Na bacia do alto e médio Rio Negro, na região Amazônica, os Espodossolos são solos com representação espacial significativa. Estes solos têm sua gênese ligada a dois diferentes processos: a um sistema de transformação Latossolo-Espodossolo, desenvolvido sobre rochas do embasamento cristalino e outro formado diretamente a partir de rochas sedimentares. Os Espodossolos armazenam grande quantidade de carbono em seus horizontes espódicos profundos. Os modelos climáticos preveem mudanças nos padrões de precipitação, com maior frequência de períodos secos na Amazônica, resultando em abaixamento do nível freático, que levaria a um aumento da porosidade, e assim aumento na mineralização da matéria orgânica estocada nestes horizontes. Diversos fatores podem influenciar nas taxas de mineralização do carbono, como os processos pedogenéticos, materiais de origem dos solos, a vegetação presente e a característica da matéria orgânica nos diferentes horizontes dos solos. Nesse contexto, o objetivo foi caracterizar a matéria orgânica, em seus aspectos físico-químicos e avaliar sua vulnerabilidade diante de mudanças pedoclimáticas. Para isto, foi necessário avaliar a distribuição de tamanho de partículas e a composição mineralógica dos solos, determinar as concentrações e composições isotópicas de carbono e de nitrogênio, de amostras de solo, verificar a característica da matéria orgânica e quantificar a mineralização de carbono do solo nos diferentes horizontes. Os resultados mostraram que a matéria orgânica presente nos horizontes espódicos encontra-se mais humificada, e essa recalcitrância acarreta menores taxas de emissão de CO2 para a atmosfera. A mineralogia do solo, assim como a distribuição do tamanho de partículas contribuíram para maior proteção da matéria orgânica, aumentando sua estabilidade e diminuindo a susceptibilidade a mineralização nesses horizontes. A distribuição de tamanho de partículas e quantidade das frações granulométricas diferentes nas duas áreas refletem a influência do material de origem, que associadas a vegetação influenciam nas concentrações e emissão de carbono. Nos horizontes espódicos as emissões e os fluxos de C para a atmosfera foram menores que nos horizontes superficiais em razão da maior humificação da matéria orgânica e, provavelmente, pela deficiência de nitrogênio. Os horizontes espódicos profundos, considerando as áreas de Barcelos e São Gabriel da Cachoeira, são responsáveis pela liberação para atmosfera de 8 x 1013 g C ano-1, valor que corresponde aproximadamente a 1 % do que volta para a atmosfera anualmente por meio da respiração do solo. Esta quantidade não pode ser negligenciada quando da elaboração de modelos de previsões de mudanças climáticas / In the upper and middle Rio Negro basin, in the Amazon region, Spodosols are soils with significant spatial representation. These soils have their genesis linked to two different processes: a system of Latosol-Spodosol transformation, developed on rocks of the crystalline basement and another formed directly from sedimentary rocks. Spodosols store large amounts of carbon in their deep spodic horizons. The climate models predict changes in precipitation patterns, with a higher frequency of dry periods in the Amazon, resulting in lowering the water table, which would lead to an increase in porosity, and thus increase the mineralization of the organic matter stored in these horizons. Several factors may influence carbon mineralization rates, such as pedogenetic processes, soil source materials, present vegetation and organic matter characteristics in different soil horizons. In this context, the objective was to characterize the organic matter, in its physicochemical aspects and to evaluate its vulnerability to pedoclimatic changes. For this, it was necessary to evaluate the particle size distribution and the mineralogical composition of the soils, determine the isotopic and carbon and nitrogen composition and concentrations of soil samples, verify the organic matter characteristic and quantify soil carbon mineralization in different horizons. The results showed that the organic matter presented in the spodic horizons is more humid, and this recalcitrance leads to lower rates of CO2 emission into the atmosphere. Soil mineralogy as well as particle size distribution contributed to greater protection of organic matter, increasing its stability and reducing susceptibility to mineralization in these horizons. The distribution of particle size and amount of different particle sizes in the two areas reflected the influence of the source material, which associated with vegetation influenced the concentrations and carbon emission. In the spodic horizons, the emissions and fluxes of C to the atmosphere were smaller than in the superficial horizons due to the greater humification of the organic matter and, probably, the nitrogen deficiency. The deep spodic horizons, considering the areas of Barcelos and São Gabriel da Cachoeira, are responsible for the release to atmosphere of 8 x 1013 g C year-1, a value that corresponds approximately to 1% of what returns to the atmosphere annually through the respiration of the soil. This amount cannot be neglected when developing forecast models of climate change

Na bacia do alto e médio Rio Negro, na região Amazônica, os Espodossolos são solos com representação espacial significativa. Estes solos têm sua gênese ligada a dois diferentes processos: a um sistema de transformação Latossolo-Espodossolo, desenvolvido sobre rochas do embasamento cristalino e outro formado diretamente a partir de rochas sedimentares. Os Espodossolos armazenam grande quantidade de carbono em seus horizontes espódicos profundos. Os modelos climáticos preveem mudanças nos padrões de precipitação, com maior frequência de períodos secos na Amazônica, resultando em abaixamento do nível freático, que levaria a um aumento da porosidade, e assim aumento na mineralização da matéria orgânica estocada nestes horizontes. Diversos fatores podem influenciar nas taxas de mineralização do carbono, como os processos pedogenéticos, materiais de origem dos solos, a vegetação presente e a característica da matéria orgânica nos diferentes horizontes dos solos. Nesse contexto, o objetivo foi caracterizar a matéria orgânica, em seus aspectos físico-químicos e avaliar sua vulnerabilidade diante de mudanças pedoclimáticas. Para isto, foi necessário avaliar a distribuição de tamanho de partículas e a composição mineralógica dos solos, determinar as concentrações e composições isotópicas de carbono e de nitrogênio, de amostras de solo, verificar a característica da matéria orgânica e quantificar a mineralização de carbono do solo nos diferentes horizontes. Os resultados mostraram que a matéria orgânica presente nos horizontes espódicos encontra-se mais humificada, e essa recalcitrância acarreta menores taxas de emissão de CO2 para a atmosfera. A mineralogia do solo, assim como a distribuição do tamanho de partículas contribuíram para maior proteção da matéria orgânica, aumentando sua estabilidade e diminuindo a susceptibilidade a mineralização nesses horizontes. A distribuição de tamanho de partículas e quantidade das frações granulométricas diferentes nas duas áreas refletem a influência do material de origem, que associadas a vegetação influenciam nas concentrações e emissão de carbono. Nos horizontes espódicos as emissões e os fluxos de C para a atmosfera foram menores que nos horizontes superficiais em razão da maior humificação da matéria orgânica e, provavelmente, pela deficiência de nitrogênio. Os horizontes espódicos profundos, considerando as áreas de Barcelos e São Gabriel da Cachoeira, são responsáveis pela liberação para atmosfera de 8 x 1013 g C ano-1, valor que corresponde aproximadamente a 1 % do que volta para a atmosfera anualmente por meio da respiração do solo. Esta quantidade não pode ser negligenciada quando da elaboração de modelos de previsões de mudanças climáticas / In the upper and middle Rio Negro basin, in the Amazon region, Spodosols are soils with significant spatial representation. These soils have their genesis linked to two different processes: a system of Latosol-Spodosol transformation, developed on rocks of the crystalline basement and another formed directly from sedimentary rocks. Spodosols store large amounts of carbon in their deep spodic horizons. The climate models predict changes in precipitation patterns, with a higher frequency of dry periods in the Amazon, resulting in lowering the water table, which would lead to an increase in porosity, and thus increase the mineralization of the organic matter stored in these horizons. Several factors may influence carbon mineralization rates, such as pedogenetic processes, soil source materials, present vegetation and organic matter characteristics in different soil horizons. In this context, the objective was to characterize the organic matter, in its physicochemical aspects and to evaluate its vulnerability to pedoclimatic changes. For this, it was necessary to evaluate the particle size distribution and the mineralogical composition of the soils, determine the isotopic and carbon and nitrogen composition and concentrations of soil samples, verify the organic matter characteristic and quantify soil carbon mineralization in different horizons. The results showed that the organic matter presented in the spodic horizons is more humid, and this recalcitrance leads to lower rates of CO2 emission into the atmosphere. Soil mineralogy as well as particle size distribution contributed to greater protection of organic matter, increasing its stability and reducing susceptibility to mineralization in these horizons. The distribution of particle size and amount of different particle sizes in the two areas reflected the influence of the source material, which associated with vegetation influenced the concentrations and carbon emission. In the spodic horizons, the emissions and fluxes of C to the atmosphere were smaller than in the superficial horizons due to the greater humification of the organic matter and, probably, the nitrogen deficiency. The deep spodic horizons, considering the areas of Barcelos and São Gabriel da Cachoeira, are responsible for the release to atmosphere of 8 x 1013 g C year-1, a value that corresponds approximately to 1% of what returns to the atmosphere annually through the respiration of the soil. This amount cannot be neglected when developing forecast models of climate change

Uma evidência contundente da ocupação pré-histórica na Amazônia são os solos de cor escura com material arqueológico, conhecidos regionalmente como Terra Preta de Índio (TPI). Apesar de amplamente estudados, alguns de seus atributos permanecem ainda pouco conhecidos, especialmente os micromorfológicos, mineralógicos e geoquímicos. Esses estudos podem identificar os processos envolvidos na gênese e evolução desses solos, e quando empregados em conjunto com estudos fitolíticos, podem auxiliar na elucidação das suas formas de uso pretéritas. O objetivo desse estudo foi obter uma aproximação da hierarquia dos processos envolvidos na gênese desses solos e as suas prováveis formas de uso em tempos pré-colombianos. A pesquisa foi conduzida no Campo Experimental do Caldeirão, Iranduba - AM. Foram estudados dois perfis com TPI (P1 e P2) e um solo adjacente com horizonte A moderado (P3). Em cada horizonte foram coletadas amostras deformadas para análises físico-químicas, mineralógicas e geoquímicas e a cada 5 cm de profundidade para análise fitolítica e isotópica. Lâminas delgadas de amostras indeformadas de horizontes selecionados foram confeccionadas e descritas em sua micromorfologia, com posterior exame em microscópio eletrônico de varredura com microanálise química. A idade dos solos foi estabelecida com base em datações 14C de carvões. A microestrutura granular das TPI é de origem zoogenética e geoquímica. A gênese dos horizontes antrópicos envolveu: i) a ação do homem descartando e queimando resíduos (antropização); ii) espessamento do horizonte A e escurecimento dos horizontes subsuperficiais por bioturbação (cumulização e melanização); iii) dispersão e translocação de colóides (argiluviação); iv) condições pedoambientais diferentes das atuais (pedorrelíquia - nódulos ferruginosos). Revestimentos de argila com extinção forte, contínua e estriada nas cerâmicas indica que o processo de argiluviação é atual. O processo de elutriação predomina no solo não antrópico. A degradação dos nódulos de ferro na TPI favorece a xantização e atua como fonte de argila (pedoplasmação). Arecaceae e Cyperaceae são mais abundantes nos horizontes antrópicos, notadamente nos níveis com maior quantidade de cerâmica. A ausência de fitólitos de plantas domesticadas indica que a formação das TPI não está relacionada com práticas agrícolas. As evidências fitolíticas demonstram que as atividades antrópicas ocorreram de forma mais intensa no P1. A rápida ciclagem de silício, evidenciada pela presença de fitólitos com silicificação incompleta, favorece a estabilidade da mineralogia caulínitica. VHE, ilita e variscita-estrengita ocorrem somente nos perfis com TPI. P2O5-CaO-K2O-NaO-Cs-Co-Zn-Cu-Ba-Rb-Ni representa a assinatura geoquímica das TPI. A presença de variscita-estrengita, tridimita e maghemita nas TPI, notadamente nas cerâmicas, confirma a formação de minerais em decorrência das práticas antrópicas. As cerâmicas apresentam predominantemente cauixi (Tubella reticulata e Parnula betesil) e cariapé (Licania utilis). A presença comum de micas primárias nesses artefatos sugere material alóctone em seu fabrico. As TPI resultam da adição de artefatos arqueológicos e melanização de horizontes pedogenéticos não antropizados. Tais atividades enriqueceram em nutrientes e alteraram a assinatura geoquímica do solo, assim como promoveram a formação de minerais. Essa antropização acelerou os processos de argiluviação e de degradação de petroplintitas. No decorrer de sua evolução, foram utilizados e adicionados resíduos de plantas, destacadamente de palmeiras e Cyperaceae. / A remarkable evidence of human occupation in Amazonian region is the existence of soils with dark colors and presence of ceramic materials, known as Indigenous Dark Earth (IDE). Despite of widely studied some of their features are still poorly understood, mainly that related to micromorphology, mineralogy and geochemical aspects. Such approach, in combination to phytolytic studies, is able to identify soil genesis processes and unravel the comprehension of occupation mechanisms of human. The aim of this study was to establish the hierarchy of these processes and their association with ancient activities of pre-Columbian populations. The research was carried out in the experimental site of Caldeirão, Iranduba city (Amazon state, Brazil). Two pedons containing surface anthropogenic horizons (P1 and P2) were directly compared to a non-anthropogenic soil (P3). In each soil horizon disturbed soil samples were sampled in order to perform physical, chemical, mineralogical and geochemical analyses. For phytolitic analyses samples were taken each 5 cm of depth. Micromorphological samples were studied in thin sections in the optical microscope and further analyzed in Scanning Electron Microscopy (SEM). The chronology was accomplished after 14C dating. The microaggregates in anthropogenic horizon are related to geochemical and biological processes. The genesis of IDE implicates in the following mechanisms: i) disposal and burning of residues by humans (anthropization); ii) deepening A horizons and darkening subsurface horizons by bioturbation (cumulization and melanization processes); iii) dispersion and migration of colloidal particles leading to argiluviation process; iv) different condictions of environment that not occur nowdays (pedorelict - ferruginous nodules). Clay coatings with extinction bands and continuous orientation in the ceramic artifacts suggest a current argiluviation process. The degradation of Fe nodules enhances the xantization process also providing clay (source of clay). The prevalent soil genesis in non-anthropic soil is the elutriation. The degradation of Fe nodules in the IDE enhances the xantization process also providing clay (pedoplasmation). The number of phytoliths of Arecaceae and Cyperaceae is higher in IDE than non-IDE, mainly in the horizons with more ceramics. The phytolitic evidence demonstrate that activities anthropic was more intense in the P1. The rapid Si cycling, highlighted by the presence of phytoliths without complete silicification, contribute to stability of kaolinitic mineralogy. HIV, illite and variscite-strengite are constrained to IDE pedons. P2O5-CaO-K2O-NaO-Cs-Co-Zn-Cu-Ba-Rb-Ni represents the geochemical signature of IDE. The presence of maghemite, variscite-strengite and tridimite strengthen a mineral forming process linked to human activity. In ceramic materials there is a prevalence of phytoliths from cauixi (Tubella reticulata and Parnula betesil) and cariapé (Licania utilis). The presence of mica suggests an alloctone material for their manufacturing. Hence the anthropic horizons result from the addition of archeological artifacts and melanization of non-anthropic horizons. These activities chemically enriched and modify the geochemical signature of soil, as soon as promoted formation of minerals. The anthropic activities conducted the argiluviation and degradation of Fe nodules. During their evolution there was a clear addition of plant residues, notably related to palm trees and Cyperaceae species.

Uma evidência contundente da ocupação pré-histórica na Amazônia são os solos de cor escura com material arqueológico, conhecidos regionalmente como Terra Preta de Índio (TPI). Apesar de amplamente estudados, alguns de seus atributos permanecem ainda pouco conhecidos, especialmente os micromorfológicos, mineralógicos e geoquímicos. Esses estudos podem identificar os processos envolvidos na gênese e evolução desses solos, e quando empregados em conjunto com estudos fitolíticos, podem auxiliar na elucidação das suas formas de uso pretéritas. O objetivo desse estudo foi obter uma aproximação da hierarquia dos processos envolvidos na gênese desses solos e as suas prováveis formas de uso em tempos pré-colombianos. A pesquisa foi conduzida no Campo Experimental do Caldeirão, Iranduba - AM. Foram estudados dois perfis com TPI (P1 e P2) e um solo adjacente com horizonte A moderado (P3). Em cada horizonte foram coletadas amostras deformadas para análises físico-químicas, mineralógicas e geoquímicas e a cada 5 cm de profundidade para análise fitolítica e isotópica. Lâminas delgadas de amostras indeformadas de horizontes selecionados foram confeccionadas e descritas em sua micromorfologia, com posterior exame em microscópio eletrônico de varredura com microanálise química. A idade dos solos foi estabelecida com base em datações 14C de carvões. A microestrutura granular das TPI é de origem zoogenética e geoquímica. A gênese dos horizontes antrópicos envolveu: i) a ação do homem descartando e queimando resíduos (antropização); ii) espessamento do horizonte A e escurecimento dos horizontes subsuperficiais por bioturbação (cumulização e melanização); iii) dispersão e translocação de colóides (argiluviação); iv) condições pedoambientais diferentes das atuais (pedorrelíquia - nódulos ferruginosos). Revestimentos de argila com extinção forte, contínua e estriada nas cerâmicas indica que o processo de argiluviação é atual. O processo de elutriação predomina no solo não antrópico. A degradação dos nódulos de ferro na TPI favorece a xantização e atua como fonte de argila (pedoplasmação). Arecaceae e Cyperaceae são mais abundantes nos horizontes antrópicos, notadamente nos níveis com maior quantidade de cerâmica. A ausência de fitólitos de plantas domesticadas indica que a formação das TPI não está relacionada com práticas agrícolas. As evidências fitolíticas demonstram que as atividades antrópicas ocorreram de forma mais intensa no P1. A rápida ciclagem de silício, evidenciada pela presença de fitólitos com silicificação incompleta, favorece a estabilidade da mineralogia caulínitica. VHE, ilita e variscita-estrengita ocorrem somente nos perfis com TPI. P2O5-CaO-K2O-NaO-Cs-Co-Zn-Cu-Ba-Rb-Ni representa a assinatura geoquímica das TPI. A presença de variscita-estrengita, tridimita e maghemita nas TPI, notadamente nas cerâmicas, confirma a formação de minerais em decorrência das práticas antrópicas. As cerâmicas apresentam predominantemente cauixi (Tubella reticulata e Parnula betesil) e cariapé (Licania utilis). A presença comum de micas primárias nesses artefatos sugere material alóctone em seu fabrico. As TPI resultam da adição de artefatos arqueológicos e melanização de horizontes pedogenéticos não antropizados. Tais atividades enriqueceram em nutrientes e alteraram a assinatura geoquímica do solo, assim como promoveram a formação de minerais. Essa antropização acelerou os processos de argiluviação e de degradação de petroplintitas. No decorrer de sua evolução, foram utilizados e adicionados resíduos de plantas, destacadamente de palmeiras e Cyperaceae. / A remarkable evidence of human occupation in Amazonian region is the existence of soils with dark colors and presence of ceramic materials, known as Indigenous Dark Earth (IDE). Despite of widely studied some of their features are still poorly understood, mainly that related to micromorphology, mineralogy and geochemical aspects. Such approach, in combination to phytolytic studies, is able to identify soil genesis processes and unravel the comprehension of occupation mechanisms of human. The aim of this study was to establish the hierarchy of these processes and their association with ancient activities of pre-Columbian populations. The research was carried out in the experimental site of Caldeirão, Iranduba city (Amazon state, Brazil). Two pedons containing surface anthropogenic horizons (P1 and P2) were directly compared to a non-anthropogenic soil (P3). In each soil horizon disturbed soil samples were sampled in order to perform physical, chemical, mineralogical and geochemical analyses. For phytolitic analyses samples were taken each 5 cm of depth. Micromorphological samples were studied in thin sections in the optical microscope and further analyzed in Scanning Electron Microscopy (SEM). The chronology was accomplished after 14C dating. The microaggregates in anthropogenic horizon are related to geochemical and biological processes. The genesis of IDE implicates in the following mechanisms: i) disposal and burning of residues by humans (anthropization); ii) deepening A horizons and darkening subsurface horizons by bioturbation (cumulization and melanization processes); iii) dispersion and migration of colloidal particles leading to argiluviation process; iv) different condictions of environment that not occur nowdays (pedorelict - ferruginous nodules). Clay coatings with extinction bands and continuous orientation in the ceramic artifacts suggest a current argiluviation process. The degradation of Fe nodules enhances the xantization process also providing clay (source of clay). The prevalent soil genesis in non-anthropic soil is the elutriation. The degradation of Fe nodules in the IDE enhances the xantization process also providing clay (pedoplasmation). The number of phytoliths of Arecaceae and Cyperaceae is higher in IDE than non-IDE, mainly in the horizons with more ceramics. The phytolitic evidence demonstrate that activities anthropic was more intense in the P1. The rapid Si cycling, highlighted by the presence of phytoliths without complete silicification, contribute to stability of kaolinitic mineralogy. HIV, illite and variscite-strengite are constrained to IDE pedons. P2O5-CaO-K2O-NaO-Cs-Co-Zn-Cu-Ba-Rb-Ni represents the geochemical signature of IDE. The presence of maghemite, variscite-strengite and tridimite strengthen a mineral forming process linked to human activity. In ceramic materials there is a prevalence of phytoliths from cauixi (Tubella reticulata and Parnula betesil) and cariapé (Licania utilis). The presence of mica suggests an alloctone material for their manufacturing. Hence the anthropic horizons result from the addition of archeological artifacts and melanization of non-anthropic horizons. These activities chemically enriched and modify the geochemical signature of soil, as soon as promoted formation of minerals. The anthropic activities conducted the argiluviation and degradation of Fe nodules. During their evolution there was a clear addition of plant residues, notably related to palm trees and Cyperaceae species.

Frequently, in evaluating plant deficiencies, one considers only those soil factors which are associated with the fertility of the soil-- mainly the levels of phosphorus, potash, nitrogen, and organic matter. A certain level of nutrition is essential for plant growth, but in order for the nutrients to exert their maximum influence on the productivity of the soil, it is equally important that a good soil environment be provided and maintained. A good environment requires that good physical conditions of soil, sir, and water be in balance.

We use standard general relativity to clarify common misconceptions about fundamental aspects of the expansion of the Universe. In the context of the new standard Lambda-CDM cosmology we resolve conflicts in the literature regarding cosmic horizons and the Hubble sphere (distance at which recession velocity equals c) and we link these concepts to observational tests. We derive the dynamics of a non-comoving galaxy and generalize previous analyses to arbitrary FRW universes. We also derive the counter-intuitive result that objects at constant proper distance have a non-zero redshift. Receding galaxies can be blueshifted and approaching galaxies can be redshifted, even in an empty universe for which one might expect special relativity to apply. Using the empty universe model we demonstrate the relationship between special relativity and Friedmann-Robertson-Walker cosmology. We test the generalized second law of thermodynamics (GSL) and its extension to incorporate cosmological event horizons. In spite of the fact that cosmological horizons do not generally have well-defined thermal properties, we find that the GSL is satisfied for a wide range of models. We explore in particular the relative entropic &quoteworth&quote of black hole versus cosmological horizon area. An intriguing set of models show an apparent entropy decrease but we anticipate this apparent violation of the GSL will disappear when solutions are available for black holes embedded in arbitrary backgrounds. Recent evidence suggests a slow increase in the fine structure constant over cosmological time scales. This raises the question of which fundamental quantities are truly constant and which might vary. We show that black hole thermodynamics may provide a means to discriminate between alternative theories invoking varying constants, because some variations in the fundamental &quoteconstants&quote could lead to a violation of the generalized second law of thermodynamics.

Les prix de marché des actifs risqués sont dictés par les actions des agents économiques qui ont des horizons d'investissement différents: ils ajustent leurs portefeuilles à des fréquences différentes et observent les rendements à différentes échelles. Dans cette thèse, nous examinons trois aspects distincts du problème des horizons multiples d'investissement. En premier lieu, nous étudions les implications théoriques de l'hétérogénéité des horizons de décision des investisseurs pour la dynamique des prix. Cette analyse est effectuée dans le cadre d'une rationalité complète et bornée. Deuxièmement, nous testons la capacité de différents modèles de séries chronologiques de volatilité des prix à représenter les propriétés des rendements boursiers simultanément à différentes échelles de temps. Enfin, nous proposons une méthode de mesure de la volatilité à échelle multiple basée sur des filtres d'ondelettes, avec application à la détection des crises financières.

<p>Inorganic chlorine (Clinorg) is generally considered to be inert and has been used as a tracer for groundwater movements. This assumption is thereby fundamental for current knowledge about soil biogeochemistry. However, recent work showed that Clinorg can be retained, i.e. immobilised, in soil, which contradicts the previous assumptions. The aim of this laboratory study was to investigate if the processes that immobilise Clinorg in soil are affected by molecular oxygen (O2), and if the immobilisation occurs in the top soil layer only or also further down were the soil structure is different from the upper soil layer. Two experimental set-ups have been established. In the first experiment regarding the O2 regime (OXANIS), the immobilisation of Clinorg was studied in soil under oxic and anoxic conditions, respectively. In a second incubation study (SOLIS) the immobilisation was studied under oxic conditions in different layers of a coniferous forest soil. To investigate the immobilisation of Clinorg, a method using radiolabelled chloride 36 (36Clinorg) was applied. The use of radiolabelled chloride is an excellent and reliable method for studying transformation processes in soil systems. The results of the laboratory study showed that Clinorg retention rates under oxic conditions were much higher than retention rates under anoxic conditions, indicating an important role of O2. Furthermore, the immobilisation of Clinorg occurred in all soil layers were oxygen is provided, but rates were highest in the top soil layer (organic layer, O-horizon). Clearly, O2 influenced the net Clinorg retention, but additional studies are required to identify the processes behind this result. The calculated immobilisation rates for Clinorg in the three soil horizons correspond to the amount of organic material detected in the different soil horizons indicating a strong connection between the occurrence of organic matter in soil and the immobilisation of Clinorg.</p>

We analyze an infinite horizon, single product, periodic review model in which pricing and production/inventory decisions are made simultaneously. Demands in different periods are identically distributed random variables that are independent of each other and their distributions depend on the product price. Pricing and ordering decisions are made at the beginning of each period and all shortages are backlogged. Ordering cost includes both a fixed cost and a variable cost proportional to the amount ordered. The objective is to maximize expected discounted, or expected average profit over the infinite planning horizon. We show that a stationary (s,S,p) policy is optimal for both the discounted and average profit models with general demand functions. In such a policy, the period inventory is managed based on the classical (s,S) policy and price is determined based on the inventory position at the beginning of each period. / Singapore-MIT Alliance (SMA)

Inorganic chlorine (Clinorg) is generally considered to be inert and has been used as a tracer for groundwater movements. This assumption is thereby fundamental for current knowledge about soil biogeochemistry. However, recent work showed that Clinorg can be retained, i.e. immobilised, in soil, which contradicts the previous assumptions. The aim of this laboratory study was to investigate if the processes that immobilise Clinorg in soil are affected by molecular oxygen (O2), and if the immobilisation occurs in the top soil layer only or also further down were the soil structure is different from the upper soil layer. Two experimental set-ups have been established. In the first experiment regarding the O2 regime (OXANIS), the immobilisation of Clinorg was studied in soil under oxic and anoxic conditions, respectively. In a second incubation study (SOLIS) the immobilisation was studied under oxic conditions in different layers of a coniferous forest soil. To investigate the immobilisation of Clinorg, a method using radiolabelled chloride 36 (36Clinorg) was applied. The use of radiolabelled chloride is an excellent and reliable method for studying transformation processes in soil systems. The results of the laboratory study showed that Clinorg retention rates under oxic conditions were much higher than retention rates under anoxic conditions, indicating an important role of O2. Furthermore, the immobilisation of Clinorg occurred in all soil layers were oxygen is provided, but rates were highest in the top soil layer (organic layer, O-horizon). Clearly, O2 influenced the net Clinorg retention, but additional studies are required to identify the processes behind this result. The calculated immobilisation rates for Clinorg in the three soil horizons correspond to the amount of organic material detected in the different soil horizons indicating a strong connection between the occurrence of organic matter in soil and the immobilisation of Clinorg.