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A comparative study of proton and alkaline earth metal binding by humic substances.

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A comparative study of proton and alkaline earth metal binding by humic substances. / Lead, J. R.; Hamilton-Taylor, J.; Hesketh, N.; Jones, M. N.; Wilkinson, A. E.; Tipping, E.

In: Analytica Chimica Acta, Vol. 294, No. 3, 30.08.1994, p. 319-327.

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Lead, J. R. ; Hamilton-Taylor, J. ; Hesketh, N. ; Jones, M. N. ; Wilkinson, A. E. ; Tipping, E. / A comparative study of proton and alkaline earth metal binding by humic substances. In: Analytica Chimica Acta. 1994 ; Vol. 294, No. 3. pp. 319-327.

Bibtex

@article{5684f6b1219d4266a38201660e364ab5,
title = "A comparative study of proton and alkaline earth metal binding by humic substances.",
abstract = "Humic substances (HS) were extracted from the soil and water of an upland catchment and characterised with respect to molecular weight, C, H, O, N and S contents and ash content. Three samples were obtained: peat humic acid, aquatic humic acid and aquatic fulvic acid. The weight average molecular weights were found to increase from 2400 for aquatic fulvic acid, to 6300 for aquatic humic acid and to 16500 for peat humic acid. Acid-base titrations were performed to assess the proton binding behaviour at different ionic strengths in NaCl and in the presence of important cation competitors (calcium and magnesium). The results from the titrations were fitted to a recently developed discrete-site/electrostatic model of cation-humic binding. Model parameters showed systematic trends with molecular weight and good agreement with parameters derived from the analysis of literature data. In the order peat humic, aquatic humic and aquatic fulvic acid, the milli-equivalents of carboxylic acid groups per gram of HS (nA) increased. In the same order both the negative log10 of the mid-range intrinsic proton dissociation constant for the strong acid groups (pKA) and the empirical constant, P, which accounts for electrostatic effects, decreased.",
keywords = "Humic substances, Proton and alkaline earth binding",
author = "Lead, {J. R.} and J. Hamilton-Taylor and N. Hesketh and Jones, {M. N.} and Wilkinson, {A. E.} and E. Tipping",
year = "1994",
month = aug,
day = "30",
doi = "10.1016/0003-2670(94)80316-1",
language = "English",
volume = "294",
pages = "319--327",
journal = "Analytica Chimica Acta",
issn = "0003-2670",
publisher = "Elsevier Science B.V.",
number = "3",

}

RIS

TY - JOUR

T1 - A comparative study of proton and alkaline earth metal binding by humic substances.

AU - Lead, J. R.

AU - Hamilton-Taylor, J.

AU - Hesketh, N.

AU - Jones, M. N.

AU - Wilkinson, A. E.

AU - Tipping, E.

PY - 1994/8/30

Y1 - 1994/8/30

N2 - Humic substances (HS) were extracted from the soil and water of an upland catchment and characterised with respect to molecular weight, C, H, O, N and S contents and ash content. Three samples were obtained: peat humic acid, aquatic humic acid and aquatic fulvic acid. The weight average molecular weights were found to increase from 2400 for aquatic fulvic acid, to 6300 for aquatic humic acid and to 16500 for peat humic acid. Acid-base titrations were performed to assess the proton binding behaviour at different ionic strengths in NaCl and in the presence of important cation competitors (calcium and magnesium). The results from the titrations were fitted to a recently developed discrete-site/electrostatic model of cation-humic binding. Model parameters showed systematic trends with molecular weight and good agreement with parameters derived from the analysis of literature data. In the order peat humic, aquatic humic and aquatic fulvic acid, the milli-equivalents of carboxylic acid groups per gram of HS (nA) increased. In the same order both the negative log10 of the mid-range intrinsic proton dissociation constant for the strong acid groups (pKA) and the empirical constant, P, which accounts for electrostatic effects, decreased.

AB - Humic substances (HS) were extracted from the soil and water of an upland catchment and characterised with respect to molecular weight, C, H, O, N and S contents and ash content. Three samples were obtained: peat humic acid, aquatic humic acid and aquatic fulvic acid. The weight average molecular weights were found to increase from 2400 for aquatic fulvic acid, to 6300 for aquatic humic acid and to 16500 for peat humic acid. Acid-base titrations were performed to assess the proton binding behaviour at different ionic strengths in NaCl and in the presence of important cation competitors (calcium and magnesium). The results from the titrations were fitted to a recently developed discrete-site/electrostatic model of cation-humic binding. Model parameters showed systematic trends with molecular weight and good agreement with parameters derived from the analysis of literature data. In the order peat humic, aquatic humic and aquatic fulvic acid, the milli-equivalents of carboxylic acid groups per gram of HS (nA) increased. In the same order both the negative log10 of the mid-range intrinsic proton dissociation constant for the strong acid groups (pKA) and the empirical constant, P, which accounts for electrostatic effects, decreased.

KW - Humic substances

KW - Proton and alkaline earth binding

U2 - 10.1016/0003-2670(94)80316-1

DO - 10.1016/0003-2670(94)80316-1

M3 - Journal article

VL - 294

SP - 319

EP - 327

JO - Analytica Chimica Acta

JF - Analytica Chimica Acta

SN - 0003-2670

IS - 3

ER -