Dissolved trace metal speciation in the Manuherikia River, Central Otago, New Zealand

1992 ◽  
Vol 43 (6) ◽  
pp. 1381 ◽  
Author(s):  
DJ Hawke ◽  
KA Hunter
Keyword(s):  
Trace Metals ◽  
Metal Speciation ◽  
Ionic Interactions ◽  
Ion Composition ◽  
River Temperature ◽  
Poor Indicator ◽  
Free Ion ◽  
Ion Activity ◽  
Ion Activities ◽  
Inorganic Speciation

The inorganic speciation of the trace metals Cu, Ni, Cd, Zn and Pb has been calculated for the pristine, subalpine Manuherikia River. Temperature, pH, ionic strength and major-ion composition were found to be important controls on the free-ion activity of trace metals. Metal -CO3-2 species were the most important complexes for Pb, Cu and Ni. The metal-HCO3- species was most important for Cd, and Zn was intermediate. Ni, Zn and Cd were present mainly as the free divalent ion, whereas Pb (up to 81% complexed) and Cu (up to 70% complexed) were strongly affected by ionic interactions. Free-ion activities of Cu2+ and Pb2+ were essentially constant along the length of the river despite significant increases in total dissolved-metal concentrations. Thus, for these metal ions, total dissolved concentrations are a poor indicator of biological availability.

scholarly journals Towards the Understanding of Water-in-Salt Electrolytes: Individual Ion Activities and Liquid Junction Potentials in Highly Concentrated Aqueous Solutions

2021 ◽  
Author(s):  
Damien Degoulange ◽  
Nicolas Dubouis ◽  
Alexis Grimaud
Keyword(s):  
Activity Coefficients ◽  
Operating Voltage ◽  
Redox Potentials ◽  
Liquid Junction ◽  
Nernst Potential ◽  
Concentrated Electrolytes ◽  
Ion Activity ◽  
Ion Activities ◽  
Single Ion Activity ◽  
Increased Activity

Highly concentrated electrolytes were recently proposed to improve the performances of aqueous electrochemical systems by delaying the water splitting and increasing the operating voltage for battery applications. While advances were made regarding their implementation in practical devices, debate exists regarding the physical origin for the delayed water reduction occurring at the electrode/electrolyte interface. Evidently, one difficulty resides in our lack of knowledge regarding ions activity arising from this novel class of electrolyte, it being necessary to estimate the Nernst potential of associated redox reactions such as Li<sup>+</sup> intercalation or the hydrogen evolution reaction. In this work, we first measured the potential shift of electrodes selective to either Li<sup>+</sup>, H<sup>+</sup> or Zn<sup>2+</sup> ions from diluted to highly concentrated regimes in LiCl or LiTFSI solutions. Observing similar shifts for these different cations and environments, we establish that shifts in redox potentials from diluted to highly concentrated regime originates in large from an increase junction potential, it being dependent on the ions activity coefficients that increase with concentration. While our study shows that single ion activity coefficients, unlike mean ion activity coefficients, cannot be captured by any electrochemical means, we demonstrate that protons concentration increases by approximatively two orders of magnitude from 1 mol.kg<sup>-1</sup> to 15-20 mol.kg<sup>-1</sup> solutions. Combined with the increased activity coefficients, this increases the activity of protons and thus the pH of highly concentrated solutions which appears acidic.

Modulation of intracellular Na+ activity and cardiac force by norepinephrine and Ca2+

1983 ◽  
Vol 244 (1) ◽  
pp. C110-C114 ◽  
Author(s):  
C. O. Lee ◽  
M. Vassalle
Keyword(s):  
Contractile Force ◽  
Intracellular Sodium ◽  
Sodium Ion ◽  
Purkinje Fibers ◽  
Intracellular Na Activity ◽  
Cardiac Purkinje Fibers ◽  
High Calcium ◽  
Ion Activity ◽  
Ion Activities ◽  
Stimulation Of

The actions of norepinephrine and high calcium on the electrical, mechanical, and intracellular sodium ion activities were studied in electrically driven canine cardiac Purkinje fibers under different conditions. It was found that norepinephrine and high calcium decrease intracellular sodium ion activity (aiNa). The exposure to either agent is followed by a transient decline of force that correlates with the lower aiNa. Inhibition of the Na+ -K+ pump by strophanthidin reduces or abolishes the decrease in aiNa by norepinephrine but not that by high calcium. It is concluded that norepinephrine and high calcium both decrease aiNa and thereby the contractile force but (unlike high calcium) norepinephrine acts through the stimulation of the Na+ -K+ pump.

Factors influencing the inorganic speciation of trace metal cations in fresh waters

1999 ◽  
Vol 50 (4) ◽  
pp. 367 ◽  
Author(s):  
Jonathan P. Kim ◽  
Keith A. Hunter ◽  
Malcolm R. Reid
Keyword(s):  
Natural Waters ◽  
Major Ions ◽  
Divalent Cations ◽  
Ion Composition ◽  
High Ph ◽  
River Waters ◽  
Inorganic Complexes ◽  
Effects Of Ph ◽  
Ph Range ◽  
Inorganic Speciation

The effects of pH and major ion composition on the chemical speciation of the divalent cations of Co, Ni, Cu, Zn, Pb and Cd have been examined after consideration of the available thermodynamic database for solution complexes of these ions. Calculations were made for two model river waters representing the 1% and 99% extremes in composition of global river waters. The results show that inorganic speciation behaviour is of two characteristic types: (a) Cu, Zn and Co are dominated by bis-hydroxy- complexes at high pH and show the greatest reduction in the fraction of free aquo ion with increasing pH; (b) Pb, Ni and Cd are dominated by carbonato- complexes at high pH and show a more gradual decrease in the fraction of free aquo ion with increasing pH. For Cu, Pb and Ni significant fractions of the labile forms of these metal ions are present as inorganic complexes in the pH range of most natural waters, whereas for Zn, Co and Cd this is true only at moderately high pH (pH >7.5). Complexing with the major ions SO42– and Cl– is important only at low pH in river waters of high ionic strength.

scholarly journals Measurement of Intracellular Calcium

1999 ◽  
Vol 79 (4) ◽  
pp. 1089-1125 ◽  
Author(s):  
Akiyuki Takahashi ◽  
Patricia Camacho ◽  
James D. Lechleiter ◽  
Brian Herman
Keyword(s):  
Laser Scanning ◽  
Cell Injury ◽  
Multiphoton Microscopy ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Ion Activity ◽  
Intracellular Ca ◽  
Ionic Changes ◽  
Ion Activities ◽  
Subcellular Level

To a certain extent, all cellular, physiological, and pathological phenomena that occur in cells are accompanied by ionic changes. The development of techniques allowing the measurement of such ion activities has contributed substantially to our understanding of normal and abnormal cellular function. Digital video microscopy, confocal laser scanning microscopy, and more recently multiphoton microscopy have allowed the precise spatial analysis of intracellular ion activity at the subcellular level in addition to measurement of its concentration. It is well known that Ca2+ regulates numerous physiological cellular phenomena as a second messenger as well as triggering pathological events such as cell injury and death. A number of methods have been developed to measure intracellular Ca2+. In this review, we summarize the advantages and pitfalls of a variety of Ca2+ indicators used in both optical and nonoptical techniques employed for measuring intracellular Ca2+ concentration.

scholarly journals When are metal complexes bioavailable?

2016 ◽  
Vol 13 (3) ◽  
pp. 425 ◽  
Author(s):  
Chun-Mei Zhao ◽  
Peter G.C. Campbell ◽  
Kevin J. Wilkinson
Keyword(s):  
Metal Complexes ◽  
Biotic Ligand Model ◽  
Metal Bioavailability ◽  
Biotic Ligand ◽  
Free Ion ◽  
Ion Activity ◽  
Classical Models ◽  
Kinetic Processes ◽  
Free Metal ◽  
Ligand Model

Environmental contextThe concentration of a free metal cation has proved to be a useful predictor of metal bioaccumulation and toxicity, as represented by the free ion activity and biotic ligand models. However, under certain circumstances, metal complexes have been shown to contribute to metal bioavailability. In the current mini-review, we summarise the studies where the classic models fail and organise them into categories based on the different uptake pathways and kinetic processes. Our goal is to define the limits within which currently used models such as the biotic ligand model (BLM) can be applied with confidence, and to identify how these models might be expanded. AbstractNumerous data from studies over the past 30 years have shown that metal uptake and toxicity are often best predicted by the concentrations of free metal cations, which has led to the development of the largely successful free-ion activity model (FIAM) and biotic ligand model (BLM). Nonetheless, some exceptions to these classical models, showing enhanced metal bioavailability in the presence of metal complexes, have also been documented, although it is not yet fully understood to what extent these exceptions can or should be generalised. Only a few studies have specifically measured the bioaccumulation or toxicity of metal complexes while carefully measuring or controlling metal speciation. Fewer still have verified the fundamental assumptions of the classical models, especially when dealing with metal complexes. In the current paper, we have summarised the exceptions to classical models and categorised them into five groups based on the fundamental uptake pathways and kinetic processes. Our aim is to summarise the mechanisms involved in the interaction of metal complexes with organisms and to improve the predictive capability of the classic models when dealing with complexes.

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