scholarly journals Sources and controls of calcium and magnesium in storm runoff: the role of groundwater and ion exchange reactions along water flowpaths

1997 ◽  
Vol 1 (3) ◽  
pp. 671-685 ◽  
Author(s):  
P. J. Chapman ◽  
B. Reynolds ◽  
H. S. Wheater
Keyword(s):  
Ion Exchange ◽  
Overland Flow ◽  
Divalent Cations ◽  
Stream Water ◽  
Storm Runoff ◽  
Natural Soil ◽  
Exchange Reactions ◽  
Mineral Horizon ◽  
Relative Contribution ◽  
Pipe Water

Abstract. A combined hydrological and chemical investigation was undertaken in a small moorland catchment at Plynlimon to determine the processes controlling storm runoff chemistry. Flow from natural soil pipes, overland flow from peat soils, throughflow from a mineral horizon and streamflow were gauged and sampled intensively during seven storms. Stormflow Ca and Mg concentrations in stream water consistently exceeded those observed in overland flow, pipeflow and throughflow. The response of Ca and Mg to increases in streamflow varied between the storms and could not be explained readily by the mixing of the dominant source waters monitored within the catchment. Intensive sampling of pipe water along a major stormflow pathway revealed a large and consistent increase in the concentration of dissolved Ca and Mg accompanied by a corresponding decrease in acidity, the magnitude of which was strongly influenced by antecedent conditions. Analyses of soil exchangeable cations along the stormflow pathway revealed soils enriched in divalent cations probably derived from a groundwater source. Laboratory leaching experiments confirmed that rapid cation exchange reactions could explain the changes in pipe water chemistry along the stormflow pathway. The relative contribution of flow from pathways where these ion exchange reactions occur strongly influences the stormflow response of Ca and Mg in the stream. The results also highlight a potentially important, indirect role for base-rich groundwater in modifying storm runoff chemistry along water flowpaths.

Modelling stream water chemistry with snowmelt

1984 ◽  
Vol 305 (1124) ◽  
pp. 427-439 ◽  
Keyword(s):  
Ion Exchange ◽  
Water Chemistry ◽  
Seasonal Variations ◽  
Stream Water ◽  
Acid Precipitation ◽  
Exchange Reactions ◽  
Stream Water Chemistry ◽  
Reservoir Models ◽  
Southern Norway ◽  
Adsorption Desorption

Simple hydrochemical reservoir models based on the mobile anion concept are described for the Birkenes and Storgam a catchments in southern Norway with acidified stream water. Key processes modelled include water routing, sulphate adsorption-desorption, ion-exchange reactions, weathering and a gibbsite equilibrium condition. The models reproduce much of the daily and seasonal variations in stream water chemistry which have been observed over several years. Model considerations have been used in an attempt to explain the acidification of stream water in these two areas. It is hypothesized that soil acidification has occurred and that acid precipitation is at least partly responsible. The results are tentative largely because the models are derived from present-day stream water chemistry.

Thermal effects in polyelectrolyte ion exchange reactions: the Jahn–Teller effect

1988 ◽  
Vol 66 (4) ◽  
pp. 974-978 ◽  
Author(s):  
Kang Sun ◽  
George E. Boyd
Keyword(s):  
Ion Exchange ◽  
Thermal Effects ◽  
Divalent Cations ◽  
Transition Element ◽  
Electronic Configuration ◽  
Standard State ◽  
Transition Elements ◽  
Exchange Reactions ◽  
Cubic Symmetry ◽  
Jahn Teller

Microcalorimetric determinations were made of the thermal effects accompanying the exchange of the divalent cations of Mn, Fe, Co, Ni, Cu, and Zn in dilute aqueous perchlorate solutions with Mg2+ ion initially bound in a crosslinked polyelectrolyte gel. The calorimetric measurements, together with microchemical equilibrium distribution determinations with the same cations, were employed to estimate the standard state Gibbs energy, enthalpy, and entropy changes associated with their ion exchange reactions.All the transition elements were selectively absorbed relative to Mg2+ with the sequence being: Mn < Fe < Co < Ni > Cu > Zn, showing divalent Ni(II) cation to possess the greatest affinity for the polyelectrolyte phase. The sequence of standard state reaction enthalpy change, ΔH0, revealed that Ni2+ also was the most exothermic of all 3d transition element cations. However, the ΔH0 values became more negative in the order: Mn < Fe < Co < Ni > Cu < Zn, showing that Cu2+ ion behaved anomalously in being less negative than expected. This behavior (and that in the ΔS0 values also) suggested that a destabilization of the octahedrally coordinated Cu2+ in aqueous solutions must occur, possibly because of Jahn–Teller effects on its d9 electronic configuration when the cation is placed in an environment of cubic symmetry. Because of a thermodynamic compensation of the magnitudes of ΔH0 and ΔS0, the position of Cu2+ in the ΔG0 value sequence was regular.

scholarly journals Ion Exchange Lithography: Localized Ion Exchange Reactions for Spatial Patterning of Perovskite Semiconductors and Insulators

2021 ◽  
pp. 2005291
Author(s):  
Lukas Helmbrecht ◽  
Moritz H. Futscher ◽  
Loreta A. Muscarella ◽  
Bruno Ehrler ◽  
Willem L. Noorduin
Keyword(s):  
Ion Exchange ◽  
Spatial Patterning ◽  
Exchange Reactions

Orthogonal Investigation of Influencing Factors on the Modification of Montmorillonite by THPC in Acid Conditions

2014 ◽  
Vol 936 ◽  
pp. 1017-1021
Author(s):  
Pan Chen ◽  
Jin Cheng Wang
Keyword(s):  
Reaction Time ◽  
Ion Exchange ◽  
Influencing Factors ◽  
Reaction Temperature ◽  
Orthogonal Test ◽  
Test Results ◽  
Phosphonium Salts ◽  
Exchange Reactions ◽  
Quaternary Phosphonium Salts

Na-MMT was modified with quaternary phosphonium salts, tetramethylolphosphonium chloride (THPC), via ion-exchange reactions, in acid conditions. Different factors such as reaction time , reaction temperature, the types of solvent, and CEC ratios, were investigated using orthogonal test. Results showed that the best combination of these four factors were A1B3C1D1, that is, the type of the solvent was acetone and water (1:1), reaction time was 3h, CEC ratio was 1:1, and the reaction temperature was 80°C.

Kinetics of Ion-Exchange Reactions in Hybrid Organic–Inorganic Perovskite Thin Films Studied by In Situ Real-Time X-ray Scattering

2018 ◽  
Vol 9 (23) ◽  
pp. 6750-6754 ◽  
Author(s):  
Alessandro Greco ◽  
Alexander Hinderhofer ◽  
M. Ibrahim Dar ◽  
Neha Arora ◽  
Jan Hagenlocher ◽  
...  
Keyword(s):  
Thin Films ◽  
Ion Exchange ◽  
Real Time ◽  
Exchange Reactions ◽  
Inorganic Perovskite ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Kinetics Of Ion Exchange

Overland flow during a storm event strongly affects stream water chemistry and bacterial community structure

2021 ◽  
Vol 84 (1) ◽  
Author(s):  
Huong T. Le ◽  
Thomas Pommier ◽  
Olivier Ribolzi ◽  
Bounsamay Soulileuth ◽  
Sylvain Huon ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Water Chemistry ◽  
Bacterial Community Structure ◽  
Overland Flow ◽  
Stream Water ◽  
Storm Event ◽  
Stream Water Chemistry

scholarly journals Thermodynamic Computations for Ion Exchange and Surface Protonation Reactions and the Implications for Acid Induced Contact Angle Evolution in Silica Rich Saline Aquifer Systems

2017 ◽  
Vol 9 (4) ◽  
pp. 98
Author(s):  
Mumuni Amadu ◽  
Adango Miadonye
Keyword(s):  
Ion Exchange ◽  
Gas Injection ◽  
Saline Aquifer ◽  
Geological Storage ◽  
Water Mobility ◽  
Free Energies ◽  
Exchange Reactions ◽  
Rock Interaction ◽  
Aquifer Systems ◽  
Thermodynamic Computations

To reduce current high concentrations of anthropogenic greenhouse gases in the atmosphere to levels stipulated by the Intergovernmental Panel on Climate Change, geological sequestration has been universally proposed. On the basis of cost analysis and global availability, deep saline aquifers are the prime targets for most proposed commercial and pilot scale projects.While the geological storage of anthropogenic carbon dioxide is expected to mitigate global warming, the technical aspects of the injection deserve to be considered for efficient injection projects. The water rock interaction phenomenon occurs due to carbonic acid generation which causes surface protonation reactions and has the potential to decrease water wettability of the system leading to enhanced water mobility and efficient gas injection. Therefore, for a saline aquifer rock with minerals capable of ion exchange reactions that consume solution protons, the wettability of such a system is likely to be preserved leading to reduced water mobility and poor gas injection. Generally, the extents to which surface protonation and ion exchange reactions occur depend on the free energy change of the reaction.In this paper, we have carried out thermodynamic computations for the free energies of surface protonation and ion exchange reactions. Based on the values of computed free energies, which show that ion exchange reactions have lower free energies, we have discussed the wettability implications for geological storage in silica rich saline aquifer systems.

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