Download or read book Resolving Spatial and Temporal Variability in Dissolved Organic Matter Characteristics Within Combined Agricultural and Stormwater Conveyances written by Bryce A. Mihalevich and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In many urban areas, stormwater runoff can threaten the ecological health of streams and downstream water bodies. Due to the increased impervious nature of urban landscapes, runoff is more 0́−flashy0́+ and as a result, high concentrations of pollutants can be transported in shorter periods of time than in more natural environments. One pollutant of concern is dissolved organic matter (DOM). DOM is important within aquatic ecosystems, but excess amounts can cause depletion in dissolved oxygen concentrations and can negatively affect aquatic organisms. This study investigated changes in DOM quantity and sources within the Northwest Field Canal (NWFC), an urban water conveyance located in Logan, Utah, USA that receives runoff during storm events. DOM was monitored at upstream and downstream locations within the canal and at selected stormwater outfalls within the study reach. During storm events, DOM concentrations were rapidly elevated to values orders of magnitude greater than in baseflow measurements, and were greater at the downstream site than at the upstream site, triggered by contributions from outfalls discharging into the canal. Changes in DOM composition during storm events confirmed that DOM is more terrestrially derived, whereas it is normally more microbially derived during baseflow conditions in the canal. These results provide better understanding of the composition of DOM in the canal system and may provide crucial information for future management of stormwater runoff that can potentially lead to the improvements of water quality in downstream water bodies.

Download or read book Influence of Land Use Land Cover and Hydrology on the Spatial and Temporal Characteristics of Dissolved Organic Matter DOM in Multiple Aquatic Ecosystems written by Shatrughan Singh and published by . This book was released on 2017 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spatial and temporal patterns of dissolved organic matter (DOM) were characterized using a combination of spectro-fluorometric measurements and multivariate analysis techniques. The study was conducted over a four-year (2012-2016) period in multiple watersheds located in the Gulf-Atlantic Coastal Plain Physiographic region of the southeast USA as well as in the Indo-Gangetic Plain of India. Surface water samples were collected from five major lakes in the Mississippi, an estuarine region in the southeastern Louisiana, and from the coastal region in the eastern Mississippi Sound in the USA, and a large river (Ganges River) in India. Absorption and fluorescence measurements were performed to generate absorption spectra and excitation-emission matrices (EEMs). Using parallel factor analyses (PARAFAC), EEM models were developed to characterize the biogeochemistry of DOM in three studies in this project. Principal component analysis and regression analyses of DOM data indicated that the northern Mississippi lakes were majorly influenced by agricultural land use, estuarine region was affected by natural DOM export from forests and wetlands, while the coastal waters were affected by a mix of anthropogenic and natural inputs of DOM. Spatial analyses indicated that DOM derived from watershed with increased wetland coverage was humic and aromatic while the DOM derived from agricultural watersheds was bioavailable. Temporal patterns of DOM in the estuary indicated the influence of hydrologic conditions and summer temperatures, and revealed strong seasonality in DOM evolution in the watershed. During high discharge periods (spring), aromatic and humic DOM was exported from the watershed while strong photochemical degradation during summer resulted bioavailable DOM. Comparison between two river systems, a highly urbanized large river and a small pristine river, indicated the influence of anthropogenic inputs of DOM in the large river system. DOM was bioavailable during summer due to anthropogenic activities in the large river system while it varied with hydrological connectivity in a small river system during summer and winter. In conclusion, this study has improved my understandings of the DOM properties, which are critical for a comprehensive assessment of biogeochemical processes undergoing in important water bodies on which our society is heavily dependent upon.

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 Dissolved Organic Matter DOM written by Oleg S. Pokrovsky and published by . This book was released on 2017 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rad Schiene Kontaktger usch Untersuchungen zur Anwendbarkeit eines Pr fstandes im Ma stab 1 8 f r Rad Schiene Rauhigkeiten written by and published by . This book was released on 1988 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spatiotemporal Variability in Dissolved Organic Matter Composition and Its Relationship to Photochemical Reactivity written by Stephanie Berg (Ph.D.) and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a ubiquitous group of biologically derived organic molecules found in all natural waters. DOM makes up a substantial amount of the carbon stored in surface waters, and its original sources include allochthonous, or terrestrial, inputs as well as autochthonous, or aquatic, inputs. It is primarily made of up small (i.e.,

Download or read book Does Dissolved Organic Matter Impact Primary Production A Study on the Effects of Terrestrially Derived Dissolved Organic Matter on Primary Production in Nutrient poor Boreal Lakes written by Bryanna Sherbo and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few decades, spatial and temporal variation in concentrations of allochthonous dissolved organic carbon (DOC) has been increasing in surface waters of boreal lakes around the world with climate change. Terrestrial landscapes export large amounts of organic matter into lakes, primarily as DOC. It is understood that DOC impacts primary production through its combined effects on light and nutrient availability. However, there remains uncertainty as to the mechanisms that cause DOC to have positive or negative effects on algal productivity. In a survey of 6-7 lakes spanning a DOC gradient (3.5-9.4 mg L-1) at International Institute of Sustainable Development-Experimental Lakes Area (IISD-ELA) in northwestern Ontario, we determined the effects of DOC on whole-lake metabolism (gross primary production (GPP), respiration, and net ecosystem production (NEP)) and depth integrated net primary production (NPP). Using in situ diel free-water oxygen method and in vitro partial pressure of CO2 incubations, we found that primary production was significantly impacted by DOC. In general, the effects of DOC on algal productivity was negative, although there was some evidence for the stimulation of whole ecosystem production by nutrients at low DOC concentrations. Epilimnetic chlorophyll, GPP, and community respiration increased significantly with DOC, and total depth integrated and sub-epilimnetic NPP decreased significantly with DOC. Lakes with the highest proportion of sub-epilimnetic production had well developed deep chlorophyll maxima (DCM). DCM were negatively correlated with DOC and are viewed as ecological hotspots for higher trophic levels. DCM and sub-epilimnetic productivity were eliminated in lakes with DOC values > 7.1 mg L-1. These results substantiate the influence of allochthonous DOC on aquatic food webs and highlight the combined effects of DOC on light and nutrient availability. The association of DOC with epilimnetic nutrients caused an increase in epilimnetic GPP (chapter 2) and decreasing light availability caused a decrease in total and sub-epilimnetic NPP (chapter 3). These contrasting effects of DOC on primary production provide further insight into the balance between nutrients and light with increasing concentrations of DOC.

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 Evaluating Spectroscopic and Chromatographic Techniques to Resolve Dissolved Organic Matter Characteristics in Streams During Storm Events written by Miranda Anne Williams and published by . This book was released on 2004 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seasonal and Spatial Variation in the Chemical Character of Dissolved Organic Matter Within a Small Boreal Forest Watershed written by Alexander W. Newman and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a significant carbon reservoir and component of the terrestrial-to-aquatic flux (Qualls et al., 1991). The terrestrial-to-aquatic carbon flux, a relatively new addition to global carbon models, is currently estimated to transfer a total of 1.7 petagrams (Pg) carbon (C) yr−1 globally (IPCC, 2013). Terrestrially derived DOM has been identified as a significant pool of organic matter in the aquatic environment. However, the quantity and chemical composition of DOM transferred, as well as the mechanisms driving its transfer, are less understood. This thesis focuses on expanding our knowledge of the processing DOM undergoes as it is transferred from terrestrial-to-aquatic environments by: 1) developing a standardized extraction methodology that can yield representative eluates when applied to sourced samples from throughout the terrestrial-to-aquatic interface and 2) applying the designed methodology to conduct a year long study of DOM quantity and composition in the terrestrial-to-aquatic interface in a boreal forest watershed. Experimental results suggest that although solid phase extraction with a divinyl benzene sorbent (SPE-PPL) yields high extraction efficiencies when applied to DOM, it is subject to selectivity. Extractions performed at high loading volumes were found to select against O-alkyl DOM hydrogen constituents, additionally all SPE-PPL experiments were found to select against nitrogenous DOM components. However, by considering proper extraction parameters, SPE-PPL can produce bulk representative eluates for nuclear magnetic resonance (NMR) analysis from land positions spanning the terrestrial-to-aquatic interface. Results from the field study revealed that DOM transferred from terrestrial-to-aquatic land positions in a boreal forest watershed is both temporally and regionally variable, however, proximity immediately downstream of ponds appeared to be a major hydrologic control, while seasonal variation in hydrologic flow paths may represent another control in boreal forest watersheds. Dissolved organic matter chemical composition and quantity in traditional boreal forest streams related to shifts in the hydraulic flow path of the watershed, indicated by changes in riverine DOM chemical composition that correlated to seasonal wet and dry periods. Increases in both dissolved organic carbon (DOC) concentration and the presence of O-alkyl DOM hydrogen functionalities in the stream indicated a shift from groundwater sources during the dry period to soil water sources during the wet period. Conversely streams downslope of ponds seemed to be buffered against shifts in DOM chemical composition associated with changes in hydrologic flow paths. Dissolved organic matter chemical composition of streams downslope of ponds were relatively constant throughout the year resembling the characterization of pond outflows, even during periods of high hydraulic conductivity, via additions of autochthonous DOM produced in the pond. These additions of autochthonous DOM are negligible in streams not downslope of ponds. Further application of this approach during key periods of DOM export, such as spring snowmelt and fall rain periods may prove help to reveal the processes controlling the terrestrial-to-aquatic carbon flux in boreal forest landscapes.

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 Spatial and Temporal Variability in Agrichemicals from a Claypan Soil written by F. Ghidey and published by . This book was released on 1994 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Hydrology on Dissolved Organic Matter Quantity and Properties in a Temporal Mediterranean Stream written by Eusebi Vázquez Garcia and published by . This book was released on 2013 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exploring Relationships Between Catchment Dissolved Organic Matter Characteristics and the Formation of Disinfection Byproducts written by Matthew Hopes and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Land Use as a Critical Determinant of Organic Matter Sources Variability and Disinfection Byproduct Precursors in the Sacramento River Watershed and Delta written by Robert Scott Eckard and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The initial translation of terrestrial organic matter from land to rivers informs all other aspects of terrestrial organic matter transport, cycling, and ultimate fate downstream. The overarching goal of this research was to identify connections between terrestrial organic matter releases and the magnitude and character of compositional change affected by those releases on adjacent and downstream aquatic organic matter. Specific objectives included (1) assessing the degree to which landscape scale organic matter sources in the Sacramento-San Joaquin Delta (the Delta) altered organic matter composition downstream; (2) synoptically investigating linkages between agricultural land use and aquatic organic matter characteristics in Willow Slough, a small agricultural watershed in Northern California; (3) evaluating terrestrial carbon export from Willow Slough and its bioavailability for use by downstream detrital ecosystems; and (4) applying terrestrial carbon export and transport information gleaned in order to support management efforts targeted at minimizing the formation of trihalomethanes (THMs) -- regulated carcinogenic compounds -- during drinking water disinfection, through watershed-level management of THM precursors. Key findings indicate that landscape scale organic matter sources in the Delta were sufficient to overwrite DOC compositional signatures integrated along tens of thousands of square miles of upstream watershed. Second, stream biogeochemistry is closely linked to land use at fine spatial scales, where local organic matter continuously supplemented aquatic organic matter composition in Willow Slough. This finding enabled calculation of organic carbon overprinting distance -- i.e., the longitudinal river travel distance over which DOC concentrations doubled -- which had a median value of 13 km in Willow Slough, highlighting strong watershed influence on passing waters. Third, storm period discharge of organic matter from agricultural watersheds varies by event, and is strongly affected by system hydrology. Bioavailable carbon released during storms in Willow Slough was found to be protein-like in composition in spite of a likely agricultural source, where 80 percent of this fraction was lost during a 21-day incubation, in comparison to 20 to 30 percent loss in DOC overall. Fourth, urban watersheds were found to be significant sources of THM precursors, releasing organic matter with median total THM formation potential of 618 [mu]g L−1, or over 7 times higher than the U.S. Environmental Protection Agency's regulated level for THMs in drinking water (80 [mu]g L−1). Agricultural irrigation is a major contributor to THM precursors, which were released at about the same rate (median 426 [mu]g L−1) during the summer irrigation period as during winter storms (460 [mu]g L−1). Finally, THM precursors added far upstream are resilient enough to degradation that they are expected to transport, with minimal loss, to downstream municipal water intakes located tens to hundreds of miles away. This finding highlights the critical need for better watershed management planning, which if deployed properly, could meaningfully reduce THM formation.

Download or read book Seasonal Variability in Absorption and Fluorescence Properties of Chromophoric Dissolved Organic Matter in the Barataria Basin Louisiana USA written by Shatrughan Singh and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seasonal and Spatial Variations in Dissolved Organic Matter Bioavailability and Nutrient Yields in Agricultural Streams written by Martha Mason Griffith and published by . This book was released on 2008 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: