decreases significantly directly after start of tolvaptan and remains constant with most patients achieving adequate suppression of urine osmolality. Patient counseling should consider that younger patients and patients with better eGFR might experience stronger urine volume increase at the beginning and advising to reduce salt and potassium intake can ameliorate aquaretic side effects. Tolvaptan treatment showed no negative impact on QoL but further investigations in larger cohorts are needed.

Using continuous electrical conductivity measurements to derive major solute concentrations in karst systems

AbstractHydrochemical data of karst springs provide valuable insights into the internal hydrodynamical functioning of karst systems and support model structure identification. However, the collection of high‐frequency time series of major solute species is limited by analysis costs. In this study, we develop a method to retrieve the individual solute concentration time series and their uncertainty at high temporal resolution for karst springs by using continuous observations of electrical conductivity () and low‐frequency ionic measurements. Due to the large ion content and non‐negligible concentrations of aqueous complexes in karst systems, the concentration of each solute species occurring as free ion and as part of aqueous complexes are computed separately. The concentration of species occurring as free ions are computed considering their contributions to the total , whereas the concentration of the species as part of complexes are obtained from speciation calculations. The pivotal role of the complexation processes for the reconstruction of solute concentration time series starting from the signal is investigated in two karstic catchments with different geologies and temporal resolution of the available hydrochemical datasets, that is the Kerschbaum dolostone system in Austria and the Baget limestone system in France. The results show that complexation processes are significant and should be considered for the estimation of the total solute concentration in case of SO4, Ca, Mg and HCO3. The signal of a karst spring can be used to interpolate and quantify the dynamics of those solutes characterized by large contribution (approximately >6%) to the total and low relative variability, that is HCO3, Ca and Mg. Moreover, the presented method can be used to estimate concentrations of solutes when applied to karst systems with stationary and hydrogeochemical homogeneous contributing area. On the contrary, the method is affected by large uncertainty in case of dynamic systems characterized by varying contributions of water from different geological areas. This study aims to contribute to the problem of hydrogeochemical data availability and to support future works on karst systems conceptualization.

Salinity and total dissolved solids measurements for natural waters: An overview and a new salinity method based on specific conductance and water type

The total concentration of dissolved constituents in water is routinely quantified by measurements of salinity or total dissolved solids (TDS). However, salinity and TDS are operationally defined by their analytical methods and are not equivalent for most waters. Furthermore, multiple methods are available to determine salinity and TDS, and these methods have inherent differences. TDS is defined as the mass of anhydrous residue remaining in a sample vessel after evaporation and subsequent oven drying at a defined temperature. Salinity is a measure of the mass of dissolved salts in a given mass of solution. In addition, there are approaches that quantify the total solute (TS) concentration, including gases. The purpose of this study is to develop a proxy method using specific conductance and major-ion water type to reliably predict salinity, TDS, and/or TS. Thus, we compared several methods to calculate salinity, TDS, and TS for 6391 surface water samples and conclude the following: TDS measurements are best suited for studies of anhydrous residue (e.g., evaporites); salinity determined by summing the speciated ion concentrations, termed S∑spec, is the most comprehensive method to represent the concentration of dissolved constituents in natural waters; and TS determinations are useful if dissolved CO2 and other gases are of interest. Thus, we utilized S∑spec to compare differences between the various salinity, TDS, and TS methods, and to develop a new proxy method to predict salinity based on specific conductance (SC) and major ion water type, termed SSC_WT. For the surface waters used in this study, the median difference between TDS and S∑Spec was between −19% and −24%, depending on the method. The median difference between SSC_WT and S∑Spec was −2.4% for the samples in this study. The SSC_WT approach is cost effective, rapid, and capable of providing reliable real-time salinity determinations at surface water sites where SC data are available and water type is known.

Hydroclimate Drives Seasonal Riverine Export Across a Gradient of Glacierized High‐Latitude Coastal Catchments

AbstractGlacierized coastal catchments of the Gulf of Alaska (GoA) are undergoing rapid hydrologic fluctuations in response to climate change. These catchments deliver dissolved and suspended inorganic and organic matter to nearshore marine environments, however, these glacierized coastal catchments are relatively understudied and little is known about total solute and particulate fluxes to the ocean. We present hydrologic, physical, and geochemical data collected during April–October 2019–2021 from 10 streams along gradients of glacial fed to non‐glacial (i.e., precipitation) fed, in one Southcentral and one Southeast Alaska region. Hydrologic data reveal that glaciers drive the seasonal runoff patterns. The ẟ18O signature and specific conductance show distinctive seasonal variations in stream water sources between the study regions apparently due to the large amounts of rain in Southeast Alaska. Total dissolved solids concentrations and yields were elevated in the Southcentral region, due to lithologic influence on dissolved loads, however, the hydroclimate is the primary driver of the timing of dissolved and suspended yields. We show the yields of dissolved organic carbon is higher and that the δ13CPOC is enriched in the Southeast streams illustrating contrasts in organic carbon export across the GoA. Finally, we illustrate how future yields of solutes and sediments to the GoA may change as watersheds evolve from glacial influenced to precipitation dominated. This integrated analysis provides insights into how watershed characteristics beyond glacier coverage control properties of freshwater inputs to the GoA and the importance of expanding study regions to multiple hydroclimate regimes.