Effects of ion pairing with calcium and magnesium on selenate availability to higher plants

Parker, David R.; Tice, Kathy R.; Thomason, David N.

doi:10.1002/etc.5620160324

Cited by 7 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The values of

(25°C) and

(25°C) are in good agreement with the values selected by the NEA (Table ) after reinterpreting the experimental data of Parker et al , who measured the Mg 2 + and Ca 2 + activities in selenate solutions with ion selective electrodes.…”

Section: Resultssupporting

confidence: 85%

“…In the most recent review on Se , formation constants were selected for eight aqueous complexes: MgSeO 4 (aq), CaSeO 4 (aq), MnSeO 4 (aq), CoSeO 4 (aq), NiSeO 4 (aq), ZnSeO 4 (aq), CdSeO 4 (aq), and UO 2 SeO 4 (aq). These formation constants were derived from seven publications using six different experimental methods: solubility , potentiometry , partition , calorimetry , spectrophotometry , or voltammetry . Selenate ions undergo relatively weak complexing interactions with these divalent cations since the formation constant logarithms range from 2.0 to 2.7 at infinite dilution.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Formation of MSeO₄(aq) complexes (M²⁺ = Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) studied as a function of temperature by affinity capillary electrophoresis

2013

View full text Add to dashboard Cite

Complexation of divalent cations (Mg(2+), Co(2+), Ni(2+), Cu(2+), Cd(2+)) by selenate ligand was studied by ACE (UV indirect detection) in 0.1 mol/L NaNO(3) ionic strength solutions at various temperatures (15, 25, 35, 45 and 55°C). For each solution, a unique peak was observed as a result of a fast equilibrium between the free ion and the complex (labile systems). The migration time corresponding to this peak changed as a function of the solution composition, namely the free and complexed metal concentrations, according to the complexation reactions. The results confirmed the formation of a unique 1:1 complex for each cation. The thermodynamic parameters were fitted to the experimental data at 0.1 mol/L ionic strength: (25°C) = -(6.5 ± 0.3), -(7.5 ± 0.3), -(7.7 ± 0.3), -(7.7 ± 0.3), and -(8.1 ± 0.3) kJ/mol and = 2.5 ± 0.2, 4.7 ± 0.4, 4.5 ± 0.6, 8.4 ± 1.1, and 7.2 ± 0.6 kJ/mol for M(2+) = Mg(2+), Co(2+), Ni(2+), Cu(2+), and Cd(2+), respectively. Complexes with alkaline earth and transition metal cations could be distinguished by their relative stabilities. The effect of the ionic medium was treated using the specific ion interaction theory and the thermodynamic parameters at infinite dilution were compared to previously published data on metal-selenate, metal-sulfate, and metal-chromate complexes.

show abstract

“…The values of

(25°C) and

Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Formation of MSeO₄(aq) complexes (M²⁺ = Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) studied as a function of temperature by affinity capillary electrophoresis

2013

View full text Add to dashboard Cite

show abstract

“…In the course of evaluating the Cu‐citrate stability constants, we also checked the Ca‐citrate constants using a Ca‐ISE as described previously [23] and test solutions containing 50 to 150 μM Ca and 40 to 350 μM citrate. With the published log K of 4.9 for the 1:1 CaL complex, the measured Ca 2+ activities exceeded the predicted values by 5 to 22%.…”

Section: Resultsmentioning

confidence: 99%

Reevaluating the free‐ion activity model of trace metal toxicity toward higher plants: Experimental evidence with copper and zinc

Parker

Pedler

Ahnstrom

et al. 2001

Enviro Toxic and Chemistry

Self Cite

View full text Add to dashboard Cite

Across a diverse spectrum of organisms, the absorption and toxicity of trace elements are usually correlated with the activity of the free metal ion, but reported exceptions to this generalization are increasing. For the first time, we tested the validity of the free-ion activity model (FIAM) in the case of terrestrial plants and organic acids that may be abundant in the soil solution and rhizosphere. Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate. Precautions were taken to prevent biodegradation of the organic acids, and its absence was confirmed by ion chromatography. Copper speciation was verified using a Cu-selective ion electrode, and published stability constants were modified to improve agreement between measured and calculated Cu2+ activities. With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity. No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn. Thus, exceptions to the FIAM occur with higher plants as well as with aquatic biota but do not seem to occur in a predictable or systematic fashion with respect to metal or organic acid under investigation. Several possible explanations for the observed departures from the FIAM are discussed, including the possibility of accidental cotransport of metal and ligand into the cytoplasm.

show abstract

“…For example, this review recommends selected data concerning the complexation of different cations by selenate ions. Only eight formation constants were selected for the following aqueous species: ZnSeO 4 (aq), CaSeO 4 (aq), NiSeO 4 (aq), CdSeO 4 (aq), CoSeO 4 (aq), MnSeO 4 (aq), MgSeO 4 (aq), UO 2 SeO 4 (aq), and were determined by conductimetry [9], potentiometry [10][11][12] or spectrophotometry [11]. Since the data selection was based on a single study for each cation, a new investigation of the formation of CaSeO 4 (aq) by CE is proposed.…”

Section: Introductionmentioning

confidence: 99%

Formation of CaSO₄(aq) and CaSeO₄(aq) studied as a function of ionic strength and temperature by CE

et al. 2009

View full text Add to dashboard Cite

Ca(2+) complexation by both sulfate and selenate ligands was studied by CE. The species were observed to give a unique retention peak as a result of a fast equilibrium between the free ions and the complexes. The change in the corresponding retention time was interpreted with respect to the equilibrium constant of the complexation reaction. The results confirmed the formation of CaSO(4)(aq) and CaSeO(4)(aq) under our experimental conditions. The formation data were derived from the series of measurements carried out at about 15, 25, 35, 45 and 55 degrees C in 0.1 mol/L NaNO(3) ionic strength solutions, and in 0.5 and 1.0 mol/L NaNO(3) ionic strength solutions at 25 degrees C. Using a constant enthalpy of reaction enabled to fit all the experimental data in a 0.1 mol/L medium, leading to the thermodynamic parameters: Delta(r)G(0.1M)(25 degrees C)=-(7.59+/-0.23) kJ/mol, Delta(r)H(0.1 M)=5.57+/-0.80 kJ/mol, and Delta(r)S(0.1 M)(25 degrees C)=44.0+/-3.0 J mol(-1) K(-1) for CaSO(4)(aq) and Delta(r)G(0.1 M)(25 degrees C)=-(6.66+/-0.23) kJ/mol, Delta(r)H(0.1 M)=6.45+/-0.73 kJ/mol, and Delta(r)S(0.1 M)(25 degrees C)=44.0+/-3.0 J mol(-1) K(-1) for CaSeO(4)(aq). Both formation reactions were found to be endothermic and entropy driven. CaSO(4)(aq) appears to be more stable than CaSeO(4)(aq) by 0.93 kJ/mol under these experimental conditions, which correlates with the difference of acidity of the anions as expected for interactions between hard acids and hard bases according to the hard and soft acids and bases theory. The effect of the ionic medium on the formation constants was successfully treated using the Specific ion Interaction Theory, leading to significantly different binary coefficients epsilon(NA+,SO(2-)(4)) = -(0.15 +/- 0.06) mol/kg-1 and epsilon(NA+,SO(2-)(4)) = -(0.26 +/- 0.10) mol/kg-1.

show abstract

Effects of ion pairing with calcium and magnesium on selenate availability to higher plants

Cited by 7 publications

References 11 publications

Formation of MSeO₄(aq) complexes (M²⁺ = Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) studied as a function of temperature by affinity capillary electrophoresis

Formation of MSeO₄(aq) complexes (M²⁺ = Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) studied as a function of temperature by affinity capillary electrophoresis

Reevaluating the free‐ion activity model of trace metal toxicity toward higher plants: Experimental evidence with copper and zinc

Formation of CaSO₄(aq) and CaSeO₄(aq) studied as a function of ionic strength and temperature by CE

Contact Info

Product

Resources

About

Effects of ion pairing with calcium and magnesium on selenate availability to higher plants

Cited by 7 publications

References 11 publications

Formation of MSeO4(aq) complexes (M2+ = Mg2+, Co2+, Ni2+, Cu2+, Cd2+) studied as a function of temperature by affinity capillary electrophoresis

Formation of MSeO4(aq) complexes (M2+ = Mg2+, Co2+, Ni2+, Cu2+, Cd2+) studied as a function of temperature by affinity capillary electrophoresis

Reevaluating the free‐ion activity model of trace metal toxicity toward higher plants: Experimental evidence with copper and zinc

Formation of CaSO4(aq) and CaSeO4(aq) studied as a function of ionic strength and temperature by CE

Contact Info

Product

Resources

About

Formation of MSeO₄(aq) complexes (M²⁺ = Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) studied as a function of temperature by affinity capillary electrophoresis

Formation of MSeO₄(aq) complexes (M²⁺ = Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) studied as a function of temperature by affinity capillary electrophoresis

Formation of CaSO₄(aq) and CaSeO₄(aq) studied as a function of ionic strength and temperature by CE