rio Tapajós é o quinto maior afluente do rio Amazonas e apresenta uma das faunas de peixes mais diversas do mundo. Esses peixes realizam funções ao longo de toda a bacia hidrográfica da Amazônia, como a dispersão de sementes, a ciclagem de nutrientes e o transporte de biomassa entre rios pobres e ricos em nutrientes. Porém, a pesca e o desmatamento podem afetar esses serviços ecossistêmicos. Para o baixo rio Tapajós ainda não se conhece os efeitos da pesca e do desmatamento nas dinâmicas populacionais das principais espécies de peixes consumidos pelas populações ribeirinhas. Definir e quantificar a estrutura da teia trófica do baixo rio Tapajós é fundamental para a compreensão da sua capacidade produtiva, e da transferência de energia para sustentar os níveis tróficos superiores. O presente estudo teve como principais objetivos analisar a estrutura da teia trófica do baixo Rio Tapajós, e avaliar a dinâmica populacional de algumas espécies de peixes simulando o incremento da pesca e do desmatamento. Para modelar a teia trófica foi utilizado o programa Ecopath com dados de desembarques pesqueiros e analise de conteúdo estomacal de peixes. Os resultados mostraram que a transferência de energia na teia trófica do Rio Tapajós se dá igualmente entre as cadeias de herbivoría e detritivoría. As espécies-chave são piscívoras- insetívoras: Acaronia nassa, Cichla spp., Pellona castelnaeana e também predadores de topo, como os botos (Inia geoffrensis, Sotalia fluviatilis). As simulações para os próximos 30 anos indicaram que: o desmatamento é o maior fator de estresse para a teia trófica, reduzindo entre 10% e 100% a biomassa dos principais grupos biológicos; o aumento da pesca incidiu negativamente na dinâmica populacional de quelônios, pirarucu, dourada e pescada levando uma diminuição de biomassa entre 40% e 100%. Os resultados deste estudo quantificam com maior precisão a função da pesca e desmatamento na dinâmica populacional dos principais peixes de importância alimentar e comercial das populações ribeirinhas do baixo Rio Tapajós, sendo relevantes para iniciativas de manejo desse ecossistema.

Foram estudados 115 pacientes, de ambos os sexos, com idade igual ou superior a 15 anos, residentes na cidade de Manus ou na sua zona rural, portadores de derrame pleural de qualquer etiologia, exceto a traumática, no período de 01/07/84 a 01/07/86. Foram estudados os aspectos etiológicos, clínicos e sócio-econômico dos pacientes, através da aplicação de um questionário padrão, bem como a realização de exames complementares, necessários para a detrminação dea etiologia do derrame pleural. Os dados coletados foram analisados , quando quantitativos, pelo teste "f' de Student, e quando qualitativos pelo teste do "Qui-quadrado", com a utilização da correção de Yates para pequenas amostras; adotando-se o nível de 5% para o alfa. No estudo da correlação utilizou-se o teste de Pearson, com igual nível de significância. O estudo demonstrou que o derrame pleural foi mais frequente no sexo masculino, em brancos, de famílias mais numerosas, de menor poder aquisitivo e de menor cobertura previdenciária que o restante da população manauara. A tuberculose foi a causa, confirmada, de maior frequência, mais comum no sexo masculino e acomentendo a faixa etária mais jovem. / We studied 115 patient, of both sexes, with the same or superior age to 15 years, rinesidents in the city of Manaus or in its rural zone, carriers of pleural effusion of any origin except the traumatic, in the period from 01/07/84 to 01/07/86. They were studied the etiologics aspects , clinicai and socioeconomic of the patients, through the application of a standard questionnaire, as well as the accomplishment of complementai exams, necessary for the determination of the origin of the pleural effusion The collected data were analyzed, when quantitative, for the test "t" of Student, and when qualitative for the test of the "Qui-square", with the use of the correction of Yates for small samples; being adopted the levei of 5% for the alpha. In the study of the correlation the test of Pearson was used, with the same significance levei. The study demonstrated that the pleural effusion was more frequent in the masculine sex, in whites, of more numerous families, of smaller purchasing power and of smaller covering social security than the remaining of the population manauara. The tuberculosis went to cause, confirmed, of larger frequency, more common in the masculine sex and reaching the youngest age group.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2014-06-09T17:08:21Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_FitoplanctonReservaDesenvolvimento.pdf: 895475 bytes, checksum: ae4b9bf44ef2aac0f6ec53481182dd7c (MD5) / Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2014-07-22T15:41:16Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_FitoplanctonReservaDesenvolvimento.pdf: 895475 bytes, checksum: ae4b9bf44ef2aac0f6ec53481182dd7c (MD5) / Made available in DSpace on 2014-07-22T15:41:16Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_FitoplanctonReservaDesenvolvimento.pdf: 895475 bytes, checksum: ae4b9bf44ef2aac0f6ec53481182dd7c (MD5) Previous issue date: 2012 / FAPESPA - Fundação Amazônia de Amparo a Estudos e Pesquisas / O ambiente amazônico é caracterizado por uma grande sazonalidade no nível da água, o que provoca uma flutuação anual, regular e de grande amplitude, no nível do rio Amazonas e seus tributários. Essas variações decorrentes dos alagamentos típicos de várzea foram denominadas como pulsos de inundação. Dentro da diversidade encontrada na várzea está o fitoplâncton, sendo que o estudo taxonômico e da diversidade desses organismos pode ser utilizado para avaliar o ambiente e inferir sobre as prováveis causas de danos ecológicos, tornando-se imprescindível para uma adequada compreensão da estrutura e funcionamento dos ecossistemas aquáticos. Além disso, a flora planctônica do estado do Amazonas com seus inúmeros ambientes aquáticos é ainda pouco conhecida. Este estudo teve como objetivo descrever e comparar a estrutura da comunidade fitoplanctônica em canais de várzea da Reserva de Desenvolvimento Sustentável Mamirauá (RDSM) e em trechos dos rios Japurá e Solimões, determinada pelos atributos: riqueza, composição e densidade, e verificar sua relação com as variáveis: temperatura, pH, oxigênio dissolvido, transparência e condutividade, nos períodos de seca (novembro/2008) e de cheia (julho/2009) do ciclo hidrológico. O estudo baseou-se em 14 amostras coletadas com rede de plâncton com malha de 20 μm, na subsuperfície da água. A comunidade fitoplanctônica esteve composta por 150 taxa, classificados em oito classes taxonômicas. A classe Chlorophyceae foi a mais representativa nos canais de várzea e a classe Bacillariophyceae nos rios, no período de seca, sendo que a classe Zygnemaphyceae predominou no período de cheia nos dois tipos de ambientes. A maior riqueza de espécies observada nas áreas de várzea está, provavelmente, associada à maior disponibilidade de nutrientes devido ao maior tempo de residência da água. O oxigênio dissolvido e a transparência foram os principais fatores determinantes da variação da riqueza e composição do fitoplâncton. Em relação à composição das espécies, através da Análise de Correspondência Destendenciada (DCA), verificou-se a separação das amostras, entre os dois períodos e entre ambientes. Esse resultado foi confirmado pela análise de similaridade (ANOSIM), mostrando que existe uma diferença significativa de composições de espécies entre os períodos e entre os tipos de ambientes. Já a composição de espécies, avaliada pelo teste de Mantel parcial, evidenciou similaridade entre amostras coletadas no período de cheia e, no de seca, a formação de um grupo de espécie para cada ambiente. Portanto, o pulso de inundação foi o principal estruturador dos parâmetros ambientais, da composição e da riqueza desta comunidade nos diferentes ambientes, determinando as variações encontradas no fitoplâncton das águas brancas desta região da Amazônia Central. / The Amazonian environment is characterized by a great seasonality in the water level, which causes a regular and broad annual fluctuation in the water level of the Amazon River and its tributaries. These variations resulting from typical floodplain flooding were termed as flood pulses. Phytoplankton among the diversity found in this floodplain and the study of taxonomic and the diversity of these organisms can be used to assess the environment and infer about the probable causes of ecological damage, which is essential for a proper understanding of the structure and functioning of aquatic ecosystems. In addition, the study of the phytoplankton community in the state of Amazonas, with its numerous aquatic ecosystems, is still little known. This study aimed to describe and compare structure of the phytoplankton community, correlating it with the abiotic variables. The collections were performed in 14 locations, using a plankton net (mesh size 20 μm) on subsurface of the water column in two stages of the hydrologic cycle: drought (November 2008) and flood (July 2009) in the Mamirauá Sustainable Development Reserve. Variables of conductivity, pH, dissolved oxygen and transparency were concomitantly measured. The phytoplankton community consisted of 150 taxa, being distributed in eight taxonomic classes. Class Chlorophyceae was the most representative in the floodplain channels and class Bacillariophyceae in rivers during the dry season; at the same time, class Zygnemaphycaea was predominant in the flood season in the two types of environments. The greatest species richness observed in the channels is probably associated with the increased availability of nutrients due to greater water residence time. Dissolved oxygen and transparency were the main determining factors of the richness variation and phytoplankton composition. Regarding the composition of species, the separation of the samples between the two periods and between environments was observed through the Detrented Correspondence Analysis. This result was confirmed by the Analysis of Similarity ANOSIM, showing a significant difference between species compositions between both seasons and types of environments. By the Mantel test, the composition of species showed similarity in the flood season and the formation of a group of species for each type of environment in the drought season. Therefore, the pulse of flooding was the main designer of environmental parameters, composition and richness of this community in different environments, determining the variations found in the phytoplankton of white water, in the Central Amazon region.

O estudo da geologia e geoquímica do carbonatito Seis Lagos e da jazida de Nb e ETR associada foi realizado a partir de testemunhos de dois furos de sondagem efetuados pela CPRM nos anos 70. Um dos furos, locado numa parte mais central do morro dos Seis Lagos, perfurou a crosta laterítica mineralizada, interpretada como formada a partir do carbonatito alterado. O outro furo, locado fora da estrutura mineralizada, perfurou a encaixante gnáissica e cortou, a 230 m de profundidade, um dique de carbonatito originalmente descrito neste trabalho. As técnicas utilizadas foram microscopia ótica, microscopia eletrônica, difratometria de raios X e análises químicas de rocha total por ICP. As características químicas e mineralógicas do carbonatito caracterizam-no como um siderita carbonatito. O Nb ocorre na forma mineralógica de chumbopirocloro; os ETR ocorrem principalmente na monazita e subordinadamente na barita e na gorceixita. O carbonatito apresenta concentrações anômalas de Nb, ETRL (especialmente pelo Ce), Ba, Sr e Pb. A crosta laterítica foi subdividida em 7 tipos texturais/composicionais, do topo para a base: crosta pisolítica, crosta fragmentada, crosta mosqueada, crosta roxa com oólitos, crosta manganesífera, crosta roxa e crosta marrom. Em todas as crostas, a hematita é o mineral mais abundante, seguido pela goethita; na crosta manganesífera (até 32% de MnO), o principal mineral de Mn é a hollandita; os ETR ocorrem na forma de florencita (secundária) e o Nb na forma de Nb-rutilo e Nb-brookita (ambos relictos). A Nb-brookita ocorre na forma de oólitos com estrutura do tipo anéis de Liesegang, sua origem pode ser ligada ao estágio hidrotermal. A crosta manganesífera exerceu um forte efeito (scavenger) sobre a distribuição vertical de alguns elementos, notadamente pelo Co, Ba, Ce e ETRP que, lixiviados de crostas superiores, foram enriquecidos na crosta manganesífera. A remobilização dos ETR durante a lateritização foi bem menor nas crostas mais inferiores. Nestas, o Ce4+ foi fortemente estabilizado e enriquecido em até 10 vezes. Além deste, somente o La foi apenas localmente um pouco enriquecido. O enriquecimento do Nb na laterita em relação ao carbonatito foi da ordem de 10 vezes, eventualmente atingindo 100 vezes. As modificações nas concentrações de Nb ao longo do perfil laterítico são associadas a variações nas composições do protólito e aos processos de abatimento da laterita. Um processo de bauxitização posterior parece ter afetado a parte superior do perfil laterítico; parte da florencita aí existente pode ser ligada a esta fase. / The geology and geochemistry of the Seis Lagos carbonatite and the Nb and REE bearing associated ore deposit were studied using cores of two drill holes performed by CPRM in the 70´s. One of the drills, allocated in a central part of the Seis Lagos hill, cut a weathered and mineralized lateritic crust that was interpreted as formed by the carbonatite alteration. The other core, allocated outside the mineralized structure, cut the gneissic host rock and a carbonatite dyke, at 230m depth. This carbonatite is first described in this report. The techniques used in this work were the optic microscopy, scanning electron microscopy, X-ray diffraction and ICP bulk rock chemical analyses. The chemical and mineralogical carbonatite data classify it as a siderite carbonatite. Th and Nb occur as plumbopyrochlore; REE as monazite and, subordinately, in barite and gorceixite. Anomalous concentrations of Nb, LREE (especially Ce), Ba, Sr and Pb were found in the carbonatite. The lateritic crust were subdivided in 7 textural/compositional types, from top to bottom: pisolitic crust, fragmented crust, mottled crust, purple crust with oolits, manganesitic crust, purple crust and brown crust. In all of the crusts, the hematite is the main mineral, followed by goethite; at the manganesitic crust (up to 32% of MnO), the main Mn mineral is hollandite; the REE occurs as florencite (secondary) and the Nb crystallize as Nb-rutile and Nb-brookite (both relict). The Nb-brookite occurs at the form of oolits with Liesegang rings structures, and its genesis may be connected to a hydrothermal stage. The manganesitic crust produced a strong effect (scavenger) over the vertical distribution of some elements, especially the Co, Ba, Ce and HREE that were leached from upper crusts and enriched in the manganesitic crust. The remobilization of REE during the lateritization process was less effective in the lower crusts. In these, the Ce4+ was strongly stabilized and enriched up to 10 times. In addition to this, only the La was locally slightly enriched. The enrichment of Nb in laterite, in relation to the carbonatite, was on average 10 times, eventually up to 100 times. The change in the Nb concentrations along the laterite profile was associated to the changes in the protolith composition and laterite collapse process. A posterior bauxitic process seems to have affected the upper lateritic profile, and part of the florencite can be connected to this stage.

Conservators treat and repair a huge array of damaged and degrading materials on a regular basis. As such, there are many techniques and protocols in place to deal with these problems successfully, be that via preventative or interventive methods. However, there is need for new and innovative techniques that offer long term stabilisation to materials and objects that are prevalent within museum collections. As an alternative to some of these conservation techniques, hydration with supercritical carbon dioxide was investigated here. Both modern and historic, hardwood and softwood samples were successfully hydrated using this technique. The addition of a co-solvent (methanol) to the supercritical fluid solvent stream was used as a method to increase the solubility of water in carbon dioxide, and therefore improve levels of hydration. To evaluate the extent of any damage being caused during the supercritical fluid treatment, microstructural and macrostructural analytical techniques were carried out. The supercritical hydration technique allowed historic wood to be hydrated and stabilised. Strength properties were seen to be maintained or improved after the supercritical treatment, providing conservators with a viable method of hydration. A feasibility study looking at the cleaning and characterisation of historic leather samples was investigated using spectroscopic methods. The sensitivity of Diffuse Reflectance Infrared Fourier Transform spectroscopy on historic leather was explored. Additionally, changes in elemental composition on the surface of the leather were monitored using Scanning Electron Microscopy Energy Dispersive spectroscopy. Cleaning historic leather via a supercritical carbon dioxide solvent stream showed the greatest potential for future work. However, the characterisation of unattributed historic leather is a vast and complex task that would require the expertise of a leather conservator, if the investigation were to be continued.

Franz Schubert (1797-1828) left many musical scores containing his earliest compositional efforts. Here 'earliest' is taken, for convenience, to refer to the works from the first extant (1810) up to and including the lied Gretchen am Spinnrade (1814), his first generally recognized masterpiece. This dissertation tells the story tracing those efforts in a chronological series of analytical essays. The essays mention only incidentally the external evidence of the home environment, lessons received, concerts attended, and so on, but refer instead primarily to the internal evidence of the compositions themselves, that is, the notes on the page. That story has not previously been told in these terms. The dissertation is thus a contribution to musical analysis applied to a quite important and certainly instructive but very little-known repertoire. An essential feature is that the story proceeds chronologically, to the (fairly large) extent that the exact chronology is known. Over a hundred works are involved, some containing several movements, so the story is necessarily long. Further, music is by no means a simple phenomenon, so the story is necessarily detailed. Another feature contributes to the tracing of the skein of anticipations of resources used in Schubert's later and more famous works, as well as to the evidence of derivation from models of other composers' works. Each work studied is provided with identifying information; musical incipits are also provided in view of the unfamiliarity of the repertoire. This identifying information, though necessary, is merely auxiliary to the story being told, and is accordingly set off from the latter. After the chronological story has been completed, a series of summaries is presented under the various categories of musical analysis; these summaries naturally refer back to the individual works. The ferreting out and telling of the story is itself the aim; no hypothesis is entertained. A review of the story yields several main results concerning the various elements of musical composition. (1) Schubert's attitude to the important matter of sonata form ranged from initial rather extreme experimentation possibly combined with some degree of misunderstanding to a clearly demonstrated ability to handle it convincingly first shown perhaps in his First Symphony D082 (October 1813). (2) Melody and text setting also showed early extremes as in the long and wild ballad Der Taucher D077 (first version September 1813 - April 1814), subsequently settling down, from about his first Opera D084 (first version October 1813 - May 1814), to a more suitable range of expression which was to serve him so well. (3) Counterpoint remained something of a weakness throughout, being used often but only in simple manifestations. (4) Harmony and orchestration were in general well handled throughout and many experiments were noted in methods of modulation. (5) An important factor to be found not in the notes but in the text of the score contributed to the mastery shown in Gretchen am Spinnrade (among other factors which are explored): Schubert's coming into contact with the inspiring poetry of Goethe. Three conclusions are offered on the broadest level. (1) The extent of Schubert's progress as a composer over the period studied was on the whole slight, because of the wealth of resources already at his disposal at the starting point at age 13. (2) The time at which Schubert wrote his first Symphony and first Opera - about October 1813 - is proposed as marking a settling down from earlier extravagance to more acceptably controlled writing. That applies to the two genres, instrumental and vocal music, on the one hand, as well as to the techniques of form and expression, on the other. It thus divides the period studied into two stages. (I naturally hope here to avoid oversimplification and acknowledge that the division is by no means watertight.) (3) By October 1814, the end of the present investigation, it was only in vocal music and specifically the lied, thus not also in instrumental or stage music, that real mastery can be recognized.

Absorbed dose distributions in lineal energy for neutrons and gamma rays were measured by using both a tissue-equivalent walled counter (TEPC) and a graphite-walled low pressure proportional counter (GPC) in the Am-Be neutron source facility at UOIT. A series of measurements were performed with the counters filled with propane-based TE gas (55.1% C3H8, 39.5% CO2 and 5.4% N2) at operating gas pressures corresponding to tissue spheres 2.0 , 4.0 and 8.0 μm in diameter. The results of these measurements indicated satisfactory performance of counters to measure microdosimetric spectra extending down to event-sizes that cover the gamma component of a mixed field. The spectra and the related mean values ̅y F and ̅y D are compared with other similar work but with monoenergetic neutrons of different energy range, the agreement between them is good. An assessment of the performance of different size TEPC has been done. An excellent agreement between their event size spectra was found and the proton edge appears at the same position on the lineal energy scale and differences in microdosimetric parameters ̅ and ̅ is not exceeding 3%, which is in the region of counting statistics. In Am-Be neutron field, the efficiency of the TEPCs was measured to have an average value of 250 counts per μSv or equivalently about 4.17 counts per minutes per μSv/hr. This efficiency is reasonable for dose equivalent measurements but needs a long integration period. The measurements showed that the dose equivalent which depends on the measurement of energy deposition by the secondary charged particles was originated mainly from elastic collisions of the incident neutrons with hydrogen atoms. Moreover the number of events in the sensitive gas is dominated by proton recoils. A non- negligible fraction of the dose equivalent resulted from gamma interactions, alpha and recoil nuclei. The energy deposition patterns in these micro-scale targets are strongly dependent on radiation quality, so differences of linear energy transfer (LET) of the components in a mixed radiation field are significant. Accordingly, in a radiation field with an unknown gamma ray energy spectrum, absorbed dose for neutrons can be obtained by the separation of neutron induced events from gamma events using their distribution in lineal energy. To separate neutron dose from gamma dose a simple lineal energy threshold technique has been used in addition to a more sophisticated methods using γ-fitting and the graphite-walled counter measurements. The results of this study will establish the degree of error introduced by using a lineal energy threshold, which is likely to be used in any hand-held neutron monitor based on TEPCs. / UOIT

The fate and mobility of boric acid in the environment is largely controlled by adsorption reactions with soil organic matter and soil minerals to form surface complexes (Marzadori et al., 1991; Su and Suarez, 1995; Yermiyahu et al., 1995; Peak et al., 2002). The effects of humic acid (HA) and dissolved CO2 on boric acid adsorption on amorphous (am)-Al(OH)3 were investigated as their influence on sorption is potentially important. Although a model system was used in the studies, the findings should be generally useful to better understand the mobility and bioavailability of boric acid in the soil ecosystems.<p>In this dissertation, boric acid adsorption on pure am-Al(OH)3 and 5% w/w HA coated am-Al(OH)3 were investigated both as a function of pH (4.5 11) and initial boric acid concentration (0 4.5 mmol L-1). Batch adsorption isotherm experiments were also conducted with samples exposed to atmospheric CO2 and anaerobic (N2) conditions to examine the effects of dissolved CO2 on boric acid adsorption. Both the pH envelope and the adsorption isotherm experiments showed that the HA coating on am-Al(OH)3 and the presence of dissolved CO2 decreased boric acid adsorption. <p>Raman spectroscopy and boron (B) K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy were used to investigate the coordination of boric acid adsorbed at mineral/water interfaces. The Raman spectroscopy was less successful than expected as there were difficulties in identifying B bands in the 5% w/w HA coated am-Al(OH)3 samples.<p>The B K-edge XANES spectroscopy yielded better results. The XANES spectra of boric acid adsorption samples showed that both trigonal BO3 and tetrahedral BO4 coordinated complexes are present on the pure and HA coated mineral surfaces. At pH 7.0 and 9.2, the adsorption of boric acid on am-Al(OH)3 is predominantly inner-sphere trigonal complexes; with minor amounts of inner-sphere tetrahedral complexes. Both macroscopic and spectroscopic experiments revealed that the combination of HA coating on am-Al(OH)3 and dissolved CO2 decreased boric acid adsorption compared to adsorption on pure am-Al(OH)3.<p>The discoveries in this dissertation contribute significantly in understanding the effects of HA and dissolved CO2 has on boric acid adsorption in the environment. Since B speciation and the stability of am-Al(OH)3 mineral and HA changes with pH, the bioavailability of B is expected to change as well with pH. The adsorption on boric acid on am-Al(OH)3 and/or HA coated am-Al(OH)3 is expected to decrease the amount of boric acid available to plants. Therefore the nutrient management regimen will have to be modified for soils that are high in natural organic matter, carbonate and/or aluminum hydroxyl species.

This study looks at how media representations change regarding Somalis in Minneapolis, Minnesota, USA, under the course of a project called “I AM A STAR for Somalia”, launched in April 2011. A quantitative content analysis of print media is employed, concentrating on factors such as actors, subjects, patterns of quoting, involvement and article prominence. Various studies are used as a foundation, including Teun Van Dijk (1991), which introduce and explain theories such as Ideology and Racism, Agenda Setting, Minimal Effects and Integration. Ultimately, the analysis reveals a change in media portrayals correlating with the I AM A STAR project; Somalis are portrayed in roles and stories which normalise their representation in the year following the launch. In the second year, however, these positive effects are not as apparent.

The fate and mobility of boric acid in the environment is largely controlled by adsorption reactions with soil organic matter and soil minerals to form surface complexes (Marzadori et al., 1991; Su and Suarez, 1995; Yermiyahu et al., 1995; Peak et al., 2002). The effects of humic acid (HA) and dissolved CO2 on boric acid adsorption on amorphous (am)-Al(OH)3 were investigated as their influence on sorption is potentially important. Although a model system was used in the studies, the findings should be generally useful to better understand the mobility and bioavailability of boric acid in the soil ecosystems.<p>In this dissertation, boric acid adsorption on pure am-Al(OH)3 and 5% w/w HA coated am-Al(OH)3 were investigated both as a function of pH (4.5 11) and initial boric acid concentration (0 4.5 mmol L-1). Batch adsorption isotherm experiments were also conducted with samples exposed to atmospheric CO2 and anaerobic (N2) conditions to examine the effects of dissolved CO2 on boric acid adsorption. Both the pH envelope and the adsorption isotherm experiments showed that the HA coating on am-Al(OH)3 and the presence of dissolved CO2 decreased boric acid adsorption. <p>Raman spectroscopy and boron (B) K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy were used to investigate the coordination of boric acid adsorbed at mineral/water interfaces. The Raman spectroscopy was less successful than expected as there were difficulties in identifying B bands in the 5% w/w HA coated am-Al(OH)3 samples.<p>The B K-edge XANES spectroscopy yielded better results. The XANES spectra of boric acid adsorption samples showed that both trigonal BO3 and tetrahedral BO4 coordinated complexes are present on the pure and HA coated mineral surfaces. At pH 7.0 and 9.2, the adsorption of boric acid on am-Al(OH)3 is predominantly inner-sphere trigonal complexes; with minor amounts of inner-sphere tetrahedral complexes. Both macroscopic and spectroscopic experiments revealed that the combination of HA coating on am-Al(OH)3 and dissolved CO2 decreased boric acid adsorption compared to adsorption on pure am-Al(OH)3.<p>The discoveries in this dissertation contribute significantly in understanding the effects of HA and dissolved CO2 has on boric acid adsorption in the environment. Since B speciation and the stability of am-Al(OH)3 mineral and HA changes with pH, the bioavailability of B is expected to change as well with pH. The adsorption on boric acid on am-Al(OH)3 and/or HA coated am-Al(OH)3 is expected to decrease the amount of boric acid available to plants. Therefore the nutrient management regimen will have to be modified for soils that are high in natural organic matter, carbonate and/or aluminum hydroxyl species.