Production and Ebullition of Methane in a Shallow Eutrophic Lake (Lake Elsinore, CA) PDF Download
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Author: Denise Nicole Martinez
Publisher:
ISBN:
Category : Gases
Languages : en
Pages : 0
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Author: Denise Nicole Martinez
Publisher:
ISBN:
Category : Gases
Languages : en
Pages : 0
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Author: Daniel F. McGinnis
Publisher: Frontiers Media SA
ISBN: 2832526225
Category : Science
Languages : en
Pages : 382
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Book Description
Author: Harold Mooney
Publisher: Univ of California Press
ISBN: 0520278801
Category : Nature
Languages : en
Pages : 1008
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Book Description
This long-anticipated reference and sourcebook for CaliforniaÕs remarkable ecological abundance provides an integrated assessment of each major ecosystem typeÑits distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of CaliforniaÕs ecological patterns and the history of the stateÕs various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the stateÕs ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of CaliforniaÕs environment and curious naturalists.
Author: Jacob Paul Shiba
Publisher:
ISBN: 9781339466019
Category : Lake Elsinore (Calif.)
Languages : en
Pages : 63
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Book Description
Methane is a powerful greenhouse gas that can be produced in bottom sediments of lakes and reservoirs and released through ebullition and other properties. Many studies have quantified ebullition rates, however, the detailed mechanisms remain incompletely understood. This study was undertaken to better understand, through in situ and laboratory measurements, the mechanisms of gas ebullition from lake sediment. Four sites on Lake Elsinore, CA with different properties were evaluated through the use of in situ hydroacoustic measurements made using a BioSonics echosounder with a 201-kHz split-beam transducer. This transducer was rigidly mounted to a telescoping stand that allows highly precise measurements of position, rise velocity, and target strength (size) of bubbles as they are released from the sediment. Methane bubble release from cohesive sediments occurred via the viscoelastic-fracture mechanism with bursts of 2-4 bubbles released from specific locations in small increments of time, typically a few seconds. Target strength of bubbles across all sites was approximately normally distributed with a mean value of -54.6±4.4 dB, corresponding to an average bubble size of 0.073 cm3. Rise velocity was also quantified and averaged 0.21±0.2 m s-1. Properties of the sediment are recognized to regulate the production, storage, and ebullition of methane. Undrained sediment shear strength, Cu, was evaluated for its role in methane storage and transport using a fall cone apparatus for sediments from 3 sites on Lake Elsinore that vary in sediment properties. Values of Cu for these soft cohesive sites were found to range from 0.092-0.342 kPa. Systematic variation under controlled laboratory conditions of water content and temperature resulted in linear changes of Cu. Values of Cu were strongly correlated with sand content and inversely correlated with water content. Sediment shear strength was also influenced by temperature, and decreased at rates of 0.0024-0.0037 kPa/°C for fine-textured cohesive sediment. Vertical bubble pressure was quantified and found to be less than sediment shear strength. Sediment shear strength affects the amount of methane stored in sediment and the mechanism of release. This was seen in the in situ target strength distributions of bubbles released from sediments, as well as laboratory core incubations of gas release from sediments.
Author: Richard Floyd Strayer
Publisher:
ISBN:
Category : Eutrophication
Languages : en
Pages : 112
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Author: Benjamin Paul Scandella
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Book Description
Methane is a potent greenhouse gas, and natural sources to the atmosphere include inland waterways and shallow oceans. However, the magnitude of these emissions and their potential for feedbacks with climate change remain poorly constrained. In many settings the majority of atmospheric methane emissions is delivered by bubbles, and the spatiotemporal heterogeneity of ebullition makes measurement challenging and impacts bubble dissolution and atmospheric emissions. In this thesis, we present an analysis of both the episodicity and spatial structure of methane venting from soft sediments in a eutrophic lake over a range of spatial scales, from 1 cm to 20 m, and using a combination of field observations and laboratory experiments. Field-scale measurements of ebullition were acquired at the bottom of Upper Mystic Lake, MA, USA, using a high-resolution multibeam sonar during multiple deployments over a 9-month period. The sonar was calibrated to estimate the gas flow rates throughout a 330 m2 lateral observation area with resolution of 0.5 m. The results confirm that ebullition is strongly episodic, with distinct regimes of high- and low-flux largely controlled by changes in hydrostatic pressure. Statistical analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over timescales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that meter-scale methane vents are ephemeral rather than persistent. Laboratory-scale measurements were made in a controlled incubation of reconstituted sediments from the same field site. Image analysis of the 0.14 m2 observation area allowed identification of individual bubble outlets and resolved their location to ~ 1 cm. While ebullition events were typically concentrated in bursts lasting ~ 2 min, some major outlets showed persistent activity over the scale of days and even months. This persistence was surprising given the ephemerality of spatial structure at the field-scale. It suggests that, at the centimeter scale, conduits are re-used as a result of a drop in tensile strength due to deformation of sediments by the rising bubbles. By combining novel measurement techniques at different scales, we elucidate the mechanisms governing bubble growth and mobility, thereby supporting estimates of global methane fluxes from lakes and how their magnitude may vary with climate change.
Author: S.K. Hamilton
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
Measurements of the composition of sediment gas bubbles and of methane emission from emergent plants in the Pantanal wetland of Brazil indicate that savanna floodplains with inundation depths > 1 m have high rates of methane emission by ebullition compared with emission by rooted emergent plants. High rates of methane production and ebullition result in high concentrations of methane in sediment bubbles, which often contained > 50% methane by volume at the deeper ( > 1m) sampling sites. The rooted emergent plants typical of the deeper waters had low rates of methane emission (0.0-0.2 mg/d) compared to species typical of inundation depths 1m (1.6-7.5 mg/d). The high rates of ebullition in the deeper vegetated waters of the Pantanal contrast with results from shallower rice fields and temperate wetlands,in which plant-mediated transport appears to be the dominant mode of methane emission. The elongated stems of rooted emergent plants tend to predominate in tropical wetlands with inundation depths 1m are evidently much less effective in the transport of methane from the sediments to the atmosphere than are the emergent stems of plants that grow in shallower waters.
Author: Erik R. Christensen
Publisher: John Wiley & Sons
ISBN: 1118111761
Category : Technology & Engineering
Languages : en
Pages : 447
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Book Description
There is need in environmental research for a book on fresh waters including rivers and lakes. Compared with other books on the topic, this book has a unique outline in that it follows pollution from sources to impact. Included in the text is the treatment of various tracers, ranging from pathogens to stable isotopes of elements and providing a comprehensive discussion which is lacking in many other books on pollution control of natural waters. Geophysical processes are discussed emphasizing mixing of water, interaction between water and the atmosphere, and sedimentation processes. Important geochemistry processes occurring in natural waters are described as are the processes specific to nutrients, organic pollutants, metals, and pathogens in subsequent chapters. Each of these chapters includes an introduction on the selected groups, followed by the physicochemical properties which are the most relevant to their behavior in natural waters, and the theories and models to describe their speciation, transport and transformation. The book also includes the most up to date information including a discussion on emerging pollutants such as brominated and phosphate flame retardants, perflurochemicals, and pharmaceutical and personal care products. Due to its importance an ecotoxicology chapter has been included featuring molecular biological methods, nanoparticles, and comparison of the basis of biotic ligand model with the Weibull dose-response model. Finally, the last chapter briefly summarizes the regulations on ambient water quality.
Author: United States. Environmental Protection Agency. National Enforcement Investigation Center
Publisher:
ISBN:
Category : Environmental protection
Languages : en
Pages : 14
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Book Description
Author: A. Tremblay
Publisher: Springer Science & Business Media
ISBN: 3540266437
Category : Science
Languages : en
Pages : 743
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Book Description
In a time when an unquestionable link between anthropogenic emissions of greenhouse gases and climatic changes has finally been acknowledged and * widely documented through IPCC reports, the need for precise estimates of greenhouse gas (GHG) production rates and emissions from natural as well as managed ecosystems has risen to a critical level. Future agreements between nations concerning the reduction of their GHG emissions will - pend upon precise estimates of the present level of these emissions in both natural and managed terrestrial and aquatic environments. From this viewpoint, the present volume should prove to a benchmark contribution because it provides very carefully assessed values for GHG emissions or exchanges between critical climatic zones in aquatic en- ronments and the atmosphere. It also provides unique information on the biases of different measurement methods that may account for some of the contradictory results that have been published recently in the literature on this subject. Not only has a large array of current measurement methods been tested concurrently here, but a few new approaches have also been developed, notably laser measurements of atmospheric CO concentration 2 gradients. Another highly useful feature of this book is the addition of - nitoring and process studies as well as modeling.
