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Author: Kelly J. Rodibaugh Publisher: ISBN: Category : Bacterial growth Languages : en Pages : 106
Book Description
Inland freshwater ecosystems, though comprising a small portion of the earth's surface, are thought to be important in the global carbon (C) cycle. Carbon processing by heterotrophic microbes (bacteria) is a critical process, contributing considerably to overall ecosystem production and processing of dissolved organic carbon (DOC). This study assesses spatial variation in C processing by heterotrophic bacterioplankton in a semi-arid river network: the Rio Grande/Rio Bravo del Norte in Texas, USA. I examined how bacterial metabolism and C processing varied with spatial differences in physicochemical conditions and patterns in DOC lability in this highly impacted riverine network. Physicochemical and biological data were collected at 14 sites from March - December of 2010. I additionally analyzed phytoplankton biomass, bacterial density, bacterial community metabolic rates [bacterial respiration (BR), bacterial productivity (BP), and bacterial growth efficiency (BGE)], and C quality parameters at a subset of nine sites within this drainage. Across the drainage, hydrology and landscape position (i.e., biogeoclimatic conditions, presence of reservoirs, and groundwater contribution to flow) substantially influenced in-stream physicochemical conditions, leading to spatial patterns in bacterial density, phytoplankton biomass, and bacterial metabolism. Bacterial C metabolism was influenced by both physicochemical and C quality - quantity gradients present within the drainage. Bacterial production and BR responded to different environmental gradients, with BP being driven by C quality and inorganic nutrients. This resulted in a negative correlation between BGE and the bacterial respiration of refractory C. Results from this study indicate that natural variation and anthropogenic impacts influence the physicochemical and biotic conditions across the Rio Grande/Rio Bravo del Norte drainage and these effects have implications for C sequestration, transformation, and transport, as well as for organic matter (OM) delivery to the Gulf of Mexico.
Author: Kelly J. Rodibaugh Publisher: ISBN: Category : Bacterial growth Languages : en Pages : 106
Book Description
Inland freshwater ecosystems, though comprising a small portion of the earth's surface, are thought to be important in the global carbon (C) cycle. Carbon processing by heterotrophic microbes (bacteria) is a critical process, contributing considerably to overall ecosystem production and processing of dissolved organic carbon (DOC). This study assesses spatial variation in C processing by heterotrophic bacterioplankton in a semi-arid river network: the Rio Grande/Rio Bravo del Norte in Texas, USA. I examined how bacterial metabolism and C processing varied with spatial differences in physicochemical conditions and patterns in DOC lability in this highly impacted riverine network. Physicochemical and biological data were collected at 14 sites from March - December of 2010. I additionally analyzed phytoplankton biomass, bacterial density, bacterial community metabolic rates [bacterial respiration (BR), bacterial productivity (BP), and bacterial growth efficiency (BGE)], and C quality parameters at a subset of nine sites within this drainage. Across the drainage, hydrology and landscape position (i.e., biogeoclimatic conditions, presence of reservoirs, and groundwater contribution to flow) substantially influenced in-stream physicochemical conditions, leading to spatial patterns in bacterial density, phytoplankton biomass, and bacterial metabolism. Bacterial C metabolism was influenced by both physicochemical and C quality - quantity gradients present within the drainage. Bacterial production and BR responded to different environmental gradients, with BP being driven by C quality and inorganic nutrients. This resulted in a negative correlation between BGE and the bacterial respiration of refractory C. Results from this study indicate that natural variation and anthropogenic impacts influence the physicochemical and biotic conditions across the Rio Grande/Rio Bravo del Norte drainage and these effects have implications for C sequestration, transformation, and transport, as well as for organic matter (OM) delivery to the Gulf of Mexico.
Author: Timothy B. Jones Publisher: ISBN: Category : Languages : en Pages :
Book Description
Fluvial systems act as conduits for terrestrial carbon transport to coastal oceans. However, riverine systems not only transport allochthonous carbon, they transform and store carbon in many different ways. The different mechanisms of transformation and storage need to be considered for fluvial systems in order to accurately account for modifications to the carbon pool when developing carbon budgets. Of interest was to investigate the carbon dynamics in the James River, in Virginia, from headwaters to the tidal fresh estuary to gain a better understanding of carbon dynamics along the continuum. Sites along the river continuum were sampled for dissolved organic carbon (DOC) concentrations and used in bioassays to determine degradation dynamics along the continuum, radiocarbon analysis was used to determine the age of the DOC and POC pool available to bacteria, impoundment effect on carbon dynamics was investigated in the Appomattox River, a tributary to the James, and landcover data was used to investigate the effects of land change on aquatic carbon dynamics. Bacterial total consumption and rates were found to be highest in the headwater streams, where carbon sources have yet to undergo degradation, downstream sites consumption remained steady up to the tidal fresh estuary where degradation was minimal. Radiocarbon analyses showed older POC (5460 years old) at a site in the middle of the continuum where anthropogenic effects may have been the cause. Samples from the impoundment of the Appomattox River to form the Lake Chesdin Reservoir provided different results from the mainstem James, as DOC concentrations fluctuated throughout the continuum and the impoundment allowed for increased storage of allochthonous carbon and production of autochthonous carbon, altering the flux of carbon and nutrients downstream. As the majority of the James River watershed is forested, the increase in anthropogenic modifications downstream showed an opposite trend with the decrease in bacterial consumption further downstream, suggesting possible anthropogenic influence on bioavailability of DOC to bacteria. Rivers were once thought of as only transporting carbon downstream, however what enters rivers in the headwaters is not always the same that concludes its journey in the ocean. Thus, the many mechanisms of transformation and storage need to be assessed when accurately constructing carbon budgets. In an Appendix, I detail modifications to the Respiratory Carbon Recovery System (ReCreS) which helped streamline sample incubation and collection. A new incubation chamber was devised with a port for a pH probe and a flat bottom for the introduction of a magnetic stir bar to reach equilibrium faster. Additionally, a new kettle lid design contained a port for a pressure gauge to prevent over pressurization during sparging. An added inline Nafion Dryer removed moisture from the gas stream before entering the vacuum line. Finally, the line was connected directly to a vacuum pump to streamline the sample collection process, removing the need to take the trapped CO2 elsewhere for processing and providing immediate recovery results.
Author: David W. Kicklighter Publisher: ISBN: Category : Languages : en Pages : 20
Book Description
Terrestrial carbon dynamics influence the contribution of dissolved organic carbon (DOC) to river networks in addition to hydrology. In this study, we use a biogeochemical process model to simulate the lateral transfer of DOC from land to the Arctic Ocean via riverine transport. We estimate that, over the 20th century, the pan-Arctic watershed has contributed, on average, 32 Tg C/yr of DOC to river networks emptying into the Arctic Ocean with most of the DOC coming from the extensive area of boreal deciduous needle-leaved forests and forested wetlands in Eurasian watersheds. We also estimate that the rate of terrestrial DOC loading has been increasing by 0.037 Tg C/yr2 over the 20th century primarily as a result of climate-induced increases in water yield. These increases have been offset by decreases in terrestrial DOC loading caused by wildfires. Other environmental factors (CO2 fertilization, ozone pollution, atmospheric nitrogen deposition, timber harvest, agriculture) are estimated to have relatively small effects on terrestrial DOC loading to Arctic rivers. The effects of the various environmental factors on terrestrial carbon dynamics have both offset and enhanced concurrent effects on hydrology to influence terrestrial DOC loading and may be changing the relative importance of terrestrial carbon dynamics on this carbon flux. Improvements in simulating terrestrial DOC loading to pan-Arctic rivers in the future will require better information on the production and consumption of DOC within the soil profile, the transfer of DOC from land to headwater streams, the spatial distribution of precipitation and its temporal trends, carbon dynamics of larch-dominated ecosystems in eastern Siberia, and the role of industrial organic effluents on carbon budgets of rivers in western Russia.
Author: J. David Allan Publisher: Springer Nature ISBN: 3030612864 Category : Science Languages : en Pages : 485
Book Description
Stream Ecology: Structure and Function of Running Waters is designed to serve as a textbook for advanced undergraduate and graduate students, and as a reference source for specialists in stream ecology and related fields. This Third Edition is thoroughly updated and expanded to incorporate significant advances in our understanding of environmental factors, biological interactions, and ecosystem processes, and how these vary with hydrological, geomorphological, and landscape setting. The broad diversity of running waters – from torrential mountain brooks, to large, lowland rivers, to great river systems whose basins occupy sub-continents – makes river ecosystems appear overwhelming complex. A central theme of this book is that although the settings are often unique, the processes at work in running waters are general and increasingly well understood. Even as our scientific understanding of stream ecosystems rapidly advances, the pressures arising from diverse human activities continue to threaten the health of rivers worldwide. This book presents vital new findings concerning human impacts, and the advances in pollution control, flow management, restoration, and conservation planning that point to practical solutions. Reviews of the first edition: ".. an unusually lucid and judicious reassessment of the state of stream ecology" Science Magazine "..provides an excellent introduction to the area for advanced undergraduates and graduate students..." Limnology & Oceanography "... a valuable reference for all those interested in the ecology of running waters." Transactions of the American Fisheries Society Reviews of the second edition: "Overall, a must for the field centre and a good starter text in stream ecology." (TEN News, October, 2007) "Highly recommended. Upper-division undergraduates through faculty." (P. R. Pinet, CHOICE, Vol. 45 (7), 2008) "... a very good, fluidly readable book which contains the latest key scientific knowledge of the ecology of running waters." (Daniel Graeber, International Review of Hydrobiology, Vol. 94 (2), 2009)
Author: Kelly J. Rodibaugh
Author: Kelly J. Rodibaugh
Author: 
Author: Hannah Laeverenz Schlogelhofer
Author: Jeng-Wei Tsai
Author: Jennifer A. Vaughn
Author: Timothy B. Jones
Author: David W. Kicklighter
Author: J. David Allan
Author: Nicoletta Leonardi
Author: