Download or read book Chemical Characterization of Dissolved Organic Matter in Relation with Hydrography in the Arctive Ocean written by Zhiyuan Gao and published by . This book was released on 2016 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular and Optical Characterization of Dissolved Organic Matter in the Central Arctic Ocean written by Xianyu Kong and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Linking Optical and Chemical Properties of Dissolved Organic Matter in Natural Waters written by Christopher L. Osburn and published by Frontiers Media SA. This book was released on 2017-01-17 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book The Organic Carbon Cycle in the Arctic Ocean written by Rüdiger Stein and published by Springer Science & Business Media. This book was released on 2011-06-27 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flux, preservation, and accumulation of organic carbon in marine systems are controlled by various mechanisms including primary p- duction of the surface water, supply of terrigenous organic matter from the surrounding continents, biogeochemical processes in the water column and at the seafloor, and sedimentation rate. For the world's oceans, phytoplankton productivity is by far the largest organic carbon 9 source, estimated to be about 30 to 50 Gt (10 tonnes) per year (Berger et al. 1989; Hedges and Keil 1995). By comparison, rivers contribute -1 about 0. 15 to 0. 23 Gt y of particulate organi.

Download or read book Chemical Characterization of Dissolved Organic Matter and Its Influence on the Chemistry of River Water written by Johannes Helmut Reuter and published by . This book was released on 1972 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Characterization of Refractory Dissolved Organic Matter written by Neal Ken Arakawa and published by . This book was released on 2016 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this thesis was to combine a chemical degradation technique together with an analytical framework centered primarily around gas chromatography (GC) to more fully interrogate the composition of aquatic dissolved organic matter (DOM). Previous studies had suggested that aliphatic compounds could represent a significant fraction of refractory organic matter isolated by solid phase extraction (SPE). These studies had also uncovered the vast complexity of DOM. Gas chromatography coupled to mass spectrometry provides superior separation capability and is ideal for examining complex mixtures of lipid-derived molecules. As such I sought to develop a comprehensive GC analysis methods to provide molecular level information for DOM isolated by solid phase extraction (SPE) onto a hydrophobic resin- PPL (Agilent Bond Elut). In Chapter II, a comprehensive chemical reduction procedure was developed and first applied to the environmental DOM standard Suwannee River Fulvic Acid (SRFA) as a proxy for marine DOM. The resulting hydrocarbons were amenable to comprehensive gas chromatography time-of-flight mass spectrometry (GCxGC-TOF-MS), and effectively resolved into multiple series of alicyclic, unsaturated compounds. This was the first direct demonstration of the isomeric complexity of aquatic DOM. Similar alicyclic compounds were recovered from the reduction of terrestrial source material, implicating resin acids and sterols as potential precursors of SRFA. In Chapter III the reduction process was applied to marine surface DOM from the Scripps Institution of Oceanography Pier, and similar alicylic compounds were found. The GCxGC-TOF-MS identified carbon backbones closely resembling carotenoids, implicating these ubiquitous and highly reactive biomolecules as the source of a significant fraction of DOM accumulating in the marine water column. The structural assignment was supported by the identification of carotenoid derived resonances in two dimensional nuclear magnetic resonance (NMR) spectra, which indicated that these molecules were highly oxidized compared to the parent molecules consistent with their present in DOM. Following up on this work in Chapter IV the carotenoid [beta]-carotene was irradiated with natural sunlight to test the hypothesis that photodegradation was one pathway that converted carotenoids into water-soluble degradation products. The first finding was that the reaction produced a series of compounds identical to compounds isolated from marine DOM. The second important result was that the reaction produced a complex mixture of isomers from a single compound that helps to at least partly explain the compositional diversity in marine DOM. Together, the data in Chapters III and IV allowed us to link a large fraction of DOM to a ubiquitous biomolecule that can now serve as a model for studies examining the formation and fate of DOM that accumulates in the ocean on long timescales. Finally, in Chapter V we sought to examine how the composition of DOM -- both the complex alicyclic fraction and small, polar biomolecules, which are considered a "fresher" signal of biological input -- evolved across a salinity gradient. Although core biochemical classes were present in all regions the data supported in situ production of compositionally similar material rather than mixing across the gradients as proposed in some studies. Together, the chapters in my thesis provide new insight in the composition of dissolved organic matter in marine and terrestrial environments. The thesis also represents the most comprehensive molecular level characterization of DOM isolated by this solid phase extraction method, which is the most commonly used isolation method in the field. My findings also provide an important foundation for future lab-based mechanistic studies of DOM cycling in the marine environment.

Download or read book Reactivity and Chemical Characterization of Dissolved Organic Matter in an Estuary written by Hussain A. Abdulla and published by . This book was released on 2009 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical characteristics of Arctic water masses written by David C. Burrell and published by . This book was released on 1970 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technical progress is reported on the utilization of multiple chemical tracers to study the sources, movements, and mixing of Arctic Ocean water masses. A wide range in scale of mixing processes is considered, from the large scale general circulation to the small scale microstructure. Results of chemical characterization of major arctic water masses by routine chemical parameters are correlated and interpreted. Methodology for continuous processing of large volumes of water from any depth for recovery of large amounts (1 gram) of organic matter for subsequent Carbon-14 dating and chemical analysis has been developed. Finally, the detection of microstructure in the Arctic Ocean and the study of turbulent mixing processes associated with this small scale structure is discussed. (Author).

Download or read book Spectroscopic Characterization of Dissolved Organic Matter written by Xiaoyan Cao and published by . This book was released on 2014 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Characterisation of Antarctic Dissolved Organic Matter written by Sahar Farzadnia and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Study of the chemical structure of dissolved organic matter (DOM) has always been of great interest due to its contribution to global carbon cycle and its recognition as a source marker. Fulvic acids are a complicated mixture of organic compounds accounting for about half of Natural Organic Matter (NOM) in fresh water and 15-20 % of the NOM in marine waters. Fulvic acid composition and structure varies depending on the geographic locations and sources of inputs, but it is generally believed that it consists of weak aliphatic and aromatic organic acids soluble in water at all pH conditions. Chemical characterisation of fulvic material from the Antarctic with its cold climate and absence of higher order plants has the advantage of simpler mixture contribution and pure microbial input to the DOM. This relative simplicity helps facilitate the data interpretation and speculating origin and formation pathways of Antarctic fulvic acids. In this study, we have comprehensively examined fulvic acids from two different areas in Antarctica. Pony Lake fulvic acid (PLFA) from McMurdo Sound area, Western Antarctica as IHSS Standard Reference fulvic acid and three other fulvic acids from Vestfold Hills, Eastern Antarctica were chosen as samples. For the first time these fulvic acids were analysed using a range of derivatisation methods coupled to gas chromatography/mass spectrometry. These methods complemented each other to demonstrate the broad range of components present in these complex fulvic acids. Our findings indicated the presence of various chemical components (apart from carbohydrates and sugars); many of which have not been previously reported in fulvic acids; they mainly include aliphatic linear and branched carboxylic acids, fatty acids (saturated and unsaturated), heterocyclic nitrogen-containing compounds, aromatics and terpenoids. Our results are the first report of the presence of unbroken tricyclic terpenoids among the products of three out of four fulvic acids tabulated. It also highlighted the feasibility of characterisation of DOM using gas chromatography without the need for depolymerisation using hydrolysis or other harsh treatments. Our results also showed that using a fractionation step prior to gas chromatography can assist with providing additional information regarding molecular-level analysis of Antarctic fulvic acid as an important aquatic microbial end-member DOM. Furthermore, fractionation clearly revealed the presence of micelle-like structure in Antarctic fulvic materials supporting the theory of supramolecular structures for Humic substances.

Download or read book Chemical Characterization of Dissolved Organic Matter DOM in Seawater written by Tracy Michelle Quan and published by . This book was released on 2005 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) This new separation protocol utilized various chromatographic techniques, including cation exchange chromatography and high- pressure liquid chromatography (HPLC) using C18 and strong cation exchange (SCX) columns. Six amino acids were isolated from a HMWDOM sample with sufficient purity and quantity for radiocarbon analysis. These amino acids had a range of A'4C values, from 121%o to -454%o. The final section investigates biological controls on the dissolved organic nitrogen (DON) pool. Total hydrolyzable amino acids (THAA), and nucleic acids were measured for four incubations: a control incubation, a grazer added incubation, a zero virus incubation, and a 10 times virus incubation. Comparison to the control showed THAA and nucleic acid release were influenced by viruses but not grazers.

Download or read book Natural Organic Matter in Water written by Mika Sillanpaa and published by Butterworth-Heinemann. This book was released on 2022-10-17 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural Organic Matter in Water: Characterization, Treatment Methods, and Climate Change Impact, Second Edition focuses on advanced filtration and treatment options, as well as processes for reducing disinfection by-products, making it an essential resource on the latest breakthroughs in the characterization, treatment and removal of natural organic matter (NOM) from drinking water. Based on the editor’s years of research and field experience, the book covers general parameters, isolation and concentration, fractionation, composition and structural analysis, and biological testing, along with removal methods such as inorganic coagulants, polyelectrolytes and composite coagulants. In addition, sections cover electrochemical and membranes removal methods such as electrocoagulation, electrochemical oxidation, microfiltration and ultrafiltration, nanofiltration, and membrane fouling. This book is a valuable guide for engineers and researchers looking to integrate methods, processes and technologies to achieve desired affects. Provides a summary of up-to-date information surrounding NOM Presents enhanced knowledge on treatment strategies for the removal of NOM Covers conventional as well as advanced NOM removal methods

Download or read book Dissolved Organic Matter Discharge in the Six Largest Arctic Rivers chemical Composition and Seasonal Variability written by Amanda J. Rinehart and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The vulnerability of the Arctic to climate change has been realized due to disproportionately large increases in surface air temperatures which are not uniformly distributed over the seasonal cycle. Effects of this temperature shift are widespread in the Arctic but likely include changes to the hydrological cycle and permafrost thaw, which have implications for the mobilization of organic carbon into rivers. The focus of this research was to describe the seasonal variability of the chemical composition of dissolved organic matter (DOM) in the six largest Arctic rivers (Yukon, Mackenzie, Ob, Yenisei, Lena and Kolyma) using optical properties (UV-Vis Absorbance and Fluorescence) and lignin phenol analysis. We also investigated differences between rivers and how watershed characteristics influence DOM composition. Dissolved organic carbon (DOC) concentrations followed the hydrograph with highest concentrations measured during peak river flow. The chemical composition of peak-flow DOM indicates a dominance of freshly leached material with elevated aromaticity, larger molecular weight, and elevated lignin yields relative to base-flow DOM. During peak flow, soils in the watershed are still frozen and snowmelt water follows a lateral flow path to the river channels. As the soils thaw, surface water penetrates deeper into the soil horizons leading to lower DOC concentrations and likely altered composition of DOM due to sorption and microbial degradation processes. The six rivers studied here shared a similar seasonal pattern and chemical composition. There were, however, large differences between rivers in terms of total carbon discharge reflecting the differences in watershed characteristics such as climate, catchment size, river discharge, soil types, and permafrost distribution. The large rivers (Lena, Yenisei), with a greater proportion of permafrost, exported the greatest amount of carbon. The Kolyma and Mackenzie exported the smallest amount of carbon annually, however, the discharge weighted mean DOC concentration was almost 2-fold higher in the Kolyma, again, indicating the importance of continuous permafrost. The quality and quantity of DOM mobilized into Arctic rivers appears to depend on the relative importance of surface run-off and extent of soil percolation. The relative importance of these is ultimately determined by watershed characteristics.

Download or read book Chemical Characterisation of Dissolved Organic Matter in Natural Matices written by Vera Thoss and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization and Remediation of Dissolved Organic Matter in Produced Oilfield Waters written by Xiaojing Wang and published by . This book was released on 2011 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved Organic Matter (DOM) has been studied intensively in many water sources such as lakes and seas due to its recalcitrance, its reactivity with other pollutants in water, its role in global carbon cycling, and the fact that DOM is a precursor of carcinogenic disinfection byproducts. The composition of DOM is complex and contains thousands of chemicals. Compared to DOM in other types of water bodies (fresh and sea waters), little research has been conducted on DOM in produced oilfield waters, and its detailed composition remains largely unknown. This works aims to understand DOM in oilfield waters through a thorough chemical characterization and examination on mechanisms for its removal through both biotic and abiotic methods, including: (1) Solid Phase Extraction of DOM; (2) FTIR and high resolution mass characterization of DOM; (3) remediation of DOM through photodegradation, clay adsorption, chemical flocculation, biodegradation, and volatilization.

Download or read book Chemical Characterization of Dissolved Organic Matter DOM in Seawater written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Funding for this research was provided by the National Science Foundation (OCE-981 8654) and the Department of Energy (DEFG0200ERG62999). Student support was also provided by a National Science Foundation Graduate Student Fellowship.

Download or read book A Chemical Characterization of Adsorbed Dissolved Organic Material from an Estuarine Source written by Brenda J. Little and published by . This book was released on 1983 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: