Theoretical prediction of single-site surface-protonation equilibrium constants for oxides and silicates in water

Sverjensky, Dimitri A.; Sahai, Nita

doi:10.1016/0016-7037(96)00207-4

Cited by 359 publications

(324 citation statements)

References 62 publications

Supporting

Mentioning

306

Contrasting

Unclassified

Order By: Relevance

“…Speciation calculations took account of aqueous complexation reactions involving all dissolved electrolyte and pH titrant ions (Na + , NO 3 -), autoionisation of water, and the speciation effects of atmospheric CO 2 dissolution (for experiments conducted in air) and aqueous complexation (Sverjensky and Sahai, 1996). Activity coefficients for aqueous species were calculated using a Debye-Huckel model.…”

Section: Surface Complexation Modellingmentioning

confidence: 99%

Surface-complexation modelling for describing adsorption of phosphate on hydrous ferric oxide surface

Mengistu

Tessema

Demlie

et al. 2015

WSA

View full text Add to dashboard Cite

Adsorption of dissolved phosphate onto synthetic hydrous ferric oxide (HFO) was measured in the laboratory as a function of pH, ionic strength, and phosphate relative concentration. Experimental data were used to constrain optimal values of surface complexation reactions using a geochemical modeling code JCHESS according to the diffuse layer model. The results provide a consistent set of model equilibrium constant (log K) values at 25° C and 100 KPa for the following reactions: These results differ significantly from previously-published estimates of log K 2 int and log K 3 int [1][2][3], and provide a more accurate fit to experimental measurements over a broad range of pH (3-12), ionic strength (0.001-0.1 mol/ℓ) and total relative phosphate concentration (12-500 µmol phosphate/g HFO). The results provide a close fit to the experimental data within a wide range of conditions, and should be adopted in modelling the chemical speciation of phosphate in natural systems containing HFO as a predominant adsorbing material.

show abstract

Section: Surface Complexation Modellingmentioning

confidence: 99%

Surface-complexation modelling for describing adsorption of phosphate on hydrous ferric oxide surface

Mengistu

Tessema

Demlie

et al. 2015

WSA

View full text Add to dashboard Cite

show abstract

“…Mobility of NH 4 + in aquifers is largely controlled by competitive cation exchange on clays (at low to neutral pH) and to Fe and Mn oxyhydroxides at pH N neutral (Sverjensky and Sahai, 1996;Buss et al, 2004). Ion concentration within the freshwater portion of the aquifer is generally high.…”

Section: Biogeochemical Conditions and Nutrient Concentrationsmentioning

confidence: 99%

Submarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer

Kroeger¹,

Swarzenski²,

Greenwood³

et al. 2007

Marine Chemistry

123

View full text Add to dashboard Cite

To separately quantify the roles of fresh and saline submarine groundwater discharge (SGD), relative to that of rivers, in transporting nutrients to Tampa Bay, Florida, we used three approaches (Darcy's Law calculations, a watershed water budget, and a 222 Rn mass-balance) to estimate rate of SGD from the Pinellas peninsula. Groundwater samples were collected in 69 locations in the coastal aquifer to examine biogeochemical conditions, nutrient concentrations and stoichiometry, and salinity structure. Salinity structure was also examined using stationary electrical resistivity measurements. The coastal aquifer along the Pinellas peninsula was chemically reducing in all locations sampled, and that condition influences nitrogen (N) form and mobility of N and PO 4 3− . Concentrations of NH 4 + , PO 4 3− and ratio of dissolved inorganic N (DIN) to PO 4 3− were all related to measured oxidation/reduction potential (pε) of the groundwater. Ratio of DIN: PO 4 3− was below Redfield ratio in both fresh and saline groundwater. Nitrogen occurred almost exclusively in reduced forms, NH 4 + and dissolved organic nitrogen (DON), suggesting that anthropogenic N is exported from the watershed in those forms. In comparison to other SGD studies, rate of PO 4 3− flux in the seepage zone (μM min Tampa Bay was higher than previous estimates, likely due to 1) high watershed population density, 2) chemically reducing conditions, and 3) high ion concentrations in fresh groundwater. Estimates of freshwater groundwater flux indicate that the ratio of groundwater discharge to stream flow is ∼ 20 to 50%, and that the magnitudes of both the total dissolved nitrogen and PO 4 3− loads due to fresh SGD are ∼ 40 to 100% of loads carried by streams. Estimates of SGD based on radon inventories in near-shore waters were 2 to 5 times greater than the estimates of freshwater groundwater discharge, suggesting that brackish and saline SGD is also an important process in Tampa Bay and results in flux of regenerated N and P from sediment to surface water. Published by Elsevier B.V.

show abstract

“…More recently, new approaches have been proposed. For instance, Sverjenski and Sahai (1996) and Crescenti and Sverjenski (1999) combine an Extended Triple Layer Model with a 2 pK approach for one surface site while a new multisite approach has been developed to account for the chemical heterogeneity of oxide surfaces (Hiemstra et al, 1989a,b). A comparison of the performance of the most commonly used surface complexation models can be found in Venema et al (1996a).…”

Section: Introductionmentioning

confidence: 99%

Metal ion binding to iron oxides

Ponthieu

Juillot

Hiemstra

et al. 2006

Geochimica et Cosmochimica Acta

144

View full text Add to dashboard Cite

Theoretical prediction of single-site surface-protonation equilibrium constants for oxides and silicates in water

Cited by 359 publications

References 62 publications

Surface-complexation modelling for describing adsorption of phosphate on hydrous ferric oxide surface

Surface-complexation modelling for describing adsorption of phosphate on hydrous ferric oxide surface

Submarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer

Metal ion binding to iron oxides

Contact Info

Product

Resources

About