Download or read book Molecular Composition of Dissolved Organic Matter Controls Metal Speciation and Microbial Uptake written by Vaughn Mangal and published by . This book was released on 2019 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

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 Towards an Understanding of Dissolved Organic Matter Molecular Composition and Reactivity in the Environment written by Barbara Cottrell and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Role of Organic Matter in Structuring Microbial Communities written by L. Kaplan and published by IWA Publishing. This book was released on 2005-03-01 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural organic matter is important to the quality of drinking water. It constitutes precursors for disinfectant by-product formation and supports regrowth of bacteria. The drinking water industry is involved in work designed to improve biological treatment of water, control bacterial regrowth in distribution systems, and measure biodegradable NOM concentrations. These efforts would benefit from a knowledge of NOM composition and structure and the composition of microbial communities that colonize biological filters and distribution systems. In this project the researchers addressed four major goals: (1) to determine the structure and composition of natural organic matter (NOM), (2) to describe the structure of heterotrophic bacterial communities supported by raw and treated source water, (3) to measure the responses of heterotrophic bacterial communities to seasonally driven variations in NOM and temperature, and (4) to determine whether bioreactor systems can serve as small-scale models for the development and refinement of drinking water treatment processes. The five source waters selected for this project included a broad range of physiographic provinces, vegetation zones, and NOM concentrations. The research team analyzed NOM and microbial communities from an analytical hierarchy involving assessment of concentration, composition, and structure. Concentrations of NOM and BOM were estimated from dissolved organic carbon (DOC) and biodegradable DOC concentrations. NOM composition was assessed from analyses of carbohydrates with ion chromatography with pulsed amperometric detection, humic substances with XAD-8 resin, and functional groups with NMR. Molecular structure was determined from tetramethylammonium hydroxide thermochemolysis (TMAH) GC/MS. Microbial community composition was assessed from comparative ribosomal ribonucleic acid (RNA) sequencing, specifically, terminal restriction fragment length polymorphisms (t-RFLP), to provide an overview of microbial population structure and detect population shifts at the level of species. NOM Composition NOM and BOM concentrations showed extensive temporal variation in all of the source waters, but a general pattern of concentration ranges was discernable, indicating that each watershed has a particular concentration signal. Compositional studies revealed that humic substances and complex carbohydrates are components of both NOM and BOM. Structural and compositional studies identified unique NOM signatures for the different source waters, with some classes of molecules observed only in specific source waters. The BOM pool included humic substances and lignin, sources generally presumed to be relatively resistant to biodegradation. Additional novel insights included the quantitative contribution of aromatic molecules to the BOM pool and the potential for bacterial demethylation of lignin. Bacterial Communities The communities of microorganisms that developed in bioreactors that were fed water from different watersheds were unique. NOM influenced the genetic composition of resulting microbial communities, and seasonal shifts were observed for watersheds possessing strong seasonal temperature signals. Thus, temperature and organic matter quantity and quality probably influenced parameters important to the biological treatment of drinking water. A comparison of bioreactor metabolism with rapid sand filters showed some overlap, suggesting the bioreactors may indicate the ultimate potential of rapid sand filters for BOM processing. The researchers recommend the following: Bioreactors designed to monitor a BOM source should ideally be inoculated, colonized, and maintained by that source; at a minimum, acclimation to the source over several months is needed. Seasonal changes in the microbial community colonizing a biologically active filter may diminish filter performance and require an acclimation period to restore performance. Molecular-based methods for both microbial and chemical analyses of drinking water and treatment processes should be targeted for continued development and implementation within the drinking water industry. Originally published by AwwaRF for its subscribers in 2004.

Download or read book Dissolved Organic Matter Dynamics in an Arctic Catchment written by Kristin Eulene Judd and published by . This book was released on 2004 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microbial Utilization and Transformation of Dissolved Organic Matter in Aquatic Environments from Streams to the Deep Ocean written by Johanna Sjöstedt and published by Frontiers Media SA. This book was released on 2021-07-28 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Intriguing Changes in Molecular Size and Composition of Dissolved Organic Matter Induced by Microbial Degradation and Self assembly written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissolved Organic Matter in Lacustrine Ecosystems written by K. Salonen and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concentrations of dissolved organic matter (DOM) in lakes are often an order of magnitude greater than concentrations of particulate organic matter; nevertheless, the biogeochemical analysis of DOM is described in only a few textbooks on limnology (most thoroughly by Wetzel). The orgins of dissolved organic substances are largely photosynthetic; DOM is either autochthonously synthesized by littoral and pelagic flora through secretions and autolysis of cellular contents, or allochthonously generated in terrestrial systems of the drainage basin, composing largely of humic substances refractory to rapid microbial degradation. The role of DOM in lacustrine ecosystems, as energy source and system regulator, however, is still poorly known. The aim of this book is: (1) to present state-of-the-art reviews of the role of dissolved autochthonous and allochthonous organic matter in pelagial and littoral zones; and (2) to focus attention on poorly understood but critical topics and hence to provide direction for future research activity.

Download or read book Dissolved Organic Matter DOM written by Oleg S. Pokrovsky and published by Nova Science Publishers. This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved Organic Matter (DOM) is a major factor controlling global biogeochemical cycles of carbon, macro- and micronutrients and toxic metals. It plays a pivotal role both in mobilisation (chemical weathering), transport (organic complexes and colloids), biological uptake and deposition (microbial and photo-degradation) of a number of essential macro- (C, N, P) and micro- (Fe, Zn, Mn, Ni, Cu Co) nutrients. The interest of scientists to DOM is rapidly increasing. Between 1950 and 2017, more than 30,000 scientific papers on DOM were published (Web of Science® All Database Search); however, more than half of them were produced over the past nine years and over the last two and a half years, more than 5,400 papers were published. Such attention to DOM is clearly motivated by a combination of global climate change issues and the main role of DOM in CO2 exchange between the atmosphere and the surface waters. Despite such a large range of scientific problems concerning DOM properties, origins, and applications, there is a very strong geographical bias in terms of the amount of research devoted to various geographical regions of the world. The majority of information concerns temperate zones and boreal regions of Scandinavia and Northern America, with very little information available on Siberia and Russia. Thus, among the less than 30,000 scientific articles devoted to various aspects of DOM since 1950, only 150-200 of them are devoted to DOM in Russia or Siberia. This book is essentially oriented towards filling these gaps of our knowledge. Among thirteen chapters, eleven of them are devoted to various aspects of DOM in Russia and Siberia. Another important and still poorly characterised aspect of natural DOM is its colloidal status: four chapters of this book deal with the colloidal speciation of DOM in rivers and lakes. Given the breadth of physico-chemical, geochemical, biological, and geographical aspects of DOM covered in this book, it will be useful for a large audience of environmental scientists, limnologists, physico-chemists, soil and landscape scientists and biogeochemists.

Download or read book Aquatic Ecosystems Interactivity of Dissolved Organic Matter written by Stuart Findlay and published by Academic Press. This book was released on 2003 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: Overviews of the source, supply and variability of DOM, surveys of the processes that mediate inputs to microbial food webs, and syntheses consolidating research findings provide a comprehensive review of what is known of DOM in freshwater. This book will be important to anyone interested in understanding the fundamental factors associated with DOM that control aquatic ecosystems."--BOOK JACKET.

Download or read book Advances in Understanding the Molecular Composition of Dissolved Organic Matter and Its Reactivity in the Environment written by Rajaa Mesfioui and published by . This book was released on 2014 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book From Freshly Produced Compounds to Refractory Molecules written by Helena Osterholz and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis includes the results of two field studies and one laboratory incubation experiment focusing on the production and turnover of freshly produced dissolved organic matter (DOM) by microorganisms. High resolution methods were applied to elucidate the DOM molecular composition and the microbial community structure, and the data was analyzed via multivariate statistics to provide novel insights into the relationship between the two key players. Main findings include 1. DOM in high latitude environments is rapidly transformed due to microbial activity, 2. the North Sea is highly impacted by the input of terrigenous DOM and the molecular DOM composition can be connected with the composition of the total and the active microbial community, and 3. refractory deep ocean-like DOM may be biologically produced by microorganisms in the laboratory within several weeks. engl.

Download or read book The Role of Dissolved Organic Matter in Structuring Microbial Community Composition written by Rachel Elizabeth Sipler and published by . This book was released on 2009 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is an important source of nutrients in aquatic systems contributing to the growth of phytoplankton and bacteria. The overall response appears to be driven by the phytoplankton and bacteria species present as well as the composition of DOM provided. This dissertation explores the bioavailability of allochthonous and autochthonous DOM sources to, and its affect on, the growth of marine phytoplankton and bacterial community abundance and composition. This research utilizes advanced chemical (electrospray ionization mass spectrometry (ESI-MS)) and molecular (terminal restriction fragment length polymorphism (TRFLP)) techniques to characterize the DOM and microbial community. To investigate the role of allochthonous DOM in phytoplankton growth, DOM from two different riverine sources from watersheds with different land use practices, was supplied to a natural cyanobacteria population. The bioavailability of autochthonous DOM was investigated by supplying DOM produced by a single culture of cyanobacteria to a natural dinoflagellate bloom community. The potential negative effect of an individual autochthonous DOM compound was investigated through the addition of marine toxin, brevetoxin, to three different natural bacterial communities. This dissertation resulted in the first ESI-MS characterization spectra of the DOM associated with three different natural phytoplankton blooms, a culture of cyanobacteria, and two different South Florida rivers. It was also the first study to identify previously uncharacterized allochthonous and autochthonous DOM masses bioavailable to natural marine phytoplankton communities. Bulk level analyses within these experiments quantified lower limits for the bioavailability of allochthonous and autochthonous DOM sources and the relative community response to each of these sources. This dissertation also represents the first molecular evaluation of the bacteria associated with a bloom and the first investigation of the allelopathic properties of brevetoxin. It has discussed and applied the use of ESI-MS to investigate the bioavailability of complex DOM, identified and quantified potential nutrient sources and linked marine toxin production to changes in bacterial community composition.

Download or read book Bioavailability of Contaminants in Soils and Sediments written by National Research Council and published by National Academies Press. This book was released on 2003-05-03 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bioavailability refers to the extent to which humans and ecological receptors are exposed to contaminants in soil or sediment. The concept of bioavailability has recently piqued the interest of the hazardous waste industry as an important consideration in deciding how much waste to clean up. The rationale is that if contaminants in soil and sediment are not bioavailable, then more contaminant mass can be left in place without creating additional risk. A new NRC report notes that the potential for the consideration of bioavailability to influence decision-making is greatest where certain chemical, environmental, and regulatory factors align. The current use of bioavailability in risk assessment and hazardous waste cleanup regulations is demystified, and acceptable tools and models for bioavailability assessment are discussed and ranked according to seven criteria. Finally, the intimate link between bioavailability and bioremediation is explored. The report concludes with suggestions for moving bioavailability forward in the regulatory arena for both soil and sediment cleanup.

Download or read book High Resolution Molecular Characterization of Photochemical and Microbial Transformation of Dissolved Organic Matter in Temperate Streams of Different Watershed Land Use written by Xiaping Li and published by . This book was released on 2014 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Investigations on the Role of Dissolved Organic Matter in Determining Ecosystem Structure and Function written by Kelton Ray McKinley and published by . This book was released on 1975 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Influence of Dissolved Organic Matter Composition on Its Reactivity in Natural and Engineered Systems written by Reid Milstead and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.