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The effects of Dissolved Organic Mat...

Chen, Weibin.

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The effects of Dissolved Organic Matter (DOM) sources on Pb 2+, Zn2+ and Cd2+ binding.

Record Type:	Electronic resources : Monograph/item
Title/Author:	The effects of Dissolved Organic Matter (DOM) sources on Pb 2+, Zn2+ and Cd2+ binding./
Author:	Chen, Weibin.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
Description:	242 p.
Notes:	Source: Dissertation Abstracts International, Volume: 78-07(E), Section: B.
Contained By:	Dissertation Abstracts International78-07B(E).
Subject:	Analytical chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10256301
ISBN:	9781369552225

The effects of Dissolved Organic Matter (DOM) sources on Pb 2+, Zn2+ and Cd2+ binding.
Chen, Weibin.

The effects of Dissolved Organic Matter (DOM) sources on Pb 2+, Zn2+ and Cd2+ binding. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 242 p.

Source: Dissertation Abstracts International, Volume: 78-07(E), Section: B.

Thesis (Ph.D.)--Trent University (Canada), 2017.

Metal binding to dissolved organic matter (DOM) determines metal speciation and strongly influences potential toxicity. The understanding of this process, however, is challenged by DOM source variation, which is not always considered by most existing metal speciation models. Source determines the molecular structure of DOM, including metal binding functional groups. This study has experimentally showed that the allochthonous-dominant DOM (i.e. more aromatic and humic) consistently has higher level of Pb binding than the autochthonous-dominant DOM (i.e. more aliphatic and proteinaceous) by more than two orders of magnitude. This source-discrimination, however, is less noticeable for Zn and Cd, although variation still exceeds a factor of four for both metals. The results indicate that metal binding is source-dependent, but the dependency is metal-specific. Accordingly, metal speciation models, such as the Windermere Humic Aqueous Model (WHAM), needs to consider DOM source variations. The WHAM input of active fraction of DOM participating in metal binding (f) is sensitive to DOM source. The commonly-used f = 0.65 substantially overestimated the Pb and Zn binding to autochthonous-dominant DOM, indicating f needs to be adjusted specifically. The optimal f value (fopt) linearly correlates with optical indexes, showing a potential to estimate fopt using simple absorbance and/or fluorescence measurements. Other DOM properties not optically-characterized may be also important to determine f opt, such as thiol, which shows strong affinity to most toxic metals and whose concentrations are appreciably high in natural waters (< 0.1 to 400 nmol L-1). Other analytical techniques rather than Cathodic Stripping Voltammetry (CSV) are required to accurately quantify thiol concentration for DOM with concentration > 1 mg L-1. To better explain the DOM-source effects, the conditional affinity spectrum (CAS) was calculated using a Fully Optimized ContinUous Spectrum (FOCUS) method. This method not only provides satisfactory goodness-of-fit, but also unique CAS solution. The allochthonous-dominant DOM consistently shows higher Pb affinity than autochthonous-dominant DOM. This source-discrimination is not clearly observed for Zn and Cd. Neither the variability of affinity nor capacity can be fully explained by the variability of individual DOM properties, indicating multiple properties may involve simultaneously. Together, the results help improve WHAM prediction of metal speciation, and consequently, benefit geochemical modelling of metal speciation, such as Biotic Ligand Model for predicting metal toxicity.

ISBN: 9781369552225Subjects--Topical Terms:

3168300
Analytical chemistry.

The effects of Dissolved Organic Matter (DOM) sources on Pb 2+, Zn2+ and Cd2+ binding.
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245 1 4 $a The effects of Dissolved Organic Matter (DOM) sources on Pb 2+, Zn2+ and Cd2+ binding.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 242 p.
500 $a Source: Dissertation Abstracts International, Volume: 78-07(E), Section: B.
500 $a Advisers: Celine Gueguen; Scott Smith.
502 $a Thesis (Ph.D.)--Trent University (Canada), 2017.
520 $a Metal binding to dissolved organic matter (DOM) determines metal speciation and strongly influences potential toxicity. The understanding of this process, however, is challenged by DOM source variation, which is not always considered by most existing metal speciation models. Source determines the molecular structure of DOM, including metal binding functional groups. This study has experimentally showed that the allochthonous-dominant DOM (i.e. more aromatic and humic) consistently has higher level of Pb binding than the autochthonous-dominant DOM (i.e. more aliphatic and proteinaceous) by more than two orders of magnitude. This source-discrimination, however, is less noticeable for Zn and Cd, although variation still exceeds a factor of four for both metals. The results indicate that metal binding is source-dependent, but the dependency is metal-specific. Accordingly, metal speciation models, such as the Windermere Humic Aqueous Model (WHAM), needs to consider DOM source variations. The WHAM input of active fraction of DOM participating in metal binding (f) is sensitive to DOM source. The commonly-used f = 0.65 substantially overestimated the Pb and Zn binding to autochthonous-dominant DOM, indicating f needs to be adjusted specifically. The optimal f value (fopt) linearly correlates with optical indexes, showing a potential to estimate fopt using simple absorbance and/or fluorescence measurements. Other DOM properties not optically-characterized may be also important to determine f opt, such as thiol, which shows strong affinity to most toxic metals and whose concentrations are appreciably high in natural waters (< 0.1 to 400 nmol L-1). Other analytical techniques rather than Cathodic Stripping Voltammetry (CSV) are required to accurately quantify thiol concentration for DOM with concentration > 1 mg L-1. To better explain the DOM-source effects, the conditional affinity spectrum (CAS) was calculated using a Fully Optimized ContinUous Spectrum (FOCUS) method. This method not only provides satisfactory goodness-of-fit, but also unique CAS solution. The allochthonous-dominant DOM consistently shows higher Pb affinity than autochthonous-dominant DOM. This source-discrimination is not clearly observed for Zn and Cd. Neither the variability of affinity nor capacity can be fully explained by the variability of individual DOM properties, indicating multiple properties may involve simultaneously. Together, the results help improve WHAM prediction of metal speciation, and consequently, benefit geochemical modelling of metal speciation, such as Biotic Ligand Model for predicting metal toxicity.
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710 2 $a Trent University (Canada). $b Environmental and Life Sciences. $3 2049953
773 0 $t Dissertation Abstracts International $g 78-07B(E).
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