Download or read book Colored Dissolved Organic Matter in Sediments and Seagrass Beds and Its Impact on Benthic Optical Properties of Shallow Water Marine Environments Data Analysis and Synthesis and Student Support written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optical properties of shallow water coastal environments are a complex function of physical and biogeochemical processes occurring both in sediments and in the water column. Developing models of the optical properties of these environments requires further knowledge of the processes affecting light alteration and modification by biogeochemical reactions in the surficial sediments and at the sediment-water interface. The goal of our work has been to examine one aspect of this problem, namely the impact of dissolved organic matter (DOM) in sediment pore waters on benthic optical properties.
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 Characterization and Optical Properties of Colored Dissolved Organic Matter During the Coastal Mixing Optics Experiment Using in Situ and Discrete Sampling Methods written by Robyn Nicole Conmy and published by . This book was released on 1999 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temporal and Spatial Patterns in Optical Properties of Colored Dissolved Organic Matter on Florida s Gulf Coast written by Robyn Nicole Conmy and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Characterization of Colored Dissolved Organic Matter (CDOM) in surface and ground waters in South Florida was conducted using fluorescence and absorption spectroscopy. Waters of the West Florida Shelf are heavily influenced by many river systems on Florida's Gulf Coast that, to the first order control CDOM distributions on the shelf. Seasonal surveys revealed that changes in the underwater light field as a result of major hurricanes and resuspension events are linked closely with a number of factors prior to a storm's passing such as the presence of persistant blooms, rainfall and discharge. Additionally, storm track and wind direction were found to play a significant role in CDOM signatures. A study of ten riversheds located between the Mississippi / Atchafalya River system and the Shark River in the Everglades revealed a wide range in CDOM seasonality. A regional dependence of CDOM was also found, where highest aromaticity and concentration of organic material was found for the southernmost watersheds. Basin characteristics, vegetation differences, land use and climatic patterns are implicated in the cause for regional differences. In addition to surface flow, organic material in groundwater was measured in deep and shallow aquifers surrounding the Tampa Bay Estuary. As a result of strong hydrologic links between shallow aquifers and the overlying surface waters, CDOM in both reservoirs were found to be quite similar. Deep aquifers (> 150 ft) however are less concentrated and have CDOM signatures more similar to marine waters. This suggests similar biogeochemical pathways of the material, including the influence of the aquatic microbial community. Furthermore, multi-spectral CDOM fluorescence measurements were shown to be a potential indicator of groundwater presence in Tampa Bay during times of low surficial discharge to the bay, and when some rivers are almost entirely spring-fed. Investigating CDOM distribution and signatures is vital to carbon budget and cycling questions. The amount and quality of organic material has significant implications for ecosystems, thereby affecting organisms that use CDOM as a food source, light availability for photosynthesis, UV shading provided to biota, satellite estimates of chlorophyll a, metal binding, materials transport and overall water quality.
Download or read book Articles de presse et programmes sur Les Brigands musique de Jacques Offenbach written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optical Properties and Photochemical Response of Colored Dissolved Organic Matter CDOM at Jobos Bay National Estuarine Research Reserve JOBANERR Puerto Rico written by Suhey Ortiz Rosa and published by . This book was released on 2010 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colored Dissolved Organic Matter in the Coastal Ocean An Optical Tool for Coastal Zone Environmental Assessment Management written by and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the article, we focus on the properties, sources, sinks, measurement techniques, and distribution patterns of the major dissolved component of ocean color, CDOM. Through an understanding of the complex characteristics and environmental interactions of the CDOM pool, we can gain valuable insight into a variety of physical and biogeochemical processes occurring in coastal and shelf regions.
Download or read book Linking Optical and Chemical Properties of Dissolved Organic Matter in Natural Waters written by and published by . This book was released on 2017 with total page 0 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 Characterization of Biologically Produced Colored Dissolved Organic Matter written by Daniel Repeta and published by . This book was released on 1999 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colored dissolved organic matter (CDOM) is one of the principal light-attenuating components of seawater. Over the past decade considerable progress has been made in describing the optical properties of CDOM. However, our understanding of CDOM structure and chemistry has not advanced apace, and we do not yet understand many of the factors that introduce and remove CDOM in seawater. Our objectives are to chemically characterize CDOM and to develop techniques for studying CDOM cycling in seawater. Recent work suggests that a large fraction of marine DOM consists of complex carbohydrates and proteins that are produced directly from biosynthesis, yet are biologically refractory towards microbial degradation. Previous studies have also suggested that a large fraction of CDOM is associated with biological activity. We wish to determine if marine phytoplankton and bacteria produce significant quantities of CDOM, and to compare the chemical characteristics of biologically produced CDOM with CDOM in seawater.
Download or read book Optical Properties of the Dissolved Organic Matter as Tracers of Microbiological and Geochemical Processes in Marine Ecosystems written by Cristina Romera Castillo and published by . This book was released on 2011 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Colored Dissolved Organic Matter and Dissolved Organic Carbon Using Combination of Ocean Color Data and Numerical Model in the Northern Gulf of Mexico written by Nazanin Chaichitehrani and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optical Properties of Chromophoric Dissolved Organic Matter as a Tracer of Terrestrial Carbon to the Coastal Ocean written by Jennifer Louise Dickson Brown and published by . This book was released on 2009 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygen and Dissolved Organic Carbon Dynamics in Permeable Coastal Sediments written by Lindsay Chipman and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: A large fraction of the continental shelf is covered by permeable sediments that are flushed by wave, wind, and tide generated bottom currents. Elevated dissolved organic carbon (DOC) concentrations in coastal zones, a diverse and abundant sediment microbial community, and advective filtration of seawater through the surface layers of permeable sediments, make these environments important zones for the cycling of organic matter. This research investigates the role of permeable sediments in the dynamics of two central components of the carbon cycle: DOC and oxygen. In Chapter 2, published in Limnology & Oceanography, I investigate decomposition rates and compositional changes of DOC when filtered through permeable sediments contained in laboratory column reactors. Substantial amounts of DOC were mineralized in the sediments and could be linked to incorporation by aerobic and anaerobic microbes. In DOC pore-water profiles measured at two study sites with permeable sediment, we observed a concave shape of the profiles in the upper 10 cm of permeable sediment resulting from transport of DOC with advective pore water flows into the sand, and DOC decomposition in the subsurface layers. We found that the flushed sand layer between the water column and deeper anoxic sediment layers acts as an effective DOC filter, with subsurface horizontal pore-water flows promoting decomposition of DOC, suggesting that permeable sediments play a key role in the cycling of organic matter. In Chapter 3, submitted to Continental Shelf Research, I use the findings of Chapter 2 for the interpretation of field time series data of DOC, DIC, and TN concentrations in the water column and coastal sediment pore waters. We use these time series to investigate the spatial and temporal dynamics of dissolved organic matter and how benthic pelagic coupling influences DOC concentrations in the permeable sediments. Our results reveal that DOC in the upper layer (0-12 cm) of the shallow sands is controlled by benthic-pelagic coupling facilitated by advective pore water filtration modulated by the regional wave climate. For the quantification of oxygen fluxes in the permeable coastal sands resulting from the benthic organic matter production and consumption and the current-induced sediment flushing, I deployed the eddy correlation technique. In order to make this technique more suitable for our shallow coastal zone with relatively rough hydrodynamic conditions (as compared to deeper marine environments), we adapted existing eddy correlation instruments for use with more durable and repairable oxygen optodes. This development is described in detail in Chapter 4 that has been submitted for publication in Limnology and Oceanography Methods. Our results show that optodes have a comparable response time to electrodes, produce similar fluxes in field deployments, and are a viable alternative for use with the eddy correlation measurement in coastal environments with strong currents and wave action. These hydrodynamic conditions are an important factor controlling production and decomposition processes at the sediment-water interface and within the sediment because they can largely control the availability of DOC and oxygen to microbial communities in the sediments. In Chapter 5, which is presently is being prepared for submission to Marine Ecology - Progress Series, we investigate the relationship between flow, wave height, DOC concentration, temperature, light, and the benthic oxygen fluxes. The results reveal a large range of production and consumption rates in the permeable coastal sediments with distinct seasonal changes. The latter are caused by the availability of degradable organic matter and the magnitude of the pore water flushing process that carries these organic substrates and oxygen into the permeable coastal sands. We conclude that the highly degradable DOC produced by pelagic and benthic primary producers enhances water column - sediment biogeochemical coupling in the coastal zone thereby increasing the contribution of the sediment surface layer in the cycling of carbon and nutrients.
Download or read book Characterization of Biologically Produced Colored Dissolved Organic Matter in Seawater written by and published by . This book was released on 2005 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chromophoric, or colored dissolved organic maller (CDOM), influences the structure of aquatic ecosystems, complicates satellite measurements of ocean productivity, and affects the bioavailability and fate of important trace organic and metal species in seawater. The goals of this project were to chemically characterize biologically produced CDOM components, to characterize CDOM in laboratory algal cultures, and to develop techniques for studying CDOM cycling in seawater. Specifically, we compared the chemical characteristics of freshwater and marine CDOM in the Mississippi River estuary and Gulf of Mexico, characterized CDOM at two open ocean sites (N. Pacific Ocean, Sargasso Sea) and compared CDOM components with CDOM produced by laboratory cultures of marine algae. CDOM was collected by adsorption onto C18 resin from acidified seawater. From this fraction we identified 2,4-dichlorobenzoic acid (2,4-DCBA) and a series of tetrachloro-biphenyl aromatic acids (TCBCAs) that are structurally related to POBs as major components. Structures were determined using proton NMR, gas chromatographylmass spectrometry, and HPLC analyses by co-injection with authentic compounds. High concentrations of chlorinated aromatic acids were found in all seawater samples, but were not found in samples of Mississippi River water. The biological production of 2,4-DCBA and TCBCAs was confirmed by their production in laboratory cultures of the marine algae Emlliana huxleyi and Isochrysis galbana. Spent culture media from these two algae contained up to 500 mug/L 2,4-DCBA and 12 mug/L TCBCAs.
Download or read book Determining optical absorption of colored dissolved organic matter in seawater with a liquid capillary waveguide written by E.J. D'SA 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 Solar Radiation enhanced Dissolution photodissolution of Particulate Organic Matter in Texas Estuaries written by Qiyuan Liu and published by . This book was released on 2013 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is crucial to carbon and nutrient biogeochemical cycling in the marine environment because it helps fuel heterotrophic microbial activity by providing substrates for degradation and remineralization. This study shows that substantial production of DOM in Texas estuaries can result from the solar radiation-enhanced dissolution (photodissolution) of particulate organic matter (POM). Experimental results showed that 0.4-6.6 mg C L−1gsed−1 of dissolved organic carbon (DOC) and 0.03-0.93 mg N L−1gsed−1 of total dissolved nitrogen (TDN) can be produced from irradiated sediment suspensions within 24 hours, and further that photodissolution may augment DOC and TDN loads in Texas estuarine waters by as much as 3-85% and 4-75%, respectively. Photodissolution can also enhance the optical thickness of the water column via the release of chromophoric dissolved organic matter (CDOM), which may subsequently further enhance photochemical processes in surrounding waters. Photoproduced CDOM appears to be of relatively high molecular weight and dominantly exhibits humic-like fluorescence, suggesting that photodissolution primarily occurs for humic moieties. Photodissolution was also observed for sterilized sediment suspensions, indicating that photochemical degradation of POM is the primary pathway of DOM production during photodissolution, as opposed to microbial mediated degradation or stimulation of benthic primary production by benthic phytoplankton or algae. Environmental and mechanistic factors controlling the extent of photodissolution in Texas estuaries may include sediment desiccation, water organic content, and sediment characteristics (organic content and lability of POM). Desiccated-rewetted sediments suspended in artificial seawater under solar irradiation produced ~40% more DOC and TDN than wet sediments, indicating the sediment dry-wet cycle may alter the 3-D structure of sediment grain matrices and thus might be a major controlling factor of photodissolution in salt marsh systems. The organic content of water used in sediment suspensions did not significantly influence DOC or TDN photoproduction by itself, but the combined influence of water organic content and sediment dry-rewet event played a substantial role in controlling the extent of photodissolution. In contrast to the results in artificial seawater, wet sediments produced slightly more DOC ([Delta]DOC=0.10 mg C gsed−1) and substantially more TDN ([Delta]TDN=0.14 mg N gsed−1) than dry-rewetted sediments in organic-rich Nueces Marsh water during 24 hours of photoincubation. Photodissolution dominantly produced humic-like DOM even though biologically labile organic matter was available in sediments, indicating that photochemical reactions preferentially occur with humic-like rather than protein-like organic matter. DOC and TDN production during photodissolution was strongly proportional to the amount of POC in sediment suspensions. On average, 69.2 ± 11.0 mg C of DOC and 9 ± 3.1 mg N of TDN was produced from 1 g of organic carbon in sediment suspensions after 24 hours of photodissolution.
Download or read book The Impact of Biogeochemical Processes on the Composition of Dissolved Organic Matter in Marine Subsurface Sediments written by Shuchai Gan and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
