This study focuses on certain urban forestry aspects of the City of Tshwane (previously Pretoria) and in particular that of growth rate and carbon sequestration estimates of street trees with the aim of quantification of the value of these trees. The relationships between tree height and crown dimensions to stem diameter and tree age, as well as the relationship between stem diameter to tree age enable the development of growth rate equations that predict tree dimensions and carbon storage. This permits the calculation of monetary values of urban trees and thus the modelling of costs and benefits of urban forests. The main objectives were (1) to develop tree height, crown diameter, crown height, and crown base height to stem diameter relationships for the indigenous street tree species Combretum erythrophyllum, Rhus lancea andRhus pendulina, (2) to develop tree height, crown diameter, crown height, crown base height and stem diameter to tree age relationships for the above street tree species, (3) to determine the 30 year carbon sequestration estimate and monetary value of 115 000 street trees to be planted mainly in poorer previously disadvantaged communities during the period 2002 to 2008 and (4) to determine the monetary value of the 33 630 Jacaranda mimosifolia street trees in the City based on the quantity of carbon stored in the trees. Combretum erythrophyllum had the most rapid growth rate in many instances, thereafter came Rhus pendulina and then Rhus lancea, which consistently had the slowest growth rate for the investigated parameters. It is estimated that the 115 000 street trees to be planted will sequestrate more than 200 000 tonne CO2 equivalent and have an estimated monetary value of more than US$2 million if a market related CO2 price of US$10.00 per tonne is assumed. The Jacaranda street trees have an estimated carbon stock of 41 978 tonne CO2 equivalent and this would value the Jacaranda urban forest at US$419 786. Copyright / Thesis (PhD)--University of Pretoria, 2010. / Plant Science / unrestricted

Seagrasses are considered highly important CO2 sinks, with the capacity to store substantial quantities of organic carbon in the living biomass and sediments, and thereby acting as a buffer against climate change. In this thesis, I have studied carbon storage variability in temperate and tropical seagrass habitats and identified factors influencing this variation. In addition, as seagrass areas are decreasing worldwide, I have assessed effects of different anthropogenic disturbances on carbon sequestration processes. The result from this thesis showed that there was a large variation in carbon storage within and among temperate, tropical and subtropical regions. The highest organic carbon stocks were found in temperate Zostera marina meadows, which also showed a larger carbon storage variability than the subtropical and tropical seagrass habitats. The tropical and subtropical seagrass meadows had inorganic carbon pools exceeding the organic carbon accumulation, which could potentially weakens the carbon sink function. The variability in organic carbon stocks was generally strongly related to the sediment characteristics of the seagrass habitats. In Z. marina meadows, the strength of the carbon sink function was mainly driven by the settings of the local environment, which in turn indicates that depositional areas will likely have higher organic carbon stocks than more exposed meadows, while in the tropics seagrass biomass was also influencing sedimentary carbon levels. Furthermore, locations with large areas of seagrass were associated with higher carbon storage in tropical and subtropical regions, which could be related to increased accumulation of both autochthonous and allochthonous carbon. In an in situ experiment, impacts on carbon sequestration processes from two types of disturbances (with two levels of intensity) were tested by simulating reduced water quality (by shading) and high grazing pressure (through removal of shoot biomass). At high disturbance intensity, reductions in the net community production and seagrass biomass carbon were observed, which negatively affected carbon sequestration and could impact the sedimentary organic carbon stocks over time. In the treatments with simulated grazing, erosion was also seen, likely due to an increase in near-bed hydrodynamics. When experimentally testing effects of increased current flow on organic carbon suspension in Z. marina sediment, a ten-fold release of organic carbon with higher current flow velocities was measured, which resulted in an increase in the proportion of suspended organic carbon by three times in relation to other sediment particles. Therefore, periods with enhanced hydrodynamic activity could result in a removal of organic carbon and thereby likely reduce the seagrass meadows’ capacity to store carbon. The findings of this thesis add to the emerging picture that there is a large natural variability in seagrasses’ capacity to store carbon, and highlight how human-induced disturbances could negatively affect the carbon sink function in seagrass meadows. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

The purpose of this study was to provide a methodological framework for the first estimates of the total carbon storage and its economic valuation in the mangrove forests of Everglades National Park (ENP), Florida. The total carbon storage in the ENP mangroves is estimated to be 7,144 Mg C/ha, much higher than tropical, boreal and temperate forests. The final selection of carbon prices for the valuation was based on the social, economic and political milieu of the study site, the biological attributes influencing the quantity and quality of carbon storage, and the status of the ENP mangroves as a protected area. The carbon storage in ENP mangroves is estimated at $50,000/ha and $614,000/ha based on the U.S. market price and social cost of carbon, respectively. The study also estimates the change in the economic value of the carbon stock in ENP mangroves in response to different scenarios of sea level rise.

Made available in DSpace on 2016-05-02T13:54:09Z (GMT). No. of bitstreams: 1 LazaroQuintinoAlves-Dissertacao.pdf: 282398 bytes, checksum: 6c06233155f4edef4588242b671b2afa (MD5) Previous issue date: 2009-02-17 / One of the greatest challenges of humankind is sustainable production with clean development mechanisms (CDM) in order to reduce the emission of greenhouse gases and provide a better world to future generations. In this context, sugarcane brandy production should be considered an agroindustrial complex which is capable of contributing to carbon sequestration. As a traditional activity in Brazil, it also generates jobs and wealth. The purpose of this research was to economically evaluate the potentialities of carbon emission and sequestration balance of sugarcane in brandy production, and verify whether the sale of carbon credits could provide additional income and increase the gross revenue in each harvest. An attempt was made to understand the history of sugarcane, a primary source of brandy, and it was found that its history is mixed with Brazil s own history, even today. We studied aspects of carbon balance, economical aspects, and the amount of trading of carbon and brandy, from April to October 2008, to assess the economic viability of sugarcane carbon sequestration and brandy. To determine the carbon sequestration balance in the sugarcane brandy agribusiness a survey was made of all the carbon sequestered by the sugarcane plantation, and also of the carbon emission during all the stages of the productive process. All this survey was based on data obtained from scientific papers. Carbon trading can be done at BM&F (Futures and Commodities Exchange) or directly by the companies that to lower their pollution levels. It is understood that the best way for small producers to engage in carbon trading is through a cooperative of CO2 trading. Alongside with the search for production of clean energy, the correctly managed sugarcane cultivation can contribute to agriculture sustainability as both a great carbon sequesterer and an additional source of income for brandy producers. / Atualmente, um dos maiores desafios da humanidade é produzir, de maneira sustentável, a partir de mecanismos de desenvolvimento limpo (MDL), reduzindo as emissões dos gases do efeito estufa (GEE) e proporcionando um mundo melhor às gerações futuras. Neste contexto, a produção de aguardente é um segmento produtivo que deve ser considerado como complexo agroindustrial com possibilidades de contribuir para o sequestro de carbono, sendo, ainda, atividade tradicional no Brasil, geradora de emprego e renda. Este trabalho teve como objetivo avaliar economicamente as potencialidades do balanço de emissão e sequestro de carbono da cana-de-açúcar utilizada no fabrico de aguardente, para verificar se a venda dos créditos de carbono pode proporcionar rendimentos extras e aumentar a receita bruta da propriedade a cada safra. Como fonte primaria da aguardente, procurou-se compreender a história da cana-de-açúcar, que se confunde com a própria história do Brasil até os dias atuais. Procurou-se estudar os aspectos do balanço de carbono e os aspectos econômicos a montante do macrossegmento da comercialização do carbono e da aguardente, no período de abril a outubro de 2008, para verificar a viabilidade econômica do sequestro de carbono e da aguardente procedentes da cana-de-açúcar. Para apurar o saldo do sequestro de carbono no agronegócio da aguardente foi realizado um levantamento de todo o carbono sequestrado pela lavoura canavieira, bem como as emissões de carbono durante todas as etapas do processo produtivo. Todo este levantamento foi estimado a partir de dados retirados de artigos publicados em revistas científicas especializadas. A comercialização de carbono pode ser através da BM&F ou diretamente com as empresas que desejam baixar o seu nível de poluição. Percebe-se que a melhor maneira de realizar a transação do carbono pelos pequenos produtores é através de uma cooperativa que tenha como objetivo a comercialização do CO2. Paralelamente à corrida pela produção de energia limpa, o cultivo da cana-de-açúcar, manejado corretamente pode contribuir para a sustentabilidade da agricultura como grande sequestradora de carbono e como fonte extra de rendimentos dos produtores de aguardente.

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Macadamia activated carbon (MAC) was impregnated with different concentrations of nitric acid and heated under reflux to improve the structural characteristics of the adsorbent for both considerable reduction and enhanced removal of Cr(VI). The chemical oxidation of ACs increased the surface oxygenated functional groups. Adsorption of Cr(VI) was carried out by varying parameters such as contact time, pH, concentration, and adsorbent dosage. The optimum operating conditions for the adsorption of Cr(VI) were pH 1, contact time 240 min, adsorbent dosage 10.67 g/L and Cr(VI) concentration 100 mg/L. The results showed that the Macadamia–based AC could be used efficiently for the treatment of chromium-containing solutions as a low-cost alternative compared to commercial AC and other adsorbent reported. The results showed that treated MAC performed better than untreated MAC, signifying the effect of secondary treatment on the enhanced removal of pollutants. Comparable to the application of ACs is the development of imprinting technologies for selective metal ion remediation in environmental samples. The combination of ion imprinting effects and functionalized carbon adsorbents produce materials which effectively remove and selectively recognize the target analyte. Macadamia activated carbon (MAC) was chemically pre-treated with nitric acid to generate carboxyl groups on the surface. The carboxylated MAC was then reacted with triethylenetetramine, N,N’-diisopropylcarbodiimide and CrCl3.6H2O to produce MACN20-imprinted sorbents (MACN20-IIP). MACN20-non imprinted (MACN20-NIP) counterparts were prepared, but Cr3+ was excluded in the synthesis. Alteration of surface structural characteristics and characterization of prepared adsorbents as confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, Brunauer–Emmett–Teller and scanning electron microscopy. MACN20-IIP and MACN20-NIP adsorbents were evaluated for their Cr3+ uptake from aqueous solution in batch format. Maximum conditions were achieved at pH 5, 50 mg/L Cr(III) initial concentration and 33.33 g/L of adsorbent dosage. Presence of co-ions slightly diminished the removal of Cr(III) by MAC-IIP adsorbents. Application of the MACN20-IIP and MACN20-NIP on spiked acid mine drainage artificial sample led to collapse in the removal efficiency of MACN20-NIP while MACN20-IIP still showed good removal efficiencies. These results demonstrated that surface imprinting led to better adsorption rates and capacity. The data was better described by the Freundlich multilayer adsorption and pseudo-second order kinetic rate model. The combination of both the carbon sorbent and the surface-mediated IIPs effectively improved total chromium remediation in aqueous systems.

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Persisting challenges associated with remediation of heavy metals from aqueous media have stirred the need for enhancement of current technologies. Cellulosic agro waste materials (AWM) as well as ion-imprinted polymers (IIP) have received ardent attention from researchers. These materials are often employed in the following industries: water and wastewater treatment, medical, pharmaceutical and packaging. Applications in water and wastewater treatment have gained significant interest due to desirable features they possess. In the case of AWM, these features include a tuneable surface area and poor porosity, basic surface functional groups and chemical stability. Some desired features in IIP include adsorption sites compatible for the ion imprint obtained after leaching with suitable reagents, rigidity and reusability. The efficacy of employing AWM and IIP for the remediation of toxic chromium from aqueous solution was explored. The current study is made up of part A and B. In part A, Macadamia nutshell powder was treated using HNO3, NaOH, as well as Fenton’s reagent. The three materials underwent a new modification which involved reacting treated adsorbents with cetyltrimethylammonium chloride (CTAC), followed by immobilization of 1,5' diphenylcarbazide (DPC) ligand. The adsorbents were ultimately washed, dried and stored for Cr(VI) batch adsorption experiments. Part B involved a synthesis of IIP and their non-imprinted polymer counterpart (NIP) for Cr(VI) sequestration in aqueous solution. This was done by precipitation polymerization of functional monomers, crosslinker and DPC-Cr(VI) complex as a template. Non-imprinted polymers were fashioned in a manner like that of IIP but with the exclusion of Cr(VI) ion template. Characterizations of the adsorbents were done using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and carbon, hydrogen, nitrogen and sulphur (CHNS) analyzer. Batch adsorption experiments were done and parameters such as solution pH, adsorbent dosage, initial Cr(VI) concentration and contact time were optimized. Working solutions were analyzed using ultraviolet-visible (UV-Vis) and atomic absorption (AA) spectroscopy. Adsorption parameters found to be optimum for DPC immobilized cellulosic adsorbents were pH 1.4, adsorbent mass of 0.1 g, 100 mg/L initial concentration and 125 minutes of contact time. The adsorption parameters determined to be optimum for IIP and NIP were pH 2.6, 0.2 g adsorbent mass, 80 mg/L initial concentration and 240 minutes of contact time. Reusability studies demonstrated the potential of adsorbents to remove Cr(VI) ions from aqueous media after successive adsorption-desorption cycles. Selectivity studies indicated that DPC immobilized adsorbents as well as IIP were able to selectively adsorb Cr(VI) ions from aqueous media in the presence of Zn(II), Cu(II), Co(II) and NI(II) ions. Kinetic models revealed that DPC immobilized cellulosic adsorbents and synthetic IIP were most fitting for pseudo-second order and pseudo first order, respectively. On the other hand, adsorption isotherm studies demonstrated that DPC immobilized cellulosic adsorbents and synthetic polymers were best fit for Freundlich and Langmuir adsorption isotherm, respectively.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13262号 / 論農博第2875号 / 新制||農||1071(附属図書館) / 学位論文||R1||N5217(農学部図書室) / (主査)教授 山下 洋, 教授 澤山 茂樹, 教授 吉岡 崇仁 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Afforestation projects in China have substantially contributed to national CO2 sequestration and play an important role in international climate change mitigation. However, these nation-wide afforestation projects are usually funded by the national government, with very large and unsustainable investments. It is important to find alternative sources of funding to finance afforestation, and convince poor farmers to become involved in afforestation projects. Carbon-subsidized afforestation could be the solution. The current study aims to find i) whether farmers need additional subsidies to reforest their marginal farmland; if so, ii) whether the value of carbon sequestration of afforestation can offset farmers' net costs. To do this, first I determine the amount of carbon sequestration though afforestation. Second, I assess the value of carbon sequestration, the costs and benefits of afforestation projects, and the costs and benefits of crop production. Third, I investigate the optimal rotation period of the plantations considering a joint production of timber and carbon, for different species. Results show that total carbon sequestration through tree biomass and soil carbon following afforestation differs among tree species and stand age as well as across regions. Economic trees sequester less carbon than ecological trees and bamboo. Among economic trees, nut trees with an inedible hard shell sequester more carbon than fruit trees. The regional context significantly influences the carbon sequestration potential, with more carbon sequestered in southern and eastern regions than in northern regions. Bamboo also shows a remarkable carbon sequestration potential, which is even greater than Chinese fir and Poplar in northern regions. Although afforestation programs have huge potential to store carbon, the voluntary acceptance by landowners crucially depends on their economic outcome. I found that usually carbon credits can compensate for the opportunity costs of alternative land uses, except i) when highly profitable croplands are afforested, in which case carbon credits are not sufficient, and ii) when croplands that generates low incomes are afforested, in which case carbon credits are not needed. Fruit trees are the most cost-effective option for afforestation. Bamboo afforestation is economically attractive if carbon revenues is included. The minimum price of carbon credit decreases with increasing project duration because more carbon is stored when time increases. This does not hold for fast-growing trees like Eucalyptus, for which the minimum price increases with extended project duration. Given the temporal variations of joint production of timber and carbon sequestration, the carbon accounting regimes (tCER, temporary Certified Emission Reductions and lCER, long-term Certified Emission Reductions) have a significant impact on the optimal rotation as well as on the revenue. Forest managers have an incentive to use tCER accounting to finance slow-growing plantations, and lCER for fast-growing ones. I perform a sensitivity analysis detects the changes of rotation period with different carbon prices and discount rates. While the optimal decision for slow-growing species (e.g. Chinese fir) is highly sensitive to changes in both variables under tCER accounting, the results concerning fast-growing species (e.g. Eucalyptus) are most sensitive under the lCER accounting regime. In contrast, carbon revenues have a minimal impact on the optimal rotation of Poplar plantations, no matter which regime is applied. I conclude that carbon-subsidized afforestation is a feasible way to offset the opportunity costs of retired farmland and support the livelihood of farmers. The findings can contribute to the efficient and sustainable management of forestry projects using carbon sequestration, while the methodology can also be applied to other regions in the world.

Since the industrial revolution, the atmospheric CO2 concentration has steadily increased due to the combustion of fossil fuels, reaching 410 ppm. According to the 2018 IPCC report, it was recognized that the anthropogenic greenhouse gas emissions caused by human activities are major drivers for global warming of 1.0 oC above the pre-industrial level. Due to the unprecedented scale of human driven CO2 emission and its environmental impact, the mitigation of climate change requires a wide range of multifaceted solutions. Thus, enormous global efforts have been placed on the development of Carbon Capture, Utilization, and Storage (CCUS) to mitigate CO2 emissions in the immediate future. Most recent reports by the U.S. National Academies and the Mission Innovation presented that ex-situ carbon mineralization is a CO2 utilization technology with a great carbon storage potential and a large market size. Also, fixing CO2 into a solid matrix of carbonate minerals is one of the most permanent methods for carbon storage. Although the ex-situ carbon mineralization presents many advantages and great potential as CCUS technology, its commercialization has been limited due to the mammoth scale of the process, slow reaction kinetic between CO2 and silicate minerals, and high energy and operating cost. In order to minimize energy and chemical (acid and base) consumption of this technology, recent researches have been focused on a two-step carbon mineralization via Pco2 swing using highly reactive heat-treated serpentine mineral. However, the elemental (Mg and Si) extractions from the complex silicate structures of heat-treated serpentine are still poorly understood and a more fundamental understanding of the Pco2 swing process is required to develop a commercial-scale plant. Thus, the objectives of this study are directed toward addressing these technical challenges. The effect of operating conditions, such as temperature, slurry density, and CO2 partial pressure, on the dissolution of heat-treated serpentine and subsequent Mg-carbonate precipitation behaviors, were studied to provide a fundamental understanding of the Pco2 swing carbon mineralization process of highly reactive silicate materials. The dissolution experiments with a wide range of temperature and slurry densities provided valuable insights into the formation of the Si-rich passivation layer and its role in the mass transfer limitation during mineral dissolution. The heat-treated serpentine dissolution behaviors with chemical additives (ligand) were also investigated to overcome the effect of the Si-rich passivation layer on Mg extraction kinetics. What is more, a unique internal grinding system was proposed and integrated with the Pco2 swing process to physically remove the Si-rich passivation layer. The diffusion-limited slow elemental (Mg and Si) extraction from the heat-treated serpentine silicate structures was significantly enhanced in the internal grinding system. A stress intensity, which is proportional to the energy transferred from grinding media to the heat-treated serpentine particles during a stress event, was used to describe the effect of the reaction parameters on the extent of the physical activation and the enhancements in mineral dissolution. For the fundamental understanding of the complex dissolution behaviors of heat-treated serpentine, the changes in the silicate structures (Q0 – Q4) of heat-treated Mg-bearing mineral (serpentine) exposed to a CO2-water system (carbonic acid) was investigated using 29Si MAS NMR and XRPD. The identified silicate structures were employed to provide insight into how Mg and Si are liberated from the different silicate structures during the dissolution process. Thermodynamic and kinetic modeling was performed to understand the Mg-carbonate precipitation behaviors in the Pco2 swing process. The effects of carbonic anhydrase, seed particles, and ligand (citrate) on precipitation behaviors were studied to improve the precipitation kinetics. This approach will bring a great paradigm shift in the energy and environmental field since the less energy-intensive and low-cost ex-situ carbon mineralization process via Pco2 swing will be able to allow long-term and sustainable carbon utilization.

The aim of this project was to study the leakage of CO2 in a Geological Carbon Sequestration (GCS) system. To define the GCS system, a tool that is known as an FEP database was used. FEPs are the features, processes and events that develop scenarios for the goal of the study. Combinations of these FEPs can produce thousands of scenarios. However, among all of these scenarios, some are more important than others for leakage. The FEPs that were used as scenario developers were the formation of the liquid flow, the salinity of the formation liquid, diffusion as a process for gas bubble transport and the depth of the reservoir layer. In this study, the leakage path is considered as the presence of a fracture in sealed caprock. The fractures can be modeled using various approaches. Here, I represented the influence of fracture modeling by applying the Equivalent Continuum Method (ECM) and the Dual-Porosity and Multi-continuum methods to leakage. This study suggests that considering groundwater in the aquifer would reduce the leakage of CO2 and that a shallower formation leads to higher leakage. This study can be expanded to future studies by including external FEPs that are related to the FEPs that were used in this study.