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Author: Sivakiruthika Natchimuthu Publisher: Linköping University Electronic Press ISBN: 917685812X Category : Languages : en Pages : 56
Book Description
Freshwater bodies such as lakes and streams release the greenhouse gases methane (CH4) and carbon dioxide (CO2) into the atmosphere. Global freshwater CH4 and CO2 emissions have been estimated to be of a similar magnitude to the global land or ocean carbon sink, and are thus significant components of global carbon budgets. However, the data supporting global estimates frequently lacks information regarding spatial and temporal variability and are thus highly inaccurate. In this thesis, detailed studies of the spatio-temporal variability of CH4 and CO2 fluxes were conducted in the open water areas of lakes and streams within a whole catchment in Sweden. One aim was also to evaluate the importance of spatio-temporal variability in lake and stream fluxes when making whole catchment aquatic or large scale assessments. Apart from the expected large spatio-temporal variability in lake fluxes, interactions between spatial and temporal variability in CH4 fluxes were found. Shallow lakes and shallow areas of lakes were observed to emit more CH4 as compared to their deeper counterparts. This spatial variability interacted with the temporal variability driven by an exponential temperature response of the fluxes, which meant that shallow waters were more sensitive to warming than deeper ones. Such interactions may be important for climate feedbacks. Surface water CO2 in lakes showed significant spatio-temporal variability and, when considering variability in both space and time, CO2 fluxes were largely controlled by concentrations, rather than gas transfer velocities. Stream fluxes were also highly variable in space and time and in particular, stream CH4 fluxes were surprisingly large and more variable than CO2 fluxes. Fluxes were large from stream areas with steep slopes and periods of high discharge which occupied a small fraction of the total stream area and the total measurement period, respectively, and a failure to account for these spatially distinct or episodic high fluxes could lead to underestimates. The total aquatic fluxes from the whole catchment were estimated by combining the measurements in open waters of lakes and streams. Using our data, recommendations on improved study designs for representative measurements in lakes and streams were provided for future studies. Thus, this thesis presents findings relating to flux regulation in lakes and streams, and urges forthcoming studies to better consider spatio-temporal variability so as to achieve unbiased large-scale estimates.
Author: Sivakiruthika Natchimuthu Publisher: Linköping University Electronic Press ISBN: 917685812X Category : Languages : en Pages : 56
Book Description
Freshwater bodies such as lakes and streams release the greenhouse gases methane (CH4) and carbon dioxide (CO2) into the atmosphere. Global freshwater CH4 and CO2 emissions have been estimated to be of a similar magnitude to the global land or ocean carbon sink, and are thus significant components of global carbon budgets. However, the data supporting global estimates frequently lacks information regarding spatial and temporal variability and are thus highly inaccurate. In this thesis, detailed studies of the spatio-temporal variability of CH4 and CO2 fluxes were conducted in the open water areas of lakes and streams within a whole catchment in Sweden. One aim was also to evaluate the importance of spatio-temporal variability in lake and stream fluxes when making whole catchment aquatic or large scale assessments. Apart from the expected large spatio-temporal variability in lake fluxes, interactions between spatial and temporal variability in CH4 fluxes were found. Shallow lakes and shallow areas of lakes were observed to emit more CH4 as compared to their deeper counterparts. This spatial variability interacted with the temporal variability driven by an exponential temperature response of the fluxes, which meant that shallow waters were more sensitive to warming than deeper ones. Such interactions may be important for climate feedbacks. Surface water CO2 in lakes showed significant spatio-temporal variability and, when considering variability in both space and time, CO2 fluxes were largely controlled by concentrations, rather than gas transfer velocities. Stream fluxes were also highly variable in space and time and in particular, stream CH4 fluxes were surprisingly large and more variable than CO2 fluxes. Fluxes were large from stream areas with steep slopes and periods of high discharge which occupied a small fraction of the total stream area and the total measurement period, respectively, and a failure to account for these spatially distinct or episodic high fluxes could lead to underestimates. The total aquatic fluxes from the whole catchment were estimated by combining the measurements in open waters of lakes and streams. Using our data, recommendations on improved study designs for representative measurements in lakes and streams were provided for future studies. Thus, this thesis presents findings relating to flux regulation in lakes and streams, and urges forthcoming studies to better consider spatio-temporal variability so as to achieve unbiased large-scale estimates.
Author: A. Tremblay Publisher: Springer Science & Business Media ISBN: 3540266437 Category : Science Languages : en Pages : 743
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.
Author: James David Hamilton Publisher: ISBN: Category : Languages : en Pages : 562
Book Description
Methane and carbon dioxide fluxes ponds and lakes in the Hudson Bay Lowland to the atmosphere from were measured from June to October 1990. The study area was located near the town of Moosonee, Ontario (51o 29' N; 80o 27' W). The study area was divided into four different sites; the Coastal Marsh, Coastal Fen, Interior Fen and the Kinosheo Lake Bog. The Kinosheo Lake bog was the furthest inland (114 km inland from the Coastal Marsh). In early July, the average daily rate of methane flux from the ponds in the Kinosheo Lake area was 20 mg CH4/m2/day, increasing to 50 mg CH4/m2/day by the end of the month. The average daily flux of carbon dioxide was 900 mg CO2/m2/day. The Coastal Fen and Interior Fen Ponds exhibited much higher fluxes of both CH4 (averaging 160 mg CH4/m2/day) and CO2 (averaging 9000 mg CO2/m2/day) than were measured at the Kinosheo Lake Bog. At all the sites the flux of CH4 and CO2 were highest in September. Differences between ponds were much greater than the differences on different dates, i.e., ponds with higher rates tended to remain higher and vice versa. All 24 ponds and lakes sampled had concentrations of CH4 and CO2 which were consistently above atmospheric equilibrium and thus were sites of net carbon loss from the Hudson Bay Lowland. Computer modelling suggests that CH4 concentration is controlled by the cfombination of wind driven gas exchange and CH4 oxidation. Carbon dioxide concentrations appear to be controlled by the combined effects of wind driven gas exchange and algal photosynthesis/respiration.
Author: Ken W. Krauss Publisher: John Wiley & Sons ISBN: 111963928X Category : Science Languages : en Pages : 484
Book Description
Explores how the management of wetlands can influence carbon storage and fluxes. Wetlands are vital natural assets, including their ability to take-up atmospheric carbon and restrict subsequent carbon loss to facilitate long-term storage. They can be deliberately managed to provide a natural solution to mitigate climate change, as well as to help offset direct losses of wetlands from various land-use changes and natural drivers. Wetland Carbon and Environmental Management presents a collection of wetland research studies from around the world to demonstrate how environmental management can improve carbon sequestration while enhancing wetland health and function. Volume highlights include: Overview of carbon storage in the landscape Introduction to wetland management practices Comparisons of natural, managed, and converted wetlands Impact of wetland management on carbon storage or loss Techniques for scientific assessment of wetland carbon processes Case studies covering tropical, coastal, inland, and northern wetlands Primer for carbon offset trading programs and how wetlands might contribute The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity.Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Author: Anne E. Altor Publisher: ISBN: Category : Carbon cycle (Biogeochemistry) Languages : en Pages : 177
Book Description
Abstract: Wetlands are important ecosystems involved in the global carbon cycle as producers and consumers of the greenhouse gases methane and carbon dioxide. The global warming potential of methane -- 23 times greater than that of carbon dioxide over a 20 year time horizon -- warrants examination of the dynamics controlling its emission from temperate zone wetlands created and restored for habitat replacement and water quality improvement. Research on carbon dynamics in created and restored ecosystems can enable greater understanding of management practices to promote carbon sequestration in these ecosystems. In the research conducted for this dissertation, ecosystem and mesocosm-scale investigations were carried out in experimental riparian wetlands of the Midwestern USA, with hydrology, vegetation and soils as independent variables. Methane and carbon dioxide fluxes were the dependent variables of interest in each of the studies. In a one-year field study, flood-pulse hydrology typical of floodplains in the Midwestern USA was simulated in two one-hectare riparian marshes. Methane fluxes were measured from February-December using non-steady-state chambers located in marsh zones with and without emergent vegetation in which soils were intermittently exposed and inundated, and in permanently inundated wetland areas. In an extension of the first, one-year study, methane and carbon dioxide flux rates were measured in the morning, afternoon and nighttime in the same experimental marshes over a second year during which hydrologic inflow was maintained at a relatively constant rate. The hydrology and physiochemical properties of soils forming the foundation for created and restored wetlands determine what processes are likely to occur in these systems. In a companion, replicated study, effects of intermittent vs. continuous inundation, and hydric vs. non-hydric soils on fluxes of methane and carbon dioxide were investigated using 20 wetland mesocosms.
Author: P. A. Matson Publisher: John Wiley & Sons ISBN: 1444313819 Category : Science Languages : en Pages : 408
Book Description
Trace gases are those that are present in the atmosphere at relatively low concentrations. Small changes in their concentrations can have profound implications for major atmospheric fluxes, and thereore, can be used as indicators in studies of global change, global biogeochemical cycling and global warming. This new how-to guide will detail the concepts and techniques involved in the detection and measurement of trace gases, and the impact they have on ecological studies. Introductory chapters look at the role of trace gases in global cycles, while later chapters go on to consider techniques for the measurement of gases in various environments and at a range of scales. A how-to guide for measuring atmospheric trace gases. Techniques described are of value in addressing current concerns over global climate change.
Author: G. Philip Robertson Publisher: Oxford University Press ISBN: 0198028261 Category : Science Languages : en Pages : 481
Book Description
Standardized methods and measurements are crucial for ecological research, particularly in long-term ecological studies where the projects are by nature collaborative and where it can be difficult to distinguish signs of environmental change from the effects of differing methodologies. This second volume in the Long-Term Ecological Research (LTER) Network Series addresses these issues directly by providing a comprehensive standardized set of protocols for measuring soil properties. The goal of the volume is to facilitate cross-site synthesis and evaluation of ecosystem processes. Chapters cover methods for studying physical and chemical properties of soils, soil biological properties, and soil organisms, and they include work from many leaders in the field. The book is the first broadly based compendium of standardized soil measurement methods and will be an invaluable resource for ecologists, agronomists, and soil scientists.
Author: Sivakiruthika Natchimuthu
Author: Sivakiruthika Natchimuthu
Author: A. Tremblay
Author: Meghan F. Cronin
Author: James David Hamilton
Author: Ken W. Krauss
Author: Anne E. Altor
Author: P. Casper
Author: P. A. Matson
Author: Achim Grelle
Author: G. Philip Robertson