Dissertations / Theses: 'Atmospheric carbon dioxide'

1

Barkley, Michael P. "Measuring atmospheric carbon dioxide from space." Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30591.

Full text

Abstract:

Satellite measurements of atmosphere CO2 concentrations are a rapidly evolving area of scientific research which can help reduce the uncertainties in the global carbon cycle fluxes and identify regional surface sources and sinks. One of the emerging CO2 measurement techniques is a relatively new retrieval algorithm called Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS) (Buchwitz et al., 2000). This algorithm is designed to measure the total columns of CO2 (and other greenhouse gases) through the application to spectral measurements in the near infrared (NIR), made by the SCIAMACHY instrument on-board ESA's ENVISAT satellite. The WFM-DOAS technique is based on fitting the logarithm of a model reference spectrum and its derivatives to the logarithm of the ratio of a measured nadir radiance and solar irradiance spectrum. In this thesis, a detailed error assessment of this technique has been conducted and it has been found necessary to include suitable a priori information within the retrieval in order to minimize the errors on the retrieved CO2 columns. Hence, a more flexible implementation of the retrieval technique, called Full Spectral Initiation (FSI) WFM-DOAS, has been developed which generates a reference spectrum for each individual SCIAMACHY observation using the estimated properties of the atmosphere and surface at the time of the measurement.

APA, Harvard, Vancouver, ISO, and other styles

2

Haworth, Matthew. "Mesozoic atmospheric carbon dioxide concentrations from fossil plant cutucles." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442779.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Murphy, Paulette P. "The carbonate system in seawater : laboratory and field studies /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8509.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Cheng, Yufu. "Effects of manipulated atmospheric carbon dioxide concentrations on carbon dioxide and water vapor fluxes in Southern California chaparral /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.

Full text

Abstract:

Thesis (Ph. D.)--University of California, Davis and San Diego State University, 2003.
Includes bibliographical references (leaves 95-101). Also available via the World Wide Web. (Restricted to UC campuses).

APA, Harvard, Vancouver, ISO, and other styles

5

DeLacy, Brendan G. Bandy A. R. "The determination of carbon dioxide flux in the atmosphere using atmospheric pressure ionization mass spectrometry and isotopic dilution /." Philadelphia, Pa. : Drexel University, 2006. http://dspace.library.drexel.edu/handle/1860%20/868.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Sindhøj, Erik. "Elevated atmospheric CO₂ in a semi-natural grassland : root dynamics, decomposition and soil C balances /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5797-1.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Kessler, Toby Jonathan 1974. "Calculating the global flux of carbon dioxide into groundwater." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/54439.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1999.
Includes bibliographical references (leaves 85-90).
In this research, the global annual flux of inorganic carbon into groundwater was calculated to be 4.4 GtC/y, with a lower bound of 1.4 GtC/y and an upper bound of 27.5 GtC/y. Starting with 44 soil PCO2 measurements, the dissolved inorganic carbon (DIC) of the groundwater was determined by equilibrium equations for the carbonate system. The calculated DIC was then multiplied by the groundwater recharge to determine the annual carbon flux per area. These PCO2 estimates were assigned to specific bio-temperatures and precipitations according to the Holdridge life-zone classification system, and regressions between PCO2, biotemperature, and precipitation were used to provide estimates for regions of the world that lacked PCO2 measurements. The fluxes were mapped on a generalized Holdridge life-zone map, and the total flux for each life-zone was found by multiplying the calculated flux by the area in each life-zone. While there was a wide range in the error, the calculations in this study strongly suggest that the flux of carbon into groundwater is comparable to many of the major fluxes that have been tabulated for the carbon cycle. The large flux that was calculated in this study was due to the high PCO2 that is common in soils. The elevated PCO2 levels are due to the decomposition of organic matter in soils, and the absorption of oxygen by plant roots. After the groundwater enters into rivers, it is possible that large amounts of CO2 is released from the surface of rives, as the carbon-rich waters re-equilibrate with the low atmospheric PCO2-
by Toby Jonathan Kessler.
S.M.

APA, Harvard, Vancouver, ISO, and other styles

8

Kambis, Alexis Demitrios. "A numerical model of the global carbon cycle to predict atmospheric carbon dioxide concentrations." W&M ScholarWorks, 1995. https://scholarworks.wm.edu/etd/1539616709.

Full text

Abstract:

A numerical model of the global carbon cycle is presented which includes the effects of anthropogenic &CO\sb2& emissions &(CO\sb2& produced from fossil fuel combustion, biomass burning, and deforestation) on the global carbon cycle. The model is validated against measured atmospheric &CO\sb2& concentrations. Future levels of atmospheric &CO\sb2& are then predicted for the following scenarios: (1) Business as Usual (BaU) for the period 1990-2000; (2) Same as (1), but with no biomass burning; (3) Same as (1), but with no fossil fuel combustion; (4) Same as (1), but with a doubled atmospheric &CO\sb2& concentration and a 2 K warmer surface temperature associated with the doubled atmospheric &CO\sb2& concentration. The global model presented here consists of four different modules which are fully coupled with respect to &CO\sb2.& These modules represent carbon cycling by the terrestrial biosphere and the ocean, anthropogenic &CO\sb2& emissions, and atmospheric transport of &CO\sb2.&. The prognostic variable of interest is the atmospheric &CO\sb2& concentration field. The &CO\sb2& concentration field depends on both the sources and sinks of &CO\sb2& as well as the atmospheric circulation. In addition, the sources and sinks vary significantly as a function of both time and geographic location. The model output agrees well with measured data at the equatorial and mid latitudes, but this agreement weakens at higher latitudes. This is due to the less adequate representation of the terrestrial ecosystem models at these latitudes. In the first scenario, the predicted concentration of atmospheric &CO\sb2& is 362 parts per million by volume (ppmv) at the end of the 10 year model run. This establishes a baseline for the next three scenarios, which predict that biomass burning will contribute 3 ppmv of &CO\sb2& to the atmosphere by the year 2000, while fossil fuel combustion will contribute 5 ppmv. The net effect of a 2 K average global warming was to increase the atmospheric &CO\sb2& concentration by approximately 1 ppmv, due to enhanced respiration by the terrestrial biosphere.

APA, Harvard, Vancouver, ISO, and other styles

9

Osterman, My. "Carbon dioxide in agricultural streams : Magnitude and patterns of an understudied atmospheric carbon source." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355402.

Full text

Abstract:

The role of streams in the global carbon budget was for a long time neglected, since they were considered passive transporters of carbon from land to sea. However, studies have shown that streams are often supersaturated in carbon dioxide (CO2), making them sources of carbon to the atmosphere. The main sources of stream CO2 are in-stream mineralization of organic matter and transport of carbon from the catchment. The catchment derived CO2 could both be of biogenic (respiration) or geogenic (weathering) origin. Most studies regarding the topic rely on measurements carried out in forest-dominated catchments, while agricultural streams are under-represented. The objective of this study was to examine partial pressure of CO2 (pCO2) in streams in catchments dominated by agriculture. This was done to increase the knowledge about agricultural influence on stream pCO2, and to provide a basis for planning mitigation strategies for reducing CO2 emissions from the agriculture sector. Sampling was performed in ten streams draining agriculture-dominated catchments around Uppsala, Sweden, from June to November 2017. Measurements of pCO2 were carried out with floating chambers, equipped with CO2 sensors. Nutrients, organic carbon, discharge and different chemical variables were also measured. For correlation tests, the method Kendall’s Tau was used. Catchments were delineated in a geographic information system (GIS) and the CORINE Land Cover dataset was used to examine land use. Stream specific median pCO2 varied from 3000 to 10 000 μatm. In some streams, pCO2 exceeded 10 000 μatm, which was outside of the sensor’s measurement range. Values of pCO2 were high compared to similar studies in forested catchments, which could indicate that occurrence of agriculture in the catchment increases stream CO2. Correlation was found between pCO2 and discharge, with negative correlation in five streams and positive correlation in two. Negative correlation was found between pCO2 and pH and percentage of dissolved oxygen, respectively. No significant correlation was found between pCO2 and fraction of agricultural land use, nutrients or organic carbon. Further studies are needed to examine the sources of CO2, since it is possible that a large part of the CO2 has a geogenic origin. The floating chamber method should be revised to reduce the sensor’s sensitivity to condensation and cold temperatures, and to increase the measuring range.

APA, Harvard, Vancouver, ISO, and other styles

10

Collins, Sinead. "Microalgal adaptation to changes in carbon dioxide." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100340.

Full text

Abstract:

It is generally accepted that global levels of CO2 will roughly double over the next century. Because of their large population sizes and fast generation times, microalgae may adapt to global change through novel mutations fixed by natural selection, such that future populations may be genetically different from contemporary ones. The prediction that microalgae may respond evolutionarily to rising CO2 was tested using populations of Chlamydomonas reinhardtii grown for 1000 generations at increasing CO2. Laboratory populations grown at high CO2 did not show a direct response to selection at elevated CO2, instead evolving a range of non-adaptive syndromes. In addition, populations selected at elevated CO2 often grew poorly at ambient CO2. The same evolutionary responses were seen in natural populations isolated from CO2 springs. CO2 uptake was measured in a subset of the laboratory selection lines, which were found to have cells that either leaked CO2, had lost the ability to induce high-affinity CO 2 uptake, or both. These phenotypes were tentatively attributed to the accumulation of conditionally neutral mutations in genes involved in the carbon concentrating mechanism (CCM). The high-CO2-selected phenotypes were found to be reversible in terms of fitness when populations were backselected in air, though wild-type regulation of the CCM was not regained. It has been suggested that phytoplankton adaptation to changes in CO2 levels is constrained by selective history. This was tested by culturing genetically distinct populations of Chlamydomonas at decreasing levels of CO2. In this case, divergence between lines was attributable to chance rather than selective history.

APA, Harvard, Vancouver, ISO, and other styles

11

Jones, Dylan Gwynn. "The effects of elevated atmospheric concentrations of carbon dioxide on trees." Thesis, Bangor University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318146.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Kaminski, Daniel Thomas. "Corrosion Inhibition of Magnesium Alloys and Influence of Atmospheric Carbon Dioxide." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460241073.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Glenn, Aaron James, and University of Lethbridge Faculty of Arts and Science. "Growing season carbon dioxide exchange of two contrasting peatland ecosystems." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005, 2005. http://hdl.handle.net/10133/259.

Full text

Abstract:

The CO2 flux of two peatlands in northern Alberta was examind during the 2004 growing season using eddy covariance measurements of net ecosystem exchange (NEE), chamber measurements of total ecosystem respiration, and empirical models driven by meteorological inputs. The two ecosystems, a poor fen and an extreme-rich fen, differed significantly in plant species composition, leaf area index, aboveground biomass and surface water chemistry. The mean diurnal pattern of NEE at the peak of the season was similar between the sites, however, the extreme-rich fen had a higher photosynthetic and respiratory capacity than the poor fen. Over the 6 month study, the poor fen was shown to accumulate between 2 to 3 times more carbon than the extreme-rich fen despite having a lower photosynthetic capacity. The evergreen nature of the poor fen site allowed for a longer season of net CO2 uptake than the deciduous species that dominated the extreme-rich fen.
xii, 126 leaves : ill. (some col.) ; 29 cm.

APA, Harvard, Vancouver, ISO, and other styles

14

Ferretti, Dominic Francesco. "The development and application of a new high precision GC-IRMS technique for N₂O-free isotopic analysis of astmospheric CO₂." [Wellington, New Zealand] : Victoria University of Wellington, 1999. http://catalog.hathitrust.org/api/volumes/oclc/154329143.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Bachman, Sarah. "Elevated atmospheric carbon dioxide and precipitation alter ecosystem carbon fluxes over northern mixed-grass prairie at the prairie heating and CO2 enrichment (PHACE) experiment in Cheyenne, Wyoming, USA." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445355711&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Mandiwana, KL, and N. Panichev. "The leaching of vanadium(V) in soil due to the presence of atmospheric carbon dioxide and ammonia." Elsevier, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001493.

Full text

Abstract:

The natural leaching of vanadium(V) with CO2 from soil-water in the presence of ammonia, a known precursor to atmospheric aerosols, has been tested by bubbling carbon dioxide through soil suspension with varying amount of ammonia. It was found that the leaching of V(V) is enhanced in the presence of ammonia. From the results of the investigation, it could be concluded that atmospheric CO2 in the presence of ammonia (the only atmospheric gas that increases the pH of soil-water) could naturally leach V(V) from soil. Furthermore, it was also shown that the presence of (NH4)2CO3 in soil could enhance the leaching of toxic V(V) species thereby making it bioavailable for both plants and animals.

APA, Harvard, Vancouver, ISO, and other styles

17

Sey, Benjamin Kweku. "Carbon dioxide and nitrous oxide production from corn and soybean agroecosystems." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102726.

Full text

Abstract:

Globally, an estimated 25% of the CO2 and 90% of the N2O is believed to come from agroecosystems. The objective of this study was to investigate the dynamics of the below-ground CO 2 and N2O concentrations and efflux in corn and soybean systems. In our field study, changes in the below-ground concentrations of CO 2 and N2O were closely related to seasonal changes in soil moisture, with the first two months of the growing season being particularly critical to the production of these gases. Tillage significantly increased CO2 content in the soil profile, however, this effect was greater in the soybean plots than in the corn plots. In our greenhouse studies, an average of about 79% of the soil respiration in corn came from rhizosphere respiration, compared to an estimated 58% in the case of soybean. Specific rhizosphere respiration was significantly higher in soybean (0.29 mg C g -1 root h-1) than corn (0.09 mg C g-1 root h-1), which supports previous observations made with regards to slower-growing plants (e.g. soybean) having relatively higher root respiration than faster growing plants. We observed a nonsignificant difference between N2O efflux in the soybean-planted soil and unplanted bulk soil, which is in contrast to the perception that legumes could stimulate more N 2O production from the soil by increasing the N pool through N 2 fixation. While corn had the greatest uptake of fertilizer N, N 2O efflux in corn pots was higher (2.84 mug N pot-1 h-1) than the soybean pots (0.06 mug N pot-1 h-1). In the laboratory setting, denitrification in the microaggregates proceeded at about 4.4 to 39.6 times higher rate than in large macroaggregates, small macroaggregates or the bulk soil, and showed the greatest response to high moisture levels (80% WFPS).

APA, Harvard, Vancouver, ISO, and other styles

18

McKinley, Galen Anile 1973. "Interannual variability of air-sea fluxes of carbon dioxide and oxygen." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16824.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 161-169).
The currently observed increase in atmospheric CO2 due anthropogenic emissions is substantially slowed by natural processes that incorporate CO2 into the terrestrial biota and the ocean. Year-to-year changes in the CO2 growth rate that exceed variations in the fossil fuel source indicate a significant variability in these global CO2 sinks. However, the enormous complexity of the terrestrial and oceanic biogeochemical systems that absorb atmospheric CO2 makes these sinks extremely difficult to understand and precisely quantify. Many techniques, including the interpretation of the relative changes in atmospheric CO2 and O2/N2, ocean modeling, and atmospheric data inversions, have been employed to estimate the mean and variability of global CO2 sinks. However, uncertainty remains large. The goal of this thesis is to improve understanding of global CO2 sinks by considering (1) the error in the atmospheric O2/N2 partitioning method due to the neglect of interannual variability in the air-sea fluxes of 02, and (2) the interannual variability of the ocean CO2 sink.
(cont.) A global, high-resolution ocean general circulation model is used to estimate the magnitude and understand the mechanisms of interannual variability in air-sea fluxes of both CO2 and 02. I find that the global variability in the fluxes of both gases are dominantly forced by large-scale physical processes governing upper ocean dynamics, particularly El Nifio / Southern Oscillation (ENSO) and, for 02, the North Atlantic Oscillation (NAO). Estimates of the extremes of CO2 and 02 flux variability for the period 1980-1998 are +/-0.5x1015 grams Carbon/yr (PgC/yr) and -70/+100x1012 mol/yr (Tmol/yr), respectively. Global 02 flux variability implies up to a 1.0 PgC/yr error in estimates of interannual variability in land and ocean CO2 sinks derived from atmospheric 02/N2 observations. This error is significant for estimates of annual sinks, but it is cumulatively negligible for estimates of mean sinks from October 1991 to April 1998. Increasing convergence of estimates of land.
by Galen Anile McKinley.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

19

Jaeger, Alexa. "Methane and carbon dioxide cycling in soils of the Harvard Forest." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117912.

Full text

Abstract:

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 18).
Soil is Earth's largest terrestrial carbon pool (Oertel et al., 2016) and can act as a net source of greenhouse gases (GHG). However, if organic material accumulates in soils faster than it is converted to CO2 by cellular respiration, soil becomes a smaller GHG source and even has the potential to become a GHG sink. Not much is known about factors that drive soil to be a source or a sink of GHG. Soil temperature and moisture have both been shown to correlate with CH4 emissions and temperature has been shown to correlate with CO 2 emissions (Jacinthe et al., 2015). Currently these relationships are not well constrained, particularly in upland soils, which are soils found at elevations between 100 and 500 m (Carating et al., 2014). Soil from the Harvard Forest was collected and used in two in-lab flux experiments to constrain the effect that soil moisture has on i.) the rate of CH4 and CO2 production/consumption and ii.) the fraction of injected CH4 that is oxidized to CO2 by soil microbes. The first experiment involved injecting vials containing soil samples with CH4 , taking an initial measurement with a residual gas analyzer (RGA), incubating for three days, and taking final measurements using the RGA. The results of this experiment indicated that cellular respiration is an important carbon source in these soils, with more CO2 coming from cellular respiration than from the oxidation of CH4. The second experiment involved injecting vials containing soil samples with CH4 and 14CH4 as a tracer, incubating for six days, and analyzing CO2 from each sample using a scintillation counter. This experiment showed a weak trend indicating that increased soil moisture may result in decreased CH4 oxidation. Results showed that decays per minute from the samples were lower than in a control. These results indicated that not all CO 2 from each sample was successfully captured and analyzed using the methods here. So while the trend may hold true, it should be supported by reconducting the experiment using a more reliable means of CO2 capture. The unexpected results from both experiments indicated that there is still much to be learned about the reactions that occur in these soils and how to perfect laboratory methods to study them.
by Alexa Jaeger.
S.B.

APA, Harvard, Vancouver, ISO, and other styles

20

Cotrufo, Maria Francesca. "Effects of enriched atmospheric concentration of carbon dioxide on tree litter decomposition." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282385.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Strader, Heidi Suzanne. "Trends in atmospheric carbon dioxide over the last ten to fifteen years." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/57752.

Full text

Abstract:

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994.
Includes bibliographical references (leaves 85-87).
by Heidi Suzanne Strader.
M.S.

APA, Harvard, Vancouver, ISO, and other styles

22

Wilkins, Diana. "Effect of elevated carbon dioxide on cherry (Prunus) : a biochemical and physiological approach." Thesis, University of Sussex, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282143.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

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.

Full text

Abstract:

Thesis (Ph. D.)--University of Sydney, 2000.
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.

APA, Harvard, Vancouver, ISO, and other styles

24

McElwain, Jennifer Claire. "Fossil stomatal parameters as indicators of palaeo-atmospheric CO2 concentration through Phanerozoic time." Thesis, Royal Holloway, University of London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362713.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Butterworth, Brian J. "Air-sea carbon dioxide exchange in the Southern Ocean and Antarctic Sea ice zone." Thesis, State University of New York at Albany, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10149297.

Full text

Abstract:

The Southern Ocean is an important part of the global carbon cycle, responsible for roughly half of the carbon dioxide (CO₂) absorbed by the global ocean. The air-sea CO₂ flux (F_c) can be expressed as the product of the water-air CO₂ partial pressure difference (ΔpCO₂) and the gas transfer velocity ( k), an exchange coefficient which represents the efficiency of gas exchange. Generally, F_c is negative (a sink) throughout the Southern Ocean and Antarctic sea ice zone (SIZ), but uncertainty in k has made it difficult to develop an accurate regional carbon budget. Constraining the functional dependence of k on wind speed in open water environments, and quantifying the effect of sea ice on k, will reduce uncertainty in the estimated contribution of the Southern Ocean and Antarctic SIZ to the global carbon cycle.

To investigate F_c in the Southern Ocean, a ruggedized, unattended, closed-path eddy covariance (EC) system was deployed on the Antarctic research vessel Nathaniel B. Palmer for nine cruises during 18 months from January 2013 to June 2014 in the Southern Ocean and coastal Antarctica. The methods are described and results are shown for two cruises chosen for their latitudinal range, inclusion of open water and sea ice cover, and large ΔpCO₂. The results indicated that ship-based unattended EC measurements in high latitudes are feasible, and recommendations for deployments in such environments were provided.

Measurements of F_c and ΔpCO₂ were used to compute k. The open water data showed a quadratic relationship between k (cm hr^–1) and the neutral 10-m wind speed (U_10n, m s^–1), k=0.245 U_10n²+1.3, in close agreement with tracer-based results and much lower than previous EC studies. In the SIZ, it was found that k decreased in proportion to sea ice cover. This contrasted findings of enhanced F_c in the SIZ by previous open-path EC campaigns. Using the NBP results a net annual Southern Ocean (ocean south of 30°S) carbon flux of –1.1 PgC yr^–1 was calculated.

APA, Harvard, Vancouver, ISO, and other styles

26

Berry, Stephanie C. Carleton University Dissertation Biology. "The influence of vegetation and soil carbon dioxide exchange on the concentration and isotopic composition of atmospheric carbon dioxide within plant canopies." Ottawa, 1994.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

27

Lukac, Martin. "Effects of atmospheric COâ†2 enrichment on root processes and mycorrhizal functioning in short rotation intensive poplar plantation." Thesis, Bangor University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391756.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Cario, Cara Hinkson. "Elevated atmospheric carbon dioxide and chronic atmospheric nitrogen deposition change nitrogen dynamics associated with two Mediterranean climate evergreen oaks /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Rochefort, Line. "Atmospheric COâ†2 and environmental determinants of plant growth : a model with Sinapis alba L." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240047.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Hemming, D. L. "Stable isotopes in tree rings : biosensors of climate and atmospheric carbon-dioxide variations." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603940.

Full text

Abstract:

The objective of this dissertation is to use the annual tree ring width and cellulose carbon and hydrogen stable compositions off three native British tree species: common beech (Fagus silvaatica L.), pedunculate oak (Quercus robur L.) and scots pine (Pinus sylvestris L.), for the period 1895 to 1994, to examine the responses of these trees to recent changes in climate and atmospheric CO₂. The high frequency δ¹³C series of all three species display the most significant correlations with the climate parameters and, using simple regression models, it is also evident that this tree ring measure provides the most accurate climate reconstructions. Vapour pressure deficit, averaged for the months July to September, is the climate parameter most significantly correlated with the δ¹³C data. However, it is shown that this may not necssarity mean that the trees are responding dominantly to this parameter. Although it is apparent that the pine species δ¹³C series is the most responsive of the species to climate fluctuations, it is also noted that the combined δ¹³C signal from all three tree species displays an enhanced climate signal. Superimposed on the common climate signals are long term trends that are comparable for the δ¹³C series of all three species and the δD of the pine trees, but do not show any common signal for the other δD series or any of the ring width series. Converting the δ¹³C data to indicators of leaf gas exchange, it is evident that the rapid increasing trend in atmospheric CO₂ concentration ([CO₂]), that began around 1930, coincides with a rising trend in leaf intrinsic water use efficiency but does not coincide with a change in the internal concentration of CO₂ in the leaf (c_i). The results suggest that the increasing [CO₂] induced all three tree species to increase assimilation rate and reduce stomatal conductance to such an extent that c_i remained initially constant. As there are no consistent increases in ring widths during this period, the dominant response could be inferred to be stomatal conductance. However, preferential partitioning of photosynthates to other plant organs, especially roots, is a common response of C₃ plants to increased [CO₂] and it is more likely that both assimilation rate and stomatal conductance have changed.

APA, Harvard, Vancouver, ISO, and other styles

31

Foote, Alexander. "Converting carbon dioxide into value added chemicals via low temperature atmospheric pressure plasmas." Thesis, University of York, 2018. http://etheses.whiterose.ac.uk/21237/.

Full text

Abstract:

Carbon dioxide is a waste product produced extensively by modern everyday life. In order to combat the growing threat of climate change atmospheric carbon dioxide levels need to be reduced and controlled. If waste carbon dioxide can be converted effectively and efficiently on a commercial basis into valuable chemicals atmospheric carbon dioxide levels can be controlled in a financially viable and potentially appealing manner. Carbon monoxide is a valuable feedstock for the chemical industry and as a base for synthesising renewable fuels. It is currently produced using high temperatures and pressures. Utilising the non-equilibrium nature of low temperature plasmas to convert carbon dioxide is of growing interest. Radio-frequency atmospheric pressure plasmas are well known for their ability to produce chemical species at low gas temperatures with high scalability for industrial processes and low operating powers. However, they have not been extensively studied for their application in converting carbon dioxide. The aim of this work was to study the effectiveness of radio-frequency atmospheric pressure plasmas for converting carbon dioxide into value added chemicals and the underlying mechanisms that cause dissociation in order to better understand how to improve the process. In order to determine the level of conversion of carbon monoxide the Fourier transform infra-red spectroscopy diagnostic was used and the power deposited in the plasma was measured to calculate the energy efficiency of the dissociation. A global model was also developed to provide a greater understanding of the reaction pathways that lead to the conversion of carbon dioxide. The predictions made by the model were then tested using two-photon absorption laser induced fluorescence by measuring both the densities of atomic oxygen and carbon monoxide and comparing them to the model predictions. Finally the ability to utilise the plasma produced carbon monoxide was studied in order to determine how viable these plasmas would be for commercial use. High yields of over 98% were obtained at the expense of energy efficiency; a maximum energy efficiency of 9% was also obtained.

APA, Harvard, Vancouver, ISO, and other styles

32

Speratti, Alicia B. "Earthworm-microbial interactions influence carbon dioxide and nitrous oxide fluxes from agricultural soils." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101652.

Full text

Abstract:

Earthworms are well known to increase decomposition of organic matter and release of plant available nutrients. They can also increase CO 2 and N2O fluxes from the soil by stimulating respiration, denitrification, and nitrification caused by soil microorganisms. The objective of this thesis was to examine the influence of different earthworm species and population numbers on CO2 and N2O fluxes from a corn agroecosystem. In the field study, earthworm treatments had a significant effect on CO2 fluxes, but there was no difference between CO 2 fluxes from the two species (Lumbricus terrestris L., Aporrectodea caliginosa Savigny) or from the two population levels (1x and 2x the naturally-occuring population). Also, the earthworm treatments had no significant effect on N2O fluxes. Since all treatments contained mixed species and similar population levels at the end of the study, it is likely that CO2 and N2O fluxes in the field were affected more by soil temperature and moisture fluctuations than by the earthworm treatments. The study was repeated in laboratory microcosms under environmental control. Again, earthworm treatments had a significant effect on CO2 fluxes, but not on N2O fluxes. Interestingly, the N 2O fluxes from microcosms containing L. terrestris came solely from denitrification, while the N2O fluxes from A. caliginosa microcosms were produced mostly by nitrification. It is not known why these species stimulate different groups of microorganisms that can produce N2O, and this remains to be investigated.

APA, Harvard, Vancouver, ISO, and other styles

33

Rahman, Sayedur. "Canopy architecture, carbon gain and grain properties of native Australian rices: effects of elevated atmospheric carbon dioxide." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27809.

Full text

Abstract:

Wild relatives of Oryza will be increasingly used in commercial rice breeding programs. However, the effects of rising atmospheric CO2 concentration on photosynthesis, light interception, canopy architecture and grain properties of the wild species are unknown. Two accessions of the Australian wild rice, O. meridionalis (Cape York and Howard Springs), were grown in ambient (aCO2, 400 ppm) and elevated CO2 (eCO2, 700 ppm) with O. sativa cv. Doongara in glasshouses and compared for photosynthesis, light interception, biomass and carbon (C) gain. For grain quality and endosperm morphology characterisation, an accession of O. australiensis was also studied. Photosynthesis (Amax) was enhanced at eCO2 by 20–50% across all genotypes, doubling the number of tillers, leaves and biomass. Light interception (¯STAR) was lower in eCO2 than in aCO2 due to denser canopies and less dispersed leaves. Nevertheless, plant biomass and C gain were higher in eCO2 than aCO2, despite less efficient light interception. Wild rices had denser crowns and lower light capture than domesticated rice in both CO2 treatments. Grain physicochemical analysis showed that seed length, seed width and 1000-seed weight were higher in eCO2 than in aCO2. Protein content decreased at eCO2 by 23% in Doongara and 15% in Howard Springs. Peak and final flour viscosity increased in the wild rices at eCO2, but in Doongara, only peak viscosity increased. SEM images showed that aleurone cell length and width were higher in Howard Springs, but the area and length of starch granules were larger in Cape York in eCO2 than in aCO2. Responses of rice endosperm morphology to eCO2 were dependent on genotype. In conclusion, Australian and Asian rice species have qualitatively distinct traits and responses to eCO2, as seen in light interception, photosynthesis, canopy architecture and grain properties.

APA, Harvard, Vancouver, ISO, and other styles

34

Lysyshyn, Kathleen E. "Carbon dioxide and methane fluxes and organic carbon accumulation in old field and northern temperate forest plantation soils." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31263.

Full text

Abstract:

Carbon dioxide (CO2) and methane (CH4) fluxes from the soil surface, and concentrations within the soil profile, were measured between June 1998 and Sept. 1999 at four adjacent forest plantations and an old field in Nepean, Ontario. The objectives of this study were to quantify seasonal CO2 and CH4 fluxes from the soil surface and within the soil profile to determine the effect of soil moisture and temperature, and forest age and species on the exchange, and establish a chronosequence of organic carbon accumulation in the forest plantations and the old field soils.
Dynamic and static chamber techniques were used to measure surface fluxes of CO2 and CH4, respectively, and soil gas concentrations were sampled with probes. In the old field and forest plantations, surface soil CO2 flux ranged from 2.9 to 27 g CO2 m-2 d-1 and 2.0 to 39 g CO2 m -2 d-1 respectively. Significant differences due to age and species of plantation were observed. Seasonal variations in CO2 efflux from the soil surface and within the soil profile were related to variation in soil temperature and moisture. Uptake of CH4 was observed at all sites and there was no significant differences in flux due to vegetation type or age. Maximum rate of CH4 consumption was 6.3 mg CH4 m-2 d-1. Methane uptake was positively related to soil moisture conditions.
The carbon content of the soil increased in all sites following the establishment of vegetation on sandy parent material. Carbon content was greatest in the upper soil profile. Rates of carbon accumulation ranged from 109 to 426 g m-2 y-1. Soil carbon increased with increasing age of plantation during the first 30 years following the establishment of vegetation on parent material, but declined as the forest plantation matured.

APA, Harvard, Vancouver, ISO, and other styles

35

Rudmann, Silvia G., of Western Sydney Hawkesbury University, Faculty of Science and Technology, and Centre for Horticulture and Plant Sciences. "Resource utilization of C4 tropical grasses at elevated CO2." THESIS_FST_HPS_Rudmann_S.xml, 2000. http://handle.uws.edu.au:8081/1959.7/65.

Full text

Abstract:

The atmospheric (CO2) partial pressure is expected to continue to increase and the scenario is that the CO2 partial pressure will reach 50-70 Pa during the 21st century.The rise in CO2 will have a direct influence on plant growth and development because CO2 is the primary substrate for photosynthesis.The aim of the studies described in this thesis was to investigate the response of grasses belonging to two subtypes to a range of CO2 partial pressures under conditions where light intensity, water and N supplies were varied.Two species which are naturalized in Australia, Panicum coloratum (NAD-ME) and Cenchrus ciliaris (NADP-ME) were chosen for a series of experiments conducted in matched growth chambers. The response of C4 plants is particularly important for Australia because they dominate the tropical grasslands that occupy 75% of the continent and form the basis for the pasture industry. Following the extensive research conducted in this study, it can be concluded that the inevitable rise in atmospheric CO2 partial pressure will increase the growth of C4 grasses when other resources are not limiting.Growth of C4 grasses will be stimulated to a greater extent under conditions of drought.
Doctor of Philsophy (PhD)

APA, Harvard, Vancouver, ISO, and other styles

36

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.

Full text

Abstract:

Thesis (Ph. D.)--University of Sydney, 2000.
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.

APA, Harvard, Vancouver, ISO, and other styles

37

Pongracic, Silvia School of Biological Sciences UNSW. "Influence of Irrigation and Fertilization on the Belowground Carbon Allocation in a Pine Plantation." Awarded by:University of New South Wales. School of Biological Sciences, 2001. http://handle.unsw.edu.au/1959.4/18164.

Full text

Abstract:

The aboveground and belowground productivity of forest systems are interlinked through complex feedback loops involving tree, soil and environmental factors. With a predicted significant change in environmental conditions through the enhanced greenhouse effect, it is important to understand the response of forest systems to these new conditions. An increase in atmospheric CO2 is predicted to increase photosynthesis, and therefore whole plant productivity at the individual tree level. However this increase in photosynthesis may result in greater requirements for nutrients, particularly nitrogen (N). In order to acquire any additional available N, trees may respond by increasing their proportional allocation of C belowground to the root system. This study aimed to quantify the belowground C allocation in a mature forest system consisting of a single species on a single site, but with different levels of water and nutrient stress. The belowground carbon dynamics of a range of irrigated and fertilized Pinus radiata stands in Australia were investigated during 1992 and 1993. Belowground carbon allocation was estimated using the model proposed by Raich and Nadelhoffer (1989) where belowground C allocation is the difference between soil respiration and carbon input through litterfall, plus coarse root production and an adjustment for any change in soil and litter layer carbon pools. This model is best described by the equation: Belowground C = Csoilresp ?? Clitterfall + Ccoarseroot+ ???Cforest floor+ ???Csoil Soil respiration, measured using a modified soda lime absorption method either every 2 weeks or every 4 weeks for 2 years, showed a range in daily soil C flux from 137 ?? 785 mgCO2.m-2.h-1. Soil respiration showed seasonal trends with summer highs and winter lows. Limited fine root biomass data could not indicate a strong relationship between measured soil respiration and fine root (>2mm diameter) biomass. Fifty three percent of the variation in soil respiration measurements in irrigated treatments was explained by a linear relationship between soil respiration, and soil temperature at 0.10 m depth and litter moisture content. In non-irrigated treatments, 61% of the variation in soil xix respiration measurements was explained by a linear relationship between soil temperature at 1 cm depth and soil moisture content. Inter-year variation was considerable with annual soil respiration approximately 20% lower in 1993 compared with 1992. Annual soil C flux was calculated by linear interpolation and ranged from 3.4 ?? 11.2 tC ha-1 across the treatments. Soil C pools remained unchanged over 10 years between 1983 and 1993 for all combinations of irrigated and fertilized stands, despite significant aboveground productivity differences over the decade. Measurements of standing litter showed a change between 1991 and 1993 for only 2 out of the 10 treatments. These two treatments had belowground C allocation estimated both with and without an adjustment for a change in standing litter. Annual litterfall C ranged almost four fold from 0.6 ?? 2.2 tC ha-1 between the treatments in 1992 and 1993, and fell within the ranges of measured litterfall over 10 years at the field site. Again inter-year variation was large, with the 1993 litterfall values being approximately 97% greater across all treatments compared with 1992 values. Belowground carbon allocation was calculated using C fluxes measured at the field site, and ranged 3 fold from 4.4 ?????? 12.9 tC ha-1 between the treatments during 1992 and 1993. In 1993 the belowground C allocation was approximately 30% lower across all treatments compared with 1992 calculations. This was due to an approximate 23% reduction in annual soil C flux, a 97% increase in litterfall C and an 18% reduction in coarse root production between 1992 and 1993. The field site was N limited, and differences in belowground C allocation could be shown across irrigated treatments with different N limitations. As N availability increased belowground C allocation was decreased in the irrigated treatments. It was difficult to determine differences in belowground C allocation caused by water stress as the effects of water and N limitation were confounded. An increase in N availability generally indicated an increase in coarse root and litterfall C production, which were reflected in increased aboveground productivity. In high N treatments the coarse root fraction of belowground C allocation comprised approximately 50% of the total belowground C allocation, whereas in the N stressed treatments coarse roots only comprised 20% of the total belowground allocation The mechanistic model BIOMASS was used to estimate annual gross primary productivity (GPP) for the different treatments at the field site. BIOMASS estimated GPPs of between 30-38 tC ha-1 for the different treatments during 1992 and 1993. The measured belowground carbon allocation ranged from 16 ?? 40 % of simulated GPP, with the lower proportion allocated belowground in the irrigated and high fertility stands. Aboveground competition through the absence of thinning also appeared to reduce allocation belowground in non- irrigated stands. A direct trade off between bole and belowground C could not be demonstrated, unless data were separated by year and by the presence or absence of irrigation. Where data were separated in this manner, only three data points defined the reasonably strong, negative relationship between bole and belowground C. The value of this relationship is highly questionable and should be interpreted with caution. Thus a decrease in belowground C allocation may not necessarily indicate a concomitant increase in bole C allocation. Inter-year variation in a number of C pools and fluxes measured at the field site was at least as great as the variation between stands having different water and N limitation. Extrapolation of belowground productivity estimates from a single years data should be undertaken cautiously. The work undertaken in this study indicated that for a given forest stand in a given soil type, an increase in N availability reduced the absolute and relative C allocated belowground. However this decrease in C belowground may not directly translate as an increase in stem growth or increased timber production. Forest productivity in an enhanced greenhouse environment is likely to result in an increased allocation of C belowground due to increased N limitation, unless adequate N is present to support a more active canopy. Further work is required to more fully understand the dynamics of the belowground system in a changing environment. However further research should focus on mature forest systems in order to isolate the impacts of natural ageing changes from perturbation effects on the forest system. This would be best undertaken in long term monitoring sites where a C history of the stand may be available.

APA, Harvard, Vancouver, ISO, and other styles

38

Wilson, Philip. "Insight into the carbon cycle from continuous measurements of oxygen and carbon dioxide at Weybourne Atmospheric Observatory, UK." Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/42961/.

Full text

Abstract:

Atmospheric measurements of carbon dioxide (CO2) and oxygen (O2) are a valuable tool to better understand the global carbon cycle. Technological improvements have resulted in near-real-time continuous measurements of both O2 and CO2 becoming viable. The increased time resolution of continuous measurements compared to discrete flask samples provides greater insight into atmospheric variations and short-term processes. These measurements will become even more relevant as the research focus shifts from the global to regional scale, for example anthropogenic emissions verification. This thesis presents a 4.5 year record of atmospheric CO2 and O2 measurements made at Weybourne Atmospheric Observatory (WAO) on the north Norfolk coast in the United Kingdom. In situ, continuous measurements cover the period October 2007 to April 2012. Data for the tracer ‘Atmospheric Potential Oxygen’ (APO) are also presented. The analytical methodology is described in detail and the data are examined on interannual, seasonal, synoptic and diurnal timescales. The precision of ambient air measurements is about ±0.03 ppm for CO2 and ±2.0 per meg for O2. The average amplitude of the WAO seasonal cycle is 14.9 ppm for CO2, 134.2 per meg for O2 and 59.0 per meg for APO, similar to other stations at similar latitudes. Interannual variability in the seasonal cycle amplitude is also investigated. Growth rates over the 4.5 year period are 2.4 ppm yr-1 for CO2, -25 per meg yr-1 for O2 and -13 per meg yr-1 for APO, also similar to other nearby stations. Short-term analyses reveal clear diurnal cycles in both CO2 and O2 that vary seasonally throughout the year. No diurnal cycle is observed in APO. A number of short-term events are explored and confirm that WAO experiences both clean marine air masses from the Arctic and North Atlantic, as well as fossil fuel pollution signals from the UK and continental Europe.

APA, Harvard, Vancouver, ISO, and other styles

39

Gascoigne-Owens, Johanna Sara. "Responses of the Câ‚„ plant Zea mays (maize) to elevated atmospheric carbon dioxide concentration." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414631.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Cambaliza, Maria Obiminda L. "Measurement of forest ecosystem-atmosphere exchange of 8¹³C-CO₂ using Fourier transform infrared spectroscopy and disjunct eddy covariance." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Spring2010/m_cambaliza_121709.pdf.

Full text

Abstract:

Thesis (Ph. D.)--Washington State University, May 2010.
Title from PDF title page (viewed on June 10, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

41

Pangga, Ireneo B. "Effects of elevated CO2 on plant architecture of Stylosanthes scabra and epidemiology of anthracnose disease /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16215.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Ghannoum, Oula, of Western Sydney Hawkesbury University, Faculty of Agriculture and Horticulture, and School of Horticulture. "Responses of C3 and C4 Panicum grasses to CO2 enrichment." THESIS_FAH_HOR_Ghannoum_O.xml, 1997. http://handle.uws.edu.au:8081/1959.7/139.

Full text

Abstract:

This project aims at investigating the effect of CO2 enrichment on the growth and gas exchange of C3, C3-C4 and C4 Panicum grasses. Potted plants were grown in soil under well watered conditions, in artificially lit environmentally controlled cabinets or naturally lit greenhouses at varying levels of CO2 enrichment. CO2 enrichment enhanced the dry weight of C3 and C4 Panicum species under optimal light and N supplies, but had no effect on the total leaf N or TNC concentrations. The high-CO2 induced photosynthetic reaction in the C3 species was accompanied by a reduced Rubisco concentration and was related to the conservation of the relative growth rate of the plant. Elevated CO2 had no effect on the photosynthetic capacity of the C4 species, but enhanced its CO2 assimilation rates under high light and N supplies. The effect of elevated CO2 on the leaf and stem anatomy reflected increased carbon supply at high CO2 in the C3 grass, and reduced transpiratory demand at high CO2 in C4 grasses. Consequently, it is clear that both C3 and C4 grasses are likely to be more productive under rising atmospheric CO2 concentrations.
Doctor of Philosophy (PhD)

APA, Harvard, Vancouver, ISO, and other styles

43

Souza, Amanda Pereira de. "A cana-de-açucar e as mudanças climaticas : efeitos de uma atmosfera enriquecida em 'CO IND. 2' sobre o crescimento, desenvolvimento e metabolismo de carboidratos de Saccharum ssp." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317739.

Full text

Abstract:

Orientadores: Marcos Silveira Buckeridge, Marilia Gaspar
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-09T03:07:16Z (GMT). No. of bitstreams: 1 Souza_AmandaPereirade_M.pdf: 752519 bytes, checksum: 0abdf68fd1d19b70a0af931741ccf052 (MD5) Previous issue date: 2007
Resumo: Desde o início da Revolução Industrial as concentrações de CO2 atmosférico aumentaram em cerca de 30% e estimativas apontam que esta concentração poderá atingir aproximadamente 720 ppm até a metade deste século. Estudos sobre o efeito do alto CO2 no desenvolvimento de diversas espécies vegetais já foram realizados, porém poucos com espécies de gramíneas tropicais do tipo C4, como é o caso da cana-de-açúcar. Considerando a importância econômica da cana e seu potencial na obtenção de biocombustíveis é importante saber como esta cultura irá responder ao aumento previsto na concentração de CO2 atmosférico. Sendo assim, o objetivo deste trabalho foi estudar o efeito do aumento do CO2 atmosférico sobre o crescimento, desenvolvimento e metabolismo de carboidratos da cana-de-açúcar visando avaliar o potencial de seqüestro de carbono e o impacto das mudanças climáticas sobre a produtividade. Parâmetros fisiológicos, bioquímicos e moleculares foram analisados em plantas cultivadas em câmaras de topo aberto durante 50 semanas com atmosfera de CO2 ambiente (~370 ppm) e elevada (~720 ppm). Os principais resultados obtidos indicam incremento em altura, na taxa fotossintética e em biomassa de colmo e folhas das plantas cultivadas sob elevado CO2. Ao final das 50 semanas foi detectado no colmo das plantas crescidas em tais condições, um aumento no teor de sacarose, de fibras e no conteúdo de celulose. A análise do perfil de transcritos de folhas após 9 e 22 semanas de cultivo usando microarranjos revelou expressão diferencial de 37 genes, sendo que 14 foram reprimidos e 23 foram induzidos e correspondem principalmente a genes de fotossíntese e desenvolvimento. Nossos resultados indicam que a cultura da cana-de-açúcar tem capacidade para seqüestro de carbono e potencial para aumento na produtividade em condições de alta concentração de CO2
Abstract: Since the beginning of the Industrial Revolution, the concentrations of CO2 in the atmosphere increased about 30% and the current forecasts point out that this concentration will reach approximately 720 ppm until the middle of this century. Studies about the effect of CO2 on the development of several plant species have been performed. However, few studies have been performed with tropical grass species having photosynthesis C4, as is the case of sugar cane. Due to the economic importance of sugar cane and its high potential to obtain biofuel, it is important to known how this crop will respond to the forecasted increase in the CO2 concentration in the atmosphere. Therefore, the goal of this work was to study the effects of increased CO2 concentration on growth, development and carbohydrate metabolism of sugar cane aiming the evaluation of the potential of this specie for carbon sequestration and the impact of the global climatic change on its productivity. Physiological, biochemical and molecular features of these plants have been analyzed during 50 weeks of growth in Open-Top-Chambers (OTCs) with ambient (~370 ppm) and elevated (~720 ppm) CO2 concentrations. After 50 weeks of growth under these conditions, we observed an increase of sucrose content, fiber an also in cellulose contents in stems of plants grown under elevated CO2. The microarray analysis of the transcriptome of leaves was obtained after 9 and 22 weeks and revealed differential expression of 37 genes. Fourteen genes were repressed and 23 induced by elevated CO2. The latter correspond mainly to the processes of photosynthesis and development. Our results indicate that the sugar cane crop has a high potential for carbon sequestration and increase of productivity under elevated CO2 concentrations
Mestrado
Biologia Celular
Mestre em Biologia Celular e Estrutural

APA, Harvard, Vancouver, ISO, and other styles

44

Barlow, James Mathew. "Interpretation of observed atmospheric variations of CO2 and CH4." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10507.

Full text

Abstract:

The overarching theme of my thesis is understanding observed variations of northern hemisphere atmospheric carbon dioxide (CO2) and methane (CH4) concentrations. I focus my analysis on high-latitude observations of these gases, as there are large stores of carbon in boreal vegetation and tundra which are vulnerable to rapid warming in the Arctic. My thesis is split into two parts. First, I use the wavelet transform to spectrally decompose observed multi-decadal timeseries for CO2 and CH4. I perform a series of numerical experiments based on synthetic data in order to characterise the errors associated with the analysis. For CO2, I analyse the phase and amplitude of the detrended seasonal cycle of CO2 to infer changes about carbon uptake by northern vegetation. I do not find a long-term change in the length of the carbon uptake period despite significant changes in the spring and autumn phase. I do find an increase in the rate of peak uptake which coincides with the observed increase in seasonal amplitude. These results suggest that the carbon uptake period of boreal vegetation has become more intense but has not changed in length, which provides evidence for an increase in net uptake of CO2 in the high latitudes. For CH4, I test the hypothesis that an increase in Arctic wetland emissions could result in a decrease in the seasonal amplitude of CH4 in the high latitudes. This hypothesis is based on the fact that the seasonal minima of CH4 roughly coincides with the peak of high latitude wetland CH4 emissions. I find that the CH4 seasonal amplitude has significantly decreased at a number of high-latitude sites. However I also find that atmospheric transport appears to drive much of the variability in high-latitude CH4 and that transport could also be responsible for the observed changes in amplitude. I show that an increase in wetland emissions is likely to have a more pronounced effect on the high-latitude CH4 seasonal cycle in the future. In the second section of my thesis, I describe a series of experiments in collaboration with the UK Astronomy Technology Centre, in which I characterise a new instrument technology for satellite applications to observe changes in CO2 from low-Earth orbit. The proof of concepts experiments were performed with a bench top hyperspectral imager. I show that the instrument is able to capture clean spectra at the wavelengths required for CO2 with low levels of scattered light between spectra.

APA, Harvard, Vancouver, ISO, and other styles

45

Sahlée, Erik. "Fluxes of Sensible and Latent Heat and Carbon Dioxide in the Marine Atmospheric Boundary Layer." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8184.

Full text

Abstract:

Oceans cover about 70% of the earth’s surface. They are the largest source of the atmospheric water vapour and act as enormous heat reservoirs. Thus in order to predict the future weather and climate it is of great importance to understand the processes governing the exchange of water vapour and heat between the ocean and atmosphere. This exchange is to a large extent mediated by turbulent eddies. Current numerical climate and weather forecast models are unable to resolve the turbulence, which means that the turbulent exchange needs to be simplified by using parameterizations.

Tower based measurements at the Östergarnsholm Island in the Baltic Sea have been used to study the air-sea turbulent exchange of latent and sensible heat and the heat flux parameterizations. Although the measurements are made at an island, data obtained at this site is shown to represent open ocean conditions during most situations for winds coming from the east-south sector. It is found that during conditions with small air-sea temperature differences and wind speeds above 10 m s^-1, the structure of the turbulence is re-organized. Drier and colder air from aloft is transported to the surface by detached eddies, which considerably enhance the turbulent heat fluxes. The fluxes where observed to be much larger than predicted by current state-of-the-art parameterizations. The turbulence regime during these conditions is termed the Unstable Very Close to Neutral Regime, the UVCN-regime.

The global increase of the latent and sensible heat fluxes due to the UVCN-regime is calculated to 2.4 W m^-2 and 0.8 W m^-2 respectively. This is comparable to the current increase of the radiative forcing due to anthropogenic emissions of greenhouse gases, reported in Intergovernmental Panel on Climate Change fourth assessment report (IPCC AR4). Thus the UVCN-effect could have a significant influence when predicting the future weather and climate.

APA, Harvard, Vancouver, ISO, and other styles

46

Klappenbach, Friedrich Wilhelm [Verfasser], and J. [Akademischer Betreuer] Orphal. "Mobile spectroscopic measurements of atmospheric carbon dioxide and methane / Friedrich Wilhelm Klappenbach ; Betreuer: J. Orphal." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1114312576/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Cogan, Austin James. "Atmospheric carbon dioxide retrieved from the Greenhouse gases Observing SATellite : method, comparisons and algorithm development." Thesis, University of Leicester, 2013. http://hdl.handle.net/2381/27690.

Full text

Abstract:

Carbon dioxide is the largest anthropogenic contributor to global warming and atmospheric concentrations have rapidly increased since the start of the industrial revolution. Networks of surface in-situ carbon dioxide sensors provide precise and accurate measurements of the global carbon dioxide concentration, including large scale temporal, seasonal and latitudinal variations. However, these observations are too sparse to allow the establishment of sub-continental carbon budgets, limiting the accuracy of climate change projections and the ability to mitigate future levels of atmospheric carbon dioxide. Satellite observations can provide data with dense spatial and temporal coverage over regions poorly sampled by surface networks. Specifically, observations in the shortwave infrared region are well suited for constraining carbon fluxes as they can provide total column carbon dioxide with high sensitivity to the source and sink locations at the surface. The first dedicated greenhouse gases sensor, the Greenhouse gases Observing SATellite (GOSAT), was launched in January 2009 by the Japanese Aerospace eXploration Agency (JAXA) and has successfully started to acquire global observations of greenhouse gases, including carbon dioxide. The University of Leicester Full Physics (UOL-FP) retrieval algorithm has been designed to estimate total column carbon dioxide from GOSAT shortwave infrared observations. The initial results were compared to coincident ground based measurements for a number of locations and compared on a global scale to a model. This showed an accuracy and precison that should provide improved surface flux estimates. Additionally, a bias correction scheme was developed that reduced observed geographical biases, allowing surface flux uncertainties to be potentially reduced further. To further develop the UOL-FP retrieval algorithm, a simulator capable of creating realistic GOSAT observations was built, allowing the investigation of different retrieval algorithm modifications, which may lead to reduced source and sink flux uncertainties and therefore aid future climate change forecasts.

APA, Harvard, Vancouver, ISO, and other styles

48

Cunniff, Jennifer. "The roles of atmospheric carbon dioxide and plant ecological traits in the origin of agriculture." Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515436.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Charalambous, Charithea. "Temperature swing adsorption process for carbon dioxide capture, purification and compression directly from atmospheric air." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33311.

Full text

Abstract:

Many reports, scientific papers, patents, and scientific news investigate the feasibility and affordability of direct carbon dioxide capture from the atmospheric air (DAC). Since carbon dioxide (CO2) is extremely diluted in the atmosphere, large volumes of air have to be handled to capture comparable amounts of CO2. Therefore, both the energy consumption and the plant size are expected to be 'prohibitive'. On the other hand, some analyses have shown that DAC is feasible and can become affordable with essential research and development. DAC has been regarded as an optional bridging or a transitional technology for mitigating CO2 emissions in the medium-term. Priorities include investing in renewable and low-carbon technologies, efficiency and integration of energy systems, and realisation of additional environmental benefits. A heavy reliance on negative emission technologies (NETs), and consequently DAC, may be extremely risky as NETs interact with a number of societal challenges, i.e. food, land, water and energy security. Although, "... capturing carbon from thin air may turn out to be our last line of defence, if climate change is as bad as the climate scientists say, and if humanity fails to take the cheaper and more sensible option that may still be available today" MacKay (2009). Certainly, more research is necessary to bring down both cost and energy requirements for DAC. This work firstly predicts the adsorption equilibrium behaviour of a novel temperature swing adsorption process, which captures carbon dioxide directly from the air, concentrates, and purifies it at levels compatible to geological storage. The process consists of an adsorption air contactor, a compression and purification train, which is a series of packed beds reduced in size and connected in-line for the compression and purification purposes, and a final storage bed. The in-line beds undergo subsequent adsorption and desorption states. The final desorbed stream is stored in a storage bed. This cyclic process is repeated for a number of times imposed by the required purity and pressure in the final bed. The process is been thermodynamically verified and optimised. Since, the overall performance of this process does not only depend on the design of the process cycle and operating conditions but also on the chosen adsorbent material, further optimisation of the adsorptive and physical properties of the solid adsorbent is investigated. Thus, the optimal parameters of the potentially used porous materials is identified. Continuing the research on different adsorbent materials, an experimental investigation on the equilibrium properties of two competitive adsorbents is also performed. Besides the thermodynamic analysis, a dynamic model is presented for the investigation of the mass and heat transfer and its influence on the adsorption rate and consequently on the overall process performance. Since the initial stream is very dilute, it is expected that the adsorption rate will be low compared to other temperature swing processes and the capture rate will be affected by the heat transfer. Finally, the design and development of an experimental laboratory-scale apparatus is presented and analysed. Future design improvements are also discussed.

APA, Harvard, Vancouver, ISO, and other styles

50

Wang, Xianzhong. "Gender-specific and intraspecific responses of Trembling Aspen (Populus Tremuloides) to elevated atmospheric Carbon Dioxide /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192119266776.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Atmospheric carbon dioxide'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles