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Washbourne, Carla-Leanne. "Engineering soils to act as carbon sinks." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2487.
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Soils containing calcium (Ca) and magnesium (Mg) bearing waste silicate minerals may be intentionally engineered to capture and store atmospheric carbon (C). Within the soil environment these minerals can capture and store atmospheric C through the process of weathering that releases Ca and Mg which then precipitate as carbonate minerals. Like natural silicates, silicate ‘wastes’ and artificial silicates sequester C through carbonation of calcium (Ca2+) and magnesium (Mg2+). Terrestrial CO2 sequestration may be promoted by the inclusion of these reactive mineral substrates in soils, and many waste sites and urban and anthropogenic soils already contain quantities of these materials. The UK Government is currently committed to reducing carbon emissions by 80% in 2050 (against a 1990 baseline) and soils have a role to play, acting as sinks for carbon. It is proposed that soil engineering measures could harness the high C turnover of the global pedologic system, ~120Pg C a-1 , to develop an efficient method of enhanced weathering. Artificial silicates have the potential to capture 192-333 Mt C a-1 , representing 2.0-3.7% of contemporary global C emissions; natural silicates present a carbon capture potential many orders of magnitude greater. Mineral carbonation in an artificial soil setting has the potential to capture inorganic carbon comparable to organic carbon accumulation. Soils of this type can accumulate 20-30 kg C m2 as carbonates (≥ organic carbon content in natural soils, ~17.5 kg C m2 for rural soils in the UK). Laboratory investigations were carried out on a number of experimental scales, from meso-scale flow-through reactors to micro-scale batch experiments, to determine the rate at which Ca and Mg could be supplied from suitable materials in engineered soil systems to perform a carbon capture function. Environmental factors were controlled for each in order to constrain their contribution to the overall process. Batch experiments were carried out at standard temperature and pressure (STP) to investigate effects of changes in solute concentration, water chemistry, agitation and particle size. pH controlled experiments were run at STP from pH 3-8, to determine the effects of pH changes on the weathering of wollastonite. Flow-through weathering experiments at STP investigated the effects of time, water chemistry, hydrogeological conditions and addition of CO2 on the weathering of steel slag. Analytical results demonstrate that Ca leaches rapidly from a number of Ca-rich artificial minerals providing great potential for carbon capture to occur on human-relevant timescales. Steel slag was shown to weather at a log rate of -9.39 to -11.88 mol Ca m-2 sec-1 in laboratory settings and -7.11 to - 7.56 mol Ca m-2 sec-1 under ambient environmental conditions in the field over 975 days. Anthropogenic soils, known to contain substantial quantities of Ca and Mg-rich minerals derived from industrial and demolition activity (including iron and steel slag, cement and concrete), were systematically sampled across two field sites. Analysis illustrated mean soil carbonate values of 21.8 ± 4.7% wt to 41.16 ± 9.89 wt % demonstrating that a large quantity of soil carbonate forms and persists in these environments, formed at a rate of 18kg CO2 t-1 a-1 . Stable isotope data ( 13C, 18O) confirm that up to 81% of C in these pedogenic carbonates is atmospherically derived. 14 C data also suggest that a significant proportion of the C present in carbonates analysed is ‘modern’. Applying a current CO2 trading cost of £8-£12 t-1 CO2, the potential value of CO2 sequestration at a study site was calculated to be £51,843 £77,765 ha-1 after 58% of its carbonation potential had been exploited. The studies contained in this thesis add to a growing body of evidence for the formation of carbonate minerals in soil settings where Ca/Mg-bearing silicate minerals occur. They also support the idea that engineered soils could be effectively utilised for carbon sequestration. Soil engineering for carbon capture provides a comparatively cheap, easy and attractive way of beginning to offset the environmental impact of certain industrial processes. Carbonation of waste silicates is a useful exercise in ‘closing the loop’ on C emissions produced in their manufacture. Carbon capture taking place on sites containing industrial waste materials is of interest to a variety of stakeholders: site owners, third sector bodies and local and national legislative bodies. Effective, low- energy field-scale implementation of mineral carbonation through soil engineering could assuage current constraints on economic performance of enhanced weathering technologies and highlight the importance of soil carbon storage.
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Mayorga, Emilio. "Isotopic constraints on sources and cycling of riverine dissolved inorganic carbon in the Amazon Basin /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/10977.
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Gudasz, Cristian. "Boreal Lake Sediments as Sources and Sinks of Carbon." Doctoral thesis, Uppsala universitet, Limnologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-150709.
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Inland waters process large amounts of organic carbon, contributing to CO2 and CH4 emissions, as well as storing organic carbon (OC) over geological timescales. Recently, it has been shown that the magnitude of these processes is of global significance. It is therefore important to understand what regulates OC cycling in inland waters and how is that affected by climate change. This thesis investigates the constraints on microbial processing of sediment OC, as a key factor of the carbon cycling in boreal lakes. Sediment bacterial metabolism was primarily controlled by temperature but also regulated by OC quality/origin. Temperature sensitivity of sediment OC mineralization was similar in contrasting lakes and over long-term. Allochthonous OC had a strong constraining effect on sediment bacterial metabolism and biomass, with increasingly allochthonous sediments supporting decreasing bacterial metabolism and biomass. The bacterial biomass followed the same pattern as bacterial activity and was largely regulated by similar factors. The rapid turnover of bacterial biomass as well as the positive correlation between sediment mineralization and bacterial biomass suggest a limited effect of bacterial grazing. Regardless of the OC source, the sediment microbial community was more similar within season than within lakes. A comparison of data from numerous soils as well as sediments on the temperature response of OC mineralization showed higher temperature sensitivity of the sediment mineralization. Furthermore, the low rates of areal OC mineralization in sediments compared to soils suggest that lakes sediments are hotspots of OC sequestration. Increased sediment mineralization due to increase in temperature in epilimnetic sediments can significantly reduce OC burial in boreal lakes. An increase of temperature, as predicted for Northern latitudes, under different climate warming scenarios by the end of the twenty-first century, resulted in 4–27% decrease in lake sediment OC burial for the entire boreal zone.
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Ridgwell, Andy J. "Glacial-interglacial perturbations in the global carbon cycle." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365134.
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Nagarathnam, Premkumar. "Novel carbon nanotube thermal interfaces for microelectronics." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31720.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Graham, Sam; Committee Member: Joshi, Yogendra; Committee Member: Kalaitzidou, Kyriaki. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Koprivnjak, Jean-François. "Sources, sinks, and fluxes of dissolved organic carbon in subarctic fen catchments." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60045.
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The sources, sinks, fluxes, spatial distributions, and temporal variations of dissolved organic carbon (DOC) in subarctic fen catchments as well as the temporal patterns of DOC in streams draining subarctic fen catchments in the region of Schefferville, Quebec were investigated.<br>In June to August sampling, DOC concentrations averaged 17 mg/L in peat water, 2-16 m/L in stream water, 49-56 mg/L in canopy throughfall, 14-19 mg/L in understory throughfall, 122-187 mg/L in stemflow, 25-39 mg/L in lichen and moss mat water, and 35-42 mg/L in soil A horizon water.<br>Precipitation and canopy and understory throughfall were all significant DOC sources with seasonal DOC fluxes to the forest floor of 0.1-0.4, 0.5-1.3, and 0.8-1.7 g DOC/m$ sp2$ of forest, respectively. The lichen and moss mats and the A soil horizon were also found to be DOC sources, whereas the B soil horizon was a DOC sink. The soil column was estimated to export 0.4-0.5 g DOC/m$ sp2$. Peat, also a DOC source, released 1.2-2.1 g DOC/m$ sp2$.<br>DOC concentrations in streams draining ten fen catchments were found to be positively correlated with the percentage of fen area in the catchments.
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Sonnerup, Rolf Erik. "Reconstructing the oceanic ¹³Seuss effect /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/11026.
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Ahmad, Ismariah. "Economics of carbon emission and sequestration in the Malaysian forest sector /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5588.
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Richmond, Nicole L. "THE CARBON BUDGET OF A SHALLOW, TROPICAL AQUIFER: SOURCES, SINKS, AND PROCESSES." Oxford, Ohio : Miami University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1070212062.
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Thesis (M.S.)--Miami University, Dept. of Geology, 2003.<br>Title from first page of PDF document. Document formatted into pages; contains vii, 127 p. : ill. Includes bibliographical references (p. 108-113).
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Fuss, Sabine, Wolf Heinrich Reuter, Jana Szolgayova, and Michael Obersteiner. "Optimal mitigation strategies with negative emission technologies and carbon sinks under uncertainty." Springer Netherlands, 2013. http://dx.doi.org/10.1007/s10584-012-0676-1.
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In recent years a body of literature has arisen on the topic of how to compose the optimal portfolio of mitigation options. The focus has been mainly on options involving shifts from high- to low- or even negative-carbon technologies. Natural sinks play an important role in any attempt to stabilize atmospheric CO2 and usually enter as a constant term in the overall carbon budget. In this paper, we introduce natural sinks to the carbon management problem and analyze the implications for negative emission technology deployment and the overall mitigation strategy. Amongst other sensitivity analyses, we also investigate the impact of uncertainty in the carbon sink, which we find to raise the importance of negative emissions in the mitigation portfolio significantly lowering the cost of the policy mix. (authors' abstract)
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Potouroglou, Maria. "Assessing the role of intertidal seagrasses as coastal carbon sinks in Scotland." Thesis, Edinburgh Napier University, 2017. http://researchrepository.napier.ac.uk/Output/975386.
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Seagrasses are marine foundation species that form ecologically important habitats in coastal areas around the world. They provide a range of ecosystem services, including coastal protection and the recently recognised large contribution to global carbon sequestration and storage. To date, the majority of published studies on the aforementioned ecosystem services is limited to specific geographic regions and seagrass species. This PhD study attempted to explore and provide the first evidence, to the best of our knowledge, on the role of Scottishseagrasses as carbon sinks and sediment stabilisers. In 2013, shoot dynamics of Zostera noltii plots were monitored biweekly and seasonally in the Forth estuary and digital images of the surveyed plots were taken for the development of a remote sensing technique which would accurately estimate the vegetation cover. In 2014, sediment samples from vegetated and unvegetated plots within beds of Z. marina and Z. noltii were collected from all the major estuaries along the east coast of Scotland, from the Firth of Forth in the south to Dornoch Firth in the north. Samples were analysed for organic matter, organic carbon, radionuclides 210Pb, 137Cs and 241Am, and δ13C in order to determine the organic matter and organic carbon density, longevity and sources of carbon respectively. To explore the role of seagrass in sediment deposition and stability, surface elevation was measured monthly in seagrass plots and bare sediment in the Forth estuary over two years. The results and main mechanisms underlying these findings are reported and discussed in detail in each chapter. In short, the proposed method based on digital images provided estimates of seagrass coverage that are more accurate than observers' estimates, with some constraints when macroalge and/or extreme light are present. Intertidal seagrass meadows in Scotland showed significantly enhanced carbon storage compared with bare sediment. Seagrass plots contained variable quantities of carbon in their sediments with species composition having a significant effect on carbon stocks, whereas depth and seagrass abundance had no effect on carbon stores. Despite their small above-ground biomass Scottish seagrass plots had a strong influence on sediment deposition and prevented erosion. Further research is needed to understand what factors drive large carbon sequestration and storage at some sites, thus contributing policy-relevant information on the prediction of the seagrass carbon hot-spots. Also, long-term datasets on surface elevation change are important in order to understand the effect of all the processes involved on sediment deposition in seagrass beds.
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Dymond, Caren. "Disturbance and climate change risks to forest carbon sinks and potential management responses." Thesis, Bangor University, 2018. https://research.bangor.ac.uk/portal/en/theses/disturbance-and-climate-change-risks-to-forest-carbon-sinks-and-potential-management-responses(416a28ec-8724-43f6-a415-513772dd7dc2).html.
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Climate change is a global crisis facing forest management. There are risks to many ecological goods and services from forests due to changes in productivity, mortality, pathogen, and wildfire dynamics. Likewise, there are opportunities such as increases in productivity or targeted funding for climate adaptation and emission reductions. To manage those risks and opportunities, we need the fundamental knowledge of forest carbon (C) cycles. Overall, my dissertation aims to improve our understanding of forest carbon dynamics and how they may respond to natural disturbances, climate change and management activities. This purpose falls within the context of the need to adapt to and mitigate climate change for the ongoing provision of ecological goods and services from forest ecosystems such as timber and biodiversity. The thesis starts with a critical analysis of six papers I have previously published. That chapter includes a synthesis of findings, critique of methods used, and identifies some areas for future research. Each subsequent chapter represents a contributing article. The overall findings of this dissertation are (i) that although forests are often GHG sinks moderate or high intensity natural disturbances can reverse that flux. (ii) That climate change effects on productivity may increase or decrease the natural sinks or even create emission sources in forests that may otherwise have been sinks. (iii) That management strategies to increase species diversity and resilience may be effective at reducing risks of emissions, but they must be assessed for individual ecosystems and may be insufficient to fully offset disturbance or climate change effects.
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Yager, Patricia L. "The microbial fate of carbon in high-latitude seas : impact of the microbial loop on oceanic uptake of CO2 /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/11001.
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Salinas, Zapata Cristian C. "Seagrass soils as paleoenvironmental tools and biogeochemical sinks for management." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2022. https://ro.ecu.edu.au/theses/2542.
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Coastal vegetation plays an essential role in regulating climate change and water quality, especially seagrass meadows that cover up to 1.6 million km2 worldwide and have been identified as globally significant filters and sinks of biogeochemical elements, including organic carbon (Corg) and nitrogen (N). Over the past century, the accelerating intensity and duration of natural and anthropogenic disturbances have caused severe regime shifts in estuarine and other coastal ecosystem dynamics, causing seagrass losses and affecting their valuable ecosystem services. Although knowledge of long-term seagrass ecosystem dynamics is scarce, including baseline conditions prior to major disturbances, the limited available information has been crucial to assess the human and natural impacts on coastal ecosystems. For example, it has provided answers to key questions related to seagrass ecology, climate change and management, including the estimation of the ecological significance and the monetary value of the biogeochemical sinks associated with seagrass ecosystems. This thesis aims to use seagrasses biogeochemical sinks as archives to reconstruct and understand : 1) baseline conditions in Australian estuaries, and spatial variability in environmental change, including perturbations that triggered the loss of seagrass meadows; 2) the significance of seagrasses in global biogeochemical cycles, as well as the processes that support their potential to store carbon and nitrogen; and 3) the losses of biogeochemical sinks as a consequence of seagrass meadow losses through human-induced impacts and extreme weather events.
In this thesis, seagrass sedimentary archives encompassing the last few centuries have been studied to decipher centennial-scale environmental change in temperate estuaries, and the impacts of marine heatwaves and eutrophication on the Corg and N biogeochemical sinks associated to seagrass ecosystems. In the first data chapter of this thesis, the impact of land-use change on the ecological dynamics of temperate estuaries in Australia is reconstructed based on the analysis of multiple proxies in seagrass sedimentary archives encompassing the last 500 years. This palaeoecological study revealed the effect of land-use change following European settlement in the 1800s in Australia on the ecological condition of the estuaries, highlighting the deterioration of seagrass meadows following increased coastal development and agriculture activity after World War II.
The second data chapter examined the effect of seagrass loss due to eutrophication on seagrass soil Corg stocks and fluxes, and provides pioneering estimates of CO2 emissions following disturbance of seagrass ecosystems that can be used to support the development of seagrass blue carbon projects (conservation and restoration) to mitigate climate change. The results showed that seagrass loss alone does not necessarily drive erosion of soil Corg, but when combined with sufficient hydrodynamic energy at the sediment surface ( > 0.20 m/s in this case), significant losses occurred (88–95% of soil Corg stocks). The study provided first-order estimates of potential CO2 emissions from eutrophication-induced seagrass loss since the 1950s in Australia, with 161,150 hectares of seagrass habitat loss that likely resulted in the release of 11–21 Tg CO2 (equivalent to a 2% increase in annual CO2 emissions from land-use change). These data will be crucial to inform the implementation of seagrass blue carbon into the Australian climate change mitigation policy.
The third data chapter assessed soil N stocks and accumulation rates in Australian seagrass meadows, and provides pioneering estimates of soil N depletion following disturbance of seagrass meadows due to eutrophication and marine heatwaves, and identified the main drivers and potential ecological consequences of those losses. The results showed that Australian seagrasses capture 216–910 Gg N yr-1, equivalent to 96–105% of N runoff from Australian catchments. On the other hand, Australian-wide seagrass losses since the 1950s likely resulted in the loss of 435-720 Gg N from their soils, which likely enhanced eutrophication processes and resulted in adverse ecological consequences.
This thesis provides novel and key information on the role of seagrasses as biogeochemical sinks and sources. This information can inform management practices of estuarine and other coastal ecosystems and highlights the value of seagrass sedimentary archives for determining baseline cycles and to reconstruct the time-course of ecological change in response to natural and anthropogenic disturbances. This thesis also highlights the need to conserve and restore seagrass meadows due to their value as natural archives and biogeochemical sinks, demonstrating their potential as a Natural-based Solution for contributing to climate change mitigation.
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Zeng, Sibo [Verfasser]. "The evolution of carbonate weathering carbon sinks under climatic and anthropogenic perturbations / Sibo Zeng." Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1238595804/34.
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Dawson, Julian J. C. "The controls on concentrations and fluxes of gaseous, dissolved and particulate carbon in upland peat dominated catchments." Thesis, University of Aberdeen, 2000. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU125517.
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A programme of field sampling was undertaken to quantify total carbon fluxes (DOC, POC, HCO3, free CO2 and CH4) from peatland catchments in Glen Dye, NE Scotland and Plynlimon, Mid-Wales. This was integrated with temporal and spatial sampling to investigate controls on contrasting concentrations and fluxes and to determine carbon sources or sinks within the stream system. Microcosms containing radiolabelled ( 14C) biofilms were also used to investigate removal of DOC from streamwater. Carbon fluxes from acidic peatlands were dominated by DOC (115-215 kg C ha-1 yr-1) and POC (8.15-97.0 kg ha -1 yr-1). In the majority of headwaters studied, DIC was exported as free CO2 (2.62-8.49 kg ha-1 yr -1). Methane-C fluxes at the outlets of catchments were <0.01 kg ha-1 yr-1. Small-scale (diurnal) temporal variations in free CO2, HCO3- and pH at the NE Scotland catchments were small compared to more productive systems; DOC showed no diurnal fluctuations. In addition, diurnal patterns were masked by marked variations in discharge. Small-scale downstream spatial changes in Brocky Burn, NE Scotland and the Upper Hafren, Mid-Wales showed that variation in climate, in particular precipitation, was also a major controlling factor on concentrations and fluxes of the different forms of carbon. However, the actual amount of carbon stored within the soils acted as an initial control on the potential DOC load within the streamwater. A peatland stream continuum linked to terrestrial carbon cycling is presented. Initially terrestrial inputs of DOC, POC, free CO2 and CH 4 dominated the upper headwaters. The soil-stream linkage was progressively reduced downstream due to autochthonous and atmospheric factors. A critical area in the peatland stream continuum occurred approximately 1 km downstream from the gaseous carbon-rich peats.
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George, Hugo. "Diving into Blue Carbon : A Review on Carbon Sequestration by Mangrove Forests, Seagrass Meadows and Salt Marshes, and Their Capacity to Act as Global Carbon Sinks." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-384028.
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During the last decade, the academic interest for Earth’s natural carbon sinks and their role concerning climate change has increased. Today, many scientists around the world are trying to calculate different ecosystem’s potential to sequester and store carbon dioxide from the atmosphere. As a newcomer to the scientific arena, the term ‘blue carbon’ has been well received by scientists in the field. ‘Blue carbon’ highlights the carbon captured and stored by productive ecosystems along the world’s coasts. The term refers to coastal wetlands – such as mangrove forests, salt marshes and seagrass meadows – and it came to life as the scientific community recognized these ecosystems’ significant potential as effective carbon sinks. New research indicates that these ecosystems’ complex and vertical root systems can store much larger amounts of carbon in the soil than any other terrestrial ecosystem. By studying this subject, scientists are trying to understand how these ecosystems can help us in the quest of removing excessive carbon dioxide from the atmosphere. The goal of this thesis is to conduct a literature review, aiming to analyse and compile the new research on ‘blue carbon’ that has been published during the last 10 years. The paper aims to investigate whether the ecosystem’s potential as carbon sinks differ from each other, and what threats they will face in the future. It will additionally review if scientists have been able to unite around any predictions about what the future for ‘blue carbon’ – and its role in mitigating climate change – will look like.<br>Under det senaste decenniet har intresset kring naturliga kolsänkors potential och roll i att mildra klimatförändringar ökat. Idag är det många forskare som arbetar med att beräkna mängden kol som olika ekosystem runt om världen kan lagra i sin biomassa och i jorden under dess rötter. Som en nykomling på den vetenskapliga arenan, har termen ’blue carbon’ blivit väl mottaget av forskare inom området. ’Blue carbon’ syftar på det kol som fixeras och lagras av de produktiva ekosystemen längs världens kuster. Termen refererar till kustbelägna våtmarker – så som mangroveskogar, saltträsk och sjögräsbäddar – och introducerades efter att den vetenskapliga världen erkänt deras imponerande potential som kolsänkor. Ny forskning tyder på att deras avancerade och vertikala rotsystem kan lagra mer koldioxid i marken än vad vanliga terrestra skogar kan. Genom att studera detta ämne försöker forskare att förstå hur dessa ekosystem kan hjälpa oss att avlägsna överskottet av koldioxid från atmosfären. Målet med denna uppsats är att utföra en litteraturstudie och analysera, samt sammanställa den nya forskningen om ’blue carbon’ som publicerats de senaste 10 åren. Uppsatsen kommer undersöka hur stor skillnad det är mellan de olika ekosystemen och vilka hot de står inför i framtiden. Dessutom kommer den undersöka ifall forskare kommit närmre i att enas kring förutsägelser om framtiden för ’blue carbon’, och hur dess roll i att mildra klimatförändringarna kommer se ut.
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Stephen, Amy Louise. "Carbon sources and sinks within the Oman-UAE ophiolite : implications for natural atmospheric CO2 sequestration rates." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/37249.
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Hyperalkaline (pH >11) spring waters across the Oman-UAE ophiolite have precipitated large-scale surface and subsurface freshwater carbonate deposits within and on mantle-sequence peridotites. Ten carbonate lithofacies have been identified that display a common stratigraphy across the region, with some on-going deposition. Alternating wet and arid climate periods, consistent with previous Quaternary climate data for Oman and the UAE, can be inferred from the morphologies and stratigraphy of carbonate lithofacies. Carbon and oxygen stable isotope ratios for individual lithofacies are consistent across the ophiolite, indicating uniform formation processes throughout the region. Modern carbonates actively precipitate via the drawdown of atmospheric CO2 into hyperalkaline groundwaters, indicated by very negative δ13C values (≈ –25‰) and δ18O (≈ –18‰) caused by kinetic fractionation. In contrast, ancient travertines display a much wider range in δ13C and δ18O, reflecting mixing of several C and O sources including atmospheric CO2, dissolved limestone CO32– and soil DIC. Radiocarbon data for ancient travertines show a series of stratigraphically impossible 14C “ages” which are interpreted to be due to the incorporation of a proportion of 14C-dead carbon. The sources of 14C-dead carbon are a mixture of dissolved limestone CO32–, soil DIC and the re-working of older carbonate deposits. The proportion of carbon from different sources must be taken into account when calculating sequestration rates of atmospheric CO2 into carbonates. The incorporation of 14C-dead carbon into carbonate lithofacies leads to a systematic offset in conventional radiocarbon ages towards older ages. Use of offset, older ages will cause underestimation of the rate of carbon sequestration, whilst the presence of 14C-dead carbon will cause overestimation of the volume of atmospheric carbon being stored. Age offsets in carbonates mean that sequestration rates taking into account all carbon in the system, e.g. from atmospheric or limestone CO32–, will be higher than previously thought.
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Pepper, David A. "Investigation of the long term physiological response of Huon pine (Lagarostrobos franklinii) to changes in atmospheric CO2 and climate using stable isotopes." Connect to full text, 1999. http://ses.library.usyd.edu.au/handle/2123/4032.
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Thesis (Ph. D.)--University of Sydney, 2000.<br>Title from title screen (viewed February 12, 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Biological Sciences, Faculty of Science. Degree awarded 2000; thesis submitted 1999. The 2 in the title is in subscript. Includes bibliographical references. Also available in print form.
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Bagga, Rajinder S. "Biological sequestration of carbon dioxide." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1171386594.
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Pepper, David A. "Investigation of the long term physiological response of Huon pine (Lagarostrobos franklinii) to changes in atmospheric CO2 and climate using stable isotopes." Phd thesis, School of Biological Sciences, 1999. http://hdl.handle.net/2123/4032.
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Thesis (Ph. D.)--University of Sydney, 2000.<br>Title from title screen (viewed February 12, 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Biological Sciences, Faculty of Science. Degree awarded 2000; thesis submitted 1999. The 2 in the title is in subscript. Includes bibliographical references. Also available in print form.
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Dietz, Carter Reynolds. "Single-phase forced convection in a microchannel with carbon nanotubes for electronic cooling applications." Thesis, Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-07052007-155623/.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2008.<br>Dr. David Gerlach, Committee Member ; Dr. Samuel Graham, Committee Member ; Dr. Minami Yoda, Committee Member ; Dr. Yogendra Joshi, Committee Chair.
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Rindy, Jenna. "Urban Trees as Sinks for Soot: Deposition of Atmospheric Elemental Carbon to Oak Canopies and Litterfall Flux to Soil." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157527/.
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Elemental carbon (EC), a product of incomplete combustion of fossil fuels and biomass, contributes to climate warming and poor air quality. In urban areas, diesel fuel trucks are the main source of EC emissions from mobile sources. After emission, EC is deposited to receptor surfaces via two main pathways: precipitation (wet deposition) and directly as particles (dry deposition). Urban trees may play an important role in removing EC from the atmosphere by intercepting and delivering it directly to the soil. The goal of this research was to quantify the magnitude of EC retention in leaf waxes (in-wax EC) and EC fluxes to the soil via leaf litterfall in the City of Denton, Texas. Denton is a rapidly growing urban location in the Dallas-Fort Worth metropolitan area. A foliar extraction technique was used to determine EC retention in leaf waxes. Foliar samples were collected monthly, from April through July, from pairs of Quercus stellata (post oak, n=10) and Quercus virginiana (live oak, n = 10) trees. Samples were rinsed with water and chloroform in a two-step process to determine EC retained in leaf waxes. A Sunset OC/EC aerosol analyzer was utilized to analyze the EC content of extracts filtered onto quartz-fiber filters. From April through July, leaf litter was collected bi-weekly under 35 trees (20 post oak, 15 live oak), and oven dried to determine dry weight. EC retained by tree canopies was estimated by multiplying in-wax EC by canopy leaf area index, while EC flux to soil was estimated by multiplying in-wax EC by leaf litterfall mass. This study shows that through retention of EC in leaf waxes, urban tree canopies represent important short-term sinks for soot in urban areas.
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Macauley, Nadine. "Impact of Carbon Sinks on Urban Heat Island Effects : Assessment Using Satellite Data in Water Scarce Region of the Thesis." Thesis, Högskolan i Gävle, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-33414.
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Urbanization modifies the thermal characteristics of the land and makes way for a succession of transformations in the urban environmental system. This phenomenon, known as Urban Heat Island (UHI), is characterized by elevated temperatures in urban areas that negatively impact on the quality of life and environment in urban areas including, increased emissions of Green House Gases (GHGs) and rising energy consumption. These impacts add to global climate change and thus, mitigating UHI is essential to mitigating global climate change. One GHG, Carbon Dioxide (CO2), accounts for about half of the Earth’s anthropogenic GHG emissions. Terrestrial ecosystems can act as Carbon sinks (C sinks), i.e. natural vegetation reservoirs that absorb more C than they release. Thus, C sinks play an essential and critical function in lowering CO2. Furthermore, providing appropriate C sinks at both the building and urban scales can decrease UHI and contribute to reduction in energy consumption. This study used Landsat 8 imagery of the site, Al Bayt Stadium in Qatar, to investigate the effects of surface UHI by computing the Land Surface Temperature (LST) difference of the site---pre- and post-construction, as well as examine the correlation between natural vegetation abundance and temperature in ten locations within the site’s vicinity. Results show that minimum, maximum and mean LST of the case study area (2014 vs. 2020) decreased 2.80 oC, 5.5 oC and 2.3 oC, respectively, as well as a decreasing trend in the LST as a function of increasing C Sinks. These results demonstrate the importance of introducing C sinks to lower LST and mitigate UHI. Mitigating UHI also has a direct effect on Energy Consumption Balance (ECB). This equilibrium is achieved not only through the introduction of C sinks, but balancing C sinks with high albedo materials and natural ventilation. Thus, this study also investigated the site’s various design aspects (e.g. cooling technology, structure and surface albedo materials, landscaping) and found that Al Bayt Stadium’s design successfully incorporates strategies to reduce energy consumption at both the urban (macro) and building (micro) scales.
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Gathany, Mark A. "Sources of variation in ecosystem carbon pools : a comparison of adjacent old- and second-growth forests /." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1102537971.
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Pumilio, John F. "Carbon neutrality by 2020 The Evergreen State College's comprehensive greenhouse gas inventory /." Online pdf file accessible through the World Wide Web, 2007. http://archives.evergreen.edu/masterstheses/Accession86-10MES/Pumilio_J%20MESThesis%202007%20.pdf.
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Karlsson, Emma. "Compositional clues to sources and sinks of terrestrial organic matter transported to the Eurasian Arctic shelf." Doctoral thesis, Stockholms universitet, Institutionen för miljövetenskap och analytisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-116876.
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The amount of organic carbon (OC) present in Siberian Arctic permafrost soils is estimated at twice the amount of carbon currently in the atmosphere. The shelf seas of the Arctic Ocean receive large amounts of this terrestrial OC from Eurasian Arctic rivers and from coastal erosion. Degradation of this land-derived material in the sea would result in the production of dissolved carbon dioxide and may then add to the atmospheric carbon dioxide reservoir. Observations from the Siberian Arctic suggest that transfer of carbon from land to the marine environment is accelerating. However, it is not clear how much of the transported OC is degraded and oxidized, nor how much is removed from the active carbon cycle by burial in marine sediment. Using bulk geochemical parameters, total OC, d13C and D14C isotope composition, and specific molecular markers of plant wax lipids and lignin phenols, the abundance and composition of OC was determined in both dissolved and particulate carrier phases: the colloidal OC (COC; part of the dissolved OC), particulate OC (POC), and sedimentary OC (SOC). Statistical modelling was used to quantify the relative contribution of OC sources to these phases. Terrestrial OC is derived from the seasonally thawing top layer of permafrost soil (topsoil OC) and frozen OC derived from beneath the active layer eroded at the coast, commonly identified as yedoma ice complex deposit OC (yedoma ICD-OC). These carbon pools are transported differently in the aquatic conduits. Topsoil OC was found in young DOC and POC, in the river water, and the shelf water column, suggesting long-distance transport of this fraction. The yedoma ICD-OC was found as old particulate OC that settles out rapidly to the underlying sediment and is laterally transported across the shelf, likely dispersed by bottom nepheloid layer transport or via ice rafting. These two modes of OC transport resulted in different degradation states of topsoil OC and yedoma ICD-OC. Terrestrial CuO oxidation derived biomarkers indicated a highly degraded component in the COC. In contrast, the terrestrial component of the SOC was much less degraded. In line with earlier suggestions the mineral component in yedoma ICD functions as weight and surface protection of the associated OC, which led to burial in the sediment, and limited OC degradation. The degradability of the terrestrial OC in shelf sediment was also addressed in direct incubation studies. Molecular markers indicate marine OC (from primary production) was more readily degraded than terrestrial OC. Degradation was also faster in sediment from the East Siberian Sea, where the marine contribution was higher compared to the Laptev Sea. Although terrestrial carbon in the sediment was degraded slower, the terrestrial component also contributed to carbon dioxide formation in the incubations of marine sediment. These results contribute to our understanding of the marine fate of land-derived OC from the Siberian Arctic. The mobilization of topsoil OC is expected to grow in magnitude with climate warming and associated active layer deepening. This translocated topsoil OC component was found to be highly degraded, which suggests degradation during transport and a possible contribution to atmospheric carbon dioxide. Similarly, the yedoma ICD-OC (and or old mineral soil carbon) may become a stronger source with accelerated warming, but slow degradation may limit its impact on active carbon cycling in the Siberian Shelf Seas.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
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Kennerstedt, Marcus, and de Moraes Felicia Pereira. "Implementering av koldioxidvärdering för grönytor." Thesis, KTH, Urbana och regionala studier, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-252796.
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IPCC förespråkar i en rapport från 2018 att kolsänkor måste få en tydligare plats i samhället om vi ska lyckas nå klimatmålen. Grönstruktur är en typ av objekt som passivt tar upp koldioxid genom fotosyntes. Genom att nyttja detta i ett planeringsskede skapas ett verktyg som går att använda för att minska halten koldioxid i atmosfären. Däremot, så värderas ej de urbana grönytor som finns idag med avseende på detta, dock finns det många andra viktiga funktioner de uppfyller inom ramen för ekologisk hållbarhet. Detta examensarbete söker att besvara frågan hur det går att implementera kolsänkor vid värdering av grönytor samtidigt som den existerande värderingen för ekologisk hållbarhet bibehålls. Arbetet är utformat med grund ifrån litteraturstudie. Där ingår även några utvalda modeller som värderar grönytor eller behandlar koldioxid på något sätt. Dessa är Grönytefaktor, Citylab, Miljökonsekvensbeskrivning, BREEAM-SE, Miljöbyggnad, och Trafikverkets Klimatkalkyl. Som ett komplement har tre intervjuer utförts med relevanta praktiker för att ge värdefulla infallsvinklar och diskussionsunderlag. Därtill har även en workshop utförts av en tvärvetenskaplig samling aktörer, med samma huvudsakliga syfte som intervjuerna. Alla modeller har sina styrkor och brister. Med hänsyn till syftet för arbetet är vissa mer relevanta än andra. Exempelvis fungerar Grönytefaktor som ett verktyg för att kvantifiera ekologisk hållbarhet, men misslyckas med att motverka eventuella underliggande problem. Citylab är en av de mer kompletta guiderna, och Miljökonsekvensbeskrivning har visserligen lagstadgat stöd i viss mån, men saknar tydliga riktlinjer för implementeringen. Klimatkalkylen används främst för transportinfrastruktur, men den livscykelmetodik som modellen är baserad på kan ge bra indikationer på hur kolsänkekvalitéer kan beräknas. Livscykelmetodiken får även stöd från BREEAM-SE och Miljöbyggnad, samt att driftfasen för en grönyta måste beaktas eftersom det är där värdet för en kolsänka skapas. Det finns tyvärr inga tydliga svar på vilken väg som är bäst att gå. Det krävs mer forskning på området med en tydligare målbild med vad som ska uppnås, vem som ska använda modellen, samt vidare forskning om till exempel hur stor kolsänkekapacitet olika typer av grönstruktur har. Det finns dock visst stöd för att Citylab i kombination med Grönytefaktor kan vara en lämplig väg att gå, men först och främst krävs det mer forskning kring grönytors potential som kolsänka och vilken kapacitet de kan bidra med.<br>IPCC advocates in a report from 2018 that carbon sinks must be given a clearer role in society if we are to reach the climate change goals. Green structure is a type of object that passively can absorb carbon dioxide through photosynthesis. By using this in a planning stage, a tool is created that can be used as a way to bring down the levels of carbon dioxide in the atmosphere. The urban green areas that exists today are not being valuated with regards to this, although there are many other important functions they fulfill within the framework of ecological sustainability. The master thesis aims to answer the question how carbon sinks can be implemented in the valuation process of green areas simultaneously with ecological sustainability. The foundation of the work is made in the form of a literature study. Included in this are a few selected models that valuates green areas or carbon dioxide in some way. These are Grönytefaktor, Citylab, Miljökonsekvensbeskrivning, BREEAM-SE, Miljöbyggnad, och Trafikverkets Klimatkalkyl. As a complementary method, three interviews have been conducted with relevant practicians to provide valuable approach angles and discussion material. In addition to this, a workshop has been conducted with a gathering of interdisciplinary actors, with the same purpose as the interviews. All models have their own strengths and weaknesses. With regards to the aim of the work, some are more relevant than others. For instance, Grönytefaktor works as a good tool to quantify ecological sustainability but fail to counteract any underlying problems. Citylab is one of the more complete guides, and Miljökonsekvensbeskrivning has statutory support, but fails to include clear guidelines for implementation. Klimatkalkylen is primarily used for transport infrastructure, but its life-cycle methodology that it is based upon could give good indications for how carbon sink qualities can be calculated. The life-cycle methodology is also given support from BREEAM-SE and Miljöbyggnad, as well as the operating phase of a green area must be included since that is when the value of a carbon sink is created. Unfortunately, there are no clear answers which way is the best to go. More research is needed within the field where a clearer purpose of what is to be achieved, whom is supposed to use it, as well as other types of research such as how great the carbon sink capacity different types of green structure inhibits. However, there are certain arguments for using Citylab in combination with Grönytefaktor, but first and foremost there is a need for more research about green areas potential as a carbon sink and with what capacity they can contribute.
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Ullbrand, Jennifer. "A comparison of SPS and HP sintered, electroless copper plated carbon nanofibre composites for heat sink applications." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-21106.
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<p>The aim of this study is to synthesize a material with high thermal conductivity and a low coefficient of thermal expansion (CTE), useful as a heat sink. Carbon nanofibres (CNF) are first coated with copper by an electroless plating technique and then sintered to a solid sample by either spark plasma sintering (SPS) or hot pressing (HP). The final product is a carbon nanofibre reinforced copper composite. Two different fibre structures are considered: platlet (PL) and herringbone (HB). The influence of the amount of CNF reinforcement (6-24 %wt), on the thermal conductivity and CTE is studied. CNF has an excellent thermal conductivity in the direction along the fibre while it is poor in the transverse direction. The CTE is close to zero in the temperature range of interest. The adhesion of Cu to the CNF surface is in general poor and thus improving the the wetting of the copper by surface modifications of the fibres are of interest such that thermal gaps in the microstructure can be avoided. The poor wetting results in CNF agglomerates, resulting in an inhomogeneous microstructure. In this report a combination of three different types of surface modifications has been tested: (1) electroless deposition of copper was used to improve Cu impregnation of CNF; (2) heat treatment of CNF to improve wetting; and (3) introduction of a Cr buffer layer to further enhance wetting. The obtained composite microstructures are characterized in terms of chemical composition, grain size and degree of agglomeration. In addition their densities are also reported. The thermal properties were evaluated in terms of thermal diffusivity, thermal conductivity and CTE. Cr/Cu coated platelet fibres (6wt% of CNF reinforcement) sintered by SPS is the sample with the highest thermal conductivity, ~200 W/Km. The thermal conductivity is found to decrease with increasing content of CNFs.</p>
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Archbold, Brad. "Using algae to capture CO₂ and as a feedstock for biofuel." Online pdf file accessible through the World Wide Web, 2007. http://archives.evergreen.edu/masterstheses/Accession86-10MES/Archbold_%20B%20MESThesis%202007.pdf.
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Silva, Cinthia Aparecida 1985. "Estoque e produção de raiz fina ao longo de um gradiente altitudinal de Floresta Atlântica na Serra do Mar, São Paulo, Brasil." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314887.
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Orientador: Carlos Alfredo Joly<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia<br>Made available in DSpace on 2018-08-27T11:49:29Z (GMT). No. of bitstreams: 1
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Previous issue date: 2015<br>Resumo: As florestas tropicais estão entre os ecossistemas terrestres mais diversos e produtivos do planeta, embora ocorram sob solos pobres. Para superar essa condição as plantas adaptam a si mesmas para alocarem biomassa adicional a órgãos onde os recursos são limitantes. Alguns desses órgãos são as raízes finas, raízes responsáveis pela absorção de água e nutrientes do solo. Elas representam um elevado custo de produção para as plantas, mas importante fonte de carbono para o solo. Devido as variações na disponibilidade de recursos influenciarem o estoque e a produção de raízes finas, as expectativas foram de que: i) o estoque e a produção anual de raízes finas aumentariam com a elevação da altitude; ii) a produção de raízes finas seria maior nos períodos de menor umidade; iii) haveria maior biomassa de raiz fina na porção superficial do solo (0-10 cm); iv) o uso de menores tempos de coleta em porções de solo pequenas não afetaria a acurácia do método escolhido. Para testar essas suposições, foram selecionados cinco hectares de Floresta Atlântica conservada. As informações sobre estrutura, composição florística e características do solo foram obtidas de estudos prévios. Em cada um desses hectares, foram instalados 16 coletores para o monitoramento da produção trimestral de raízes finas. O menor estoque e produção total de raízes finas foi encontrado na Floresta Ombrófila Densa Submontana e o maior na Floresta Ombrófila Densa Montana. Os períodos das maiores produções coincidiram com os das maiores temperaturas e precipitações acumuladas e a maior biomassa de raízes finas foi observada na camada de 0-10 cm. A adaptação do método não influenciou significativamente na amostragem das raízes finas. A variável que mais explicou a produção anual foi o conteúdo de água no solo. Com base De acordo com tais resultados, a conclusão foi que as variações climáticas ao longo do gradiente altitudinal não determinaram diretamente o estoque de raízes finas, mas as variações sazonais influenciaram na produção. Quaisquer alterações que venham a ocorrer nas taxas de precipitação, poderão assim, desencadear mudanças significativas na maneira como a Floresta Atlântica aloca carbono, investindo mais em raízes finas do que nos demais órgãos<br>Abstract: Tropical forests are among the most diverse and productive ecosystems on the planet, however they occur in poor soils. To overcome this condition plants adapt themselves allocating additional biomass to organs where resources are limiting. Some of these organs are the fine roots, roots responsible for absorbing water and nutrients from the soil. They represent a high cost of production to the plants, but at the same time, they are an important source of carbon to the soil. Variations in the resources available can influence stock and production of fine roots and because of that, the expectation was that: i) fine root stock and annual production would increase with elevation; ii) fine roots production would be higher in periods of lower moisture; iii) a higher fine roots biomass would be found in the superficial soil layer (0-10 cm); iv) the use of a short time of sampling in smaller soil portions should not affect the accuracy of the chosen method. To test these hypotheses five plots located in Atlantic Forest along an elevation gradient were selected. The information about the forest structure, floristic composition and soil traits were known from previous studies. Each individual plot had 16 ingrowth cores were installed to monitor the quarterly production of fine roots. Submontane Forest had the smallest stock and annual production of fine roots, while Montane Forest had the highest ones. Periods of higher production coincide with higher temperatures and accumulated rainfall. The first layer of soil, from zero to 10 cm, had the highest fine roots biomass. The method adaptation did not significantly influence the fine roots sampling. The soil water content was the variable which best explained annual production. According to the research results, the conclusion achieved was that the fine roots stock is not directly influenced by climatic variation over elevation, but the seasonal variation influenced the fine roots production. Any possible changes in precipitation rates, may thus trigger significant changes in the way that Atlantic Forest allocates carbon, investing more in fine roots that in other organs<br>Mestrado<br>Biologia Vegetal<br>Mestra em Biologia Vegetal
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Wang, Yuting [Verfasser], Mathias [Akademischer Betreuer] Palm, Justus [Gutachter] Notholt, and Annette [Gutachter] Ladstätter-WeißEnmayer. "Using solar FTIR spectrometry to investigate the sources and sinks of carbonyl sulfide and its application to the carbon cycle / Yuting Wang ; Gutachter: Justus Notholt, Annette Ladstätter-Weißenmayer ; Betreuer: Mathias Palm." Bremen : Staats- und Universitätsbibliothek Bremen, 2016. http://d-nb.info/1120555353/34.
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Mervine, Evelyn Martinique. "Determining timescales of natural carbonation of peridotite in the Samail Ophiolite, Sultanate of Oman." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77785.
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Thesis (Ph. D.)--Joint Program in Marine Geology and Geophysics (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Determining timescales of the formation and preservation of carbonate alteration products in mantle peridotite is important in order to better understand the role of this potentially important sink in the global carbon cycle and also to evaluate the feasibility of using artificially-enhanced, in situ formation of carbonates in peridotite to mitigate the buildup of anthropogenic CO₂ emissions in the atmosphere. Timescales of natural carbonation of peridotite were investigated in the mantle layer of the Samail Ophiolite, Sultanate of Oman. Rates of ongoing, low-temperature CO₂ uptake were estimated through ¹⁴C and ²³⁰Th dating of carbonate alteration products. Approximately 1-3 x 10⁶ kg CO₂/yr is sequestered in Ca-rich surface travertines and approximately 10⁷ kg CO₂/yr is sequestered in Mg-rich carbonate veins. Rates of CO₂ removal were estimated through calculation of maximum erosion rates from cosmogenic 3He measurements in partially-serpentinized peridotite bedrock associated with carbonate alteration products. Maximum erosion rates for serpentinized peridotite bedrock are ~5 to 180 m/Myr (average: ~40 m/Myr), which removes at most 10⁵-10⁶ kg CO₂/yr through erosion of Mg-rich carbonate veins.<br>by Evelyn Martinique Mervine.<br>Ph.D.
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Rosner, Hillary. "Tropical rainforests: Carbon sink or carbon source?" Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1439430.
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Girard, Léo. "Étangs piscicoles et services écosystémiques : Relations entre pratiques de gestion, maintien de la biodiversité et stockage de carbone." Electronic Thesis or Diss., Paris, AgroParisTech, 2024. http://www.theses.fr/2024AGPT0008.
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L'Europe renferme de nombreux paysages d'étangs, pour beaucoup avec une origine pouvant remonter au Moyen-âge et une vocation historique de production piscicole. Ces milieux, malgré qu'ils soient anthropisés, sont connus pour leur capacité à présenter une biodiversité importante, avec des espèces rares, voir endémiques ou menacées. Avec l'abandon de la pisciculture, combiné à d'autres menaces comme le changement climatique, un nombre significatif de ces étangs ont disparus au cours des dernières décennies. Jusqu'à récemment, et ce malgré le rôle important qu'ils peuvent jouer, ces petits plans d'eau ont de plus été négligés en Recherche, mais également par les politiques publiques.Dans ce travail de thèse nous nous sommes intéressés aux effets de différentes pratiques de gestion piscicoles sur certains services écosystémiques rendus par les étangs piscicoles. Dans un premier temps, nous avons analysé la pratique de l'assec et ses impacts à la fois sur la biodiversité et sur la productivité en poissons. Dans un second temps, nous avons exploré les impacts de différentes gestions de la densité piscicole sur les caractéristiques des communautés de macrophytes. Et enfin, nous avons étudié les étangs piscicoles comme potentiels puits ou sources de carbone, et les effets des pratiques de gestion sur ces bilans carbone.Pour compléter les connaissances scientifiques sur ces thématiques, nous avons capitalisé sur des données historiques collectées en Dombes (Ain, France) depuis 2007, mais également sur des données collectées dans le cadre du projet européen PONDERFUL, entre 2021 et 2022, en Dombes et dans le Midden-Limburg (Belgique). Nous avons analysé à la fois des données sur la physico-chimie de l'eau et des sédiments, ainsi que des données de biodiversité (macrophytes, phytoplancton et macroinvertébrés), de stockage et d'émissions de carbone, ainsi que sur les pratiques de gestion piscicoles (distance au dernier assec, empoissonnage, fertilisation).Nos résultats démontrent que l'assec constitue une pratique agroécologique majeure pour la pisciculture extensive en étang. Cet assèchement volontaire favorise la recolonisation des macrophytes ainsi que leur diversité lors de la remise en eau. La deuxième année en eau est caractérisée par un “état instable” d'équilibre entre les deux producteurs primaires. Cet état apparait comme étant favorable à la fois à la biodiversité, à la production mais également au stockage du carbone. L'intensification de la production, à travers une augmentation des densités piscicoles, a néanmoins des effets négatifs sur la richesse spécifique des macrophytes. Elle impacte également la structure des communautés. Les étangs piscicoles possèdent des sous-ensembles d'espèces, nichés dans les communautés plus riches des étangs gérés sans poissons. Nous avons également pu montrer une très forte variabilité sur les bilans carbone réalisés sur 20 étangs piscicoles. En moyenne, les étangs monitorés apparaissent comme étant plutôt des puits de carbone, à hauteur d'environ 4 tonnes de CO2 équivalent stocké par hectare et sur 6 mois. La phase d'assec est quant à elle caractérisée par des émissions de gaz à effet de serre importantes.Tous ces éléments permettent de confirmer que les étangs piscicoles, associés à des pratiques extensives, peuvent fournir de nombreux services écosystémiques. La production piscicole n'est pas antinomique de la conservation de la biodiversité. La pérennité de ces milieux dans les paysages européens, et des services fournis, passe par le maintien de ces pratiques de gestion. Même si concilier les services d'approvisionnement et de support semble possible, à l'avenir, une hiérarchisation des services souhaités sera nécessaire, notamment au regard des effets inverses que peuvent avoir certaines pratiques de gestion<br>Europe is home to a large number of “pond landscapes”, many with origins dating back to the Middle Ages and a historic vocation for fish farming. Despite their man-made nature, these environments are known for their capacity to harbor significant biodiversity, with rare, even endemic or endangered species. With the abandonment of fish farming, combined with other threats such as climate change, a significant number of these ponds have disappeared in recent decades. Until recently, and despite the important role they can play, these small water bodies have been neglected in research, but also in public policies.In this PhD thesis work, we looked at the effects of different fish farming management practices on ecosystem services provided by fish ponds. First, we analyzed the practice of drying-out ponds and its impact on both biodiversity and fish yields. Secondly, we explored the impacts of different fish density management on macrophyte community characteristics. And finally, we studied fish ponds as potential carbon sinks or sources, and the effects of management practices on these carbon balances.To contribute to the scientific knowledge on these topics, we capitalized on historical data collected in the Dombes region (Ain, France) since 2007, but also on data collected as part of the European PONDERFUL project, between 2021 and 2022, in Dombes and Midden-Limburg (Belgium). We analyzed data on water and sediment physico-chemistry, as well as biodiversity (macrophytes, phytoplankton and macroinvertebrates), carbon storage and emissions, and fish farming management practices (time since the last dry year, fish stocking, fertilization).Our results show that drying-out is a major agroecological practice for extensive pond fish farming. This voluntary draining facilitates the recolonization of macrophytes and their diversity when the pond is re-watered. The second year in water is characterized by an "unstable state" of equilibrium between the two primary producers. This state appears to be favorable to biodiversity, production and carbon storage. Intensification of production, through increased fish densities, nevertheless has negative effects on macrophyte species richness. It also impacts community structure. Ponds used for fish farming have subsets of species that nest in the richer communities of ponds managed without fish. We were also able to show a very high degree of variability in the carbon balances of 20 fish ponds. On average, monitored ponds appear to be carbon sinks, with around 4 tonnes of CO2 equivalent stored per hectare over 6 months. The dry year, on the other hand, is characterized by high greenhouse gas emissions.All these elements confirm that fish ponds, combined with extensive practices, can provide numerous ecosystem services. Fish production is not incompatible with biodiversity conservation. The sustainability of these environments in European landscapes, and of the ecosystem services they provide, depends on the maintenance of these management practices. Even if it seems possible to reconcile provisioning and support services, in the future it will be necessary to establish a hierarchy of desired services, particularly in view of the inverse effects that certain management practices may have
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Broman, Nils. "Värdeskapande av koldioxid frånbiogasproduktion : En kartläggning över lämpliga CCU-tekniker för implementeringpå biogasanläggningar i Sverige." Thesis, Linköpings universitet, Industriell miljöteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-171793.
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Carbon dioxide from biogas production is currently considered to be without value and isbecause of this released into the atmosphere in the biogas upgrading process. The residualgas is a potential carbon source and can create value in the biogas manufacturing process.By finding a suitable value-creating process that utilizes carbon dioxide, it can be possibleto provide both economic and environmental incentives for companies to develop theiroperations. This project explored the possibility to create value from this CO2. Through anevaluation of the technical maturity of CCU technologies, a recommendation could be givenat the end of the project. An analysis of technical barriers, such as pollutants in the gas, aswell as barriers in the form of competence and corporate culture were examined in orderto provide a reasoned recommendation. The project mapped which value-creating systemswould be suitable for biogas producers in a Swedish context. This included established methaneand carbon dioxide upgrading techniques currently in use and suitable CCU techniquesthat can interact with the selected upgrading processes and serve as value creators. Based onthis survey, it was then possible to identify common, critical variables for these systems. Thereafter,a recommendation of an appropriate CCU technology could be given depending onthe CO2 composition produced. One conclusion from the study was that carbon dioxide concentrationsfrom the residual gas was often high (approx. 97-98 %) and did not contain anycorrosive or toxic components, and that this largely depends on how the digestion reactor ishandled in the production process. Thus, questions were raised about what the actual limitationsof the CCU are, as they did not seem to be technical. CCU techniques that proved to beof particular interest were pH regulation of sewage plants, CO2 as a nutrient substrate for thecultivation of microalgae, and manufacturing of dry-ice for refrigerated transports. All of thesetechnologies currently have a sufficiently high degree of technical maturity to be installedalready today. Other CCU techniques, such as "’Power to gas”, require a high CO2 concentrationand were discarded as the literature review did not suggest the economic potential forthem as they require additional CO2 upgrading steps. Instead, CCU techniques were chosenthat could be implemented directly with the existing CO2 quality. Furthermore, it was concludedthat one reason why CCU technologies have not been widely implemented is internalbarriers between distributors and manufacturers (or users) of CCU technologies. Thus, theuse of carbon dioxide from biogas production and implementation of CCU technologies canbe promoted by eliminating barriers in companies, such as a lack of both knowledge andfinancial incentives.<br>Koldioxid från biogasproduktion betraktas i dagsläget som utan värde och släpps ut i atmosfärenvid uppgradering av biogas. Restgasen är en potentiell kolkälla och kan vara värdeskapandeför biogasprocessen. Genom att finna en lämplig värdeskapande process som utnyttjarkoldioxid går det att ge både ekonomiska och miljömässiga incitament till företag att utvecklasin verksamhet. I detta projekt undersöktes möjligheten att skapa värde av denna CO2.Genom en utvärdering av den tekniska mognadsgraden hos CCU-tekniker kunde en rekommendationges vid projektets slut. En analys av tekniska hinder, såsom föroreningar i gassammansättningen,såväl som hinder i form av kompetens och företagskultur undersöktes för attkunna ge en motiverad rekommendation. I projektet kartlades vilka värdeskapande systemsom skulle passa för biogasproducenter i en svensk kontext. Detta inkluderade etableradeuppgraderingstekniker för metan- och koldioxid som används i dagsläget. I projektet undersöktesäven lämpliga CCU-tekniker som kan samverka med de valda uppgraderingsprocessernaoch och agera värdeskapande. Utifrån denna kartläggning kunde det sedan anges vilkagemensamma, kritiska variabler som finns för dessa system. Därefter kunde en rekommendationav lämplig CCU-teknik ges beroende på den producerade CO2 sammansättningen. Enslutsats i projektet var att koldioxid från restgasen ofta var av hög koncentration (ca. 97-98 %)och ej innehöll några korrosiva eller toxiska komponenter, och att detta till stor del beror påhur rötkammaren är hanterad i produktionsprocessen. Således väcktes frågor kring vilka defaktiska begränsningarna för CCU är, då de inte torde vara tekniska. CCU-tekniker som visadesig vara av särskilt intresse var pH-reglering av avloppsverk, CO2 som näringssubstratför odling av mikroalger, samt tillverkning av kolsyreis för kyltransporter. Samtliga dessatekniker har tillräckligt hög teknisk mognadsgrad för att kunna installeras i dagsläget. AndraCCU-tekniker, såsom ”Power to gas”, kräver en hög CO2-koncentration och avfärdades dålitteraturstudien inte talade för den ekonomiska potentialen i dessa eftersom de kräver ytterligareuppgraderingssteg för CO2. Således valdes istället CCU-tekniker som skulle gå attimplementera direkt med den befintliga CO2 kvalitén. Vidare drogs slutsatsen att en anledningtill att CCU-tekniker inte har blivit vida implementerade till stor del är interna hindermellan distributörer och tillverkare (eller utnyttjare) av CCU-tekniker. Således kan användandetav koldioxid från biogasproduktion och implementering av CCU-tekniker främjasgenom att eliminera hinder hos företag. I projektet yttrade sig detta som bristande ekonomiskaincitament och okunskap. Ett ökat användande av CCU-tekniker kan också uppnås genomatt införa lagar och regler som begränsar användandet av föråldrade tekniker som drivs avfossila bränslen, och som kan ersättas av klimatvänliga CCU-tekniker.
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Renforth, Phil. "Mineral carbonation in soils : engineering the soil carbon sink." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1216.
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Rapid anthropogenic climate change is one of the greatest challenges that human civilisation will face in the 21st century. A 25-180 % increase in atmospheric carbon dioxide content since the early 1800’s and a predicted increase of 2-3% each year will lead to a 2-6°C rise in tropospheric temperatures. The consequences of increased atmospheric temperatures are profound and would put unsustainable strain on human infrastructure, which was conservatively estimated in the Stern Review (2006) to cost approximately 20% of GDP. Given the political, technical, economic and social barriers preventing the transition to a low carbon economy, there is an unequivocal need to research ‘geoengineering’ technologies that can bridge the gap between carbon emission reduction targets and actual emissions. Soil mineral carbonation is one such technology. The atmosphere is one of the smallest carbon pools at the Earth’s Surface (depending on how each pool is demarcated). Soils turn over the quantity of carbon in the atmosphere in under a decade and collectively form one of the largest carbon pools (3-4 times the quantity of carbon in the atmosphere). Land use change since the agricultural revolution has released 256 GtC (40 % of anthropogenic emissions). Research investigating the potential for carbon accumulation in soils is primarily focused on restoring organic carbon concentration to pre-agricultural values through modification of farming practices. The research presented in this thesis is the first that explores the potential of increasing the inorganic carbon pool as an emissions mitigation technology. Inorganic carbon accumulation is promoted by introducing divalent cation rich (predominantly calcium and magnesium) silicate and hydroxide minerals into the soil, which weather and supersaturate the soil solution with respect to carbonate minerals (predominantly calcite, aragonite, magnesite and dolomite). The carbon in the resultant precipitate is derived from the atmosphere. This is analogous to mineral carbonation technologies which induce carbonate precipitation from silicate weathering in industrial scale reactors at elevated temperatures and pressures. However, carbonation in soil exploits natural weathering processes to the same effect with minimal energy and infrastructure input. The research presented in this thesis broadly investigates soil mineral carbonation by contributing work towards the fundamental issues associated with application of soil mineral carbonation technology. Research activity described herein covers a range of laboratory batch weathering experiments, field work, geochemical modelling, plant growth trials, soil microcosm experiments and literature reviews. While eclectic, all work packages contribute to the same goal of describing the efficacy, effectiveness and potential impacts of soil mineral carbonation. The efficacy of mineral carbonation technology is primarily limited by the availability of appropriate silicate bearing material. A literature search suggests that approximately 15-16 Gt a- 1 of silicate rich ‘waste’ materials are produced as a consequence of human activity. This has a carbon capture potential between 190 and 332 MtC a-1, which is equivalent to other emissions mitigation strategies. Quarrying silicate specifically for carbonation is a suggested strategy that may be able to store on the order of 102 GtC a-1 (based on two sites in the US). Therefore, mineral carbonation may form part of global mitigation strategies collectively equivalent to 14 GtC a-1 to stabilise the CO2 concentration of the atmosphere at 500 parts per million by volume. Considering that the potential capacity of soil mineral carbonation is sufficient to act as a substantial emissions mitigation strategy it was appropriate to investigate issues associated with the application of such a technology. In the first instance, sites known to contain silicates were investigated. These include soils developed on natural silicates (on the Whin Sill in Northumberland), construction and demolition waste (at a brownfield site and waste transfer stations) and slag (at a former steelworks). Interpretation of fieldwork results suggests that inorganic carbon accumulation is rapid (up to 38 gC kg-1(soil) a-1), and is orders of magnitude xxv greater than organic carbon accumulation in natural soils. The average concentration of inorganic carbon (20-30 Kg m-3) is equivalent to organic carbon in natural soils. The unusually light carbon and oxygen isotope ratios of the carbonate (-3.1 ‰ and -27.5 ‰ for δ13C and -3.9 ‰ and -20.9 ‰ for δ18O) were used to determine that up to 55% of the carbon was derived from the atmosphere. The rate of carbon capture, which is the same as the precipitation rate of carbonate, is a function of solution chemistry. The more supersaturated a solution is with respect to a carbonate mineral, the more rapid the precipitation rate. Saturation of a solution is a function of divalent cation and carbonate anion concentration. Therefore, the supply of each of these components was investigated in laboratory experiments. Batch weathering experiments were used to investigate the supply of calcium from artificial silicates (hydrated cement gel). Up to 70-80 % of the calcium contained in the mineral was removed, which is consistent with efficiencies reported for conventional mineral carbonation. The log rate of weathering was between -10.66 and -6.86 mol Ca cm-2 sec-1, which is several orders of magnitude greater than that usually reported for natural silicates. Microcosm experiments were conducted to investigate the rate of supply of carbonate from the organic carbon mineralisation in high pH solutions. The research clearly demonstrates that high pH solutions inhibit the breakdown of organic carbon as a function of nutrient supply. Where organic carbon was successfully mineralised the log rates (-3.4 mmol g-1(field moist soil) sec-1) were equivalent to that found in previous studies. While the influx of dissolved carbonate mineral components into the soil solution is the primary controlling step in the rate of carbon accumulation, there is a complex relationship between soil physical properties and geochemistry. This was highlighted in a numerical model that was constructed for this thesis, which suggests that soil pore volume and particle size distribution are important variables. An additional numerical model was constructed to investigate the transportation of silicate material to the application site. This model suggests that an economics of soil mineral carbonation is a function of transport costs, the value of the silicate material and the price of carbon. Field observations, growth trials, microcosm experiments and previous research suggest a complex interaction between biology, weathering and carbonate precipitation. Additional work is required to investigate carbonate precipitation mediated by plant and microorganism activity and the degree to which soil mixed with silicates impact on ecosystem functioning. This research has demonstrated that mineral carbonation in soils could form a substantial emissions mitigation strategy, but additional work is required in a number of areas to which this thesis provides a suitable foundation.
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Johannessen, Sophia. "A photochemical sink for dissolved organic carbon in the ocean." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ57364.pdf.
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Landschutzer, Peter. "Variability of the global ocean carbon sink (1998 through 2011)." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/48677/.
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In this thesis a newly developed 2–step neural network approach is used to reconstruct basin–wide monthly maps of the sea surface partial pressure of CO₂ (pCO₂) at a resolution of 1°X1° for both the Atlantic Ocean from 1998 through 2007 and the global ocean from 1998 through 2011. From those, air–sea CO₂ flux maps are computed using a standard gas exchange parameterization and high–resolution wind speeds. Observations form the basis of the studies conducted in this thesis. The neural network estimates benefit from a continuous improvement of the observations, i.e., the Surface Ocean CO₂ Atlas (SOCAT) database. Additionally, bottle samples were collected along the UK–Caribbean line to investigate the variability of the sea surface pCO₂ and its drivers. The neural network derived pCO₂ estimates fit the observed pCO₂ data with a root mean square error (RMSE) of about 10 μatm in the Atlantic Ocean from 1998 through 2007 and about 12 μatm in the global ocean from 1998 through 2011, with almost no bias in both studies. A check against independent pCO₂ data reveals a larger RMSE, in particular in regions with strong pCO₂ variability and gradients. Temporal mean contemporary flux estimates for the Atlantic Ocean (-0.45±0.15 Pg C ·yr⁻¹) and the global ocean (-1.54±0.65 Pg C ·yr⁻¹) agree well with recent studies. Trends and variabilities within the considered time periods are strongly influenced by climate modes. The global results from 1998 through 2011 reveal the strongest variability of the air-sea CO₂ fluxes in the Equatorial Pacific (±0.12 Pg C · yr⁻¹,±1σ), mainly driven by the El Niño Southern Oscillation (ENSO) climate mode. Trends towards a strengthening of the Southern Ocean carbon sink (-0.36±0.07 Pg C ·yr⁻¹ · decade⁻¹) from 1998 through 2011 are potentially linked to the recent weakening of the Southern Annular Mode (SAM) index.
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Fernández-Martínez, M., S. Vicca, I. A. Janssens, et al. "Atmospheric deposition, CO2, and change in the land carbon sink." NATURE PUBLISHING GROUP, 2017. http://hdl.handle.net/10150/625758.
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Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and generalised mixed models, we found that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011. Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks in these forests. We also found that the reduction of sulphur deposition in Europe and the USA lead to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, trends in climate and nitrogen deposition did not significantly contribute to changing carbon fluxes during the studied period. Our findings support the hypothesis of a general CO2-fertilization effect on vegetation growth and suggest that, so far unknown, sulphur deposition plays a significant role in the carbon balance of forests in industrialized regions. Our results show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling.
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Gedye, Sharon Jane. "Mass balance in recent peats." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266139.
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Bairam, Emna. "Etude des processus écophysiologiques caractérisant la distribution du carbone entre les sources et les puits au sein de la charpentière du pommier. Eléments pour un modèle fonction-structure." Thesis, Rennes, Agrocampus Ouest, 2017. http://www.theses.fr/2017NSARC129/document.
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La synthèse et le transport du carbone chez le pommier repose sur un ensemble de mécanismes complexes et imbriqués dépendants de facteurs endogènes et exogènes. Uneapproche combinant une caractérisation écophysiologique et l’utilisation d’un modèle structure-fonction de la plante (Functional-Structural Plant Model, FSPM) présente un moyenintéressant pour ce champ de recherche dans la mesure où un modèle structure-fonction permet d’intégrer la topologie et la géométrie de la plante et de ses différents organes à l’ensemble des facteurs impliqués dans l’assimilation et le transport du carbone et de l’eau. Le travail présenté ici a contribué à la compréhension des relations sources-puits mais égalementà l’élaboration d’un modèle FSPM à plusieurs niveaux. Premièrement, le développement de modèles de prédiction de l’architecture des différentes pousses du pommier à partir de variables simples apporte un moyen novateur pour simplifier la simulation de l’architecturedes branches mais égalementpour quantifi er de façon robuste la surface foliaire. Deuxièmement,l’établissement d’un réseau de corrélations entrevariables morphométriques des différents organes issus dubourgeon mixte met en évidence les organes les plus connectésà l’échelle du spur. Enfi n, une étude des relations sourcespuitsà l’échelle de la branche a permis, d’une part, une caractérisationde la régulation de la photosynthèse nette desfeuilles en réponse à des changements dans le ratio sources/puits mais aussi en fonction des types de feuilles et, d’autrepart, à mettre la lumière sur l’infl<br>The synthesis and the transport of carbon in apple are basedon a whole host of complex and interlaced mechanisms thatdepend on endogenous and exogenous factors. An approachthat combines the ecophysiological characterisation with theuse of a Functional-Structural Plant Model (FSPM) representsan interesting method in this fi eld of research, inasmuch assuch an FSPM allows integrating the topology and the geometryof the plant and its constituting organs with the entiretyof factors involved in assimilation as well as water andcarbon transport. The present study has contributed to thebetter understanding of the source-sink relations characterizingthis system but also to the elaboration of a multi-scaledFSPM. First, the development of models for the prediction ofthe architecture of different shoot types in apple from simplevariables provides a novel way to simplify the simulationof theinitial structure of branches but also to quantify leaf area in arobust manner. Second, the creation of a network of correlationsamong morphometric variables of the different organsformed by the mixed bud of apple clearly shows the functionalrelations among the spur organs. In the end, the study ofsource-sink relations at the branch scale has allowed, on theone hand, to characterize the regulation of net photosynthesisas a function of a changed source/sink ratio but also asa function of leaf type and, on the other hand, to shed somelight on the infl uence that the competition among fruits hason increasing sink strength and thus regulating the leaf
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Nye, Adrienne Juliana. "Hyper-lignified root systems as a carbon sink in Arabidopsis thaliana." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13909.
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Lignified plant cell walls represent an immense carbon sink to offset rising atmospheric carbon dioxide (CO₂) due to the chemical stability and structural diversity of the bonds formed between lignin subunits, making it the slowest decomposing component of dead vegetation. This thesis explores the feasibility of increasing lignin deposition in roots through overexpression of SND1 (Secondary Wall Associated NAC Domain Protein 1), a key transcriptional activator involved in regulating secondary wall biosynthesis in fibres, under the control of two different putative root-specific promoters, 4-coumarate:CoA ligase 1 (4CL1) and glutathione S-transferase-tau class 19 (GSTU19). Transgenic plants were analyzed at: 1) the molecular level (transcription of lignin pathway genes and regulatory transcription factors (TFs) involved in cell wall biosynthesis), 2) the chemical level (lignin content) and 3) the plant growth and development level (phenotyping and microscopy). Results showed that: i) SND1 was overexpressed in a tissue-specific manner in roots, ii) SND1 overexpression caused an upregulation of its previously known direct downstream targets, iii) SND1 overexpression did not result in a modification of indicative lignin biosynthetic pathway genes in roots, iv) plants overexpressing SND1 in roots generally produced plants with decreased total lignin content, v) plants overexpressing SND1 in roots generally showed an increase in lateral root density, and vi) seed traits, plant growth and development, plant height and lignin deposition patterns in roots remained unaltered. Misregulation of SND1 in roots did not result in the predicted increase in lignin deposition patterns in this organ.
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Cross, Andrew. "An investigation of carbon flows from forest soils, in relation to climatic warming." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3805.
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Rises in anthropogenic CO2 emissions are now widely acknowledged to be responsible for changes in the global climate, with potentially disastrous consequences if these rises continue unchecked. Although knowledge of ecosystem responses to climate change has improved, there are still large underlying uncertainties regarding their response to warming. Of all the ecosystems with the potential to mitigate rises in CO2, forests are arguably the most important because of their huge land area and store of carbon. A large proportion of the carbon stored in forests is found in the soil, and it is the response of this soil carbon to temperature that is the main determinant of a forest’s ability to act as a carbon sink, or indeed source. Understanding the response of soil carbon flux to temperature, as well as the contribution of soil carbon flux to the carbon balance of forests as a whole is crucial in helping to improve modelling approaches. In this thesis I first examined the temperature response of old and new soil organic carbon from a Sitka spruce plantation under controlled laboratory conditions. Both the old and new soil organic carbon showed similar temperature sensitivities after prolonged incubation at 20 °C, thus implying a similar response to increasing temperatures. Using a variety of different methods (root intensity, meshing and stable isotope analysis) I then studied the responses under field conditions. These methods showed that autotrophic respiration was responsible for up to 50 % of total soil respiration, and was more sensitive to temperature than heterotrophic respiration. Finally, I compared the contributions and determinants (particularly temperature and moisture) of soil respiration fluxes to ecosystem fluxes at a temperate (Sitka spruce) and Mediterranean (Maritime pine) forest. Temperature was found to be the dominant driver of soil respiration fluxes at the temperature forest, whilst soil respiration was limited by moisture at the Mediterranean forest. Statistically significant relationships between net ecosystem productivity and soil respiration (and the stable isotope signature of soil respiration) were found at both forests, indicating a close coupling between above-ground processes and soil respiration.
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Mendon?a, J?nior Jurandir Rodrigues de. "Os reservat?rios eutrofizados da regi?o tropical semi?rida atuam como emissores ou como sequestradores de di?xido de carbono?" Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16015.
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Previous issue date: 2014-03-31<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>The aquatic ecosystems can play a role as carbon-dioxide-source or carbon-dioxide-sink systems due to the high predominance of heterotrophic or autotrophic metabolism. The primary production can strongly affect the carbon balance (CO2) through the consumption of carbon dioxide in the photosynthesis, especially in eutrophic environment, acting as a carbon sink. The present study tested the hypothesis that the eutrophic reservoirs in tropical semi-arid region are carbon dioxide-sink systems due to the high primary productivity presented in these systems. Five Brazilian reservoirs from the semi-arid in the northeast region were monitored monthly during four years (2010 to 2013) with a prolonged drought event identified during the study. The results showed an increasing level of eutrophication over the period of prolonged drought, with the predominance of autotrophy. Significant negative correlations were observed between the partial pressure of CO2 (pCO2) (p<0,001) and chlorophyll-a in the Boqueir?o, Passagem das Tra?ras, Dourado and Gargalheiras reservoirs, showing a pattern of the carbon dioxide-sink systems. However, this pattern was not found in Cruzeta reservoir. In summary, in the tropical semi-arid region, hydrological and morphometric variables can lead to different behaviors of the water-supply reservoirs on the carbon metabolism. The eutrophic reservoirs evaluated showed a negative relationship between pCO2 and Chl-a, which suggests that these water bodies show an autotrophic metabolism and behave as carbon dioxide- sink systems<br>Os ecossistemas aqu?ticos podem atuar como emissores ou sequestradores de carbono em fun??o da predomin?ncia do metabolismo heterotr?fico ou autotr?fico. A produ??o prim?ria pode afetar fortemente o balan?o de carbono (CO2) atrav?s do consumo de di?xido de carbono na fotoss?ntese, especialmente em ambiente eutr?ficos, atuando como sumidouros. O presente estudo testou a hip?tese de que reservat?rios eutrofizados da regi?o tropical semi?rida s?o sequestradores de CO2 em fun??o da alta produtividade evidenciada nesses sistemas. Cinco reservat?rios da regi?o semi?rida do nordeste do Brasil foram monitorados mensalmente durante o per?odo de 2010 ? 2013, com um evento de seca prolongada identificado durante o estudo. Os resultados mostraram um crescente n?vel de eutrofiza??o ao longo do per?odo de seca prolongada com predomin?ncia de autotrofia. Foram observadas correla??es negativas significativas entre a press?o parcial de CO2 (pCO2) (p<0,001) e clorofila-a nos reservat?rios Boqueir?o, Passagem das Tra?ras, Dourado e Gargalheiras, evidenciando um padr?o de sequestro de CO2 desses sistemas. Por?m, este padr?o n?o foi encontrado no reservat?rio Cruzeta. Em s?ntese, na regi?o semi?rida tropical, as vari?veis hidrol?gicas e morfom?tricas podem direcionar diferentes comportamentos dos reservat?rios de abastecimento no metabolismo do carbono. Os reservat?rios eutrofizados avaliados apresentaram uma rela??o negativa entre pCO2 e Chl-a o que sugere que estes corpos h?dricos evidenciam um metabolismo autotr?fico e se comportam como sequestradores de CO2
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Rossi, Lorenzo Matteo Walter. "Embankment as a carbon sink : a study on carbon sequestration pathways and mechanisms in topsoil and exposed subsoil." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG083.
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La séquestration du carbone (C) fait l'objet d'une attention scientifique et politique croissante dans le cadre de la réduction des gaz à effet de serre. Les sols géotechniques ont été négligés en raison de leur potentiel de séquestration du carbone, et l'attention étant concentrée sur les sols agricoles et naturels. Nous visons à évaluer le potentiel des talus géotechniques comme puits de carbone et, par l'étude des espèces végétales et des sols présentant des caractéristiques contrastées, à mettre en lumière les mécanismes de séquestration du carbone organique et les rôles des différents acteurs impliqués. Nous visons non seulement à quantifier le C gagné et perdu dans le sol, mais aussi son origine (nouveau C frais et ancien C préexistant) et comment il est réparti dans différents pools de C qui montrent une stabilité du C différente (qualité du C stocké). Tout d'abord, nous avons évalué la séquestration du carbone dans différents pools de carbone sous un sol semé de 12 espèces herbacées différentes sur une période de 10 mois. La caractérisation des différents traits de racine a permis de comprendre l'influence de la stratégie d'alimentation des ressources en racines (représentée par le spectre économique de la racine) sur la séquestration du carbone. Nous avons montré que les espèces dont les caractéristiques racinaires sont associées à une production élevée de C labile entraînent une augmentation plus élevée de C dans le pool stable de SILT+CLAY (<20µm). Les espèces dont les traits de racine sont associés à un faible apport de C récalcitrant favorisent plutôt l'accumulation dans la fraction POM instable. Ensuite, grâce à une expérience de marquage isotopique stable de 183 jours (CO2 constamment enrichi en 13C), nous avons pu étudier la dynamique du C dans différents pools de C sous deux espèces (L. perenne et M. sativa) sur deux sols (terre végétale, profondeur 0-30 cm et sol remonté, profondeur 110-140 cm) aux caractéristiques opposées. Nous avons mis en évidence le grand intérêt de faire le pont entre l'origine du C et les pools de C lors de l'étude des destins du C du sol, ce qui permet de dévoiler des processus que les méthodes plus traditionnelles cachent. Le nouveau C et l'ancien C présentaient une covariation synergique, avec des pertes plus faibles de l'ancien C associées à de nouvelles entrées de C plus élevées. Ceci est conforme à l'hypothèse de l'utilisation préférentielle du substrat. Cette hypothèse a également été validée par l'étude de l’effet d’amorçage et de la respiration du sol. Celle-ci a montré que la teneur en CO2 inhalé était plus élevée lorsque les entrée C de la plante étaient élevées, tout en augmentant la minéralisation de l’ancien C lorsque les entrées de C de la plante étaient faibles, c’est-à-dire dans le sous-sol. De plus, nous avons validé l'hypothèse de réconciliation entre 'l'hypothèse de l'Utilisation Préférentielle des Substrats' et 'l'hypothèse de la Concurrence', cette dernière déterminant le 'priming effect' dans le sous-sol à faible fertilité. Nous avons observé de nouveaux apports significatifs de C d'origine végétale dans la fraction SILT+CLAY (<20µm, très stable) à l'appui de la preuve de l'effet d'ensevelissement in vivo dans l'hypothèse de la pompe à carbone microbienne du sol. L'effet de l'espèce s'est produit principalement sur les entrées de nouveaux C, mais il a été maîtrisé par l'effet du sol, avec un stockage de C plus faible dans un sol de faible qualité (faible activité et biomasse d'azote et microbienne). Les conditions microbiologiques ont été le principal moteur de la nouvelle accumulation de C et de l'ancienne perte de C et ont aidé à expliquer pourquoi aucun effet de la saturation en C du sol - une théorie centrale dans des études récentes sur la séquestration de C - n'a été trouvé dans le carbone protégé. Cette compréhension fondamentale des interactions plantes-sol nous aide à mieux optimiser la gestion des sols et de la végétation des talus des routes<br>Carbon (C) sequestration is receiving increasing scientific and political attention in a framework of greenhouse gasses mitigation. However, geotechnical soils have been neglected for their C sequestration potential, with the global attention focusing on agricultural and natural soils. In the present thesis project we aim to assess the potential of geotechnical embankments as C sink, and, through the study of plant species and soils showing contrasting features, shed light on SOC sequestration mechanisms and the role of the different actor involved. We aim not only to quantify the C gained and lost in soil, but even its origin (fresh new C input or old preexistent C) and how it is partitioned in different C pools characterized by different C stability (quality of stored C). First, we evaluated the C storage in different pools under soil sowed with 12 different herbaceous species in a 10 months experiment. Assessing different root traits allowed understanding the influence of root economic spectrum on C storage. We showed how traits linked to high labile C are linked to a higher C increase in the stable SILT+CLAY pool (<20µm). Root traits related to a low input of recalcitrant, instead, favor accumulation in the unstable POM fraction. Thanks to a 183 days stable isotope labelling experiment (CO2 constantly enriched with 13C) we were able to study the C dynamics in different C pools under two species (L. perenne and M. sativa) sowed on two soil (topsoil, 0-30cm depth and subsoil brought to the surface, 110-140 cm depth) showing contrasting characteristics. We evidenced the great interest of bridging C origin and C pools when studying soil C fates, allowing unveiling processes those more traditional methods would hide. New C and old C showed synergetic covariation, with lower old C losses associated to higher new C inputs. This is in good accordance with the Preferential Substrate Utilization hypothesis (Cheng and Kuzyakov, 2005). The Preferential Substrate Utilization hypothesis was also validated with the study of priming effect and soil respiration, that showed higher plant derived C in respired CO2 when plant C input were high, while increasing old C mineralization when plant C input were low, i.e. in subsoil. We observed significant plant derived new C input in the SILT+CLAY fraction (<20µm, highly stable) supporting evidence of the in vivo entombing effect in the soil Microbial Carbon Pump hypothesis (Liang et al., 2017). The species effect mainly occurred on new C input, but it was overpowered by the soil effect, with lower C storage in low quality soil (low nitrogen and microbial biomass and activity). In general, microbiological conditions were the main driver for new C accumulation and old C loss, and helped to explain why no effect of soil C saturation – a central theory in recent studies on C sequestration - was find in the protected carbon. Such fundamental understanding of plant-soil interactions help us to better optimize soil and vegetation management for road embankment revegetation
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ROSSI, Lorenzo Matteo Walter. "Embankment as a carbon sink: a study on carbon sequestration pathways and mechanisms in topsoil and exposed subsoil." Doctoral thesis, Università degli studi di Cassino, 2019. http://hdl.handle.net/11580/75251.
Full textAbstract:
Carbon (C) sequestration is receiving increasing scientific and political attention in a framework of greenhouse gasses mitigation. However, geotechnical soils have been neglected for their C sequestration potential, with the global attention focusing on agricultural and natural soils. In the present thesis project, we aim to assess the potential of geotechnical embankments as C sink, and, through the study of plant species and soils showing contrasting features, shed light on C sequestration mechanisms and the role of the different actors involved. We aim not only to quantify the C gained and lost in soil, but even its origin (fresh new C input or old preexistent C) and how it is partitioned in different C pools characterized by different C stability (quality of stored C). First, we evaluated the C storage in different pools under soil sowed with 12 different herbaceous species in a 10 months experiment. Assessing different root traits allowed understanding the influence of root economic spectrum on C storage. We showed how traits linked to high labile C are linked to a higher C increase in the stable SILT+CLAY pool (<20µm). Root traits related to a low input of recalcitrant, instead, favor accumulation in the unstable POM fraction. Thanks to a 183 days stable isotope labelling experiment (CO2 constantly enriched with 13C) we were able to study the C dynamics in different C pools under two species (Lolium perenne and Medicago sativa) sowed on two soil (topsoil, 0-30cm depth and subsoil brought to the surface, 110-140 cm depth) showing contrasting characteristics. We evidenced the great interest of bridging C origin and C pools when studying soil C fates, allowing unveiling processes those more traditional methods would hide. New C and old C showed synergetic covariation, with lower old C losses associated to higher new C inputs. This is in good accordance with the Preferential Substrate Utilization hypothesis. The Preferential Substrate Utilization hypothesis was also validated with the study of priming effect and soil respiration, that showed higher plant derived C in respired CO2 when plant C input was high, while increasing old C mineralization when plant C input was low, i.e. in subsoil. We observed significant plant derived new C input in the SILT+CLAY fraction (<20µm, highly stable) supporting evidence of the in vivo entombing effect in the soil Microbial Carbon Pump hypothesis. The species effect mainly occurred on new C input, but it was overpowered by the soil effect, with lower C storage in low quality soil (low nitrogen and microbial biomass and activity). In general, microbiological conditions were the main driver for new C accumulation and old C loss, and helped to explain why no effect of soil C saturation – a central theory in recent studies on C sequestration - was found in the protected carbon. Such fundamental understanding of plant-soil interactions helps us to better optimize soil and vegetation management for road embankment revegetation
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Lebehot, Alice. "A variable North Atlantic sink for anthropogenic CO2 : modelling observed change." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/32759.
Full textAbstract:
To determine the maximum carbon dioxide (CO2) emissions consistent with a given global warming threshold, the scientific community must robustly quantify what proportion of human emitted CO2 will be taken up by the terrestrial and marine carbon reservoirs. The North Atlantic Ocean is a region of intense uptake of atmospheric CO2. To assess how the North Atlantic CO2 sink has evolved over the past decades and understand the mechanisms involved in that uptake, observations and models are used. To appreciate the strengths and limitations of observation-based and modelled products, I explore the sources of uncertain- ties of two widely-used biogeochemical observational products (GLODAP and SOCAT), and carefully evaluate the latest generation of Earth System Models (ESMs) (i.e. the CMIP5 models) against these data. The lack of robust uncertainties on observation-based estimates of the North Atlantic CO2 uptake has so far limited the community’s ability to use observed trends to evaluate CO2 uptake behaviour simulated by the models. Here, by making use of the strengths of observation-based and modelled products, a novel gap-filling and uncertainty assessment method is developed to (1) robustly quantify the recent change in the basin-wide North Atlantic CO2 sink, and (2) evaluate simulations of the recent uptake in ESMs. Through the assessment of robust interpolation uncertainties on the annually-varying North Atlantic CO2 uptake and on the resulting trends over the period 1992-2014, I find that (1) the North Atlantic CO2 uptake increased at a rate of 0.081 ± 0.012 PgC/yr/decade from 1992- 2014, corresponding to an additional uptake of 2.2 PgC over this interval relative the flux in the 1992, and (2) state-of-the-art ESMs are consistently biased to lower trend values, with a mean that is about three times smaller than the observation-based trend, equating to an additional uptake of only 0.72 ± 0.40 PgC over the period 1992-2014. I further show that the inability of these models to capture the observed increase in CO2 uptake is due primarily to biases in modelled ocean biogeochemistry, which I explore through comparison with observations. Our current understanding of the ocean carbon-cycle, as synthesised by ESMs, cannot explain the recent behaviour of the North Atlantic CO2 sink. Current projections may therefore underestimate the contribution of the North Atlantic to mitigating increasing future atmospheric CO2 concentrations.
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Lazarova, Sofiya. "Investigating the role of sucrose phosphate synthase and hexokinase in carbon sink strength." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55000.
Full textAbstract:
The production, transport and assimilation of organic carbon ultimately drive the growth of plants. In this work, two enzymes, Sucrose Phosphate Synthase (SPS) and Hexokinase (HXK), prominent in their role of carbon production in the form of sucrose at the source, have been examined for their role at the sink, where carbon is assimilated. It has been postulated that the presence of sucrose-forming enzymes in the sink serves a function to reform sucrose from apoplastic cleavage or partake in a “futile” cycle of sucrose cleavage and such that small changes in metabolite enable large changes in sink carbon strength. In order to determine if SPS is involved in carbon sink strength, A. thaliana TDNA insertional lines and P. trichocarpa RNAi stem and developing xylem with decreased SPS transcript expression were analyzed. It was determined that loss of SPS transcript generally increases soluble sugars: sucrose, glucose and fructose, in the leaf and stem as well as starch in the leaf. Structural carbohydrates were generally unaffected and Klason soluble lignin decreased. Similarly, A. thaliana TDNA insertional lines with decreased HXK transcript expression were utilized to determine the role of HXK using stem tissue as a carbon sink model. Soluble sugars mainly increased in the leaf of athxk3 TDNA insertional line whereas starch increased in both leaf and stem of the same line. Interestingly, structural carbohydrate levels of the cell wall were perturbed in HXK TDNA insertional lines. The results were found to be consistent with the postulated roles of SPS and HXK that predict a function in sucrose formation from apoplastic cleavage, which allows for fine-tuning of major intracellular metabolites and adjustment of sink strength.<br>Forestry, Faculty of<br>Graduate
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Cavan, Emma. "Sink or swim : the fate of particulate organic carbon in the interior ocean." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/401166/.
Full textAbstract:
Without small oceanic organisms atmospheric CO2 levels would be about 200 ppm higher than they are today; phytoplankton convert dissolved inorganic carbon (DIC) to particulate organic carbon (POC) during photosynthesis, influencing the air-sea exchange of CO2. Eventually some of this POC is exported out of the upper ocean, often as either phytodetrital aggregates or zooplankton faecal pellets. Because of the complexity of this biological carbon pump (BCP), the fate of the exported POC in the mesopelagic zone is difficult to predict. To make things more complex all of these processes vary temporally and spatially. Marine snow catchers (MSCs) were used to analyse fast and slow sinking particles separately, which is a unique approach as slow sinking POC fluxes are not often quantified. To investigate what controls the fate of particles in the upper mesopelagic zone (50 - 500 m) particles were collected from three contrasting oceanic regions: the Southern Ocean (SO), Equatorial Tropical North Pacific (ETNP) oxygen minimum zone (OMZ) and the temperate North Atlantic. In all sampling areas the slow sinking POC flux was as large if not larger than the fast sinking POC flux. This emphasises the importance of slow sinking particles in the upper mesopelagic zone. The main outcome from this thesis is the importance of the role of zooplankton in BCP processes. For instance the efficiency which particles were exported from the mixed layer varied inversely with primary production in the SO, and was likely due to the zooplankton grazing down the phytoplankton. When extending the data to include the ETNP and the North Atlantic this relationship still held, conflicting the long-standing theory that as primary production increases export efficiency increases. In the ETNP oxygen minimum zone a high proportion of exported POC sank through the mesopelagic zone. Microbial oxygen uptake incubations showed for the first time that fast sinking particles are turned over significantly slower than slow sinking particles (0.13 d?1 and 5 d?1 respectively). Microbial degradation of POC could explain most of the fast sinking POC attenuation with depth, with the remainder lost due to abiotic fragmentation. Therefore it is likely that zooplankton degradation of particles is reduced in OMZs as their abundance and metabolism are lowered. This reduces the overall remineralistion of POC, hence a higher fraction of POC is transferred to depth in OMZs. Phytoplankton lipid biomarkers dominated lipid particle composition throughout the upper mesopelagic zone in the ETNP, further emphasising the minor role of zooplankton in OMZs. Comparing the observations with an ecosystem model output at all three oceanic sites further emphasised the importance of zooplankton in the BCP. The model poorly parameterises zooplankton processing of particles and thus the observations and model matched best in the ETNP, where zooplankton processing of particles is naturally low. Changes in climate will effect the abundance and distribution of these small organisms. Further understanding of how zooplankton community structure and metabolism may change in the future will be important to predict how atmosphericCO2 levels may change.