Download or read book Sources and Fates of Dissolved Organic Carbon in Rural and Urban Watersheds in Brazos County Texas written by Danielle Cioce and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Bryan/College Station (B/CS) region has been reported to have elevated concentrations of dissolved organic carbon (DOC) in surface water. Increased DOC concentrations are worrisome as DOC has been shown to be an energy source for the recovery and regrowth of E. coli and many watersheds are impaired by high bacteria levels. To examine the sources and fates of DOC in rural and urban regions to better understand DOC movement though the environment, seven watersheds were studied. To investigate source, streams were analyzed using diffuse reflectance near infrared spectroscopy (DR-NIR) and carbon isotopes. Fate of DOC was determined through monthly streams samples, gathered between March 2011 and February 2012, which were incubated for biodegradable DOC (BDOC). Soil in the region was sampled based on land use categories. Soil was analyzed for DOC and BDOC as well as DOC adsorption, the other major fate of DOC. Above ground vegetation was sampled in conjunction with soil and analyzed for BDOC. Data indicated that fecal matter from cliff swallows provided considerable organic material to streams in the B/CS region as shown through DR-NIR. Carbon isotope values in streams ranged from -23.5 +/- 0.7% to -26.8 +/- 0.5%. Stream spectra may be able to predict carbon isotope values in streams (Adj. R2 = 0.88). Mean annual stream DOC concentrations ranged from 11 +/- 3 mg/L to 31 +/- 12 mg/L, which represents a significant decrease in DOC between 2007 and 2011. Concurrent increases in pH and conductivity were also recorded. The decrease in DOC and the increases in pH and conductivity may be due to impacts of high sodium irrigation tap water. Biodegradable DOC was low in streams, which is likely due to DOC being present in streams in refractory forms that are resistant to microbial breakdown. Soil chemistry, including soil adsorption, was greatly influenced by sodium. The elevated adsorption coefficients and release values seen in highly developed and urban open areas can be attributed to frequent exposure to high sodium irrigation water. The results indicate that sodium is a major driver of DOC in the system. Sound management decisions concerning irrigation water chemistry and urban development might eventually emerge to protect water quality as a result of this research.

Download or read book Determining Sources of Dissolved Organic Carbon and Nutrients in an Urban Basin Using Novel and Traditional Methods written by Krittika Govil and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Water quality in urban ecosystems is sensitive to localized disturbances potentially affecting those mechanisms which influence nutrient cycles. The Carters Creek Basin has been reported to have elevated concentrations of dissolved organic carbon (DOC). In combination with high terrestrial nutrient export from non-point sources and point source effluent discharge, this has been suggested to contribute to E.Coli recovery and regrowth. Spatial identification of loading "hot-spots" or locations of elevated nutrient concentrations of non-point, terrestrial sources may provide critical information necessary for appropriate mitigation efforts and watershed management. This study used traditional and novel methods for source tracking nutrients and dissolved organic carbon in small urban and rural watersheds in Brazos County, Texas. A nested watershed approach allowed identification of problem areas of nutrient loading. A novel cost-effective technique using diffuse reflectance near-infrared spectroscopy was used to identify sources of DOC. Monthly stream sampling was conducted at 12 sites from 2012 to 2013. Impacts of human activity on landscape features determining source pathways for nutrient retention, transport, and conversion were identified in this study. Higher nitrate-N (0.12-22.8 mg L−1), orthophosphate-P (0.11-3.60mgL−1), and DOC concentrations (18.6-68.1 mg L−1) were found across the watershed than in 2007. Factors such as increased erosion, sodic soil dispersion, land use, and flow conditions wereidentified as possible causes for increased carbon (C), nitrogen (N) and phosphorus (P) observed in the basin. This study supported the use of near-infrared spectroscopy to elucidate watershed sources of carbon. The major sources of DOC into the Carter Creek basin watersheds were leachate from soil and turfgrass. Rural subwatersheds had less complicated source signatures than their urban counterparts. Urban impervious runoff signatures also clustered with stream water signatures, especially during high flow in October and September. These results indicate that specific vegetation such as turfgrass used for landscapes in urban watersheds coupled with sodic irrigation may alter traditional nitrogen, phosphorus and carbon cycling in urbanizing watersheds. Spatial source tracking will enable efficient pollution mitigation and protect water quality as a result of this study. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152459

Download or read book Dissolved Organic Carbon Release from Mineral Soils and Sediments in an Irrigated Agricultural System written by Sandrine J. Matiasek and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water interactions with soil and vegetation are greatly altered in agricultural watersheds compared to natural landscapes, which impacts sources and fates of organic carbon (OC). While mineral soil horizons in natural ecosystems primarily act as filters for dissolved organic carbon (DOC) leached from organic surface horizons, tilled soils largely lack an organic horizon and their mineral horizons therefore act as a source for both DOC and sediment to surface waters. Irrigated watersheds highlight this difference, as DOC and total suspended sediment (TSS) concentrations simultaneously increase during the low-discharge irrigation season, suggesting that sediment-associated OC may constitute a significant source of DOC. While DOC solubilized from sediments and soils has been found to be compositionally similar to stream DOC, the contributions of mineral-bound OC solubilization to agricultural streams remain poorly quantified. To address this, we conducted abiotic solubilization experiments using sediments (suspended and bed) and soils from an irrigated agricultural watershed in northern California, USA. Sediments (R2 > 0.99) and soils (0.74

Download or read book Sources and Fate of Dissolved Organic Matter in the Amazon River Basin written by Sonya Marie Remington and published by . This book was released on 2008 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Dissolved Organic Carbon written by Shawn P. McElmurry and published by . This book was released on 2008 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissolved Organic Matter in Atmospheric Deposition written by Lidiia Iavorivska and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) in the atmosphere affects air quality and climate. Unlike inorganic constituents that typically consist of single compounds, DOM is a mixture of multiple organic compounds having varying molecular weights, reactivity and solubility. Dissolved organic carbon (DOC) is typically used as a measure of the total DOM present in solution. In the atmosphere, DOC originates from emissions of various biogenic and anthropogenic sources, such as vegetation, incomplete combustion of fossil fuels, biomass burning, and sea-spray. The ultimate fate of atmospheric DOC is to be oxidized to inorganic forms of carbon dioxide and carbon monoxide, or to be removed from the atmosphere and transferred to the landscape through deposition. Deposition can occur as wet deposition via precipitation and as dry deposition via surface settling of particles and gases. The concentration, or quantity, of DOC in precipitation plays an important role in the carbon cycle and in other elemental cycles; while the chemical composition, or quality, of DOC in precipitation largely determines its fate in the environment. Rain and snow deposited to the landscape are a source of nutrient enrichment to ecosystems and water bodies, and are especially important as an input of carbon in coastal regions. Since DOC in precipitation is highly chemically reactive and bioavailable it influences rates of productivity in aquatic ecosystems. Despite the significance of DOC to many ecosystem processes, knowledge about its contributions to landscapes in precipitation remains limited. With anthropogenic influences on the carbon cycle now widely recognized, the need for synthesis of existing datasets on atmospheric deposition of DOC and further determining its rates and drivers is great. My dissertation is focused on wet deposition of DOC and assesses the magnitude and patterns of variation of organic matter in precipitation over space and time. The dissertation is organized into four manuscripts. Chapter 1 is a literature review where I provide a new data synthesis from 83 contemporary, peer-reviewed studies where organic carbon (OC) in precipitation was measured at sites around the world. Data regarding the concentrations of OC in precipitation and rates of atmospheric deposition were compiled in a common set of units and presented along with the summary statistics. These data give insights into the magnitude and regional variability of OC in precipitation. Organic carbon was ubiquitous in precipitation in rural and urban locations; with DOC in precipitation spanning several orders of magnitude between locations. This synthesis brings attention to atmospheric deposition as an under-sampled piece of the global carbon cycle; highlights gaps in data availability and challenges for data inter-comparison; and provides a unique data set that can be used for toward exploring future changes in the carbon cycle. Chapter 2 aims to understand how DOC concentration and composition in precipitation change temporally from storm to storm. Precipitation samples were collected at the Susquehanna Shale Hills Critical Zone Observatory watershed (Pennsylvania, USA) during 90 storm events. Observational data revealed temporal variability associated with seasonality and meteorological conditions. Using a mixed modeling statistical approach, I showed that there are multiple processes that work in synergy to influence the quantity and quality of DOC in precipitation. Factors related to storm properties, emission sources, and to the chemical composition of the atmosphere could explain more than 60% of the storm to storm variability in DOC concentrations. This study provided observations on changes in DOC that can be useful in modeling of atmospheric chemistry and in considering temporal changes in ecosystem nutrient balances and microbial activity.Chapter 3 explores how DOC concentration and composition vary throughout the course of storm events. I measured DOC in sequential samples during 13 storms at the Shale Hills watershed. The observational data generated hypotheses about potential factors that influence variability of DOC within storms. While previous studies have observed that concentrations of other elements in precipitation typically decrease over the course of individual storms, results from this study showed that DOC concentrations are highly variable. During most storms concentrations decreased towards the end of the event; however increasing concentrations in the later stages of some storms highlight that DOC removal with precipitation is not merely an exponential decay process. The variability of DOC during events is related to the balance between the cloud microphysics, atmospheric chemical transformations, and synoptic scale gradients in the abundance of organic compounds in the boundary layer. This work advances understanding of physicochemical processes occurring during storms that are relevant to studies of atmospheric chemistry, carbon cycling, and ecosystem responses.Chapter 4 quantifies spatial gradients in wet atmospheric DOC deposition across the state of Pennsylvania (USA). DOC concentrations were measured in selected precipitation samples collected for six years at a network of atmospheric deposition monitoring sites. A simple modeling approach was used to estimate the first statewide, annual estimates of wet atmospheric DOC deposition. Results showed that DOC inputs with wet deposition in Pennsylvania represented about one-third as much as literature reported values for DOC exported by rivers from watersheds in the region. The rates of DOC wet deposition showed a pronounced seasonality and spatial distribution, with highest deposition rates observed in the summer, especially at the sites located in western Pennsylvania.

Download or read book The Distribution of Organic Carbon in the Brazos River Basin written by James Mark Brooks and published by . This book was released on 1970 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies on the Distribution and Fates of Dissolved Organic Carbon written by Clifford N. Dahm and published by . This book was released on 1980 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissolved Organic Matter Sources and Dynamics in an Agricultural Watershed written by Sandrine Journet Matiasek and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Agriculture is a dominant land use on Earth, but its impacts on dissolved organic matter (DOM) sources, processing, and fate remain relatively unclear. The goal of this research was to study DOM sources and dynamics in an irrigated agricultural watershed of Central Valley, California by 1) assessing the quantitative and qualitative impacts of organic matter (OM) desorption from sediments and soils, and by 2) generating an amino acids time series to link seasonal processes (natural and anthropogenic) to changes in stream DOM chemistry and reactivity. Abiotic desorption experiments revealed that mineral-bound organic carbon (OC) desorption is a predictable and finite process in agricultural surface waters, contributing 5 - 7% of the annual dissolved OC (DOC) export, with local maxima up to 50% of typical field runoff concentrations and 20% of winter storm DOC concentrations. The relevance of OM desorption was even more evident at the molecular level. Relative to mineral-bound OM, desorbed DOM was nitrogen-poor and depleted in amino acids and lignin. Distinct fractionation patterns of amino acids and lignin phenols led to a more acidic DOM pool that appeared substantially more degraded than particulate OM, with decreased mole fractions of basic amino acids, increased molar contributions of non-protein amino acids, decreased degradation index values, and increased proportions of acidic lignin phenols. If unaccounted for, the profound alteration of DOM composition incurred by desorption could lead to misinterpretations of indicators commonly used to assess the diagenetic state of OM. At the watershed scale, the role of land use and hydrologic controls on labile DOM dynamics was evidenced by elevated total hydrolyzable amino acid (THAA) concentrations throughout the low-discharge irrigation season and by seasonal compositional differences. DOM during winter baseflow was the most degraded, with the lowest THAA content and the lowest degradation index (DI), while winter storms and summer irrigation were two critical hydrologic regimes for DOM cycling with the largest amino acid contents, the largest proportions of basic amino acids, and the largest DI values, indicative of a relatively fresh DOM pool. The biogeochemical relevance of irrigation practices was therefore demonstrated by the mobilization of DOM similar in concentration and reactivity to DOM during winter storms.

Download or read book Origin Composition and Fate of Dissolved Organic Carbon written by D. J. Repeta and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Factors Controlling Dissolved Organic Carbon Lability and Ecological Fate in the East Branch Swift River Massachusettes written by Eric M. Hall and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluvial systems have been estimated to transform, transport, or store 2.75 petagrams (Pg) of Organic Carbon (OC) per year. Although approximately 1Pg per year of terrestrial carbon is fluxed to the atmosphere through inland waters, little is known about the factors regulating its eventual ecological fate. 28 day lability incubations were conducted concurrent with the measurement of several environmental parameters including discharge, nutrient concentration, DO13C, and DOC:DON at several sites along Bigelow Brook and the East Branch of the Swift River, Massachusetts. Temporal and spatial variation of DOC, DOC:DON and DO13C were explored. Two distinct DOC consumption rates, short and long term, as well as overall consumption rate (k), were evaluated to determine the interactions with source, quality, and nutrients. Dissolved organic nutrient concentrations significantly increased long term consumption rates but had little effect on short term rates suggesting that short term rate may be tightly coupled to local, in stream, processes. The short term rate was significantly correlated to k. Interestingly, few significant relationships were found between various rate metrics and the source or quality of the DOC. A large recalcitrant DOC pool persisted after the 28 day period suggestive of downstream export of a large fraction of initial DOC pool.

Download or read book Dissolved Organic Carbon Dynamics During the Snowmelt Period in a Small Urban Watershed written by Jaclyn L. O'Riley and published by . This book was released on 2012 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissolved Organic Matter in a Rural Piedmont Watershed written by Louis A. Kaplan and published by . This book was released on 1980 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissolved Organic Carbon and Disinfection By product Precursors in Waters of the Chickahominy River Basin Virginia and Implications for Public Supply written by Gary K. Speiran and published by . This book was released on 2000 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Compilation of Hydrologic Data Green Creek Brazos River Basin Texas 1967 written by Geological Survey (U.S.). Water Resources Division. Texas District and published by . This book was released on 1967* with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Distribution of Organic Carbon in the Brazos River Basin written by and published by . This book was released on 1970 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sources and Characteristics of Dissolved Organic Carbon in Arid Region Water Supplies written by My-Linh T. Nguyen and published by . This book was released on 2002 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: