PhD - Science / Analysis of charcoal from Middle Stone Age layers at Sibudu Cave, KwaZulu-Natal, shows evidence of environmental change during the Last Glacial. Layers analysed encompass the end of the cold stadial, Oxygen Isotope Stage (OIS) 4, and the warmer interstadial, OIS 3. Layers are divided – on the basis of lithic industry associations and taxonomic content – into the Howiesons Poort (HP) (dated to ca. 61 000 years ago), and the early, middle and late post-HP assemblages (ca. 60-55 000, 55-50 000 and 50-33 000 years ago respectively). This project aims to identify evidence for environmental change, characterise this change using qualitative and quantitative analyses, and compare the results to evidence from other proxies at Sibudu Cave and elsewhere in South Africa. HP layers (GS, GR, GR2) are dominated by evergreen forest taxa, including Podocarpus spp., Buxus sp., Brachylaena sp., Sapium/Spirostachys and Ptaeroxylon obliquum. Kirkia sp. suggests a warm, woodland savanna habitat grew beyond the forest vegetation. Early post-HP layers (Eb, SPCA, BSp) contain taxa from evergreen, riverine forest communities, including Erica spp., Leucosidea sericea, and Rapanea melanophloeos. Some of the taxa in these layers suggest a shift in vegetation, possibly related to the marine regression of the Last Glacial, bringing taxa currently found further inland towards the site. Fewer evergreen forest components, and more bushveld taxa, are present in the middle post-HP (RSp, OMOD, MOD) than in the previous layers. Some of the taxa are only found in northern South Africa in regions that are significantly drier than modern KwaZulu-Natal. These layers also contain more Acacia spp. and other Fabaceae taxa and fewer Erica spp. than the samples from the early post-HP. This may be a result of environmental change, a change in wood selection, charcoal fragmentation, or sampling bias. Layer Bu, within the late post-HP, contains evergreen and deciduous taxa many of which are found in KwaZulu-Natal today. Kirkia sp. again provides evidence for a dry habitat not iv currently found in the region. Many Types were defined in Bu, which may indicate a vegetation community for which there is currently no reference material. Temperature and moisture indices produced using the Factor Analysis suggest warm and moist conditions during the HP layers. During the early post-HP conditions became cooler with intermediate moisture levels. Subsequently, conditions were warm and dry (middle post-HP) and then warm with a little more moisture indicated (late post-HP). Good fuelwoods were routinely collected during the post-HP. In contrast, the HP layers are dominated by Podocarpus spp. and many of the good fuelwoods, such as Acacia spp. and Erica spp., are absent. This pattern may be a result of changes in the environment, sample bias or a development of awareness of wood properties between the HP and post-HP occupations. The charcoal results corroborate palaeoenvironmental interpretations provided by seeds and macrofauna from Sibudu Cave. When the Sibudu Cave data are combined with data from other sites it is apparent that, although conditions in the summer rainfall region during the Last Glacial were generally dry, there is evidence for localised variation in vegetation and climate.

A crescente busca por formas de energia mais limpas e renováveis têm colocado o carvão vegetal como possível alternativa ao fóssil na siderurgia brasileira. A secagem de toras de EUCALYPTUS Saligna é uma importante etapa do processo de carbonização. O objetivo deste trabalho é analisar o comportamento de algumas variáveis que afetam os processos de secagem e carbonização da madeira para produção de carvão vegetal, assim como entender o efeito da pré-secagem na carbonização; visando estabelecer coeficientes básicos de engenharia neste processo. Para isso, foi determinada a densidade básica da madeira através do método de Máximo Teor de Umidade (TEU); foram secadas toras de madeira a temperatura constante de 120°C, foram feitos ensaios de carbonização em retorta de aço inoxidável aquecida com resistência elétrica e finalmente foram feitos ensaios de perda de massa durante a carbonização com amostras cúbicas de 10 mm de lado; neste ultimo ensaio foi variada a temperatura de carbonização e o tempo de secagem das amostras antes de serem carbonizadas. Foram utilizadas toras de EUCALYPTUS Saligna com sete anos de idade. A secagem de toras de EUCALYPTUS Saligna a 120°C apresentou duas fase de velocidade variável. A densidade básica do EUCALYPTUS Saligna diminuiu no sentido centro periferia e os valores médios obtidos foram 0,59 g/cm³ no centro, 0,49 g/cm³ no ponto médio entre o centro e casca, e 0,44 g/cm³ na periferia. A carbonização de toras em retorta com taxa de aquecimento inicial entre 4,3°C/min e 5,4°C/min, apresentou comportamento exotérmico; de tal forma que a temperatura nominal do forno pouco afetou o rendimento em carvão. Para taxas de aquecimento inicial maiores que 12,6°C/min não se observaram temperaturas da madeira superiores a do forno. Para a carbonização a 420°C,o rendimento em carvão diminui com o tempo de carbonização; para uma hora a carbonização é incipiente. O teor de carbono fixo para a carbonização a duas ou três horas apresentou pouca variação. Carbonizações de amostras pequenas de eucalipto indicaram rendimento em carvão de 38,2% a 420°C e 20,94% a 950°C. Em relação a posição da amostra na tora, observa-se que, quando carbonizadas a 420°C, a perda de massa ocorre aumentando na direção centro periferia, no sentido das menores densidades. Aumentando-se a temperatura de carbonização, a perda de massa aumenta até 500°C; Já a 950°C a perda de massa resultou a mesma que a 500°C, mas com o aumento da temperatura diminui o tempo para atingir massa constante. A carbonização com temperatura variável ate 420°C, de amostras com umidade de equilíbrio, apresentou menor perda de massa que a carbonização de amostras secas em estufa. Finalmente foram avaliados os conceitos relacionados à exotermia e endotermia da madeira assim como aos processos de secagem e carbonização da madeira, de modo a direcionar trabalhos futuros do Grupo de Pesquisa. / The use of charcoal as a thermal and reducing agent in the process of iron ore reduction has great potential as a promoter of sustainability for the steel industry. In order to fully realize this potential it is required the continuous generation of basic knowledge that allows to obtain the technological coefficients of the various process steps. This paper presents experimental results on drying Eucalyptus saligna with the aim to carbonization of the same for the production of charcoal. The following parameters were determined: basic wood density, thermal profile survey of eucalyptus logs, kiln drying speed, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) of wood samples and carbonization of wood with different moisture levels. The results obtained can be used in the determination of technological parameters of the carbonization processes.

Cheung Lok Ying Teresa = 竹炭模板上形成的二氧化硅與碳化硅納米線及其表徵 / 張樂影. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Cheung Lok Ying Teresa = Zhu tan mo ban shang xing cheng de er yang hua gui yu tan hua gui na mi xian ji qi biao zheng / Zhang Leying. / ABSTRACT --- p.i / 摘要 --- p.iii / ACKNOWLEDGEMENTS --- p.v / TABLE OF CONTENTS --- p.vii / LIST OF FIGURE CAPTIONS --- p.xi / LIST OF TABLE CAPTIONS --- p.xv / Chapter Chapter 1 --- Introduction / Chapter 1.1. --- Biomineralization process --- p.1 / Chapter 1.2. --- Structures in biological matters --- p.2 / Chapter 1.2.1. --- Bone --- p.2 / Chapter 1.2.2. --- Wood --- p.3 / Chapter 1.3. --- Biomorphic products and their potential applications --- p.4 / Chapter 1.3.1 --- Environment conscious products --- p.4 / Chapter 1.3.2 --- Properties --- p.5 / Chapter 1.3.3 --- Carbide and oxide composites --- p.5 / Chapter 1.4 --- Common fabrication approaches --- p.6 / Chapter 1.4.1 --- Gaseous infiltration --- p.7 / Chapter 1.4.2 --- Liquid infiltration --- p.7 / Chapter 1.4.3 --- Sol-gel method --- p.8 / Chapter 1.5 --- Growth of nanowires --- p.8 / Chapter 1.5.1 --- Vapor-liquid-solid (VLS) mechanism --- p.9 / Chapter 1.5.2 --- Solution-liquid-solid (SLS) mechanism --- p.9 / Chapter 1.5.3 --- Vapor-solid (VS) mechanism --- p.10 / Chapter 1.6 --- Goals of the project --- p.10 / Chapter 1.6.1 --- Feedbacks on previous works --- p.10 / Chapter 1.6.2 --- Our breakthrough approach --- p.11 / Chapter 1.7 --- Thesis layout --- p.12 / References --- p.13 / Figures --- p.17 / Chapter Chapter 2 --- Samples preparation and characterization methods / Chapter 2.1 --- Materials selections --- p.22 / Chapter 2.1.1 --- Selection of materials for biomorphic substrate --- p.22 / Chapter 2.1.2 --- Selection of solution for infiltration --- p.23 / Chapter 2.2 --- Samples preparation --- p.24 / Chapter 2.2.1 --- Pyrolysis of raw bamboo --- p.24 / Chapter 2.2.2 --- Infiltration of reactants --- p.25 / Chapter 2.2.3 --- Sintering conditions --- p.26 / Chapter 2.3 --- Characterization methods --- p.26 / Chapter 2.3.1 --- Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) --- p.27 / Chapter 2.3.2 --- Transmission electron microscopy (TEM) and EDS --- p.27 / Chapter 2.3.3 --- High-resolution transmission electron microscopy (HRTEM) --- p.27 / Chapter 2.3.4 --- X-ray diffraction (XRD) --- p.28 / Chapter 2.3.5 --- X-ray photoelectron spectroscopy (XPS) --- p.28 / Chapter 2.3.6 --- Fourier transform infrared spectroscopy (FTIR) --- p.29 / Chapter 2.4 --- Conclusions --- p.29 / References --- p.30 / Figures --- p.31 / Tables --- p.33 / Chapter Chapter 3 --- Bamboo biomorphic substrates / Chapter 3.1 --- Overview --- p.34 / Chapter 3.2 --- Volumetric shrinkage and weight loss --- p.34 / Chapter 3.3 --- General morphology --- p.35 / Chapter 3.4 --- Intrinsic impurities --- p.35 / Chapter 3.5 --- Structures --- p.36 / References --- p.38 / Figures --- p.39 / Chapter Chapter 4 --- Silica / Chapter 4.1 --- Overview --- p.43 / Chapter 4.2 --- Thermal analyses --- p.44 / Chapter 4.2.1 --- Raw biomorphic substrates --- p.44 / Chapter 4.2.2 --- Infiltrated biomorphic substrates --- p.45 / Chapter 4.3 --- Experiments --- p.46 / Chapter 4.4 --- Characterization in general --- p.47 / Chapter 4.4.1 --- General morphologies --- p.47 / Chapter 4.4.2 --- Tips of the SiO2 nanowires --- p.48 / Chapter 4.5 --- Effects of sintering duration --- p.48 / Chapter 4.6 --- Effects of sintering temperature --- p.49 / Chapter 4.6.1 --- "Different temperatures, held for one hour" --- p.50 / Chapter 4.6.2 --- "Different temperatures, held for ten hours" --- p.50 / Chapter 4.7 --- Growth mechanisms --- p.52 / Chapter 4.8 --- Summary --- p.54 / References --- p.56 / Figures --- p.58 / Tables --- p.75 / Chapter Chapter 5 --- Silicon carbide / Chapter 5.1 --- Overview --- p.76 / Chapter 5.2 --- Experiments --- p.77 / Chapter 5.3 --- Characterization in general --- p.78 / Chapter 5.3.1 --- General morphologies --- p.78 / Chapter 5.3.2 --- Stacking faults and twinning --- p.79 / Chapter 5.3.3 --- Tips of the SiC nanowires --- p.81 / Chapter 5.4 --- Growth mechanisms --- p.82 / Chapter 5.5 --- Summary --- p.83 / References --- p.84 / Figures --- p.87 / Chapter Chatper 6 --- Conclusions and future works / Chapter 6.1 --- Main results of this projects --- p.101 / Chapter 6.2 --- Future works --- p.103 / References --- p.104

Maintaining an adequate level of soil organic matter and nutrients cycling is crucial to the success of any soil management in the humid tropics. Cover crops, compost, or manure additions have been used successfully to supply nutrients to crops but the benefits of such amendments are often short-lived in the tropics, since decomposition rates are high. This study focused on charcoal which, when utilised as a soil amendment is termed ‘biochar’. Throughout this thesis, the terms ‘charcoal’ and ‘biochar’ are used interchangeably depending on the context. Charcoal exhibits physiochemical properties potentially suitable for soil improvement as well as for the safe and long-term storage of carbon in the environment. As a way of investigating its recalcitrance as a carbon store, O:C ratios have been shown to reflect the extent of oxidation and therefore decomposition of charcoal. This study aimed to fill a gap in the research by describing the effects of biochar on the water retention capacity of soil under laboratory conditions. It also provides a detailed snapshot of the first ten years of recalcitrance under natural conditions, using X-Ray Photoelectron Spectroscopy (XPS) to determine elemental oxygen and carbon ratios of whole charcoal fragments and how these are affected by the surrounding environment over time. Mechanisms of oxidation are described, showing how both biotic and abiotic factors influence the degradation of charcoal in the soil. It also investigated how these properties affect the nutrient and water retention capability of charcoals of different ages in the laboratory. Results of charcoal/soil mixtures showed significant reduction in nitrate leachate losses with no reduction in performance over a ten year period of residing in the soil. It was also shown that charcoal addition to a sandy soil resulted in a significantly increased available water content. Both these results were argued to support the idea that charcoal is of potential beneficial amendment to sandy, degraded soils.

Approximately 3 billion people in developing countries rely on solid fuels for their cooking, heating and lighting needs (Smith 2000). Household air pollution (HAP) from the incomplete combustion of these fuels constitutes the fourth leading risk factor for death and morbidity worldwide, and the number one risk factor for disease burden in some developing nations, including Ghana (Lim et al. 2013; Institute for Health Metrics and Evaluation 2016). While research shows biomass fuel combustion presents a significant global health and environmental burden, no regional, national or global policies have been enacted to reduce fine particulate matter (PM2.5) and black carbon (BC) emissions from cooking with biomass fuels. More data on personal exposures to particulate matter and BC from cooking with biomass are needed across geographic areas to assess whether exposure is mediated by (cultural) cooking customs, practices and behaviors. These data are critical in informing improved cookstove design as well as policies aimed at reducing harmful emissions and exposures from biomass smoke. The overall objective of this proposal is to examine personal exposures to cooking and non-cooking sources of HAP, characterize the elemental composition of the fine particulate matter across two common biomass fuels (charcoal and wood), and assess acute respiratory symptoms in pregnant women cooking with biomass fuels in rural Ghana. Through aerosol monitoring of PM2.5, our goal is to identify and apportion sources of personal exposures borne by cooks in rural Ghana, in order to inform mitigation policies and intervention design to alleviate health burden associated with cooking with biomass fuels. Specifically, in Aim 1 we propose to measure personal exposures and kitchen air concentrations of PM2.5 and BC across cooking locations, (i.e. enclosed, semi-enclosed, outdoor) and assess cooking characteristics (e.g. fuel, kitchen type, ethnicity) as possible determinants of exposure. In Aim 2, we will characterize the elemental composition of personal and kitchen air samples across fuel and kitchen types. These two aims will allow us to assess cooking and non-cooking sources of personal HAP exposure based on air monitoring data, composition of the filters, and survey-based cooking characteristics/demographics. In Aim 3, we propose to characterize the prevalence of adult respiratory symptoms in 1183 pregnant women in the region, and assess associations between personal exposure, measured by personal carbon monoxide (CO), and other cooking and non-cooking determinants of personal exposure, including fuel type, years cooked, kerosene lamp, mosquito coils, and charcoal production.

Os resíduos orgânicos alimentares são um tipo de resíduo de difícil aproveitamento. Milhões de toneladas de lixo orgânico são descartados todos os anos, sobretudo os de origem alimentar, sendo que boa parte não é reaproveitada. Tradicionalmente, quando reaproveitados, esses resíduos são destinados à compostagem. No entanto, para que esse processo seja bemsucedido, é necessário que os resíduos sejam separados corretamente a fim de que a qualidade do produto final seja aceitável para o uso como fertilizante. Uma alternativa proposta de utilização dos resíduos alimentares consiste na produção de material carbonáceo obtido pela carbonização ou torrefação destes. Avaliam-se as propriedades e as características qualitativas e quantitativas desses materiais carbonáceos e seus derivados, como a composição, a resistência mecânica e a microestrutura. Tenciona-se, desse modo, contribuir para o conhecimento das possíveis aplicações desses carvões, materiais carbonosos e derivados em diversas áreas da indústria, inclusive na siderúrgica. / Millions of tons of organic waste are discarded every year, especially from food sources, and most of it is not reused. Traditionally, when reused, this kind of waste is destined for composting. However, for that procedure to be successful it is necessary that the waste is properly separated so that the quality of the final product is acceptable for fertilizer. An alternative reuse of food waste constitutes obtaining carbonaceous material by carbonization or torrefaction of this material. This work studies the charcoalmaking that uses these kind of residues, the characteristics of charcoals obtained, and the possible applications for these carbonaceous materials. The properties and the qualitative and quantitative characteristics of this object of study, such as its composition, its mechanical resistance and its microstructure, are evaluated. It is intended to contribute to the knowledge of the possible applications of these charcoals in several areas of industry, including in the steel industry.

Phosphorus has long been recognized by agriculturists as being one of the elements essential for plant growth. Although the total phosphorus content of a soil may be high, the amount of phosphate actually available for plant growth is often low. Many agencies such as inherent low solubilities of phosphate compounds, adsorption on Ca C03, adsorption in the diffuse double layer of clay micelles, and chemical precipitation of phosphate which refers to the removal of phosphate ions from solution and their chemical bonding to the solid phase have been studied to explain the lack of phosphate availability.

<p>This thesis investigates social impacts of charcoal use in households in the Tanzanian town Babati. In Tanzania a majority of the population use charcoal and firewood as their main energy source. A part from the environmental problems connected to charcoal use; there are also considerable social impacts on women’s daily lives. Cooking and collection of wood fuel are time-consuming and restricts the possibilities for women to work and study. The thesis includes an investigation on how the Tanzanian government tackles problems connected to charcoal use, social as well as environmental. The result shows that the Tanzanian government is working with charcoal related problems to some extent but as previous studies shows there are still more that can be done. The main efforts made concentrate on information campaigns and promotion of more energy efficient equipments. One important problem is however that wood fuel is the cheapest available energy source and hence the incentives to start using other, more sustainable, energy sources are very small. The thesis also investigates possibilities for Babati households to substitute charcoal use with renewable energy sources available in the town. The result shows that the possibilities to use renewable energy currently are very limited and mainly affordable to richer households.</p>

In 1987, Burney and collaborators (Journal of Archaeological Science (1994) 21, 273–281) recovered a ca. 8 m sediment core from the western basin of Laguna Tortuguero, Puerto Rico that spanned the last ca. 7000 calibrated years. They produced a detailed microscopic charcoal record, and from an initial peak in charcoal at ca. 5300 cal yr B.P. suggested that humans had colonized the island some 2000 years earlier than documented by the archaeological evidence then available. In 2008, two sediment cores were recovered from the eastern basin of Laguna Tortuguero. AMS dates on macrofossils indicate the profile extends to 7600 calibrated years, but it includes an interval with missing sediment marked by a layer of shell hash and bracketed by radiocarbon dates of 5144 and 1648 cal yr B.P. Stable carbon and nitrogen isotopic analyses show evidence for a drastic change in depositional environment following this event. Microscopic charcoal concentrations peak just below and at the contact of the shell hash, with the first of three high-charcoal levels positioned immediately above the date of 5144 cal yr B.P. The microscopic charcoal record appears to support the interpretations of Burney et al. (1994) of human colonization around 5300 cal yr B.P., although the fires recorded in the Laguna Tortuguero sediments may also be driven by regional climate shifts. Desiccation of Laguna Tortuguero, a hurricane or multiple hurricanes, or a tsunami could explain the missing sediments and the large change in depositional environment that occurs above the shell hash. AMS dating of sediment from the mud-water interface at the 2008 core site suggests a possible hard-water effect of ca. 1200 cal yr for dates on the algal gyttja above the shell hash, which if true would mean that the event that deposited the shell hash may have occurred as late as ca. 448 cal yr B.P. (A.D. 1502).

This thesis investigates social impacts of charcoal use in households in the Tanzanian town Babati. In Tanzania a majority of the population use charcoal and firewood as their main energy source. A part from the environmental problems connected to charcoal use; there are also considerable social impacts on women’s daily lives. Cooking and collection of wood fuel are time-consuming and restricts the possibilities for women to work and study. The thesis includes an investigation on how the Tanzanian government tackles problems connected to charcoal use, social as well as environmental. The result shows that the Tanzanian government is working with charcoal related problems to some extent but as previous studies shows there are still more that can be done. The main efforts made concentrate on information campaigns and promotion of more energy efficient equipments. One important problem is however that wood fuel is the cheapest available energy source and hence the incentives to start using other, more sustainable, energy sources are very small. The thesis also investigates possibilities for Babati households to substitute charcoal use with renewable energy sources available in the town. The result shows that the possibilities to use renewable energy currently are very limited and mainly affordable to richer households.