The Experts below are selected from a list of 2604 Experts worldwide ranked by ideXlab platform
Javiera Cervinisilva - One of the best experts on this subject based on the ideXlab platform.
-
steady state dissolution kinetics of mineral Ferric Phosphate in the presence of desferrioxamine b and oxalate ligands at ph 4 6 and t 24 0 6 c
Chemical Geology, 2012Co-Authors: Javiera Cervinisilva, Josh Kearns, Jillian F BanfieldAbstract:Abstract Ferric Phosphate (FePO4·2H2O) is one of the most common secondary Phosphate minerals in the environment. Nevertheless, few studies address the biological dissolution mechanism(s) of FePO4·2H2O. This paper reports steady-state dissolution rates of synthetic FePO4·2H2O at 4 ≤ pH0 ≤ 6 by desferrioxamine-B (DFO-B) and oxalate (Ox) ligands. The composition of the influent solution was 10 mM NaClO4, 5 mM MES buffer. The influent solution was adjusted to 4 ≤ pH0 ≤ 6 by adding aliquots of HNO3 or NaOH stock solution. The initial concentrations of DFO-B and Ox, [DFO-B]0 and [Ox]0, ranged from 0 to 135 μM, and 0 to 345 μM. Geochemical thermodynamic equilibrium modeling was conducted using MINEQL+ (Schecher and McAvoy, 1998). Speciation calculations were based on thermodynamic formation constants at 298.17 K, K298 (infinite dilution reference state). Ligand-promoted dissolution rates were determined after steady-state values. Iron concentrations in the effluent solution were quantified (t > 500 h). Typical effluent-flow rate was maintained at 0.10 ± 0.01 mL min− 1. The measured dissolution rate of FePO4·2H2O by DFO-B and Ox, RDFO–OxObs, was compared to the sum of dissolution rates by DFO-B (RDFO-B) or Ox (ROx), RDFO–OxSum (RDFO–OxSum = RDFO‐B + ROx). Results were analyzed using the t student test. Obtained data values with p ≤ 0.05 (⁎) and ≤ 0.01 (⁎⁎) were considered to differ statistically from control experiments. Dissolution rates by DFO-B (RDFO-B) increased with [DFOB]0, and no evidence of surface masking became apparent. By contrast, dissolution rates by Ox (ROx) varied with [Ox]0 and pH0. The kinetics of dissolution by Ox was not explained by a first-order mineral dissolution behavior. Dissolution rates by DFO-B and Ox (RDFO–OxObs) surpassed RDFO-B or ROx, and increased with proton activity. Reacting FePO4·2H2O with DFO-B and high amounts of Ox resulted in higher values for RDFO–OxObs relative to RDFO-B. Observed (RDFO–OxObs) to calculated (RDFO–OxSum = RDFO‐B + ROx) ratio was found to be highest at [DFOB]0 = 50 μM and [Ox]0 = 49 μM. Increases in the proton activity favors the dissolution of FePO4·2H2O by DFO-B and Ox, explained because the sequestration of Fe(III) at the surface vicinity in the form of adsorbed Fe(III)-oxalate complexes. A direct comparison between the dissolution behavior of FePO4·2H2O by DFO-B and Ox against those for goethite (α-FeOOH) and Al goethite (AlFeOOH) was conducted. The dissolution behavior was found to be a function of the mineral structure. RDFO-B values for FePO4·2H2O by 22.5 μM DFO-B surpassed those for α-FeOOH or α-AlFeOOH by 20 μM DFO-B, namely, 37, and 11.6 and 3–5 μmol kg− 1 h− 1, respectively. ROx values for FePO4·2H2O by 49 mM Ox surpassed that for α-FeOOH by 70 μM Ox or α-AlFeOOH by 50 μM Ox, namely, i.e., 12, and 0.7 and 0.1 μmol kg− 1 h− 1. The latter results agree with the idea of the inhibition of Fe release in goethite because its sequestration in the form of adsorbed Fe(III) oxalate complexes. In contrast, a different scenario holds true for dissolution by 50 μM DFO-B and 49 μM Ox. The dissolution rates for FePO4·2H2O, α-FeOOH, and α-AlFeOOH correspond to 50, and 39–42 and 71–129 μmol kg− 1 h− 1, respectively. The high extent of iron release from Al goethite is best explained because high-energy surface sites formed after Al substitution in goethite.
Akitami Ichihara - One of the best experts on this subject based on the ideXlab platform.
-
Ferric Phosphate-dissolving Compound, Alfafuran, from Alfalfa (Medicago sativa L.) in Response to Iron-deficiency Stress
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Akira Noguchi, Teruhiko Yoshihara, Akitami Ichihara, Susumu Sugihara, Masayoshi Koshino, Makoto Kojima, Yoshikuni MasaokaAbstract:A Ferric Phosphate-dissolving compound was isolated from alfalfa (Medicago sativa L.) and characterized as 2-(3,5-dihydroxyphenyl)-5,6-dihydroxybenzofuran, which was named alfafuran.
-
Dissolution of Ferric Phosphate by alfalfa (Medicago sativa L.) root exudates
Plant and Soil, 1993Co-Authors: Yoshikuni Masaoka, Teruhiko Yoshihara, Susumu Sugihara, Masayoshi Koshino, Makoto Kojima, Akitami IchiharaAbstract:Alfalfa ( Medicago sativa L.) was grown in hydroponic culture to investigate adaptation to Fe-deficiency. Root exudates released into the nutrient solution from Fe-deficient plants were trapped and condensed on an amberlite XAD-4 resin column. The diethyl ether fraction of these exudates dissolved Ferric Phosphate remarkably. The dissolving capability was about 62 times higher than that of root exudates obtained from Fe-sufficient plants in complete nutrient solution. The Fe-dissolving compound was separated and identified. It was a new natural compound with molecular formula C_14H_10O_5 and was identified as 2-(3′,5′-dihydroxyphenyl)-5,6-dihydroxybenzofuran by means of mass spectrometry and ^1H-nuclear magnetic resonance. This new compound worked as a phytoalexin and inhibited completely the fungal growth of Fusarium oxysporum f. sp. phaseoli .
Yoshikuni Masaoka - One of the best experts on this subject based on the ideXlab platform.
-
Characteristics of root Fe 3+ -reduction and root exudate secretion under Fe-deficient conditions in alfalfa
Plant Nutrition for Sustainable Food Production and Environment, 1997Co-Authors: Yusuke Arakawa, Yoshikuni MasaokaAbstract:The induction of Fe3+-reduction in intact root tissue and Ferric Phosphate dissolution by root exudates were examined periodically during culture of alfalfa in Fe-free medium. The Fe3+-reduction rate was highest (0.72 μmol g-1 hr-1) on day 10 of culture, and rapidly decreased thereafter. Fe3+-reductase activity might be negatively modulated by high Cu or Mn accumulation in the alfalfa plant. In contrast, Ferric Phosphate dissolution by root exudates increased abruptly on day 10 and was maintained at 13–33 nmol g-1 d-1 thereafter. The root exudate accounted for only 0.2% of Fe3+-reduction. In conclusion, Ferric Phosphate dissolution is controlled by different biochemical processes, but Fe3+-reductase activity is influenced by high intracellular Cu or Mn accumulation.
-
Ferric Phosphate-dissolving Compound, Alfafuran, from Alfalfa (Medicago sativa L.) in Response to Iron-deficiency Stress
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Akira Noguchi, Teruhiko Yoshihara, Akitami Ichihara, Susumu Sugihara, Masayoshi Koshino, Makoto Kojima, Yoshikuni MasaokaAbstract:A Ferric Phosphate-dissolving compound was isolated from alfalfa (Medicago sativa L.) and characterized as 2-(3,5-dihydroxyphenyl)-5,6-dihydroxybenzofuran, which was named alfafuran.
-
Dissolution of Ferric Phosphate by alfalfa (Medicago sativa L.) root exudates
Plant and Soil, 1993Co-Authors: Yoshikuni Masaoka, Teruhiko Yoshihara, Susumu Sugihara, Masayoshi Koshino, Makoto Kojima, Akitami IchiharaAbstract:Alfalfa ( Medicago sativa L.) was grown in hydroponic culture to investigate adaptation to Fe-deficiency. Root exudates released into the nutrient solution from Fe-deficient plants were trapped and condensed on an amberlite XAD-4 resin column. The diethyl ether fraction of these exudates dissolved Ferric Phosphate remarkably. The dissolving capability was about 62 times higher than that of root exudates obtained from Fe-sufficient plants in complete nutrient solution. The Fe-dissolving compound was separated and identified. It was a new natural compound with molecular formula C_14H_10O_5 and was identified as 2-(3′,5′-dihydroxyphenyl)-5,6-dihydroxybenzofuran by means of mass spectrometry and ^1H-nuclear magnetic resonance. This new compound worked as a phytoalexin and inhibited completely the fungal growth of Fusarium oxysporum f. sp. phaseoli .
Jillian F Banfield - One of the best experts on this subject based on the ideXlab platform.
-
steady state dissolution kinetics of mineral Ferric Phosphate in the presence of desferrioxamine b and oxalate ligands at ph 4 6 and t 24 0 6 c
Chemical Geology, 2012Co-Authors: Javiera Cervinisilva, Josh Kearns, Jillian F BanfieldAbstract:Abstract Ferric Phosphate (FePO4·2H2O) is one of the most common secondary Phosphate minerals in the environment. Nevertheless, few studies address the biological dissolution mechanism(s) of FePO4·2H2O. This paper reports steady-state dissolution rates of synthetic FePO4·2H2O at 4 ≤ pH0 ≤ 6 by desferrioxamine-B (DFO-B) and oxalate (Ox) ligands. The composition of the influent solution was 10 mM NaClO4, 5 mM MES buffer. The influent solution was adjusted to 4 ≤ pH0 ≤ 6 by adding aliquots of HNO3 or NaOH stock solution. The initial concentrations of DFO-B and Ox, [DFO-B]0 and [Ox]0, ranged from 0 to 135 μM, and 0 to 345 μM. Geochemical thermodynamic equilibrium modeling was conducted using MINEQL+ (Schecher and McAvoy, 1998). Speciation calculations were based on thermodynamic formation constants at 298.17 K, K298 (infinite dilution reference state). Ligand-promoted dissolution rates were determined after steady-state values. Iron concentrations in the effluent solution were quantified (t > 500 h). Typical effluent-flow rate was maintained at 0.10 ± 0.01 mL min− 1. The measured dissolution rate of FePO4·2H2O by DFO-B and Ox, RDFO–OxObs, was compared to the sum of dissolution rates by DFO-B (RDFO-B) or Ox (ROx), RDFO–OxSum (RDFO–OxSum = RDFO‐B + ROx). Results were analyzed using the t student test. Obtained data values with p ≤ 0.05 (⁎) and ≤ 0.01 (⁎⁎) were considered to differ statistically from control experiments. Dissolution rates by DFO-B (RDFO-B) increased with [DFOB]0, and no evidence of surface masking became apparent. By contrast, dissolution rates by Ox (ROx) varied with [Ox]0 and pH0. The kinetics of dissolution by Ox was not explained by a first-order mineral dissolution behavior. Dissolution rates by DFO-B and Ox (RDFO–OxObs) surpassed RDFO-B or ROx, and increased with proton activity. Reacting FePO4·2H2O with DFO-B and high amounts of Ox resulted in higher values for RDFO–OxObs relative to RDFO-B. Observed (RDFO–OxObs) to calculated (RDFO–OxSum = RDFO‐B + ROx) ratio was found to be highest at [DFOB]0 = 50 μM and [Ox]0 = 49 μM. Increases in the proton activity favors the dissolution of FePO4·2H2O by DFO-B and Ox, explained because the sequestration of Fe(III) at the surface vicinity in the form of adsorbed Fe(III)-oxalate complexes. A direct comparison between the dissolution behavior of FePO4·2H2O by DFO-B and Ox against those for goethite (α-FeOOH) and Al goethite (AlFeOOH) was conducted. The dissolution behavior was found to be a function of the mineral structure. RDFO-B values for FePO4·2H2O by 22.5 μM DFO-B surpassed those for α-FeOOH or α-AlFeOOH by 20 μM DFO-B, namely, 37, and 11.6 and 3–5 μmol kg− 1 h− 1, respectively. ROx values for FePO4·2H2O by 49 mM Ox surpassed that for α-FeOOH by 70 μM Ox or α-AlFeOOH by 50 μM Ox, namely, i.e., 12, and 0.7 and 0.1 μmol kg− 1 h− 1. The latter results agree with the idea of the inhibition of Fe release in goethite because its sequestration in the form of adsorbed Fe(III) oxalate complexes. In contrast, a different scenario holds true for dissolution by 50 μM DFO-B and 49 μM Ox. The dissolution rates for FePO4·2H2O, α-FeOOH, and α-AlFeOOH correspond to 50, and 39–42 and 71–129 μmol kg− 1 h− 1, respectively. The high extent of iron release from Al goethite is best explained because high-energy surface sites formed after Al substitution in goethite.
-
Steady-state dissolution kinetics of mineral Ferric Phosphate in the presence of desferrioxamine-B and oxalate ligands at pH=4-6 and T=24±0.6°C
Chemical Geology, 2012Co-Authors: Javiera Cervini-silva, Josh Kearns, Jillian F BanfieldAbstract:Abstract Ferric Phosphate (FePO 4 ·2H 2 O) is one of the most common secondary Phosphate minerals in the environment. Nevertheless, few studies address the biological dissolution mechanism(s) of FePO 4 ·2H 2 O. This paper reports steady-state dissolution rates of synthetic FePO 4 ·2H 2 O at 4 ≤ pH 0 ≤ 6 by desferrioxamine-B (DFO-B) and oxalate (Ox) ligands. The composition of the influent solution was 10 mM NaClO 4 , 5 mM MES buffer. The influent solution was adjusted to 4 ≤ pH 0 ≤ 6 by adding aliquots of HNO 3 or NaOH stock solution. The initial concentrations of DFO-B and Ox, [DFO-B] 0 and [Ox] 0 , ranged from 0 to 135 μM, and 0 to 345 μM. Geochemical thermodynamic equilibrium modeling was conducted using MINEQL + (Schecher and McAvoy, 1998). Speciation calculations were based on thermodynamic formation constants at 298.17 K, K 298 (infinite dilution reference state). Ligand-promoted dissolution rates were determined after steady-state values. Iron concentrations in the effluent solution were quantified ( t > 500 h). Typical effluent-flow rate was maintained at 0.10 ± 0.01 mL min − 1 . The measured dissolution rate of FePO 4 ·2H 2 O by DFO-B and Ox, R DFO–Ox Obs , was compared to the sum of dissolution rates by DFO-B ( R DFO-B ) or Ox ( R Ox ), R DFO – Ox Sum ( R DFO – Ox Sum = R DFO ‐ B + R Ox ). Results were analyzed using the t student test. Obtained data values with p ≤ 0.05 ( ⁎ ) and ≤ 0.01 ( ⁎⁎ ) were considered to differ statistically from control experiments. Dissolution rates by DFO-B ( R DFO-B ) increased with [DFOB] 0 , and no evidence of surface masking became apparent. By contrast, dissolution rates by Ox ( R Ox ) varied with [Ox] 0 and pH 0 . The kinetics of dissolution by Ox was not explained by a first-order mineral dissolution behavior. Dissolution rates by DFO-B and Ox ( R DFO–Ox Obs ) surpassed R DFO-B or R Ox , and increased with proton activity. Reacting FePO 4 ·2H 2 O with DFO-B and high amounts of Ox resulted in higher values for R DFO–Ox Obs relative to R DFO-B . Observed ( R DFO – Ox Obs ) to calculated ( R DFO – Ox Sum = R DFO ‐ B + R Ox ) ratio was found to be highest at [DFOB] 0 = 50 μM and [Ox] 0 = 49 μM. Increases in the proton activity favors the dissolution of FePO 4 ·2H 2 O by DFO-B and Ox, explained because the sequestration of Fe(III) at the surface vicinity in the form of adsorbed Fe(III)-oxalate complexes. A direct comparison between the dissolution behavior of FePO 4 ·2H 2 O by DFO-B and Ox against those for goethite (α-FeOOH) and Al goethite (AlFeOOH) was conducted. The dissolution behavior was found to be a function of the mineral structure. R DFO-B values for FePO 4 ·2H 2 O by 22.5 μM DFO-B surpassed those for α-FeOOH or α-AlFeOOH by 20 μM DFO-B, namely, 37, and 11.6 and 3–5 μmol kg − 1 h − 1 , respectively. R Ox values for FePO 4 ·2H 2 O by 49 mM Ox surpassed that for α-FeOOH by 70 μM Ox or α-AlFeOOH by 50 μM Ox, namely, i.e., 12, and 0.7 and 0.1 μmol kg − 1 h − 1 . The latter results agree with the idea of the inhibition of Fe release in goethite because its sequestration in the form of adsorbed Fe(III) oxalate complexes. In contrast, a different scenario holds true for dissolution by 50 μM DFO-B and 49 μM Ox. The dissolution rates for FePO 4 ·2H 2 O, α-FeOOH, and α-AlFeOOH correspond to 50, and 39–42 and 71–129 μmol kg − 1 h − 1 , respectively. The high extent of iron release from Al goethite is best explained because high-energy surface sites formed after Al substitution in goethite.
Josh Kearns - One of the best experts on this subject based on the ideXlab platform.
-
steady state dissolution kinetics of mineral Ferric Phosphate in the presence of desferrioxamine b and oxalate ligands at ph 4 6 and t 24 0 6 c
Chemical Geology, 2012Co-Authors: Javiera Cervinisilva, Josh Kearns, Jillian F BanfieldAbstract:Abstract Ferric Phosphate (FePO4·2H2O) is one of the most common secondary Phosphate minerals in the environment. Nevertheless, few studies address the biological dissolution mechanism(s) of FePO4·2H2O. This paper reports steady-state dissolution rates of synthetic FePO4·2H2O at 4 ≤ pH0 ≤ 6 by desferrioxamine-B (DFO-B) and oxalate (Ox) ligands. The composition of the influent solution was 10 mM NaClO4, 5 mM MES buffer. The influent solution was adjusted to 4 ≤ pH0 ≤ 6 by adding aliquots of HNO3 or NaOH stock solution. The initial concentrations of DFO-B and Ox, [DFO-B]0 and [Ox]0, ranged from 0 to 135 μM, and 0 to 345 μM. Geochemical thermodynamic equilibrium modeling was conducted using MINEQL+ (Schecher and McAvoy, 1998). Speciation calculations were based on thermodynamic formation constants at 298.17 K, K298 (infinite dilution reference state). Ligand-promoted dissolution rates were determined after steady-state values. Iron concentrations in the effluent solution were quantified (t > 500 h). Typical effluent-flow rate was maintained at 0.10 ± 0.01 mL min− 1. The measured dissolution rate of FePO4·2H2O by DFO-B and Ox, RDFO–OxObs, was compared to the sum of dissolution rates by DFO-B (RDFO-B) or Ox (ROx), RDFO–OxSum (RDFO–OxSum = RDFO‐B + ROx). Results were analyzed using the t student test. Obtained data values with p ≤ 0.05 (⁎) and ≤ 0.01 (⁎⁎) were considered to differ statistically from control experiments. Dissolution rates by DFO-B (RDFO-B) increased with [DFOB]0, and no evidence of surface masking became apparent. By contrast, dissolution rates by Ox (ROx) varied with [Ox]0 and pH0. The kinetics of dissolution by Ox was not explained by a first-order mineral dissolution behavior. Dissolution rates by DFO-B and Ox (RDFO–OxObs) surpassed RDFO-B or ROx, and increased with proton activity. Reacting FePO4·2H2O with DFO-B and high amounts of Ox resulted in higher values for RDFO–OxObs relative to RDFO-B. Observed (RDFO–OxObs) to calculated (RDFO–OxSum = RDFO‐B + ROx) ratio was found to be highest at [DFOB]0 = 50 μM and [Ox]0 = 49 μM. Increases in the proton activity favors the dissolution of FePO4·2H2O by DFO-B and Ox, explained because the sequestration of Fe(III) at the surface vicinity in the form of adsorbed Fe(III)-oxalate complexes. A direct comparison between the dissolution behavior of FePO4·2H2O by DFO-B and Ox against those for goethite (α-FeOOH) and Al goethite (AlFeOOH) was conducted. The dissolution behavior was found to be a function of the mineral structure. RDFO-B values for FePO4·2H2O by 22.5 μM DFO-B surpassed those for α-FeOOH or α-AlFeOOH by 20 μM DFO-B, namely, 37, and 11.6 and 3–5 μmol kg− 1 h− 1, respectively. ROx values for FePO4·2H2O by 49 mM Ox surpassed that for α-FeOOH by 70 μM Ox or α-AlFeOOH by 50 μM Ox, namely, i.e., 12, and 0.7 and 0.1 μmol kg− 1 h− 1. The latter results agree with the idea of the inhibition of Fe release in goethite because its sequestration in the form of adsorbed Fe(III) oxalate complexes. In contrast, a different scenario holds true for dissolution by 50 μM DFO-B and 49 μM Ox. The dissolution rates for FePO4·2H2O, α-FeOOH, and α-AlFeOOH correspond to 50, and 39–42 and 71–129 μmol kg− 1 h− 1, respectively. The high extent of iron release from Al goethite is best explained because high-energy surface sites formed after Al substitution in goethite.
-
Steady-state dissolution kinetics of mineral Ferric Phosphate in the presence of desferrioxamine-B and oxalate ligands at pH=4-6 and T=24±0.6°C
Chemical Geology, 2012Co-Authors: Javiera Cervini-silva, Josh Kearns, Jillian F BanfieldAbstract:Abstract Ferric Phosphate (FePO 4 ·2H 2 O) is one of the most common secondary Phosphate minerals in the environment. Nevertheless, few studies address the biological dissolution mechanism(s) of FePO 4 ·2H 2 O. This paper reports steady-state dissolution rates of synthetic FePO 4 ·2H 2 O at 4 ≤ pH 0 ≤ 6 by desferrioxamine-B (DFO-B) and oxalate (Ox) ligands. The composition of the influent solution was 10 mM NaClO 4 , 5 mM MES buffer. The influent solution was adjusted to 4 ≤ pH 0 ≤ 6 by adding aliquots of HNO 3 or NaOH stock solution. The initial concentrations of DFO-B and Ox, [DFO-B] 0 and [Ox] 0 , ranged from 0 to 135 μM, and 0 to 345 μM. Geochemical thermodynamic equilibrium modeling was conducted using MINEQL + (Schecher and McAvoy, 1998). Speciation calculations were based on thermodynamic formation constants at 298.17 K, K 298 (infinite dilution reference state). Ligand-promoted dissolution rates were determined after steady-state values. Iron concentrations in the effluent solution were quantified ( t > 500 h). Typical effluent-flow rate was maintained at 0.10 ± 0.01 mL min − 1 . The measured dissolution rate of FePO 4 ·2H 2 O by DFO-B and Ox, R DFO–Ox Obs , was compared to the sum of dissolution rates by DFO-B ( R DFO-B ) or Ox ( R Ox ), R DFO – Ox Sum ( R DFO – Ox Sum = R DFO ‐ B + R Ox ). Results were analyzed using the t student test. Obtained data values with p ≤ 0.05 ( ⁎ ) and ≤ 0.01 ( ⁎⁎ ) were considered to differ statistically from control experiments. Dissolution rates by DFO-B ( R DFO-B ) increased with [DFOB] 0 , and no evidence of surface masking became apparent. By contrast, dissolution rates by Ox ( R Ox ) varied with [Ox] 0 and pH 0 . The kinetics of dissolution by Ox was not explained by a first-order mineral dissolution behavior. Dissolution rates by DFO-B and Ox ( R DFO–Ox Obs ) surpassed R DFO-B or R Ox , and increased with proton activity. Reacting FePO 4 ·2H 2 O with DFO-B and high amounts of Ox resulted in higher values for R DFO–Ox Obs relative to R DFO-B . Observed ( R DFO – Ox Obs ) to calculated ( R DFO – Ox Sum = R DFO ‐ B + R Ox ) ratio was found to be highest at [DFOB] 0 = 50 μM and [Ox] 0 = 49 μM. Increases in the proton activity favors the dissolution of FePO 4 ·2H 2 O by DFO-B and Ox, explained because the sequestration of Fe(III) at the surface vicinity in the form of adsorbed Fe(III)-oxalate complexes. A direct comparison between the dissolution behavior of FePO 4 ·2H 2 O by DFO-B and Ox against those for goethite (α-FeOOH) and Al goethite (AlFeOOH) was conducted. The dissolution behavior was found to be a function of the mineral structure. R DFO-B values for FePO 4 ·2H 2 O by 22.5 μM DFO-B surpassed those for α-FeOOH or α-AlFeOOH by 20 μM DFO-B, namely, 37, and 11.6 and 3–5 μmol kg − 1 h − 1 , respectively. R Ox values for FePO 4 ·2H 2 O by 49 mM Ox surpassed that for α-FeOOH by 70 μM Ox or α-AlFeOOH by 50 μM Ox, namely, i.e., 12, and 0.7 and 0.1 μmol kg − 1 h − 1 . The latter results agree with the idea of the inhibition of Fe release in goethite because its sequestration in the form of adsorbed Fe(III) oxalate complexes. In contrast, a different scenario holds true for dissolution by 50 μM DFO-B and 49 μM Ox. The dissolution rates for FePO 4 ·2H 2 O, α-FeOOH, and α-AlFeOOH correspond to 50, and 39–42 and 71–129 μmol kg − 1 h − 1 , respectively. The high extent of iron release from Al goethite is best explained because high-energy surface sites formed after Al substitution in goethite.