THE ROLE OF SEASONAL SALT AND WATER FLUXES IN THE GENESIS OF SOLONETZIC B HORIZONS

1987 ◽  
Vol 67 (4) ◽  
pp. 721-730 ◽  
Author(s):  
S. FULLERTON (nee Landsburg) ◽  
S. PAWLUK
Keyword(s):  
Water Table ◽  
Water Flux ◽  
Dominant Mode ◽  
Salt Transport ◽  
Salt Flux ◽  
Water Fluxes ◽  
Moisture Movement ◽  
Soil Temperatures ◽  
Capillary Movement

Seasonal salt and water fluxes into Black Solonetz soils were evaluated at two sites in east-central Alberta. The dominant mode of moisture movement into the soil pedon was by capillary movement of water upwards from the water table. Solonization occurred in the Bntj horizons as a consequence of salt transport; the salts responsible were NaHCO3 and Na2SO4. Seasonal salt and water fluxes were identified at both research sites. From May to November when soil temperatures were above 0 °C, capillary movement and evaporation were the major mechanisms responsible for salt transport, concentration and deposition. From December to March when soil temperatures were below 0 °C water moved upwards from the water table towards the freezing zone depositing salts upon freezing. Key words: Genesis, solonetzic; season, groundwater, salt flux, water flux

Glomerulotubular balance in a mathematical model of the proximal nephron

1990 ◽  
Vol 258 (3) ◽  
pp. F612-F626 ◽  
Author(s):  
A. M. Weinstein
Keyword(s):  
Tight Junction ◽  
Proximal Tubule ◽  
Water Permeability ◽  
Water Flux ◽  
Salt Transport ◽  
Salt Flux ◽  
Filtration Fraction ◽  
Epithelial Junctions ◽  
Permeability Increase ◽  
Glomerulotubular Balance

A nonelectrolyte model of proximal tubule epithelium has been extended by the inclusion of a compliant tight junction. Here "compliance" signifies that both the junctional salt and water permeability increase and the salt reflection coefficient decreases in response to small pressure differences from lateral interspace to tubule lumen. In previous models of rat proximal tubule, there has been virtually no sensitivity of isotonic salt transport to changes in peritubular oncotic force. With the inclusion of junctional compliance, decreases in peritubular protein can open the junction and produce a secretory salt flux. Thus the model can represent the "backflux hypothesis," as it was originally put forth (J. E. Lewy and E. E. Windhager, Am. J. Physiol. 214: 943-954, 1968). Additional calculations, simulating a tight junction with negligible water permeability, reveal that the quantitative impact of peritubular protein can be realized whether or not there is substantial junctional water flux. The epithelial model of proximal tubule has also been incorporated into a model of the proximal nephron, complete with glomerulus, peritubular capillary, and interstitium. The interstitial compartment is well mixed and interstitial pressure and osmolality are determined iteratively to achieve balance between tubule reabsorption and capillary uptake. For this model, two domains of operation are identified. When interstitial pressures are low, junctions are closed, and filtration fraction has no effect on proximal reabsorption. When interstitial pressures are relatively elevated, epithelial junctions are open, and proximal salt reabsorption changes in proportion to changes in filtration fraction. In neither domain, however, does the model tubule augment salt flux with isolated increases in luminal flow rate (at constant filtration fraction). The absence of a separate effect of tubule fluid flow on salt transport precludes perfect glomerulotubular balance.

scholarly journals Fluid and solute transport across the retinal pigment epithelium: a theoretical model

2020 ◽  
Vol 17 (163) ◽  
pp. 20190735
Author(s):  
Mariia Dvoriashyna ◽  
Alexander J. E. Foss ◽  
Eamonn A. Gaffney ◽  
Rodolfo Repetto
Keyword(s):  
Ion Channels ◽  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Water Flux ◽  
Chemical Species ◽  
Osmotic Gradient ◽  
Water Fluxes ◽  
Fluid Accumulation

The retina is composed of two main layers—the neuroretina and the retinal pigment epithelium (RPE)—that are separated by a potential gap termed the sub-retinal space (SRS). Accumulation of fluid in the SRS may result in a retinal detachment. A key function of the RPE is to prevent fluid accumulation in the SRS by actively pumping fluid from this space to the choroid. We have developed a mathematical model of this process that incorporates the transport of seven chemical species: Na + , K + , Cl − , HCO 3 − , H + , CO 2 and H 2 CO 3 . This allows us to estimate solute and water fluxes and to understand the role of the different membrane ion channels. We have performed a global sensitivity analysis using the extended Fourier amplitude sensitivity test to investigate the relative importance of parameters in generating the model outputs. The model predicts that flow across the RPE is driven by an osmotic gradient in the cleft gap between adjacent cells. Moreover, the model estimates how water flux is modified in response to inhibition of membrane ion channels and carbonic anhydrase (CA). It provides a possible explanation for how CA inhibitors, which are used clinically to prevent fluid accumulation in the SRS, may be acting.

scholarly journals Transport Models of Ammonium Nitrogen in Wastewater from Rare Earth Smelteries by Reverse Osmosis Membranes

2020 ◽  
Vol 12 (15) ◽  
pp. 6230
Author(s):  
Shuanglin Gui ◽  
Zhaohuan Mai ◽  
Jiaqi Fu ◽  
Yuansong Wei ◽  
Jinbao Wan
Keyword(s):  
Rare Earth ◽  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Driving Force ◽  
Water Flux ◽  
Ammonium Nitrogen ◽  
Salt Transport ◽  
Salt Flux ◽  
Operating Pressure ◽  
Concentration Difference

Wastewater from rare earth smelteries contains large amounts of ammonium nitrogen (NH4+-N), which causes severe environmental problems. In this contribution, the desalination efficiency of reverse osmosis (RO) was investigated in the treatment of NH4Cl or NaCl solutions from 0.1 to 40 g/L under different operating pressures with a commercial RO membrane. Experimental results showed that when an operating pressure above 30 bar is applied to the 5 g/L NH4Cl solution, the permeate was found to meet the discharge standards of NH4+-N. Compared to NH4Cl, the permeate fluxes of NaCl solutions were higher due to the higher net driving force and lower propensity to membrane fouling. Theoretical models indicate a linear relationship between water flux and the net driving force for both NH4Cl and NaCl solutions. On the contrary, a power function between the salt flux and concentration difference correlated well with the experimental data for salt transport. The equations for water and salt transport obtained by this work would provide a facile and practical means for predicting the membrane performance in design and optimization of RO processes for the treatment of wastewater from the rare earth industry.

scholarly journals Evaluating Fertilizer-Drawn Forward Osmosis Performance in Treating Anaerobic Palm Oil Mill Effluent

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 566
Author(s):  
Ruwaida Abdul Wahid ◽  
Wei Lun Ang ◽  
Abdul Wahab Mohammad ◽  
Daniel James Johnson ◽  
Nidal Hilal
Keyword(s):  
Palm Oil ◽  
Pure Water ◽  
Water Flux ◽  
Forward Osmosis ◽  
Salt Flux ◽  
Palm Oil Mill Effluent ◽  
Performance Ratio ◽  
Water Recovery ◽  
Flux Decline ◽  
Palm Oil Mill

Fertilizer-drawn forward osmosis (FDFO) is a potential alternative to recover and reuse water and nutrients from agricultural wastewater, such as palm oil mill effluent that consists of 95% water and is rich in nutrients. This study investigated the potential of commercial fertilizers as draw solution (DS) in FDFO to treat anaerobic palm oil mill effluent (An-POME). The process parameters affecting FO were studied and optimized, which were then applied to fertilizer selection based on FO performance and fouling propensity. Six commonly used fertilizers were screened and assessed in terms of pure water flux (Jw) and reverse salt flux (JS). Ammonium sulfate ((NH4)2SO4), mono-ammonium phosphate (MAP), and potassium chloride (KCl) were further evaluated with An-POME. MAP showed the best performance against An-POME, with a high average water flux, low flux decline, the highest performance ratio (PR), and highest water recovery of 5.9% for a 4-h operation. In a 24-h fouling run, the average flux decline and water recovered were 84% and 15%, respectively. Both hydraulic flushing and osmotic backwashing cleaning were able to effectively restore the water flux. The results demonstrated that FDFO using commercial fertilizers has the potential for the treatment of An-POME for water recovery. Nevertheless, further investigation is needed to address challenges such as JS and the dilution factor of DS for direct use of fertigation.

‘Looping caves’ versus ‘water table caves’: The role of base-level changes and recharge variations in cave development

Geomorphology ◽  
2014 ◽  
Vol 204 ◽  
pp. 683-691 ◽  
Author(s):  
Franci Gabrovšek ◽  
Philipp Häuselmann ◽  
Philippe Audra
Keyword(s):  
Water Table ◽  
Base Level

Linking soil water and solutes fluxes to soil properties and vegetation types: insights from a case-study in the high tropical Andes of Ecuador

2021 ◽  
Author(s):  
Sebastián Páez-Bimos ◽  
Veerle Vanacker ◽  
Marcos Villacis ◽  
Marlon Calispa ◽  
Oscar Morales ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Conservation ◽  
Water Flux ◽  
Water Fluxes ◽  
Vegetation Types ◽  
Tropical Andes ◽  
Conservation Area ◽  
Solute Fluxes ◽  
Doc Concentration ◽  
Water Conservation Area

<p>The high tropical Andes ecosystem, known as páramo, provides important hydrological services to densely populated areas in the Andean region. In order to manage these services sustainably, it is crucial to understand the biotic and abiotic processes that control both water quality and fluxes. Recent research in the páramo highlights a knowledge gap regarding the role played by soil-vegetation interactions in controlling soil-water processes and resulting water and solute fluxes.</p><p>Here, we determine the hydrological and geochemical fluxes in four soil profiles in the páramo of the Antisana´s water conservation area in northern Ecuador. Water fluxes were measured biweekly with field fluxmeters in the hydrological year Apr/2019- Mar/2020 under two contrasting vegetation types: tussock-like grass (TU) and cushion-forming plants (CU). Soil solution was collected in parallel with wick samplers and suction caps for assessing the concentrations of dissolved cations, anions and organic carbon (DOC). In addition, soil moisture was measured continuously in the upper meter of the soil profile, i.e. first three horizons (A, 2A and 2BC), using water content reflectometers. The vertical water flux in the upper meter of each soil profile was simulated using the 1D HYDRUS model. We carried out a Sobol analysis to identify sensitive soil hydraulic parameters. We then derived water fluxes by inverse modeling, based on the measured soil moisture. We validated the calculated water fluxes using the fluxmeter data. Solute fluxes were estimated by combining the water fluxes and the soil solution compositions.</p><p>Our preliminary results suggest that water fluxes and DOC concentration vary under different vegetation types. The fluxmeter data from the 2A horizon indicates that the cumulative water flux under TU (2.8 - 5.7 l) was larger than under CU (0.8 – 1.1 l) during the dry season (Aug-Sep and Dec-Jan). However, the opposite trend was observed in the wet season for maximum water fluxes. Moreover, the DOC concentration in the uppermost horizon was higher under CU (47.3 ±2.2 mg l<sup>-1</sup>) than under TU (3.1 ±0.2 mg l<sup>-1</sup>) vegetation during the monitoring period. We associate the water and solute responses under different vegetation types to the contrasting soil hydro-physical and chemical properties (e.g., saturated hydraulic conductivity and organic carbon content) in the uppermost soil horizon. Our study illustrates the existence of a spatial association between vegetation types, water fluxes and solute concentrations in Antisana´s water conservation area. By modelling the hydrological balance of the upper meter of the soil mantle, the water and solute fluxes will be estimated for soils with different vegetation cover.</p><p> </p>

scholarly journals The Na+/H+ exchanger isoform 3 is required for active paracellular and transcellular Ca2+ transport across murine cecum

2013 ◽  
Vol 305 (4) ◽  
pp. G303-G313 ◽  
Author(s):  
Juraj Rievaj ◽  
Wanling Pan ◽  
Emmanuelle Cordat ◽  
R. Todd Alexander
Keyword(s):  
Water Movement ◽  
Water Flux ◽  
Wild Type Mouse ◽  
Wild Type ◽  
Rt Pcr ◽  
Ussing Chambers ◽  
Voltage Clamps ◽  
Paracellular Absorption ◽  
Mouse Intestine

Intestinal calcium (Ca2+) absorption occurs via paracellular and transcellular pathways. Although the transcellular route has been extensively studied, mechanisms mediating paracellular absorption are largely unexplored. Unlike passive diffusion, secondarily active paracellular Ca2+ uptake occurs against an electrochemical gradient with water flux providing the driving force. Water movement is dictated by concentration differences that are largely determined by Na+ fluxes. Consequently, we hypothesized that Na+ absorption mediates Ca2+ flux. NHE3 is central to intestinal Na+ absorption. NHE3 knockout mice (NHE3−/−) display impaired intestinal Na+, water, and Ca2+ absorption. However, the mechanism mediating this latter abnormality is not clear. To investigate this, we used Ussing chambers to measure net Ca2+ absorption across different segments of wild-type mouse intestine. The cecum was the only segment with net Ca2+ absorption. Quantitative RT-PCR measurements revealed cecal expression of all genes implicated in intestinal Ca2+ absorption, including NHE3. We therefore employed this segment for further studies. Inhibition of NHE3 with 100 μM 5-( N-ethyl- N-isopropyl) amiloride decreased luminal-to-serosal and increased serosal-to-luminal Ca2+ flux. NHE3−/− mice had a >60% decrease in luminal-to-serosal Ca2+ flux. Ussing chambers experiments under altered voltage clamps (−25, 0, +25 mV) showed decreased transcellular and secondarily active paracellular Ca2+ absorption in NHE3−/− mice relative to wild-type animals. Consistent with this, cecal Trpv6 expression was diminished in NHE3−/− mice. Together these results implicate NHE3 in intestinal Ca2+ absorption and support the theory that this is, at least partially, due to the role of NHE3 in Na+ and water absorption.

Unsettling Brian Eno'sMusic for Airports

2017 ◽  
Vol 14 (2) ◽  
pp. 305-333
Author(s):  
VICTOR SZABO
Keyword(s):  
Public Administration ◽  
Human Experience ◽  
Dominant Mode ◽  
Air Travel ◽  
Music Listening ◽  
Recorded Music ◽  
Personal Consumption ◽  
Ambient Music ◽  
Commercial Spaces

AbstractIn the liner notes to his albumAmbient 1: Music for Airports(1978), Brian Eno (1948–) defined Ambient music in contradistinction to Muzak's ‘derivative’ instrumental pop arrangements. Ambient music's historians and critics have often followed Eno by describing Ambient music as an alternative to conventional ‘background’ or ‘programmed’ music for commercial spaces. Such descriptions can be misleading, however, given that Ambient music's dominant mode of reception is selective personal consumption, not public administration. This article investigates the aesthetics of Eno'sAirports, and elucidates the organizing role of the Ambient genre, within their primary reception context of personal recorded music listening. A comparison with The Black Dog'sMusic for Real Airports(2010) shows how Ambient music then and now reflexively affords atmospheric use by translating a sense of physical dwelling and passage into mixed musical moods. By expressing ambivalenceaboutthe reality of airports and air travel, these Ambient records characteristically convey apprehension about the technological administration of human experience – a phenomenon that includes personal recorded music listening.

scholarly journals Consequences of Increased Variation in Peatland Hydrology for Carbon Storage: Legacy Effects of Drought and Flood in a Boreal Fen Ecosystem

2021 ◽  
Vol 8 ◽  
Author(s):  
Evan S. Kane ◽  
Catherine M. Dieleman ◽  
Danielle Rupp ◽  
Kevin H. Wyatt ◽  
Allison R. Rober ◽  
...  
Keyword(s):  
Water Table ◽  
Algal Biomass ◽  
Gross Primary Production ◽  
Temporal Trends ◽  
Sink Strength ◽  
Legacy Effects ◽  
Algal Production ◽  
Rich Fen ◽  
C Cycling

Globally important carbon (C) stores in boreal peatlands are vulnerable to altered hydrology through changes in precipitation and runoff patterns, groundwater inputs, and a changing cryosphere. These changes can affect the extent of boreal wetlands and their ability to sequester and transform C and other nutrients. Variation in precipitation patterns has also been increasing, with greater occurrences of both flooding and drought periods. Recent work has pointed to the increasing role of algal production in regulating C cycling during flooded periods in fen peatlands, but exactly how this affects the C sink-strength of these ecosystems is poorly understood. We evaluated temporal trends in algal biomass, ecosystem C uptake and respiration (using static and floating chamber techniques), and spectroscopic indicators of DOM quality (absorbance and fluorescence) in a boreal rich-fen peatland in which water table position had been experimentally manipulated for 13 years. Superimposed on the water table treatments were natural variations in hydrology, including periods of flooding, which allowed us to examine the legacy effects of flooding on C cycling dynamics. We had a particular focus on understanding the role of algae in regulating C cycling, as the relative contribution of algal production was observed to significantly increase with flooding. Ecosystem measures of gross primary production (GPP) increased with algal biomass, with higher algal biomass and GPP measured in the lowered water table treatment two years after persistent flooding. Prior to flooding the lowered treatment was the weakest C sink (as CO2), but this treatment became the strongest sink after flooding. The lower degree of humification (lower humification index, HIX) and yet lower bioavailability (higher spectral slope ratio, Sr) of DOM observed in the raised treatment prior to flooding persisted after two years of flooding. An index of free or bound proteins (tyrosine index, TI) increased with algal biomass across all plots during flooding, and was lowest in the raised treatment. As such, antecedent drainage conditions determined the sink-strength of this rich fen—which was also reflected in DOM characteristics. These findings indicate that monitoring flooding history and its effects on algal production could become important to estimates of C balance in northern wetlands.

The Na+-K+-ATPase α2-subunit isoform modulates contractility in the perinatal mouse diaphragm

2004 ◽  
Vol 287 (5) ◽  
pp. C1300-C1310 ◽  
Author(s):  
Tatiana L. Radzyukevich ◽  
Amy E. Moseley ◽  
Daniel A. Shelly ◽  
Gregory A. Redden ◽  
Michael M. Behbehani ◽  
...  
Keyword(s):  
Action Potential ◽  
Knockout Mice ◽  
Dominant Mode ◽  
Resting Potential ◽  
Force Frequency ◽  
Cellular Functions ◽  
Tetanic Force ◽  
Potential Threshold ◽  
Rate Of Activation

This study uses genetically altered mice to examine the contribution of the Na+-K+-ATPase α2 catalytic subunit to resting potential, excitability, and contractility of the perinatal diaphragm. The α2 protein is reduced by 38% in α2-heterozygous and absent in α2-knockout mice, and α1-isoform is upregulated 1.9-fold in α2-knockout. Resting potentials are depolarized by 0.8–4.0 mV in heterozygous and knockout mice. Action potential threshold, overshoot, and duration are normal. Spontaneous firing, a developmental function, is impaired in knockout diaphragm, but this does not compromise its ability to fire evoked action potential trains, the dominant mode of activation near birth. Maximum tetanic force, rate of activation, force-frequency and force-voltage relationships, and onset and magnitude of fatigue are not changed. The major phenotypic consequence of reduced α2 content is that relaxation from contraction is 1.7-fold faster. This finding reveals a distinct cellular role of the α2-isoform at a step after membrane excitation, which cannot be restored simply by increasing α1 content. Na+/Ca2+ exchanger expression decreases in parallel with α2-isoform, suggesting that Ca2+ extrusion is affected by the altered α2 genotype. There are no major compensatory changes in expression of sarcoplasmic reticulum Ca2+-ATPase, phospholamban, or plasma membrane Ca2+-ATPase. These results demonstrate that the Na+-K+-ATPase α1-isoform alone is able to maintain equilibrium K+ and Na+ gradients and to substitute for α2-isoform in most cellular functions related to excitability and force. They further indicate that the α2-isoform contributes significantly less at rest than expected from its proportional content but can modulate contractility during muscle contraction.

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