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Author: Dennis A. Hansell
Publisher: Academic Press
ISBN: 0124071538
Category : Science
Languages : en
Pages : 712
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Book Description
Marine dissolved organic matter (DOM) is a complex mixture of molecules found throughout the world's oceans. It plays a key role in the export, distribution, and sequestration of carbon in the oceanic water column, posited to be a source of atmospheric climate regulation. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, focuses on the chemical constituents of DOM and its biogeochemical, biological, and ecological significance in the global ocean, and provides a single, unique source for the references, information, and informed judgments of the community of marine biogeochemists. Presented by some of the world's leading scientists, this revised edition reports on the major advances in this area and includes new chapters covering the role of DOM in ancient ocean carbon cycles, the long term stability of marine DOM, the biophysical dynamics of DOM, fluvial DOM qualities and fate, and the Mediterranean Sea. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, is an extremely useful resource that helps people interested in the largest pool of active carbon on the planet (DOC) get a firm grounding on the general paradigms and many of the relevant references on this topic. Features up-to-date knowledge of DOM, including five new chapters The only published work to synthesize recent research on dissolved organic carbon in the Mediterranean Sea Includes chapters that address inputs from freshwater terrestrial DOM
Author: Dennis A. Hansell
Publisher: Academic Press
ISBN: 0124071538
Category : Science
Languages : en
Pages : 712
Get Book Here
Book Description
Marine dissolved organic matter (DOM) is a complex mixture of molecules found throughout the world's oceans. It plays a key role in the export, distribution, and sequestration of carbon in the oceanic water column, posited to be a source of atmospheric climate regulation. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, focuses on the chemical constituents of DOM and its biogeochemical, biological, and ecological significance in the global ocean, and provides a single, unique source for the references, information, and informed judgments of the community of marine biogeochemists. Presented by some of the world's leading scientists, this revised edition reports on the major advances in this area and includes new chapters covering the role of DOM in ancient ocean carbon cycles, the long term stability of marine DOM, the biophysical dynamics of DOM, fluvial DOM qualities and fate, and the Mediterranean Sea. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, is an extremely useful resource that helps people interested in the largest pool of active carbon on the planet (DOC) get a firm grounding on the general paradigms and many of the relevant references on this topic. Features up-to-date knowledge of DOM, including five new chapters The only published work to synthesize recent research on dissolved organic carbon in the Mediterranean Sea Includes chapters that address inputs from freshwater terrestrial DOM
Author: Reid Milstead
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Dissolved organic matter (DOM) is a complex heterogeneous mixture of organic compounds that is found in all water systems. DOM is derived from both terrestrial and microbial sources. The composition of DOM can vary greatly depending on a number of variables, including time of year, surrounding groundcover type, and water column depth. The characterization of DOM composition is increasingly performed using high-resolution mass spectrometry, although different instrumentation and techniques may yield different results. Importantly, DOM plays a key role in a number of chemical processes in both natural and engineered systems, such as the generation of carbon dioxide (CO2) from surface waters, the degradation of aquatic contaminants, and the formation of disinfection byproducts (DBPs) during drinking water treatment. The composition of DOM determines its reactivity in all of these processes. Using both bulk and high-resolution analytical techniques, the photooxidation of DOM can be explored. DOM compounds that are more oxidized and aromatic tend to be associated with the consumption of oxygen and the production of CO2. Bulk scale measurements show that DOM becomes less aromatic and lower in molecular weight as a result of partial photooxidation. High-resolution mass spectrometry also provides evidence of oxygen addition and the loss of CO2 from DOM during irradiation experiments. However, the chemical formulas that are most photolabile vary depending on the initial composition of DOM. Using light exposure experiments the kinetics of degradation of four contaminants were quantified for a large set of diverse waters. Using this information, we evaluated the relationships between indirect photolysis rate constants and the formation of photochemically produced reactive intermediates (PPRI) using linear regression analysis. Additionally, quencher experiments were performed to identify the PPRI associated with the degradation of each contaminant in all waters. Triplet state DOM (3DOM) and singlet oxygen (1O2) were identified as critical for atorvastatin, carbamazepine, and sulfadiazine, while hydroxyl radical (•OH) is important for benzotriazole. Our results suggest that quenching experiments should be used with caution due to the non-targeted nature of quenching compounds and the interconnection of PPRI. All of these factors result in probe compounds possibly overstating the importance of PPRI in the indirect photolysis of common contaminants. The characterization of DOM in drinking waters reveals a high degree of variability in DOM composition and reactivity with chlorine, particularly in groundwater samples. Despite the variability in DOM composition, novel DBPs with up to three halogen substituents are compositionally similar among all waters. These novel DBPs are positively correlated with trihalomethane and, to a lesser extent, the formation of haloacetonitriles. This suggests that some low molecular weight DBPs and novel DBPs detected via high-resolution mass spectrometry share similar aromatic precursors, providing evidence that low molecular weight DBPs are useful proxies for the formation of unknown, unidentified high molecular weight DBPs. Compared to Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS), Orbitrap MS yields significantly fewer formula matches and appears to have a bias towards sulfur-containing formulas and against nitrogen-containing formulas. Additionally, the choice of calibration method is particularly important for the less powerful Orbitrap MS. The matched formulas yielded from Orbitrap MS tend to be more oxidized and less highly saturated than those yielded by FT-ICR MS. Despite these differences, the formulas produced by both instruments tend to yield similar relative differences between samples, suggesting that Orbitrap MS is an acceptable replacement for FT-ICR MS in some cases.
Author: Christopher L. Osburn
Publisher: Frontiers Media SA
ISBN: 2889450813
Category :
Languages : en
Pages : 244
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Book Description
A substantial increase in the number of studies using the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) as a proxy for its chemical properties in estuaries and the coastal and open ocean has occurred during the last decade. We are making progress on finding the actual chemical compounds or phenomena responsible for DOM’s optical properties. Ultrahigh resolution mass spectrometry, in particular, has made important progress in making the key connections between optics and chemistry. But serious questions remain and the last major special issue on DOM optics and chemistry occurred nearly 10 years ago. Controversies remain from the non-specific optical properties of DOM that are not linked to discrete sources, and sometimes provide conflicting information. The use of optics, which is relatively easier to employ in synoptic and high resolution sampling to determine chemistry, is a critical connection to make and can lead to major advances in our understanding of organic matter cycling in all aquatic ecosystems. The contentions and controversies raised by our poor understanding of the linkages between optics and chemistry of DOM are bottlenecks that need to be addressed and overcome.
Author: Reid Milstead
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Dissolved organic matter (DOM) is a complex heterogeneous mixture of organic compounds that is found in all water systems. DOM is derived from both terrestrial and microbial sources. The composition of DOM can vary greatly depending on a number of variables, including time of year, surrounding groundcover type, and water column depth. The characterization of DOM composition is increasingly performed using high-resolution mass spectrometry, although different instrumentation and techniques may yield different results. Importantly, DOM plays a key role in a number of chemical processes in both natural and engineered systems, such as the generation of carbon dioxide (CO2) from surface waters, the degradation of aquatic contaminants, and the formation of disinfection byproducts (DBPs) during drinking water treatment. The composition of DOM determines its reactivity in all of these processes. Using both bulk and high-resolution analytical techniques, the photooxidation of DOM can be explored. DOM compounds that are more oxidized and aromatic tend to be associated with the consumption of oxygen and the production of CO2. Bulk scale measurements show that DOM becomes less aromatic and lower in molecular weight as a result of partial photooxidation. High-resolution mass spectrometry also provides evidence of oxygen addition and the loss of CO2 from DOM during irradiation experiments. However, the chemical formulas that are most photolabile vary depending on the initial composition of DOM. Using light exposure experiments the kinetics of degradation of four contaminants were quantified for a large set of diverse waters. Using this information, we evaluated the relationships between indirect photolysis rate constants and the formation of photochemically produced reactive intermediates (PPRI) using linear regression analysis. Additionally, quencher experiments were performed to identify the PPRI associated with the degradation of each contaminant in all waters. Triplet state DOM (3DOM) and singlet oxygen (1O2) were identified as critical for atorvastatin, carbamazepine, and sulfadiazine, while hydroxyl radical (•OH) is important for benzotriazole. Our results suggest that quenching experiments should be used with caution due to the non-targeted nature of quenching compounds and the interconnection of PPRI. All of these factors result in probe compounds possibly overstating the importance of PPRI in the indirect photolysis of common contaminants. The characterization of DOM in drinking waters reveals a high degree of variability in DOM composition and reactivity with chlorine, particularly in groundwater samples. Despite the variability in DOM composition, novel DBPs with up to three halogen substituents are compositionally similar among all waters. These novel DBPs are positively correlated with trihalomethane and, to a lesser extent, the formation of haloacetonitriles. This suggests that some low molecular weight DBPs and novel DBPs detected via high-resolution mass spectrometry share similar aromatic precursors, providing evidence that low molecular weight DBPs are useful proxies for the formation of unknown, unidentified high molecular weight DBPs. Compared to Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS), Orbitrap MS yields significantly fewer formula matches and appears to have a bias towards sulfur-containing formulas and against nitrogen-containing formulas. Additionally, the choice of calibration method is particularly important for the less powerful Orbitrap MS. The matched formulas yielded from Orbitrap MS tend to be more oxidized and less highly saturated than those yielded by FT-ICR MS. Despite these differences, the formulas produced by both instruments tend to yield similar relative differences between samples, suggesting that Orbitrap MS is an acceptable replacement for FT-ICR MS in some cases.
Author: Xiaping Li
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 73
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Book Description
The objective of the present study was to provide better understanding of the effects of watershed land use on molecular composition of streamwater DOM and molecular transformations associated with photochemical and microbial processing of DOM. We compared DOM from headwater streams draining forest-dominated watersheds (FW) and pasture-dominated watersheds (PW) in the lower Chesapeake Bay region (Virginia, USA). Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry analysis was conducted on streamwater DOM prior to and after laboratory incubations: 1) bacteria-only incubations; 2) light-only incubations; and 3) combined light+bacterial incubations. Results showed that DOM in FW streams and PW streams differed in molecular characteristics--the former was characterized by greater structural complexity and aromaticity, higher proportions of condensed aromatic molecules and black carbon-like components, while the latter was higher in the proportions of lipid-like components, protein-like components and aliphatic compounds. Relative to DOM from FW streams, DOM from PW streams was more reactive to bacterial transformation. Protein-like components, lipid-like components and unsaturated hydrocarbon-like components are primarily responsible for the changes associated with bacterial transformation of DOM. However, similar behavior was also observed for DOM in FW streams and PW streams under the influence of bacterial and photochemical processes. Bacterial transformation reduced the proportions of lipid-like components but increased the proportions of lignin-like components and carboxyl-rich alicyclic molecule-like components, indicating that lipid-like components was a bioreactive class while lignin-like components and carboxyl-rich alicyclic were resistant to bacterial processing. Photochemical processes, alone or combined with microbial alterations, increased the proportions of protein-like components, which may be due to the light stimulation of autochthonous production of protein-like components, and increased the relative abundance of carboxyl-rich alicyclic molecule-like components, which indicates the refractory nature of these molecules. Photochemical processes also significantly reduced the amount of dissolved black carbon-like components, which suggests dissolved black carbon was a photoreactive class, countering the conventional view that black carbon was an inter group in carbon cycle. Collectively, these findings suggest that human land use in upstream watersheds may lead to alterations to the molecular composition of streamwater DOM as well as to its behavior to photochemical and microbial processing.
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Author: Sunghwan Kim
Publisher:
ISBN:
Category : Biogeochemistry
Languages : en
Pages :
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Book Description
Abstract: There is currently little molecular level information available for dissolved organic matter (DOM). In this study, electrospray ionization mass spectrometry (ESI-MS) with ultra-high resolution has been used to study DOM at a molecular level. High resolution mass spectra of DOM routinely contains several thousand peaks with a multitude of peaks in each nominal mass region. To study the spectra at the molecular level, the individual peaks need to be examined, a process that is arduous and time consuming. In this study, use of the van Krevelen diagram is demonstrated as an innovative graphical interpretation tool for ultra-high resolution mass spectrometric data of DOM. Plotting of ESI-FT ICR-MS data from DOM indicates that lignin or tannin type molecules compose the main portion of readily ionizable DOM molecules. In addition, many peaks corresponding to hydrogen deficient molecules are observed. These hydrogen deficient molecules found in DOM samples can be related to black carbon derived material. The process of consumption and utilization of DOM by microorganisms is investigated by employing plug-flow thin film bioreactors and ultra-high resolution mass spectrometry of DOM from inflow and outflow water samples. It is shown that the DOM molecules are subject to modifications to lower molecular weight molecules by micro-organisms. Applying van Krevelen analyses for mass spectral data reveals that relative importance of the peaks with low H/C ratios (especially the peaks in the region that has been assigned to black carbon molecules) are generally increased from inflow to outflow water samples. This is consistent in two sets of bioreactor samples collected from two different locations. The current study clearly demonstrates that the method employed in a significant breakthrough in the ability to recognize such a biologically refractory form of DOM.
Author: Yaroslav Verkh
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Book Description
Individual hazardous chemicals and substance mixtures with synergistic toxicity ef-fects occur in the dissolved organic matter (DOM) of wastewater and negatively im-pact human health. Yet a large number of chemicals and their treatment by-products in wastewater makes the tracking of individual compounds nearly impossible and de-mands new analytical strategies. The thesis describes the development and evaluation of non-targeted and suspect anal-ysis methods aimed at the transformation of DOM and micro-contaminants of interest during wastewater treatment using liquid chromatography-high-resolution mass spec-trometry (LC-HRMS) data. On one hand, a non-targeted method to track transformations of DOM in a multiphase wastewater treatment using LC-HRMS data was developed. LC-MS signals were ex-tracted, aligned, and had their isotopologues clustered and elemental composition pre-dicted using open license software MZmine 2 in a way that conceptually prioritized the detection of anthropogenic compounds.
Author: Vaughn Mangal
Publisher:
ISBN:
Category :
Languages : en
Pages : 596
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Book Description
Aquatic contaminant mobility and biological availability is strongly governed by the complexation oforganic and inorganic ligands. Dissolved organic matter (DOM) is a complex, heterogeneous mixture of organic acids, amino acids, lipids, carbohydrates and polyphenols that varyin composition and cancomplex to dissolved metalsthereby altering their fate in aquatic systems. The research conductedin this doctoral dissertation addresses1) how DOM compositiondiffers betweenphytoplanktontaxa and 2) how DOM composition affectsmetal speciation and its subsequent microbial bioavailabilityin laboratory and field conditions.To accomplish this, a series of analytical methods were developed and applied toquantifythiols, sulphur containing DOM moieties,and the molecular composition of DOM.The works presented in this thesisrepresentsone of the first comprehensiveand multipronged analyses of the impact of phytoplankton metabolite exudates on microbial metalbioavailability.This dissertationdemonstratedthe analytical versatility of high-resolution mass spectrometry as a tool for compound specific information, as well as having the capabilities to obtain speciation information of organometallic complexes. Thework presentedin this PhDstrengthens the understanding compositional differences of both autochthonous and allochthonous DOM andtheir effects on metal biogeochemistry. Keywords:Dissolved organic matter, Mercury, Cadmium, High Resolution Mass Spectrometry, Phytoplankton, Churchill, Metal Bioavailability.
Author: Paula G. Coble
Publisher: Cambridge University Press
ISBN: 0521764610
Category : Science
Languages : en
Pages : 407
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Book Description
A core text on principles, laboratory/field methodologies, and data interpretation for fluorescence applications in aquatic science, for advanced students and researchers.
Author: Xianyu Kong
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Dissolved organic matter (DOM) in the ocean is a complex mixture of molecules derived from autochthonous (marine) or allochthonous (terrestrial) origins. DOM plays an important role in marine biogeochemical cycles by attenuating light available for primary production, serving as an energy and nutrient source for heterotrophic communities, regulating the ultraviolet and visible light absorption, undergoing photochemical processing, and acting as a trace metal ligand. DOM in the Central Arctic Ocean (CAO) is influenced by increased freshwater input and associated terrestrial materials in recent decades due to rapid climate change. The quantification of DOM sources (terrestrial versus marine) in the water column of the CAO is not well constrained. Few studies have systematically investigated the seasonality and spatial variability of DOM by combining optical and molecular-level analytical techniques in the CAO, especially during winter. State of the art chemical characterization of DOM is subject to major challenges: Solid phase extraction (SPE) that is often used to desalt and pre-concentrate marine DOM introduces chemical fractionation effects, which limits the comparability between analytical results for original samples and those carried out for SPE-DOM. There is no specific method to quantify fractionation effects, nor specific guidelines to avoid fractionation. Using mass spectrometry, quantitative DOM analyses is challenged by selective ionization of molecules and the large number of unresolved structural isomers that prevent classical external calibration. In the first part of this thesis, a method was developed to quantitatively track optical or chemical fractionation during SPE and investigate the potential mechanisms. We found a decrease in extraction efficiency of dissolved organic carbon (DOC), fluorescence and absorbance, and polar organic substances with increasing carbon loading on the SPE column. As the surface loading of the solid-phase increased, the dominant extraction mechanism shifted from PPL physisorption to increased DOM self-assembly, resulting in optical and chemical fractionation. The relative DOC loading (DOCload) was used to assess the carbon loading during SPE, and a double sigmoid model was applied to our online permeate fluorescence data as a function of DOCload, which allowed us to assess the degree of variability induced by DOCload. This finding has ample implications for the future processing and previous interpretation of chemical characteristics in SPE-DOM of aquatic organic matter. For the second part of the thesis, original water samples were acquired from the “Multidisciplinary Drifting Observatory for the Study of Arctic Climate” (MOSAiC) expedition. The water column samples covered a full year (2019 / 2020) and included the regions Amundsen Basin, western Nansen Basin and Yermak Plateau and Fram Strait. Samples were analyzed using optical spectroscopy to determine chromophoric DOM (CDOM) and fluorescent DOM (FDOM). In addition, a new method was applied that used Fourier transform ion cyclotron resonance mass spectrometry hyphenated to high performance liquid chromatography (LC-FTMS). The method allowed DOM analysis in original filtered water and thus avoided the chemical fractionation introduced by SPE. During the MOSAiC expedition, DOC concentrations and CDOM characteristics in the water column were primarily influenced by regional differences. These differences were largely dependent on terrestrially-derived DOM (tDOM) input by the transpolar drift (TPD) as indicative of average 136% and 45% higher aCDOM(350) and DOC concentration, respectively, in the Amundsen compared to the western Nansen Basin and Yermak Plateau, and slightly modified by seasonal changes. Despite the convenient identification of tDOM, optical spectroscopy was not suitable to quantify the contribution of tDOM to bulk DOC or to track sea ice derived DOM in the water column. In contrast, using LC-FTMS, we found quantitative linear correlation between the summed mass peak magnitudes for each sample (intsum) and DOC concentration. By combing LC-FTMS and source identification with optical parameters, we were able to quantify DOM sources (terrestrial versus marine) in the water column: 83% of the summed peak magnitude of all samples could be related to marine or terrestrial sources. tDOM contributed ∼17% (or 8 μmol kg-1) to deep DOC (~2000 m) in the CAO and was more refractory and had a higher state of unsaturation compared to marine DOM. The quantitative characterization of DOM in original seawater from different origin is a major step in the field of research. It provides a unique and new insight into the molecular changes in marine DOM composition and an improved understanding of the terrestrial DOM distribution in the CAO.
