Call number: LD2668 .T4 1985 C52 / Master of Science

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The winemaking process involves a complex microbial flora where the interaction of yeasts, lactic acid bacteria and acetic acid bacteria play an important role in the quality and wholesomeness of the final product. Yeasts are primarily responsible for alcoholic fermentation. Malolactic fermentation follows alcoholic fermentation and is conducted by lactic acid bacteria. These bacteria are important in winemaking and can have a positive or negative effect on the wine quality. Biogenic amines are one of the compounds produced by lactic acid bacteria, which affect the hygienic quality and wholesomeness of the wine negatively and directly pose a health risk to the consumer. The demand of consumers for higher quality and healthier foods has led to renewed interest in studies on biogenic amines. Biogenic amines occur in a wide variety of food products, such as cheese, dried sausage, sauerkraut, fishery products, chocolates, wine and beer. This thesis focussed on the presence of biogenic amines in wine. The first objective of the study was to determine the ability of lactic acid bacteria isolated from South African wine to produce biogenic amines, using a decarboxylase screening plate method. The potential to produce the biogenic amines histamine, tyramine, putrescine and cadaverine was investigated. The results obtained showed that Lactobacillus species (Lactobacillus brevis and Lactobacillus hilgardil) might be the lactic acid bacteria responsible for tyramine and putrescine production and that it can contribute significantly to the overall biogenic amine content in wines. The results also suggest that amine production is strain dependent and not species specific. None of the lactic acid bacteria tested had the ability to produce histamine or cadaverine. It is important to remember that the ability of the lactic acid bacteria to produce biogenic amines has only been investigated in synthetic media and that it does not necessarily imply similar behaviour in wine. Wine represents a complex environment with a wide number of factors influencing microbial growth and decarboxylase activity and, thus, further investigation is necessary to determine if these amine-producing bacteria behave similarly in wine conditions. In addition, the polymerase chain reaction (PCR) amplification method was used for the identification of the tyrosine decarboxylase (TOe) gene in some of the tyramine-producing lactic acid bacteria. This was followed by the sequencing of the amplified products, which are partial TOe gene sequences, of two L. brevis strains and of a L. hilgardii strain. Only one tdc gene sequence has been described for bacteria (Enterococcus faecalis), while a partial TOC gene sequence from L. brevis lOEB 9809 was described. An amino acid sequence alignment of the three TOe gene fragments, obtained in this study, with the known TOe gene fragment of L. brevis lOEB 9809 and the tdc gene of E. faecalis showed a high degree of relatedness and conserved regions. To meet consumer demands, procedures are necessary to prevent the formation of amines in food products. One way of preventing the formation of biogenic amines is to relate amine production with certain lactic acid bacteria species involved in the winemaking process. Another possible way would be to develop a rapid detection method for bacteria carrying amino acid decarboxylase genes. The results of this study provide knowledge about which lactic acid bacteria in the winemaking process could contribute to the production of biogenic amines and the sequencing of additional partial TOe genes could possibly assist in the development of a rapid detection method for tyramine-producing lactic acid bacteria in food products. / AFRIKAANSE OPSOMMING: Die wynmaakproses behels 'n komplekse mikrobiese flora waar die interaksie van giste, melksuurbakterieë en asynsuurbakterieë 'n belangrike rol speel in die kwaliteit en heilsaamheid van die finale produk. Giste is primêr verantwoordelik vir alkoholiese fermentasie. Appelmelksuurgisting volg op alkoholiese fermentasie en word deur melksuurbakterieë uitgevoer. Hierdie bakterieë is belangrik in die maak van wyn en kan 'n positiewe of negatiewe uitwerking op die kwaliteit van wyn hê. Biogeniese amiene is een van die komponente wat deur melksuurbakterieë geproduseer kan word en wat die higiëniese kwaliteit en heilsaamheid van die wyn benadeel. Dit hou ook 'n gesondheidsrisiko vir die verbruiker in. Die vereiste van verbruikers vir hoër kwaliteit en gesonder voedselprodukte het nuwe belangstelling in studies op biogeniese amiene ontlok. Biogeniese amiene kom in 'n wye verskeidenheid voedselprodukte voor, soos kaas, droëwors, suurkool, vis, sjokolade, wyn en bier. Hierdie tesis fokus op die teenwoordigheid van biogeniese amiene in wyn. Die eerste doelwit van die studie was om melksuurbakterieë, wat uit Suid- Afrikaanse wyn geïsoleer is, se vermoë te bepaal om biogeniese amiene op dekarboksilase-agarplate te produseer. Die potensiaal om die biogeniese amiene histamien, tiramien, putresien en kadawerien te produseer, is bestudeer. Die resultate wat verkry is, toon dat Lactobacillus-spesies (Lactobacillus brevis en Lactobacillus hilgardit) vir tiramien- en putresienproduksie verantwoordelik is en dat hulle 'n belangrike bydrae kan lewer tot die totale biogeniese amienkonsentrasie in wyn. Die resultate dui ook daarop dat die produksie van amiene afhanklik is van die ras, en nié 'n spesifieke spesie nie. Geen melksuurbakterieë wat getoets is, het die vermoë getoon om histamien of kadawerien te produseer nie. Dit is belangrik om in ag te neem dat die vermoë van die melksuurbakterieë om amiene te produseer slegs in sintetiese media bestudeer is en dat dit nie noodwendig dieselfde gedrag in wyn sal toon nie. Wyn is 'n komplekse omgewing met 'n wye verskeidenheid faktore wat die mikrobiese groei en dekarboksilase-aktiwiteit kan beïnvloed, daarom is verdere studie nodig om vas te stelof hierdie amien-produserende bakterieë dieselfde gedrag in wyn sal toon. Die polimerase-kettingreaksie (PKR) amplifikasie-metode is vir die identifikasie van die tirosiendekarboksilase-geen (TDK) in sommige van die tiramienproduserende melksuurbakterieë gebruik. Dit is gevolg deur die volgordebepaling van die geamplifiseerde produkte, wat gedeeltelike TDK-geenvolgordes is, van twee L. brevis- en van een L. hilgardii-ras. Slegs een tdk-geenvolgorde is al voorheen vir bakterieë beskryf, nl. Enterococcus faecalis, asook 'n gedeeltelike TDK-geenvolgorde vir L. brevis lOEB 9809. 'n Vergelyking van die aminosuurvolgordes van die drie TDK-geenfragmente wat in die studie verkry is, het 'n hoë graad van ooreenkoms en gekonserveerde areas met die bekende TDK-geenfragment van L. brevis lOEB 9809 en die tdk-geen van E. faecalis getoon. Om verbruikers se behoeftes te bevredig, is dit noodsaaklik dat die vorming van amiene in voedselprodukte voorkom word. Een manier van voorkoming is om amienproduksie aan sekere melksuurbakterieë wat in die wynmaakproses betrokke is, te koppel. 'n Ander manier sal wees om 'n vinnige metode te ontwikkel vir die opsporing van bakterieë wat aminosuurdekarboksilase-gene dra. Die resultate van die studie verskaf kennis van watter melksuurbakterieë in die wynmaakproses tot die produksie van biogeniese amiene kan bydra. Die volgordebepaling van addisionele gedeeltelike TDK-gene kan moontlik tot die ontwikkeling van 'n vinnige opsporingsmetode van tiramien-produserende melksuurbakterieë in voedselprodukte bydra.

Biogenic volatile organic compounds (BVOC) are a wide-ranging group of trace gas components in the atmosphere which are emitted naturally from Earth’s surface. It is now recognised that biogenically sourced VOCs are far more significant on a global scale than those from anthropogenic sources, with up to 10 times greater emissions. Very few field-based studies of fluxes from plant canopies have been undertaken, particularly for non-terpenoid compounds. This thesis presents mixing ratio and flux measurements of BVOC from a range of temperate plant canopies: Douglas fir, short-rotation coppice willow, Miscanthus and mixed peatland vegetation. The virtual disjunct eddy covariance technique (vDEC) using a proton transfer reaction mass spectrometer (PTR-MS) as a fast VOC sensor was used for all measurements except for peatlands, where grab samples were collected on adsorbent sampling tubes for later chromatographic analysis. The PTR-MS was also utilised for measuring the rate of degradation of VOCs during laboratory chamber experiments. Mixing ratios and fluxes of VOCs measured within and above a Douglas fir forest were the first canopy-scale measurements for this species. Fluxes of monoterpenes were comparable to previous studies while isoprene was also detected (standard emissions factors up to 1.15 μg gdw -1 h-1 and 0.18 μg gdw -1 h-1, respectively). Emissions of oxygenated VOCs were also found to be significant, highlighting the importance of quantifying a wider variety of VOCs from biogenic sources, other than isoprene and monoterpenes. Results for bioenergy crops Miscanthus and willow showed that willow was a high isoprene emitter (20 μg gdw -1 h-1), but no measureable VOCs were detected from Miscanthus. This indicates that future expansion of bioenergy crops, and hence species selection, should take resultant air quality and human health impacts – due to changing VOC emissions – into account. Fluxes of BVOC from a Scottish peatland are the first reported measurements for this ecosystem in a temperate climate. Additionally, to assess the impact of nitrogen deposition on VOC fluxes, BVOC measurements were taken from sample plots in a pre-existing, long-term field manipulation study to assess impacts of wet nitrate or ammonium deposition on peatland. The peatland was found to be a significant source of isoprene and monoterpenes (590 and 1.5 μg m-2 h-1 respectively) and there was evidence that emissions were affected by wet nitrogen treatment. Isoprene emissions were reduced by both nitrate and ammonium treatment, while nitrate increased β- pinene fluxes. Increasing atmospheric nitrogen concentrations are therefore predicted to have an impact on VOC emission. Chamber studies showed that the rate of loss of α-pinene from the gas-phase during oxidation – and hence potential formation of secondary organic aerosol (SOA) – decreased with increasing isoprene mixing ratio. This was not observed for limonene. These results show that as isoprene mixing ratios increase with increasing global temperatures, negative feedback on radiative forcing from SOA particles may be suppressed. Results from this thesis provide valuable experimental data for a range of temperate plant canopies, which will help constrain modelled predictions of future VOC emissions. Additionally, the importance of understanding the effects of land use and environmental change on VOC emissions was demonstrated.

No description available.

A atmosfera terrestre contém nitrogênio e oxigênio, sendo este último, um composto altamente reativo e fundamental ao desenvolvimento e manutenção da vida. Além desses gases, diversos outros compostos em pequenas concentrações, os quais podem atuar como reagentes e/ou catalisadores também a compõe. Os compostos gasosos variados e material particulado (orgânico e inorgânico) de diferentes dimensões lançados constantemente à atmosfera são provenientes de fontes diversas. Tais fontes podem ser de origem natural ou antrópica e ainda, podem ser pontuais, difusas, primárias, secundárias, móveis e/ou estacionárias. Os processos envolvendo transformações químicas na atmosfera são extremamente importantes porque tendem a manter a sua composição em estado estacionário. A vegetação, que constitui uma fonte natural, é responsável pela emissão de grandes quantidades de compostos carbonados para a atmosfera. Dentre os vários compostos orgânicos emitidos da superfície do planeta, destacam-se em particular, alguns gases traços, denominados compostos orgânicos voláteis (COVs). A emissão dos compostos orgânicos voláteis pela vegetação ocorre, em escala global, predominantemente nos trópicos ou nos meses de verão em outras regiões. As reações fotoquímicas dos compostos orgânicos voláteis desempenham um papel diferenciado e importante na química da troposfera, podendo alterar de forma significativa a concentração de ozônio em áreas tanto urbanas quanto rurais. O presente projeto contempla o estudo de alguns dos inúmeros compostos orgânicos voláteis de origem biogênica (COVBs) emitidos pela vegetação constituinte, das regiões da Floresta Amazônica, da Mata Atlântica e da floresta Tropical da Guiana Francesa, comparando-se os dados de saída gerados pelos Modelos MOZART-4 e CAM-Chem. A escolha dos sítios experimentais para realização deste estudo se deu em parte em função da importância dos locais em termos de biodiversidade, extensão territorial, influência na climatologia (local e/ou regional), bem como também em função da acessibilidade, proximidade a centros urbanos e alterações devido à influência humana. O procedimento metodológico adotado para coleta das amostras de COVBs se deu por meio da técnica conhecida como acumulação de vórtices turbulentos (Relaxed Eddy Accumulation - REA), a qual faz uso de um dispositivo coletor denominado acumulador compacto de vórtices turbulentos (Compact Relaxed Eddy Accumulator - CREA). As amostras gasosas de COVBs foram coletadas por meio de cartuchos comerciais apropriados, compostos por diferentes materiais adsorvedores que apresentavam afinidade química também diferenciada para os variados compostos aos quais foram expostos. Estudos primários para determinação da natureza dos cartuchos que foram utilizados neste projeto foram realizados, a fim de se obter dispositivos adequados a este propósito. Os resultados evidenciam, como esperado, que a presença de isopreno é predominante em todos os sítios experimentais, sendo sua concentração média diária máxima de 5,0 ± 0,3 μg/cm3 registrada na Amazônia e de 8,0 ± 0,4 μg/cm3 (concentração diária) na floresta da Guiana Francesa, seguido pelo alfa-pineno cuja concentração máxima obtida foi de aproximadamente 1,6 ± 0,08 μg/cm3 no último sítio experimental, ambos detectados na estação seca. A emissão de isopreno e dos monoterpenos ocorreu de forma mais acentuada na época seca em comparação ao período úmido. Contudo, observou-se em algumas situações uma pequena discrepância. De maneira geral os resultados gerados pelos modelos estão subestimados, como exceção do parâmetro de radiação fotossinteticamente ativa (PAR), o que indica que a defasagem entre os resultados observados e os simulados pode estar relacionada parâmetros de OH-, NOx e em algumas reações químicas fotoquímicas envolvendo o ozônio. / The Earth\'s atmosphere contains nitrogen and oxygen, the last one being a highly reactive compound and fundamental to the development and maintenance of life. Besides these gases, many other compounds in small concentrations, which can act as reactants and /or catalysts can be found in the atmosphere. Various gaseous compounds and particulate matter (organic and inorganic) of different dimensions constantly released into the atmosphere come from various sources. Such sources can be natural or anthropogenic and still be punctual, diffuse, primary, secondary, mobile and or stationary. Processes involving chemical transformations in the atmosphere are extremely important because they tend to maintain their steady-state composition. The vegetation, which is a natural source, is responsible for producing large amounts of carbon compounds in the atmosphere. Among the various organic compounds emitted from the planet\'s surface, stand out in particular, some trace gases, called volatile organic compounds (VOCs). The emission of volatile organic compounds by vegetation occurs on a global scale, predominantly in the tropics or in the summer months in other regions. The photochemical reactions of volatile organic compounds play an important and unique role in the chemistry of the troposphere, which can significantly change the concentration of ozone in both urban and rural areas. This project involves the study of some of the numerous biogenic volatile organic compounds (BVOC) emitted by vegetation from the Amazon Forest, the Mata Atlântica forest and the Tropical forest of French Guiana, comparing the output data generated by MOZART -4 and CAM-Chem models. The choice of experimental sites for this study was in part due to the importance of local biodiversity , territorial extent , influence the weather (local and/or regional), and also because of accessibility, proximity to urban centers and changes due to human influence . The methodological procedures for collecting samples of VOCs was through the technique known as eddy accumulation (Relaxed Eddy Accumulation - REA), which uses an equipment known as compact relaxed eddy accumulator (CREA). The gas samples were collected from BVOCs through appropriate commercial cartridges, composed of different materials showed that chemical affinity adsorbents also differentiated for the various compounds which were exposed. Primary studies to determine the nature of cartridges that were used in the field campaigns were conducted in order to obtain devices suitable for this purpose. The results show, as expected, the presence of isoprene as a prevalent compound in all experimental sites, with maximum daily average concentration of 5,0 ± 0,3 μg/cm3 registered on the Amazon basin and 8,0 ± 0,4 μg/cm3 (daily concentration) in the forest of French Guiana, followed by alpha-pinene, whose maximum concentration obtained was approximately 1,6 ± 0,08 μg/cm3 in the last experimental site, both detected in the dry season. The emission of isoprene and monoterpenes occurred sharply in the dry season compared to the wet season. However, it was observed in some situations a small discrepancy. In general, the results generated by the models are underestimated, as an exception of photosynthetically active radiation parameter (PAR), indicating that the gap between the observed and simulated results can be related to OH- and NOx parameters and some chemical reactions involving photochemical ozone.

Latossolos são os solos mais representativos do Brasil, comumente associados a solos altamente intemperizados, profundos, e muito homogêneos. Essa homogeneização é atribuída ao processo de formação denominado bioturbação, que é a mistura de partículas do solo, inclusive fitólitos, que em condições tropicais são principalmente causadas pela ação de cupins, formigas, minhocas, e raízes de plantas. Os fitólitos são corpos de sílica opalina formados através da absorção do ácido monossilícico pelas raízes das plantas, que após a transpiração são polimerizados e tomam forma da célula ou tecido em que foram depositados. A análise fitolítica tem sido utilizada para reconstituições do clima, vegetação e ambientes pretéritos, pois sua composição (sílica biogênica) permite uma preservação nos solos, por longos períodos. Entretanto, as reconstituições paleoambientais realizadas em Latossolos têm sido contestadas devido à expressiva atividade biológica nesses solos, que podem \'pertubar\' a assembleia fitolítica colocando em dúvida a validade da técnica. Considerando a hipótese de que a bioturbação não é um processo homogêneo em todo o perfil, o estudo objetivou compreender a influência da atividade biológica na distribuição de fitólitos em dois Latossolos de texturas contrastantes. Os resultados obtidos para as análises químicas e físicas classificaram os solos em LATOSSOLO VERMELHO Distrófico típico (Perfil 1), e LATOSSOLO VERMELHO-AMARELO Distrófico típico (Perfil 2). Neste trabalho não foram feitas datações, impossibilitando o estabelecimento da cronologia dos eventos, porém as análises isotópicas e fitolíticas sugerem que estes solos foram formados sob vegetação mista de plantas do ciclo C3 e C4, com predomínio de plantas C3. As análises dos resultados não marcam mudanças climáticas, apenas oscilações de momentos mais secos que o atual. O protocolo adotado de observação e quantificação por área de feições biológicas em blocos e seções delgadas permitiu inferir que a bioturbação apresentou maior influência nos níveis do solo onde se constatou pela análise isotópica períodos em que as condições ambientais eram mais quentes e úmidas, esse comportamento refletiu na distribuição de fitólitos ao longo do perfil, com maiores concentrações de morfotipos em superfície e declínio com a profundidade. O contraste textural entre os solos estudados também promoveu diferenças na preservação dos fitólitos. No perfil de textura mais argilosa, os fitólitos apresentaram maior grau de preservação, em contrapartida, no perfil de textura média, e portanto menores teores de argila, óxidos de ferro e matéria orgânica, a superfície dos fitólitos estiveram mais expostas ao contato com os grãos de quartzo, favorecendo o ataque químico, fazendo com que nesse perfil os fitólitos fossem menos preservados. A presença de fitólitos corroídos em superfície e o aparecimento de fitólitos bem preservados em maiores profundidades indicou mistura causada pela bioturbação, mesmo em zonas onde a mesma foi menos expressiva. Por outro lado, mesmo com fortes indícios de mistura em atributos morfológicos, físicos e químicos a bioturbação não ocasionou alterações bruscas nas assembleias de fitólitos, indicando que os Latossolos mesmo sendo intensamente remodelados pela fauna edáfica e ação de raizes representam um bom registro de mudanças ambientais. / Ferralsols are the most representative soils of Brazil, commonly associated weathered, deep, and very homogeneous soils. This homonegenization is attributed to the formation process called bioturbation, which is the mixture of the soil particles, including phytoliths, which in tropical conditions are mainly caused by action of termites, ants, eartworms, e plant roots. Phytoliths are opaline silica bodies formed by the uptake of monossilicic acid by plant roots, which after evapotranspiration are polymerized and take the form of the cell or tissue in which they were deposited. The phytolytic analysis has been used for reconstitutions of the climate, vegetation and past environments, since its composition (biogenic silica) allows a preservation in the soils, for long periods. However, the paleoenvironmental reconstitutions carried out in Ferralsols have been challenged due to the significant biological activity in these soils, which may \'disturb\' the phytolithic assembly, casting doubt on the validity of the technique. Considering the hypothesis that bioturbation is not a homogeneous process throughout the profile, the study aimed to understand the influence of biological activity on the distribution of phytoliths in two Latosols of contrasting textures. The results obtained for the chemical and physical analysis classified the soils in Rodhic Ferralsol (clayic, dystric) (profile 1), Haplic Ferralsol (loamic, dystric) (profile 2). In this work no dating was made, making it impossible to establish the chronology of the events, but the isotopic and phytolytic analyzes suggest that these soils were formed under mixed vegetation of C3 and C4 plants, with predominance of C3 plants. The analyzes of the results do not mark climatic changes, only oscillations of moments drier than the present one. Bioturbation showed greater influence in the soil in periods where the environmental conditions were hotter and wetter, this behavior reflected in the distribution of phytoliths along the profile, with higher concentrations of surface morphotypes and decline with depth. The textural contrast between the studied soils also promoted differences in the preservation of phytoliths. In the more clayey texture profile, the phytoliths presented a higher degree of conservation, in contrast, in the medium texture profile, and therefore lower levels of clay, iron oxides and organic matter, the phytoliths were more exposed to the contact of their surface with the with higher quartz grains, providing larger areas of contact for the chemical attack, making the phytoliths less preserved in this profile. The presence of corroded phytoliths on the surface and the appearance of well preserved phytoliths at greater depths indicated a mixture caused by bioturbation, even in areas where it was less expressive. On the other hand, even with strong mix of evidence in morphological attributes, physical and chemical bioturbation did not cause abrupt changes in phytoliths assemblies, indicating that Latosols even being intensively refurbished by the soil fauna and roots of action represent a good record of environmental changes .

Les composés organiques volatils d’origine biogénique (COVB) contribuent à plus de 90% des émissions des COV dans l'atmosphère. Ces composés sont éliminés de l’atmosphère par réaction avec les photo-oxydants (OH, NO3, Cl et O3) et par photolyse. Ces processus sont gouvernés par un mécanisme en chaîne dont les porteurs sont des radicaux libres tels que les radicaux peroxyles RO2 qui jouent un rôle clé dans la dégradation atmosphérique des COV. Dans ce contexte, cette thèse se concentre d’une part sur l’étude cinétique en température et mécanistique de la réaction d’ozonolyse, la détermination des spectres UV et la photolyse de six COV oxygénés insaturés (trans-2-pentènal, trans-2-hexènal, 2-méthyl-2-pentènal, 1-pentèn-3-ol, cis- 2-pentèn-1-ol et trans-3-hexèn-1-ol), et d’autre part l’étude de la réactivité de trois radicaux peroxyles (CH3OCH2O2, CH3C(O)CH2O2 et (CH3)2C(OH)CH2O2) vis-à-vis des radicaux nitrates à différentes températures. Trois dispositifs expérimentaux sont utilisés : une chambre de simulation atmosphérique couplée à une spectroscopie infrarouge à transformée de Fourier (FTIR) et à une chromatographie en phase gazeuse associée à une spectrométrie de masse (GC/MS), un dispositif de mesure des spectres UV-Visible et la photolyse laser couplée à une spectrométrie UV-visible et diode laser. Ces dispositifs associés à des méthodes de traitement permettent d'extraire des données cinétiques en température, mécanistiques et spectroscopiques. Les paramètres cinétiques obtenus sont utilisés pour estimer les durées de vie atmosphériques des espèces étudiées. Les résultats mécanistiques sont utilisés pour élaborer les mécanismes d’ozonolyse de ces composés. Toutes ces données permettent d’enrichir les bases de données cinétiques, mécanistiques et spectroscopiques qui alimentent les modèles atmosphériques. / Biogenic volatile organic compounds (BVOC) account for 90% of VOC emissions in the atmosphere. These VOCs can be removed from the atmosphere by reaction with photo-oxidants (OH, NO3, Cl and O3) as well as by photolysis. All these processes are governed by a chain mechanism whose carriers are mainly free radicals such as peroxy radicals RO2. Hence the importance of characterizing the reactivity of these species that play a key role in the atmospheric degradation of VOCs. In this context, this thesis focuses on the determination of the temperature dependent kinetic data as well as the mechanism of the ozonolysis reaction and the UV absorption spectra along the photolysis of six unsaturated oxygenated VOCs (trans- 2-pentenal, trans-2-hexenal, 2-methyl-2-pentenal, 1-penten-3-ol, cis-2-penten-1-ol and trans-3-hexen-1-ol). Likewise, the temperature dependent kinetic parameters of the reaction of three peroxy radicals (CH3OCH2O2, CH3C(O)CH2O2 et (CH3)2C(OH)CH2O2) with nitrate radicals were also determined. Three experimental setups coupled to treatment methods were used to extract these data: an atmospheric simulation chamber coupled to both a Fourier-transform infrared spectroscopy (FTIR) and a gas chromatography connected to a mass spectrometry (GC/MS), a device for measuring UV-Visible spectra and a laser photolysis coupled with UV-visible spectrometry and laser diode spectroscopy. The kinetic parameters were used to estimate the atmospheric lifetimes of the studied species. While the mechanistic data were used to establish their ozonolysis mechanisms. All the collected data enrich kinetic, mechanistic and spectroscopic databases, improving atmospheric models specially those involving VOCs.

Peat soils are known to be a significant emitter of atmospheric greenhouse gasses. However, the spatial and temporal variability in production and release of greenhouse gases (such as methane) in peat soils remains uncertain, particularly for low-latitude peatlands like the Florida Everglades, as the majority of studies on gas dynamics in peatlands focus on northern peatlands. The purpose of the work outlined here is focused on understanding the spatial and temporal variability in biogenic gas dynamics (i.e. production and release of methane and carbon dioxide) by implementing various experiments in the Florida Everglades at different scales of measurement, using noninvasive hydrogeophysical methods. Non-invasive methods include ground-penetrating radar (GPR), gas traps, time-lapse cameras, and hydrostatic pressure head measurements, that were constrained with direct measurements on soil cores like porosity, and gas composition using gas chromatography. By utilizing the measurements of in-situ gas volumes, we are able to estimate gas production using a mass balance approach, explore spatial and temporal variabilities of gas dynamics, and better constrain gas ebullition models. A better understanding of the spatial and temporal variability in gas production and release in peat soils from the Everglades has implications regarding the role of subtropical wetlands in the global carbon cycle, and can help providing better production and flux estimates to help global climate researchers improve their predictions and models for climate change. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

The climatic history of the planet Earth is characterized by long- and short-term climatic variations. Oxygen isotopic data clearly shows how during the Cenozoic (from 65 Ma to the present) our planet shifted over time, from greenhouse to icehouse climate states up to the present. Along this progressive cooling, the record is dotted by rapid warming and cooling transient events, from which the causes are not yet fully understood. One problem with paleoceanographic reconstructions is that the older the event, the harder it is to find a sedimentary record in which the paleoclimatic proxies are preserved enough to be used with confidence. This work has the goal of illustrating the possibility to develop a new paleoenvironmental indicator based on the magnetic properties of magnetite crystals synthetized by magnetotactic bacteria. The sensibility of such crystals to small changes in dissolved oxygen content in the pore water and water column is well known, and can be exploited to reconstruct such changes from the sedimentary record. Qualitative information regarding this topic are defined in scientific literature, but, so far, no quantitative study has been performed. This is the first attempt to quantify the preservation of biogenic magnetite as a function of oxygenation state of waters, and is based on recent sediment extracted from cores collected in the coastal region of Rio de Janeiro (Saco do Mamanguá, Paraty). From these, where it was possible to obtain magnetic data relative to magnetite crystals together as well with as direct measurements of pore water chemistry. The results of this first attempt were used to analyze climatic and oceanographic conditions in two other sites, representative of key past environmental events during the Paleocene. The first case study was performed in a newly descripted sedimentary outcrop in central Turkey, of middle Eocene age, representative of a period of rapid warming (Middle Eocene Climatic Optimum, MECO). The second case study was done using material from a marine sediment core collected in the Ross Sea (Antarctica) that covers from the late Eocene to the Middle Miocene, a period that saw the onset of the modern, permanent ice sheet cover in the Antarctic continent. / A historia climática da Terra é caracterizada por variações climáticas de curto e longo prazo, com variações de condições, as vezes extremas. Dados de isótopos de oxigênio mostram claramente que durante o Cenozoico (desde 65 Ma até o presente) o nosso planeta passou de uma fase quente caracterizada por marcado efeito estufa (durante o Paleoceno) para um período progressivamente mais frio em direção ao presente. Ambos esses estados são caracterizados pela alternância de eventos transientes quentes e frios de relativa curta duração, sendo que destes a maioria ainda não é plenamente compreendida. Um dos principais problemas das reconstruções paleoceangráficas é que quanto mais antigo o evento mais difícil encontrar sequências sedimentares cujo registro de proxies paleoambientais seja preservado e confiável. Este trabalho visa explicitar a possibilidade de desenvolver um novo indicador paleoambiental, baseado em propriedades magnéticas de cristais de magnetita biosintetizados por bactérias magnetotáticas. Tais cristais biogênicos são notavelmente sensíveis a pequenas variações de oxigênio dissolvido na coluna de água e na agua intersticial entre os poros dos sedimentos marinhos, e essa sensibilidade pode ser explorada para reconstruir variações climáticas no registro sedimentar do passado. Informações qualitativas estão disponíveis na literatura cientifica mas, até agora, não existem estudos que quantifiquem essa relação. Esta primeira tentativa de quantificar a preservação de magnetita biogênica em função do estado de oxigenação de águas se baseia em testemunhos coletados na costa do estado do Rio de Janeiro (Saco do Mamanguá, Paraty), onde foi possível coletar dados magnéticos relativos aos cristais de magnetita biogênica concomitantemente a medidas diretas de química da água intersticial. Os resultados desse primeiro estudo foram aplicados para reconstruções de variações climáticas e oceanográficas em duas seções que registram importantes mudanças climáticas durante o Paleogeno. No primeiro caso, um afloramento localizado na Turquia central de idade Eocenica e representativo de um período de rápido aquecimento (Ótimo Climático do Eoceno Médio, Middle Eocene climatic Optimum, MECO). No segundo caso, um testemunho coletado no Mar de Ross (Antártica) que abrange o período entre o Eoceno superior e o Mioceno médio, durante o qual houve a formação da primeira cobertura de gelo permanente no continente antártico.

Die acinösen Speicheldrüsen der Schabe Periplaneta americana sind reich durch serotonerge, dopaminerge und GABAerge Fasern innerviert. Die biogenen Amine Serotonin (5-HT) und Dopamin (DA) induzieren die Sekretion eines NaCl-haltigen Primärspeichels. Die physiologische Rolle der GABAergen Innervation des Drüsenkomplexes war bislang unbekannt. Weiterhin wurde vermutet, dass Tyramin (TA) und Octopamin (OA) an der Speichelbildung beteiligt sind. Mittels intrazellulärer Ableitungen von sekretorischen Acinuszellen mit und ohne Stimulierung des Speicheldrüsennervs (SDN) sollte daher die Wirkung von GABA, TA und OA im Speicheldrüsenkomplex untersucht werden. Intrazelluläre Ableitungen aus Acinuszellen zeigten, dass sowohl DA als auch 5 HT biphasische Änderungen des Membranpotentials induzierten. Diese bestanden aus einer initialen Hyperpolarisation und einer darauf folgenden transienten Depolarisation. Stimulierung des SDN mittels einer Saugelektrode verursachte ebenfalls biphasische Änderungen des Membranpotentials der Acinuszellen, die mit den DA- bzw. 5-HT-induzierten Änderungen kinetisch identisch waren. Dieses Ergebnis zeigte, dass die elektrische Stimulierung des SDN im Nerv-Speicheldrüsenpräparat eine verlässliche Methode zur Untersuchung der Wirkungen von Neuromodulatoren auf die dopaminerge und/oder sertotonerge Neurotransmission ist. Die Hyperpolarisation der DA-induzierten Potentialänderungen wurde durch eine intrazelluläre Ca2+-Freisetzung und die Öffnung basolateral lokalisierter Ca2+-gesteuerter K+-Kanäle verur-sacht. Die DA- und 5-HT-induzierte Depolarisation hing kritisch von der Aktivität eines basolateral lokalisierten Na+-K+-2Cl--Symporters ab. GABA, TA und OA potenzierten die elektrischen Antworten der Acinuszellen, wenn diese durch SDN-Stimulierung hervorgerufen wurden. Dabei war OA wirksamer als TA. Dieses Ergebnis zeigte, dass diese Substanzen als im Drüsenkomplex präsynaptisch und erregend als Neuromodulatoren wirken. Pharmakologische Untersuchungen ergaben, dass die erregende Wirkung von GABA durch einen G-Protein-gekoppelten GABAB-Rezeptor vermittelt wurde. Messungen der durch SDN-Stimulierung induzierten Flüssigkeits- und Proteinsekretionsraten zeigten, dass beide Parameter in Anwesenheit von GABA verstärkt waren. Dies ließ auf eine verstärkte serotonerge Neurotransmission schließen, da nur 5-HT die Bildung eines Protein-haltigen Speichels verursacht. Immuncytochemische Untersuchungen zeigten, dass die Drüsen tyraminerge und octopaminerge Innervation empfangen. Weiterhin wurde der erste charakterisierte TA-Rezeptor (PeaTYR1) der Schabe auf einem paarigen, lateral zur Drüse ziehenden Nerv markiert, der auch tyraminerge Fasern enthielt. Die vorliegende Arbeit trug zum Verständnis der komplexen Funktionsweise der Speicheldrüse der Schabe bei und erweiterte das lückenhafte Wissen über die neuronale Kontrolle exokriner Drüsen in Insekten. / The cockroach Periplaneta americana has acinar type salivary glands. The secretory acini consist of P-cells, responsible for electrolyte and water secretion and C-cells that secrete protein into the saliva. Salivation is controlled by the dopaminergic and GABAergic salivary neurons SN1 and SN2, and by several smaller serotonergic neurons. Dopamine (DA) and serotonin (5-HT) induce the secretion of a NaCl-rich saliva. The physiological role of the GABAergic innervation was unknown. Furthermore, the cellular actions of the biogenic amines DA and 5-HT were poorly understood. Based on studies on other insect salivary glands a role for octopamine (OA) and tyramine (TA) acting as neuromodulators was suggested. In this study, intracellular recordings of the basolateral membrane potential of acinar cells were performed to examine direct and modulating actions of the biogenic amines DA, 5-HT, OA, TA and of GABA. A nerve-gland preparation was developed and used to investigate the actions of neuromodulators, namely GABA, OA and TA. DA and 5-HT induced biphasic membrane potential changes, consisting of an initial hyperpolarization and a transient depolarization. The DA-induced hyperpolarization was mediated by intracellular Ca2+-release and subsequent opening of basolateral Ca2+-dependent K+-channels. The DA- and 5-HT-induced depolarization was dependent on the presence of extracellular Na+ and the activity of a basolateral Na+-K+-2Cl--cotransporter. Electrical stimulation of the salivary duct nerve (SDN) by means of a suction electrode induced membrane potential changes with the same kinetics as those induced by bath application of DA and 5-HT. These results suggested that electrical nerve stimulation is a adequate method to investigate presynaptic effects of neuromodulators. GABA, OA and TA affected neither the resting membrane potential of the acinar cells, nor the DA- or 5 HT- induced potential changes. When GABA was applied during SDN-stimulation, it enhanced the amplitudes of the membrane potential changes of the acinar cells as well as fluid- and protein secretion rates of the glands. Pharmacological experiments revealed that the excitatory action of GABA in the gland complex is mediated by a metabotropic GABA receptor (GABAB-type). OA and TA enhanced the membrane potential changes of the acinar cells when these were induced by SDN-stimulation, suggesting presynaptic excitatory roles for both amines in the gland complex. Immunocytochemistry revealed rich innervation of the salivary glands with octopamine- immunoreactive fibers that were also stained by the tyramine-antibody, and with tyramine-immunoreactive fibers lacking octopamine-immunoreactivity. Since the tyramine receptor PeaTYR1 is expressed in the salivary gland complex, its distribution was investigated by using a specific antibody. Immunoreactivity was detected in a paired nerve of unknown root. This nerve innervated only few acini lying in the periphery of the gland complex and contained tyraminergic fibers. This study extends our knowledge about the complex neuronal control and function of insect salivary glands.