The effects of acidic deposition on cation leaching from three deciduous forest canopies

1985 ◽  
Vol 15 (6) ◽  
pp. 1055-1060 ◽  
Author(s):  
Gary M. Lovett ◽  
Steven E. Lindberg ◽  
Daniel D. Richter ◽  
Dale W. Johnson
Keyword(s):  
Acidic Deposition ◽  
Deciduous Forest ◽  
Major Ions ◽  
Exchange Process ◽  
Charge Balance ◽  
Exchange Reactions ◽  
Cation Leaching ◽  
Counter Ions ◽  
Deposition Effect ◽  
A Charge

Canopy leaching or retention of all major ions was determined for three deciduous forests in eastern Tennessee that are currently receiving wet and dry acidic deposition. For all three canopies, the retention of atmospherically deposited cations (H+ and [Formula: see text]) exceeded retention of deposited anions [Formula: see text] on a charge-equivalent basis. Charge balance was maintained by ion exchange between the deposited cations and K+, Ca2+, and Mg2+ on the canopy surfaces. It was found that 40–60% of the leaching of K+, Ca2+, and Mg2+ from these canopies results from this exchange process, with the remainder attributable to coleaching with plant-derived anions. Because the cation exchange can be largely attributed to retention of deposited H+, we interpret it as a measure of the acidic deposition effect on foliar cation leaching. Dry deposition was found to be an important input for most of the major cations and anions. The data indicate that organic anions may be important counter ions to cation leaching, especially in the absence of acidic deposition, and that acid–base reactions in the canopy can obscure the true H+-exchange reactions between the deposition and the canopy.

Acidic atmospheric deposition and canopy interactions of adjacent deciduous and coniferous forests in the Georgia Piedmont

1993 ◽  
Vol 23 (6) ◽  
pp. 1114-1124 ◽  
Author(s):  
Rosanna Cappellato ◽  
Norman E. Peters ◽  
Harvey L. Ragsdale
Keyword(s):  
Atmospheric Deposition ◽  
Deciduous Forest ◽  
Major Ions ◽  
Coniferous Forest ◽  
Base Cations ◽  
Base Cation ◽  
Coniferous Forests ◽  
Cation Leaching ◽  
Major Mechanism ◽  
Georgia Piedmont

The effects of acidic atmospheric deposition on leaching of base cations from the canopy and the origin of the major ions in throughfall and stemflow were evaluated in a 2-year study of adjacent deciduous and coniferous forests at Panola Mountain Research Watershed in the Georgia Piedmont. In each forest, the NO3− and SO42− in throughfall and stemflow were derived primarily from atmospheric deposition, whereas the base cations Ca2+, Mg2+, and K+ were derived primarily from canopy leaching. Acidic atmospheric deposition was partially neutralized in each forest. Exchange of H+ with base cations appeared to be the major mechanism for the neutralization of atmospheric acidity by the deciduous canopy. Major neutralization mechanisms could not be differentiated in the coniferous canopy. Base-cation leaching accounted for 86% of the base cations in throughfall and stemflow in the deciduous forest and 69% in the coniferous forest. Exchange with H+ accounted for about 30% of base cations in throughfall in the deciduous forest, whereas it could not be clearly estimated in coniferous throughfall. The current level of acidic atmospheric deposition is hypothesized to have caused an increased leaching of base cations of the deciduous canopy, but methods were insufficient to determine its effect on the coniferous canopy.

scholarly journals Polyelectrolyte Gels: A Unique Class of Soft Materials

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 102
Author(s):  
Ferenc Horkay
Keyword(s):  
Exchange Process ◽  
Interaction Strength ◽  
Soft Materials ◽  
Industrial Applications ◽  
Future Research ◽  
Swelling Kinetics ◽  
Polyelectrolyte Gels ◽  
Ion Exchange Process ◽  
Counter Ions ◽  
Kinetics Of

The objective of this article is to introduce the readers to the field of polyelectrolyte gels. These materials are common in living systems and have great importance in many biomedical and industrial applications. In the first part of this paper, we briefly review some characteristic properties of polymer gels with an emphasis on the unique features of this type of soft material. Unsolved problems and possible future research directions are highlighted. In the second part, we focus on the typical behavior of polyelectrolyte gels. Many biological materials (e.g., tissues) are charged (mainly anionic) polyelectrolyte gels. Examples are shown to illustrate the effect of counter-ions on the osmotic swelling behavior and the kinetics of the swelling of model polyelectrolyte gels. These systems exhibit a volume transition as the concentration of higher valence counter-ions is gradually increased in the equilibrium bath. A hierarchy is established in the interaction strength between the cations and charged polymer molecules according to the chemical group to which the ions belong. The swelling kinetics of sodium polyacrylate hydrogels is investigated in NaCl solutions and in solutions containing both NaCl and CaCl2. In the presence of higher valence counter-ions, the swelling/shrinking behavior of these gels is governed by the diffusion of free ions in the swollen network, the ion exchange process and the coexistence of swollen and collapsed states.

Low Temperature Phase Transition (Pt) and Defect Formation (Df) in Silicon with Dioxide Inclusions Under X-Ray Irradiation

1995 ◽  
Vol 396 ◽  
Author(s):  
SH.M. Makhkamov ◽  
S.N. Abdurakhmanova
Keyword(s):  
Phase Transition ◽  
Charge Exchange ◽  
Defect Formation ◽  
Exchange Process ◽  
Temperature Phase ◽  
X Rays ◽  
Charge Exchange Process ◽  
X Ray ◽  
Temperature Phase Transition ◽  
A Charge

AbstractStudies of galvanomagnetic and electrical parameters of p- type Si : SiO2 in the temperature range 80 – 400 K have shown that X-ray irradiation at 80 K (Mo Ka,β and braking radiation hvmax. = 50 heV) leads to various transformations of the spectrum of electron- hole states in the band gap of such material, depending on the flux density of the X-rays. Two main processes are observed: the defect (vacancy and divacancy) formation and a charge exchange of native defects localized at the Si – SiO2 interface. The charge exchange process is rather collective and stimulated one because it is in response to an X-ray-induced ferroelectric phase transition in the SiO2- phase.

scholarly journals Productivity and Quality Responses of Salt-Stressed Roses to Supplemental Calcium

2014 ◽  
Vol 32 (3) ◽  
pp. 155-162
Author(s):  
Alma R. Solís-Pérez ◽  
Raul I. Cabrera
Keyword(s):  
Chemical Composition ◽  
Major Ions ◽  
Shoot Length ◽  
Plant Tissues ◽  
Sodium Accumulation ◽  
Leaf Chlorophyll ◽  
Counter Ions ◽  
Supplemental Calcium ◽  
Leaf Tissues ◽  
Chlorophyll Index

Plants of Rosa × spp. L. ‘Happy Hour’ grafted on the rootstocks R. × ‘Manetti’ and R. × ‘Natal Briar’ were salinized with 12 mM NaCl and received supplemental calcium (Ca) applications (as CaSO4) of 0, 2.5, 5.0, 7.5 and 10 mM. Additional plants were salinized with 6 mM Na2SO4 and supplemented with 5 mM CaSO4 and compared to non-salinized, no supplemental Ca control plants. Cumulative flowers harvested, shoot length and leaf chlorophyll index were similar for both rootstocks across salt treatments, but Manetti plants had higher dry weights in flowers and most plant tissues except roots. Productivity and water relations in NaCl-salinized plants were not responsive to supplemental Ca. Conversely, calcium-supplemented plants salinized with Na2SO4 had better productivity and quality than those with NaCl, and were similar to non-stressed control plants. Salt injury symptoms were evident only on NaCl-treated plants, regardless of Ca supplements, and closely associated with chloride, but not sodium, accumulation, in leaf tissues. The extent of the ameliorative properties of supplemental calcium applications on salinized rose plants is influenced by the salinity level, the chemical composition of the salinizing solution (major ions and counter-ions) and the cultivar (scion) and rootstock selection.

Speciation Calculations

1993 ◽  
Author(s):  
Greg M. Anderson ◽  
David A. Crerar
Keyword(s):  
Water Solution ◽  
Chemical Species ◽  
General Rule ◽  
Charge Balance ◽  
Complex Ions ◽  
Chemical Systems ◽  
Unknown Species ◽  
Acetic Acid Water ◽  
Equilibrium Concentrations ◽  
A Charge

This chapter focuses on one of the most common questions asked about natural chemical systems: what are the concentrations or activities of the different species present in a system at complete chemical equilibrium? We might be concerned, for example, with oxygen or sulfur fugacities, with the activities of complex ions, or activity ratios of reduced and oxidized species of the same component. In practice, these calculations range from trivially simple to enormously complex, depending on the number of species (and components) in the system. We will follow roughly this order—from trivial to complex—and outline some of the most common approaches used in performing speciation calculations. This simplest procedure is probably used most often, and works best with systems containing relatively few chemical species. As a general rule of thumb, you might try this if there are fewer than 10 species, but move on to another more sophisticated method for more complicated systems. As an example, we will solve for the equilibrium concentrations of all species in an acetic acid + water solution of a given concentration, m. Specifically, we might be interested in the pH of a 0.1 m HAc solution, but in calculating this we will also get the activities of all other species, whether we need them or not. This is one of the simplest examples imaginable, but the method works exactly the same way with more complicated systems. An excellent reference on this general approach is Butler (1964, Chap. 3). There are six steps to follow:… 1. Write all species of relevance or interest. Count the number of unknown species. You will need this many equations. 2. Write all known equilibrium constant equations. 3. If there are charged species, write a charge balance equation. 4. Write all known mass balance equations. 5. You should now have the same number of equations as unknown species. Reduce these by algebraic substitution to one (or two) equations that can be solved for the unknown concentrations. At first, assume all activity coefficients are 1.0.

scholarly journals A Charge-Equalization Circuit with an Intermediate Resonant Energy Tank

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6566
Author(s):  
Yao-Ching Hsieh ◽  
You-Chun Huang ◽  
Po-Chun Chuang
Keyword(s):  
Lithium Iron Phosphate ◽  
Control Unit ◽  
Iron Phosphate ◽  
Intermediate Energy ◽  
Open Circuit ◽  
Charge Balance ◽  
Resonant Energy ◽  
Zero Current Switching ◽  
Zero Current ◽  
A Charge

In this paper, we propose a novel charge-equalization circuit for series-connected batteries. The circuit is composed of an intermediate resonant energy tank, formed by an inductor and a capacitor, and selection switches connected to each battery. The advantage of the proposed circuit is that an exchange of unbalanced charge can be established between any two batteries via the intermediate energy tank. In addition, more than one adjacent battery can serve as a charge-transference party on either side through proper activation of the associated selection switches. Moreover, by virtue of the resonant tank, zero-current switching can be achieved to significantly reduce the transference losses. A laboratory circuit with a control unit was designed for eight 2.5 Ah lithium iron phosphate (LiFePO4) batteries in series. The test results demonstrate that the proposed charge-equalization circuit can realize charge balance effectively. With the charge-equalization circuit, the worst open-circuit voltage difference can be reduced to less than 20 mV under offline conditions, which helps the batteries operate more efficiently.

ON THE VANISHING COUPLINGS IN $\hat{A}\hat{D}\hat{E}$ AFFINE TODA FIELD THEORIES

1992 ◽  
Vol 07 (23) ◽  
pp. 5707-5718
Author(s):  
YOSHIHIRO SAITOH ◽  
TOKUZO SHIMADA
Keyword(s):  
Field Theory ◽  
Field Theories ◽  
Charge Balance ◽  
Massless Theory ◽  
Balance Condition ◽  
Interaction Terms ◽  
Exponential Interaction ◽  
A Charge ◽  
Higher Order Corrections ◽  
Toda Field Theory

We show that certain vanishing couplings in the [Formula: see text] affine Toda field theories remain vanishing even after higher-order corrections are included. This is a requisite property for the Lagrangian formulation of the theory. We develop a new perturbative formulation and treat affine Toda field theories as a massless theory with exponential interaction terms. We show that the nonrenormalization comes from the Dynkin automorphism of the Lie algebra associated with these theories. A charge balance condition plays an important role in our scheme. The all-order nonrenormalization of vanishing couplings in [Formula: see text] affine Toda field theory is also proved in a standard massive scheme.

Nuclear magnetic resonance studies of ketone.BF3 complexes. I. Exchange reactions in methylene chloride solution

1968 ◽  
Vol 46 (12) ◽  
pp. 2147-2157 ◽  
Author(s):  
R. J. Gillespie ◽  
J. S. Hartman
Keyword(s):  
Chloride Solution ◽  
Methylene Chloride ◽  
Chemical Exchange ◽  
Exchange Process ◽  
Exchange Reactions ◽  
Methylene Chloride Solution ◽  
Donor Acceptor ◽  
Group 3 ◽  
Proton Resonances ◽  
Increasing Temperature

1H and 19F n.m.r. studies of BF3 adducts of some simple methyl ketones in methylene chloride solution have led to the following conclusions. (1) Only 1:1 adducts are formed which are not appreciably dissociated. (2) The down-field shifts of the proton resonances caused by complexation with BF3 are essentially independent of the ketone and depend only on the distance of the proton from the carbonyl group. (3) BF3 exchange is rapid on the n.m.r. time scale at room temperature, but the exchange process can be slowed sufficiently by lowering the temperature that separate signals due to free and complexed species can be observed. (4) Collapse of the 10B−11B isotope shift with increasing temperature showed that a second chemical exchange process, which exchanges fluorine among boron atoms, occurs in addition to the process of rapid breaking and re-forming of donor–acceptor bonds. A possible mechanism for this fluorine scrambling reaction is discussed.

Catalytic deuterium exchange reactions with organics. XXVII. The alkylbenzenes on self-activated Group VIII transition metals

1966 ◽  
Vol 19 (12) ◽  
pp. 2299 ◽  
Author(s):  
BD Fisher ◽  
JL Garnett
Keyword(s):  
Transition Metal Oxides ◽  
Exchange Process ◽  
Kinetic Studies ◽  
Platinum Oxide ◽  
Activation Process ◽  
Group Viii ◽  
Exchange Reactions ◽  
Π Complex ◽  
Cis And Trans ◽  
In Cis

Exchange reactions between heavy water and the alkylbenzenes have been investigated on the following self-activated Group VIII transition metal oxides: PtO2,2H2O; PdO; Rh2O3; IrO2,2H2O; RuO2,H2O; ReO2; and Ni2O3. All oxides except Ni2O3 are self-activated by benzene up to 180�. Order of ease of self-activation is Pt > Pd > Rh, Ru, Ir > Re > Ni. Trends in deuteration rates of the alkylbenzenes on self-activated platinum oxide are generally similar to those obtained on hydrogen prereduced platinum. At 130�, some differences in reactivity are observed and these are attributed to reagent displacement effects from the presence of small percentages of dimer (1%) associated with the self-activation process. Compared with hydrogen prereduced catalysts, significant differences in isotope orientation are observed with certain alkylbenzenes on self-activated catalysts. Multiple deuteration effects which are accentuated on self-activated catalysts have been used to confirm isotope orientation and also the participation of a π-complex mechanism for the exchange process. Isomerization and exchange in cis- and trans-stilbenes on self-activated platinum have also been interpreted by the dissociative n-complex substitution mechanism. The advantages of self-activated catalysts in general deuterium and tritium labelling work have been evaluated. Possible correlations between exchange results and electron spin resonance data for charge-transfer adsorption on the above oxides are discussed. Preliminary kinetic studies with self-activation are also reported.

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