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Testing copper-speciation predictions in freshwaters over a wide range of metal–organic matter ratios

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Testing copper-speciation predictions in freshwaters over a wide range of metal–organic matter ratios. / Ahmed, Imad; Hamilton-Taylor, John; Lofts, Stephen; Meeussen, C. L.; Lin, Chun; Zhang, Hao; Davison, William.

In: Environmental Science and Technology, Vol. 47, No. 3, 2013, p. 1487–1495.

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Ahmed, Imad ; Hamilton-Taylor, John ; Lofts, Stephen ; Meeussen, C. L. ; Lin, Chun ; Zhang, Hao ; Davison, William. / Testing copper-speciation predictions in freshwaters over a wide range of metal–organic matter ratios. In: Environmental Science and Technology. 2013 ; Vol. 47, No. 3. pp. 1487–1495.

Bibtex

@article{db2866cada254450b25a5268073ce1cf,
title = "Testing copper-speciation predictions in freshwaters over a wide range of metal–organic matter ratios",
abstract = "The harsh chemical conditions involved in the isolation of fulvic acids (FA) and humic acids (HA) have been identified as a possible contributing factor to the significant mismatch between in situ measurements and model predictions of trace metal speciation in freshwaters, resulting from the use of isolated FA and HA in model calibration. A set of experimental assays were developed to enable Cu binding to DOM to be measured over the full range of [Cu]/[DOC] ratios (1–460 μmol g–1) observed in surface freshwaters. They were applied to the widely used and traditionally isolated Suwannee River HA and FA and to DOM isolated from headwater streams by a mild procedure using minimal chemical treatment. Good agreement was observed between measured free ion activities and those predicted using both WHAM/Model VII and NICA–Donnan speciation models for both traditionally and mildly isolated DOM. Agreement to within a factor of 2 for WHAM/Model VII contrasts with 100-fold differences previously reported between in situ Cu2+ measurements and model predictions for a wide range of conditions. The results demonstrate that (a) existing speciation models are capable of accurately predicting Cu-humic binding in natural waters at environmentally realistic [Cu]/[DOC] ratios, under equilibrium conditions, and (b) that the isolation procedures traditionally used for HA and FA do not appreciably affect their binding characteristics.",
keywords = "Geochemical Speciation, Organic Matter, WHAM, NICA-Donnan, Freshwater",
author = "Imad Ahmed and John Hamilton-Taylor and Stephen Lofts and Meeussen, {C. L.} and Chun Lin and Hao Zhang and William Davison",
year = "2013",
doi = "10.1021/es304150n",
language = "English",
volume = "47",
pages = "1487–1495",
journal = "Environmental Science and Technology",
issn = "0013-936X",
publisher = "American Chemical Society",
number = "3",

}

RIS

TY - JOUR

T1 - Testing copper-speciation predictions in freshwaters over a wide range of metal–organic matter ratios

AU - Ahmed, Imad

AU - Hamilton-Taylor, John

AU - Lofts, Stephen

AU - Meeussen, C. L.

AU - Lin, Chun

AU - Zhang, Hao

AU - Davison, William

PY - 2013

Y1 - 2013

N2 - The harsh chemical conditions involved in the isolation of fulvic acids (FA) and humic acids (HA) have been identified as a possible contributing factor to the significant mismatch between in situ measurements and model predictions of trace metal speciation in freshwaters, resulting from the use of isolated FA and HA in model calibration. A set of experimental assays were developed to enable Cu binding to DOM to be measured over the full range of [Cu]/[DOC] ratios (1–460 μmol g–1) observed in surface freshwaters. They were applied to the widely used and traditionally isolated Suwannee River HA and FA and to DOM isolated from headwater streams by a mild procedure using minimal chemical treatment. Good agreement was observed between measured free ion activities and those predicted using both WHAM/Model VII and NICA–Donnan speciation models for both traditionally and mildly isolated DOM. Agreement to within a factor of 2 for WHAM/Model VII contrasts with 100-fold differences previously reported between in situ Cu2+ measurements and model predictions for a wide range of conditions. The results demonstrate that (a) existing speciation models are capable of accurately predicting Cu-humic binding in natural waters at environmentally realistic [Cu]/[DOC] ratios, under equilibrium conditions, and (b) that the isolation procedures traditionally used for HA and FA do not appreciably affect their binding characteristics.

AB - The harsh chemical conditions involved in the isolation of fulvic acids (FA) and humic acids (HA) have been identified as a possible contributing factor to the significant mismatch between in situ measurements and model predictions of trace metal speciation in freshwaters, resulting from the use of isolated FA and HA in model calibration. A set of experimental assays were developed to enable Cu binding to DOM to be measured over the full range of [Cu]/[DOC] ratios (1–460 μmol g–1) observed in surface freshwaters. They were applied to the widely used and traditionally isolated Suwannee River HA and FA and to DOM isolated from headwater streams by a mild procedure using minimal chemical treatment. Good agreement was observed between measured free ion activities and those predicted using both WHAM/Model VII and NICA–Donnan speciation models for both traditionally and mildly isolated DOM. Agreement to within a factor of 2 for WHAM/Model VII contrasts with 100-fold differences previously reported between in situ Cu2+ measurements and model predictions for a wide range of conditions. The results demonstrate that (a) existing speciation models are capable of accurately predicting Cu-humic binding in natural waters at environmentally realistic [Cu]/[DOC] ratios, under equilibrium conditions, and (b) that the isolation procedures traditionally used for HA and FA do not appreciably affect their binding characteristics.

KW - Geochemical Speciation

KW - Organic Matter

KW - WHAM

KW - NICA-Donnan

KW - Freshwater

U2 - 10.1021/es304150n

DO - 10.1021/es304150n

M3 - Journal article

VL - 47

SP - 1487

EP - 1495

JO - Environmental Science and Technology

JF - Environmental Science and Technology

SN - 0013-936X

IS - 3

ER -