In most of Africa archaeological charcoal samples are often used to establish chronology through radiocarbon dating, but are rarely used to address why people may have selected specific wood taxa for particular purposes. This thesis is an enquiry into the palaeo-ethnobotanical and palaeoecological implications of charcoal assemblages dated to the late Holocene from the Great Zimbabwe and Chigaramboni sites, Zimbabwe. The research provided a more detailed picture of socio-economic utilization of wood, such as the use of woods for iron smelting, construction and domestic hearths. Previous excavations at Great Zimbabwe and Chigaramboni have produced large samples of charcoal at specific activity sites and at a few different depths thus giving a minor perspective of time. There was a wider selection of wood at Great Zimbabwe as compared to Chigaramboni. Charcoal samples analyzed in this thesis are a product of purposeful human action and they represent a subsample of the local vegetation and related human activities contemporaneous with the period of sites’ use. A substantial effort has been invested in the development of a modern vegetation reference collection database. This will go a long way in assisting future researchers in the region and is an extremely valuable and essential primary contribution to the development of wood charcoal studies in the region. Thirty different tree species were burnt at Great Zimbabwe and indicate the multipurpose nature of the settlement. In contrast only 14 species were exploited at Chigaramboni which is an iron and metallurgical processing site. The latter fuel woods were also used at Great Zimbabwe. Based on the cracks and fissures in the charcoal it is postulated that the firewood used in metallurgy were collected whilst they were wet. Since Spirostachys africana and Colophospermum mopane do not occur in the area today it is suggested that there was long distance movement of wood, particularly those with excellent construction qualities. It is quite possible that the inhabitants of Great Zimbabwe, or their trading partners, opted to travel long distances in order to collect those particular logs. The fuel woods used at the two sites occur in the region today so it is likely that the Miombo woodlands of Great Zimbabwe and Chigaramboni have not changed notably from the time of occupation by their original inhabitants to date. Based on the mesophytic species identified, such as Acacia robusta, Acacia sieberiana, Acacia xanthophloea, Acacia polyacantha, Acacia burkei, Faurea saligna, Schotia brachypetala, Kigelia africana and Parinari curatellifolia, it is concluded that the inhabitants of ancient Great Zimbabwe and Chigaramboni archaeo-metallurgical site experienced a mesic environment. New excavations of different occupation levels would be required to determine vegetation and climate fluctuations during the past but at present there is a moratorium on such disturbance of the historical sites.

This research mainly focuses on the electromagnetic shielding effectiveness of bamboo -charcoal, using cement mortar with bamboo-charcoal ingredient replacing parts of thin aggregates weight, and then finds the feasibility of electromagnetic shielding effectiveness by using bamboo-charcoal applied to cement mortar. Experiment contains two parts, one is to use different proportions of bamboo-charcoal with replacing with thin aggregates weights( 0%¡B3%¡B5% and 7% ),and the other is to use three kinds of thickness(3mm¡B4mm and 5mm), to measure the effectiveness of electrom- agnetic shielding, and to probe into whether cement mortar with bamboo-charcoal ingredient can shield electromagnetic or not. After researching on cement mortar with bamboo-charcoal, it can be used in civil engineering and ocean engineering, and this experiment will act on the premise which is not affecting the property of cement mortar with bamboo-charcoal, continuing using the condition of reference(Yu,2007) to probe into the electromagnetic shielding effectiveness of cement mortar with bamboo-charcoal, expecting this material can be used to domestic architecture, for protecting the health of our home environment.

Thesis (Ph. D.)--Columbia University, 1927. / Vita.

Contiguous macroscopic charcoal analyses were performed on a 9.03 m long lake sediment core from Roe Lake on Pender Island in the Gulf Islands National Park Reserve of British Columbia, Canada to reconstruct the island’s fire history over the last 10,000 years. Charcoal particles >150μm were counted to quantify charcoal concentrations, charcoal accumulation rates and mean fire return intervals. Results show that the early Holocene was characterized by high charcoal accumulation rates and frequent low-severity fire with a mean fire return interval of 100 ± 29 years. Forests at the time were dominated by Pseudotsuga menziesii with an open canopy and fern taxa, particularly Pteridium aquilinum, being common in the understorey. This open vegetation, coupled with warm and dry summer climate, likely created conditions conducive to this fire regime. Charcoal accumulation rates decreased in the middle to late Holocene, and fire frequency decreased, resulting in a mean fire return interval of 167 ± 43 years. Climate cooled and moistened along with a decrease in seasonality during this time and the canopy closed, establishing closed-canopy Pseudotsuga menziesii forests. Climate appears to be the primary factor controlling fire regimes near Roe Lake for most of the Holocene. At times, shifts in the fire regime cannot be explained by changes in climate. Fire frequency increased between 7000-5000 cal yr BP, coincident with a peak in Quercus garryana pollen, despite cooling and moistening climate. Fire likely maintained patches of Q. garryana savanna during this time. Fire again became more common contrary to trends in climate after ~2500 cal yr BP. This late Holocene increase in fire is also seen elsewhere in the Pacific Northwest and may be a reflection of increased climate variability due to more frequent El Niño events or an increase in human-lit fires. Indigenous populations on southern Vancouver Island commonly used fire as a resource management tool and it is likely that people on Pender Island did as well. As fire management practices shift from fire suppression to more sustainable practices, this study offers the Gulf Islands National Park Reserve important baseline information on the area’s natural fire regime to help guide future conservation efforts. / Graduate / 2023-04-07

Through an exploration of media and technique, this project sought to represent pregnant silence and portentous darkness within architecture: ephemeral effect drawn in stasis. A sequence of three rooms - formed constructively, but intuited through tone - imagine interior worlds in which the stage is perpetually set, but the performance itself never begins. / Master of Architecture / Through an exploration of media and technique, this project sought to represent pregnant silence and portentous darkness within architecture: ephemeral effect drawn in stasis. A sequence of three rooms - formed constructively, but intuited through tone - imagine interior worlds in which the stage is perpetually set, but the performance itself never begins.

Biochar is a form of stable organic carbon whose application to soils has the potential to sequester large amounts of atmospheric CO2 while improving the physical, chemical and biological properties of soil. However, the optimal rates and methods of biochar application are unknown for many situations. Three experiments were performed to test methods of biochar application to soils as a stand-alone amendment, in combination with biosolids as a complementary amendment and in-situ through controlled landscape burning. The first was a greenhouse pot study, which involved combining biochar with spoil from an Appalachian surface coal mine to grow trees. Biochar combined with mine soil produced a much higher growth rate for trees, and pure biochar helped tree root growth, suggesting that it might be useful as a broadcasted amendment, as a nursery growing medium or as a backfill in tree planting holes. The second experiment explored methods to combine biochar and biosolids materials to form a granular product. Combining biochar and biosolids before applications reduced windborne losses of biochar as well as the nutrient leachate produced by the biosolids. Drum rolling was found to work best for producing aggregate granules. Wetting pure biochar to 100% gravimetric water content before applications reduced windborne losses from over 50% to under 5% as compared to when it was applied as a dry product. A series of controlled burns were conducted in the third experiment to determine the ideal range of meteorological conditions to produce the highest possible biochar yields in-situ. Relative humidity, forest litter moisture and ambient temperature were found to be the governing factors over the tonnage of biochar produced. Up to 3.0 Mg Ha-1 of biochar were produced under ideal conditions by controlled burning. Repeated high-yielding burns have the potential accumulate large amounts of biochar in the soil to improve soil properties. / Ph. D.

Quantifying charcoal particles preserved in sedimentary environments is an established method for estimating levels of fire activity in the past, both on human and geological timescales. It has been proposed that the morphology of these particles is also a valuable source of information, for example allowing inferences about the nature of the vegetation burned. This thesis aims to broaden the theoretical basis for these methods, and to integrate morphometric study of sedimentary charcoal with its quantification. Three key questions are addressed: firstly, whether the elongation of mesocharcoal particles is a useful indicator of fuel type; secondly, whether different sedimentary archives tend to preserve different charcoal morphologies; and finally, the critical question of how morphology affects charcoal quantification. The results corroborate the idea that grasses and trees produce mesocharcoal with distinctly different aspect ratios. However, the application of this as an indicator of vegetation change is complicated by the inclusion of species which are neither grasses nor trees, and by considerations of the effects of transportation. Charcoal morphotypes in diverse sedimentary environments are shown to be influenced by vegetation types, transportation history, and nature of the fire that produced them. Previous research has treated charcoal quantification and charcoal morphology as separate issues. Here it is shown that understanding morphology is essential for the accurate quantification of charcoal, since it affects the relationship between volumes and the two-dimensional areas from which measurements are taken. Understanding this relationship could allow such measurements to be used not just as relative measures of past fire activity, but to enable the accurate quantification of the charcoal sequestered in soils and sediments. This has important implications for our ability to understand the effects of fire on carbon cycling, and the role that fire plays in the Earth system.

No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Biochar (charcoal) is lauded by many scientists as an effective way to remove carbon dioxide from the atmosphere and storing it in a very stable form in the soil for hundreds to thousands of years, whilst promoting soil fertility and productivity. Considering that no significant amounts of charcoal are presently accumulating in the environment, despite considerable amounts produced globally in natural and man-made fires, this study focuses on understanding the degradation of biochar and its interactions with plants and soil organisms. The following experiments were conducted to achieve this goal. Controlled chemical oxidation of biochar, using different concentrations of hydrogen peroxide, was conducted in an attempt to mimic the enzymatic degradation of biochar by basidiomycetes. The changes occurring in biochars structure and chemistry were assessed afterwards. Furthermore, aerobic and anaerobic digestion of biochar was conducted in vitro, and in vivo to investigate the changes occurring in biochar‘s elemental composition and chemistry during oxidation and factors that play a determining role in the rate of biochar degradation. The influence of biochar in soil on free-living and symbiotic microbial communities as well as its impact on total plant biomass production and root development was assessed in three greenhouse pot trials using wheat and green beans as test plants It was proven that biochar is almost fully H2O2-degradable, mostly through hydroxylation and carboxylation reactions which led to the formation of various short chained carboxylic acids, surface saturation with acidic functional groups as determined by the surface acidity measurements and proven by the increase in the intensity of FT-IR peaks associated with carboxyl and phenolic C-O groups. Furthermore, hydrogen peroxide treatment resulted in preferential removal of volatile organic carbons and led to the purification of biochar as evident by the new, more intense and sharper peaks in the region of 1600-1000 cm-1. These FT-IR peaks are considered as the more recalcitrant fraction of biochar and were shown to be mostly associated with transformation products of lignin and cellulose formed during pyrolysis. The incubation trial confirmed that biochar cannot be utilized as a sole carbon source without the addition of nutrients or glucose, to activate microbial activity within the columns. Furthermore, abiotic oxidation can be facilitated by oxidative soil minerals such as birnessite, but oxidation with atmospheric oxygen did not result in the evolution of CO2 from biochar. The average CO2 production in pot trials without plants in both the fertilized and unfertilized treatments increased linearly (R2= 0.80; 0.79 respectively) with increasing biochar application rates when biochar was the main carbon sources. Anaerobic degradation of biochar by a methanogenic consortium was much more efficient in utilizing biochar as a carbon source, compared to aerobic digestion. The anaerobic digesters maintained a chemical oxygen demand (COD) removal efficiency of 30% per week with continuous production of CO2, whilst methane production was very erratic. We proposed that better control over pH and alkalinity as well as an increase in hydraulic retention time would improve both the COD removal efficiency and methane production. Field incubations resulted in various degrees of oxidation at different incubation sites. An increase in the oxygen content and a decreased in the carbon content of biochar‘s elemental composition and also an increase in the surface acidity due to a larger amount of carboxyl acid groups on the surface as seen in the increase in the FT-IR peak at 1700 cm-1 confirmed that biochar are susceptible to oxidation under field conditions. We came to the conclusion that oxidation and mineralization of biochar in this trial occurred at a faster rate in soils with a higher microbial activity. The pot trials, confirmed that biochar does not serve as a fertilizer even though it did increase total biomass production between biochar application rates of 0.05-2.5 % (w/w). For agricultural purposes the addition of biochar should always be applied together with NPK fertilizer. In both the wheat and green bean trials it was confirmed that biochar application rates of 0.05-0.5% (w/w) on the sandy, slightly acidic soil used in this trial resulted in the greatest biomass production and fertilizer use efficiency. Biochar additions resulted in considerable increases in soil pH and C/N ratios which were considered as the main reasons for the decrease in microbial biomass in the unfertilized green bean treatments as it made the uptake of N more limited. The addition of fertilizer however, alleviated N-supply constraints and as a result promoted microbial growth at all biochar application rates of pot trial 1. However, biochar did not promote mycorrhyzal colonization and caused a decrease in the mycorrhizal colonization of roots with increasing biochar application rates and within biochar layers. Biological nitrogen fixation, however, reacted positively to the addition of biochar. High biochar application rates significantly enhanced the plants reliance on these symbiotic relationships. We hypothesized that biochar physically immobilized N into its microvoids through capillary suction and then served as a physical barrier between plant roots and absorbed N. However, immobilzation of N by microbes could also have contributed to the decrease in N uptake if one takes into account that microbial activity was higher (respiration data) at the higher biochar application rates. Further investigations are needed to warrant this hypothesizes. / AFRIKAANSE OPSOMMING: Biochar (houtskool) is deur talle wetenskaplikes die lof toegeswaai as ‘n doeltreffende manier om koolstofdioksied uit die atmosfeer te verwyder en in ‘n baie stabiele vorm in die grond vir honderde tot duisende jare te stoor, terwyl dit die grondvrugbaarheid en produktiwiteit bevorder. As daar in ag geneem word dat geen beduidende hoeveelheid houtskool in die omgewing opgaar nie ondanks groot hoeveelhede wat wêreldwyd deur natuurlike en mensgemaakte brande gevorm word, is die doel van hierdie studie om die afbraak en die interaksie van biochar met plante en grondmikrobes beter te verstaan. Om hierdie doel te bereik is die volgende eksperimente uitgevoer: Beheerde chemiese oksidasie is op die biochar toegepas deur gebruik te maak van verskillende konsentrasies waterstofperoksied in 'n poging om die ensiematiese afbraak van biochar deur basidiomysete na te maak. Die veranderinge wat plaasvind in die struktuur en chemie van biochar is daarna bestudeer. Daarbenewens is die aerobiese and anearobiese afbraak van biochar toegepas beide in vitro- en in vivo-, om die veranderinge wat in biochar se elementele samestelling en chemie plaasvind gedurende oksidasie en ook die faktore wat 'n bepalende rol in die tempo waarteen biochar afbreek, te ondersoek. Die invloed van biochar in die grond op vrylewende en simbiotiese mikrobiese populasies, sowel as die impak daarvan op die totale plant biomassa produksie en ontwikkeling van plantwortels, is vasgestel tydens drie groeitonnel potproewe waarby koring en boontjies as planttoetsspesies gebruik is Dit is bewys dat biochar byna volledig deur H2O2 afgebreek kan word, meestal deur hidroksilasie en karboksilasie reaksies wat gelei het tot die vorming van 'n verskeidenheid kort ketting karboksielsure, 'n biochar oppervlak versadig met suurvormende funksionele groepe soos bepaal en bewys deur die toename in intensiteit van die FT-IR (Fourier Transvorm Infrarooi Spektroskopie) pieke geassosieer met karboksiel en fenoliese C-O groepe. Die behandeling van biochar met H2O2 het by voorkeur die vlugtige organise koolstof verwyder wat gelei het tot suiwering van die biochar, wat bevestig is deur die nuwe, meer intens en skerper FT-IR pieke in die area tussen 1600-1000 cm-1. Die FT-IR pieke word beskou as die meer weerstandbiedende fraksie van biochar en daar is bewys dat die pieke meestal met getransformeerde produkte van lignien en sellulose wat tydens pirolise gevorm is, geassosieer word. Die inkubasie proef het bevestig dat biochar nie deur mikrobes benut kan word as enigste bron van koolstof sonder die byvoeging van nutriente of glukose nie, om die mikrobes binne die inkubasie kolom te aktiveer. Daarbenewens kan abiotiese oksidasie van biochar deur oksidatiewe grondminerale soos birnessite (δ-MnO2) gefasiliteer word, terwyl oksidasie van biochar deur atmosferiese suurstof nie tot enige CO2 produksie gelei het nie. Nogtans het die gemiddelde CO2 produksie in die boontjie potproef, sonder die plante, in beide die onbemeste en bemeste behandelings linieer toegeneem (R2= 0.80; 0.79 onderskeidelik) met toenemende aanwendingskoers van biochar, toe biochar die dominante bron van koolstof was. Anaerobiese afbraak van biochar deur 'n metanogeniese konsortium was heelwat meer effektief in die benutting van biochar as enigste koolstofbron in vergelyking met aerobiese afbraak. Die anaerobiese verteertoestel het konstant 30% van die chemiese suurstof behoefte (CSB) weekliks verwyder, gepaardegaande met die voortdurende produksie van CO2, terwyl metaangasproduksie baie onegalig was. Dit word voorgestel dat met beter beheer oor pH en alkaliniteit en ook 'n langer hidrouliese retensie tyd, kan beide die CSB verwyderingseffektiwiteit en metaangasproduksie verbeter kan word. Veld inkubasies het verskeie mates van oksidasie meegebring tussen die verskillende inkubasie liggings. 'n Toename in die suurstofinhoud en 'n afname in die koolstof inhoud van biochar se elementele samestelling sowel as 'n toename in die oppervlak suurheid weens die groter hoeveelheid karboksielsure aan die oppervlak soos blyk uit die FT-IR piek by 1700 cm-1, het bevestig dat biochar wel vatbaar is vir oksidasie onder veld kondisies. Die gevolgtrekking was dat biochar oksidasie en mineralisasie in hierdie proef teen 'n vinniger tempo plaasgevind het in die gronde met hoer mikrobiese aktiwiteit. Die potproewe het bevestig dat biochar nie as bemestingsstof sal dien nie, alhoewel dit tot 'n toename in die biomassa produksie gelei het tussen die biochar aanwendingskoerse van 0.05-2.5% (w/w). Vir landbou doeleindes moet die aanwending van biochar altyd gepaardgaan met NPK bemesting. Beide die koring- en boontjie proewe het bevestig dat die biochar aanwendingskoerse tussen 0.05-0.5% (w/w) op die sanderig, effens suur grond wat gebruik is in die proef, gelei het tot die hoogste biomassa produksie en bemestingseffektiwiteit. Die toediening van biochar het gelei tot merkbare toenames in grond pH en C/N verhoudings en hierdie toestande was beskou as die hoof redes vir die afname in mikrobiese biomassa in die onbemeste boontjie behandelings omdat dit die opname van N meer beperk. Die toediening van bemesting het egter die beperkings op N voorsiening opgehef en as gevolg hiervan die mikrobiese biomassa bevorder by alle biochar aanwendingskoerse. Biochar het egter nie mikorrisa kolonisasie bevorder nie en het gelei tot =n afname in die mikorrisa kolonisasie van die wortels met toenemende biochar aanwendingskoerse en binne in die biochar lae van potproef 1. Biologiese stikstof vaslegging het egter positief reageer op die toediening van biochar. Hoë biochar aanwendingskoerse het beduidend die plant se afhanklikheid op hierdie simbiotiese verhouding verhoog. Ons hipotese is dat die biochar fisies N immobiliseer binne in die mikro-ruimtes deur kapillêre suigaksie en dan as 'n fisiese versperring dien tussen die plantwortels en die geabsorbeerde N. Die immobilisasie van minerale N deur mikrobes kon egter ook grootliks bygedra het tot die afname in N opname as daar in ag geneem word dat mikrobiese aktiwiteit (respirasie data) hoër was by die hoër biochar aanwendingskoerse. Verdere ondersoeke moet daarom uitgevoer word om hierdie hipotese te bevestig.