Made available in DSpace on 2017-07-25T19:30:49Z (GMT). No. of bitstreams: 1 Vinicius Bodanese Demarch.pdf: 4544559 bytes, checksum: 0b845832e5b93d68dc7656c22253c5b7 (MD5) Previous issue date: 2014-05-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With continued population growth, food scarcity and declining quality and quantity from natural resources, current agricultural practices should be reconsidered. A better understanding of the spatial variability of soil and climatic components, as well as their numerous interactions on the yield of agricultural crops is the current approach called Precision Agriculture. Thus, identify management zones, targeting areas with relative homogeneity as a broad set of variables, can be approximate to management of spatial variability. There weregeoreferenced soil samples divided into three layers, P5 (0 - 0.05m), P10 (0.05 to 0.01 m) and P20 (0.10 - 0.20 m). The first analysis it is the landscape model, which was considered the angle of the geomorphic surface for management class delineation. The crop was segmented into four geomorphic segments, top surface, convex surface, the concave surface and plain. The second analysis was designed as mathematical technique, making use of multivariate statistical analysis, performing hierarchical cluster analysis (HCA) considering similarity between samples, and principal component analysis (PCA), the variances describing characteristics of soil attributes. For each measured layer of the soil, the samples are segmented by means of HCA into four zones management as approximate 60% similarity at Euclidean distance. To verify the significance of the segmentations,drew on comparison of average 5% by orthogonal contrasts test, considering each segment or mathematical landscape management zone as a treatment in the analysis. In the case of landscape segments considered, there were no significant differences between the means of soil attributes and yield components of soybean considered. The contrasts applied to the areas of mathematical systems differed significantly from each other for most soil properties and yield components under analysis. Thus, the use of multivariate analysis can be a tool in order to provide differentiation with regard to handling of agricultural areas. / Com contínuo aumento populacional, escassez alimentar e declínio qualitativo e quantitativo dos recursos naturais, as atuais práticas agrícolas devem ser reconsideradas. O melhor entendimento da variabilidade espacial de atributos do solo e componentes climatológicos, bem como, suas inúmeras interações sobre o rendimento das culturas agrícolas é abordagem atual da chamada Agricultura de Precisão. Assim, delimitar zonas de manejo, segmentando áreas que apresentem relativa homogeneidade quanto a amplo conjunto de variáveis, pode ser aproximação para manejo da variabilidade espacial. Realizaram-se coletas georeferenciadas de solo estratificadas em três camadas, P5 (0 - 0,05 m), P10 (0,05 - 0,01 m) e P20 (0,10 - 0,20 m). A primeira análise realizada trata-se de modelo de paisagem, onde se considerou a angulação da superfície geomórfica para delimitação dos segmentos. A lavoura foi segmentada em quatro segmentos geomórficos, superfície de topo, superfície convexa, superfície côncava e planície. A segunda análise foi denominada como técnica matemática, valendo-se de análise estatística multivariada, realizando-se análise hierárquica de agrupamentos (HCA) considerando similaridade entre amostras, e análise de componentes principais (PCA), descrevendo características nas variâncias dos atributos do solo. Para cada camada de solo avaliada, segmentaram-se as amostras através da HCA, em quatro zonas de manejo conforme similaridade aproximada de 60 % em distância euclidiana. Para verificar a significância das segmentações, valeu-se de teste de comparação de média por contrastes ortogonais a 5 %, considerando cada segmento de paisagem ou zona de manejo matemática como um tratamento na análise. No caso dos segmentos de paisagem considerados, não houve diferenças significativas entre as médias dos atributos de solo e componentes de rendimento da cultura da soja considerados. Os contrastes aplicados para as zonas de manejo matemáticas diferiram significativamente entre si para a maioria dos atributos do solo e componentes de rendimento em análise. Sendo assim, a utilização de análise multivariada pode ser interessante no sentido de fornecer diferenciações quanto ao manejo de áreas agrícolas.

A homogeneidade do solo em sistema de plantio direto, é um assunto questionável, pois alguns autores têm considerado que, com o passar do tempo, há aumento da homogeneidade do solo, outros têm verificado a redução. A hipótese deste trabalho é que em sistema de plantio direto consolidado existe correlação e dependência espacial dos atributos físicos-hídrico do solo e do desenvolvimento vegetativo da soja, sendo a cokrigagem colocalizada interpolador mais representativo destas correlações. O objetivo foi avaliar a variabilidade espacial de atributos físicos do solo e do desenvolvimento vegetativo da soja em sistema de plantio direto, adotado há mais de 19 anos. O trabalho foi desenvolvido na fazenda-escola da Universidade Estadual de Ponta Grossa - Paraná. A área de estudo tem como cultura a soja e está inserida em um relevo cuja declividade máxima, no sentido da pendente, é de aproximadamente 10 %. Nesta área, foram avaliados atributos físicos e hídrico do solo, como: densidade do solo (Ds), granulometria (areia e argila) e condutividade hidráulica saturada (Kfs). Avaliou-se, ainda, atributos de planta: altura da planta, estádio reprodutivo e stand. Para tais avaliações, foi demarcado um grid com espaçamento 10 x 10 metros, onde as avaliações foram realizadas em cada ponto. A análise dos dados foi efetuada por geoestatística, utilizando o pacote de programas GEOSTAT, para todas as variáveis que apresentaram dependência espacial. Foi obtido mapa de krigagem, e para todas as que apresentaram correlação, mapas de cokrigagem e cokrigagem colocalizada. A precisão de tais mapas foi obtida por meio dos menores valores de variância e a raiz quadrada do erro médio (RMSE). Verificou-se existência de dependência espacial na área em estudo, sendo a declividade um dos fatores responsáveis pela variação e o outro fator pode ser atribuído ao manejo uniforme adotado na área. Existiu correlação direta e positiva entre Kfs e areia e negativa com argila. Os atributos que influenciaram positivamente o desenvolvimento da planta foram a Kfs e, negativamente, a densidade do solo (Ds). Quanto aos métodos de estimação, o que obteve o mapa mais representativo da condição real, para a maioria das variáveis estudadas, foi a cokrigagem colocalizada. Apenas para a correlação argila x areia não houve ganho no uso da cokrigagem colocalizada, por isso, a cokrigagem ordinária foi a mais indicada. / The homogeneity of the soil in no-tilled system is being a highly controversial question, as some authors have claimed that there is an increasing in the soil homogeneity over time, while others have proven it to be reduced. The hypothesis is that in established no-tillage system is no correlation and spatial dependence of the physical-hydric soil properties and soybean vegetative development, cokriging-located interpolator being most representative of these correlations The objective was to evaluate the spatial variability of the soil physical attributes and soybean vegetative growth along 19-years of no-tillage system. The study was carried out at the farm-school from the Universidade Estadual de Ponta Grossa - Paraná. The area was cultivated with soybean in a topossequence with a maximum slope of10 %. In this area, were evaluated physical and hydrical soil properties, e.g. soil bulk density (Ds), soil texture (sand and clay) and saturated hydraulic conductivity (Kfs). It was also evaluated plant characteristics such as plant height, reproductive stage and standFor these assessments, it was delimited a 10 x 10 meters grid, where the assessments were carried out in each point. The data analysis was performed using a specific geostatistic software GEOSTAT, for all spatial-dependent variables. A kriging map was obtained from the results, and for all those correlated variables cokriging maps and cokriging-located have been also performed. The maps accuracy were achieved from the smallest values of variance and square root of the mean error (RMSE). The results indicated the existence of spatial dependence in the study area with the slope and soil management the mainly dependent factors, wherein in the latter the spatial variability is disregarded. Kfs was direct and positively correlated with sand, and a negatively with clay. The soil attribute that influenced positively the plant development was Kfs, whilst the bulk density (Ds) influenced negatively. With regard to the estimative methods, cokriging-located produced the most accurate and representative map of the real conditions for most of the variables. The low correlation between sandy and clay fractions makes the ordinary cokriging is being more appropiate than the cokriging-located.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-02-13T13:10:07Z No. of bitstreams: 1 Moises Tenorio Ferrer.pdf: 2245013 bytes, checksum: 440b63b0a25d6263c4d43cc9c2a774c9 (MD5) / Made available in DSpace on 2017-02-13T13:10:07Z (GMT). No. of bitstreams: 1 Moises Tenorio Ferrer.pdf: 2245013 bytes, checksum: 440b63b0a25d6263c4d43cc9c2a774c9 (MD5) Previous issue date: 2016-07-27 / The aim of this study was to analyze the spatial variability of the composition and quality of refrigerated raw milk in the state of Alagoas and in the middle region of Pernambuco Agreste, in the years 2014 and 2015. Thus, were obtained from the three companies in the dairy sector submitted to the federal inspection service (SIF) that collect milk in the state of Alagoas and in the middle region of Pernambuco Agreste, 3863 monthly official reports on somatic cell count (SCC) and total bacterial (CBT), fat, protein, lactose, total solids and nonfat dry extract of 432 different tanks direct expansion milk in the years 2014 and 2015. the data were analyzed for spatial dependence and geographically weighted regression, using the ArcGIS 10.3 software. It was observed predominantly spatial distribution of CBT log 5.07 to 5.19 and diffuse areas with values from 5.20 to 5.54. It was observed predominant value of somatic cell score (SCS) from 2.81 to 2.99; sites with from 1.87 to 2.80; places with 3.00 to 3.16, and isolated points with peaks from 3.17 to 3.39. It was identified low influence of altitude, rainfall and altitude interaction x rainfall on the ECS and the CBT log. The analysis of spatial dependence was observed that there is high spatial dependence between variables fat, lactose and total solids. Still, protein, ECS and CBT log have moderate spatial dependence and the dry extract low spatial dependence. The altitude, rainfall and altitude interaction x rainfall have low influence on the fat, lactose, protein, total solids, nonfat dry extract, ECS and CBT log. Finally, geostatistics is an important tool for the analysis of milk quality, helping the classical statistics for better understanding of the phenomenon when the variable is regionalized. / O objetivo com este trabalho foi analisar a variabilidade espacial da composição e qualidade do leite cru refrigerado no Estado de Alagoas e na mesorregião do Agreste pernambucano, nos anos de 2014 e 2015. Para tanto, foram obtidos, junto as três empresas do setor de lácteos submetidas ao serviço de inspeção federal (SIF) que captam leite no Estado de Alagoas e na mesorregião do Agreste pernambucano, 3.863 laudos oficiais mensais sobre a contagem de células somáticas (CCS) e bacteriana total (CBT), os teores de gordura, proteína, lactose, sólidos totais e extrato seco desengordurado do leite de 432 diferentes tanques de expansão direta nos anos de 2014 e 2015. Os dados foram analisados quanto a dependência espacial e regressão geograficamente ponderada, com o uso do software ArcGIS 10.3. Foi observada distribuição espacial predominante da log CBT de 5,07 a 5,19 e áreas difusas com valores de 5,20 a 5,54. Foi observado valor predominante do escore de células somáticas (ECS) de 2,81 a 2,99; locais com 1,87 a 2,80; locais com 3,00 a 3,16, e pontos isolados com picos de 3,17 a 3,39. Foi identificada baixa influência da altitude, da precipitação pluviométrica e da interação altitude x precipitação sobre o ECS e o log CBT. Quanto a análise da dependência espacial, foi observado que há dependência espacial alta entre as variáveis gordura, lactose e sólidos totais. Ainda, proteína, ECS e log CBT têm dependência espacial moderada e o extrato seco desengordurado baixa dependência espacial. A altitude, precipitação pluviométrica e a interação altitude x precipitação têm baixa influência sobre os teores de gordura, lactose, proteína, sólidos totais, extrato seco desengordurado, ECS e log CBT. Por fim, a geoestatística é uma ferramenta importante para a análise da qualidade do leite, auxiliando a estatística clássica para um melhor entendimento do fenômeno quando a variável é regionalizada.

Made available in DSpace on 2017-07-10T19:25:10Z (GMT). No. of bitstreams: 1 Nelson.pdf: 9957138 bytes, checksum: 2755a98d59b67d1599170871a86fe3cd (MD5) Previous issue date: 2012-04-09 / Samples of soil and plant properties are collected and analyzed to apply at precision agriculture (PA) and obtain information that can help on a decision making in order to correct problems that have been detected in the studied areas. Thus, computer systems are used to generate thematic maps by interpolation of sample data to measure information for nonsampled locations. The choice of interpolation method to be used is an important aspect, since most of the interpolators do not preserve the original data, so the thematic map is affected. The accuracy with which the spatial distribution maps of yield and soil properties are produced during the interpolation process influences the implementation and use of PA. A set of data from 55 samples of chemical properties of a soil and 130 samples of soybean yield, 2010/2011 harvest, were analyzed to compare three interpolation methods (inverse distance, inverse distance squared and ordinary kriging) on the thematic maps drawing. Maps of ten chemical properties of soil and two samples concerning yield were compared, using Kappa, Tau and CDR. It was observed some variation with the results and that the interpolation influence depends on the attribute and data frequency. However, kriging and inverse square distance were considered the methods that generated maps with lower dispersion of data / No uso da agricultura de precisão (AP), amostras de atributos do solo e planta são coletadas e analisadas visando à obtenção de informações que sirvam como subsídio para a tomada de decisão, a fim de se corrigirem problemas detectados nas áreas analisadas. Para tanto, são utilizados sistemas computacionais capazes de gerar mapas temáticos, através da interpolação dos dados amostrais, visando mensurar informações para os locais não amostrados. Um aspecto importante é a escolha do método de interpolação a ser utilizado, visto que a maioria dos interpoladores não preservam os dados originais, assim, afetam o mapa temático gerado. A acurácia com que os mapas de distribuição espacial da produtividade e dos atributos do solo são produzidos no processo de interpolação influencia a aplicação e utilização da AP. Um conjunto de dados referentes a 55 amostras de atributos químicos do solo e 130 amostras de produtividade de soja, safra 2010/2011, foram analisados com o objetivo de comparar três métodos de interpolação (inverso da distância, inverso do quadrado da distância e krigagem ordinária) na construção de mapas temáticos. Foram comparados mapas de dez atributos químicos do solo e duas amostragens da produtividade, utilizando os índices Kappa, Tau e CDR. Constatou-se variação nos resultados e que a influência do interpolador depende do atributo e da frequência dos dados. Porém, a krigagem e o inverso do quadrado da distância foram considerados os métodos que geraram mapas com menor dispersão dos dados

Made available in DSpace on 2017-05-12T14:48:35Z (GMT). No. of bitstreams: 1 Nelson.pdf: 9957138 bytes, checksum: 2755a98d59b67d1599170871a86fe3cd (MD5) Previous issue date: 2012-04-09 / Samples of soil and plant properties are collected and analyzed to apply at precision agriculture (PA) and obtain information that can help on a decision making in order to correct problems that have been detected in the studied areas. Thus, computer systems are used to generate thematic maps by interpolation of sample data to measure information for nonsampled locations. The choice of interpolation method to be used is an important aspect, since most of the interpolators do not preserve the original data, so the thematic map is affected. The accuracy with which the spatial distribution maps of yield and soil properties are produced during the interpolation process influences the implementation and use of PA. A set of data from 55 samples of chemical properties of a soil and 130 samples of soybean yield, 2010/2011 harvest, were analyzed to compare three interpolation methods (inverse distance, inverse distance squared and ordinary kriging) on the thematic maps drawing. Maps of ten chemical properties of soil and two samples concerning yield were compared, using Kappa, Tau and CDR. It was observed some variation with the results and that the interpolation influence depends on the attribute and data frequency. However, kriging and inverse square distance were considered the methods that generated maps with lower dispersion of data / No uso da agricultura de precisão (AP), amostras de atributos do solo e planta são coletadas e analisadas visando à obtenção de informações que sirvam como subsídio para a tomada de decisão, a fim de se corrigirem problemas detectados nas áreas analisadas. Para tanto, são utilizados sistemas computacionais capazes de gerar mapas temáticos, através da interpolação dos dados amostrais, visando mensurar informações para os locais não amostrados. Um aspecto importante é a escolha do método de interpolação a ser utilizado, visto que a maioria dos interpoladores não preservam os dados originais, assim, afetam o mapa temático gerado. A acurácia com que os mapas de distribuição espacial da produtividade e dos atributos do solo são produzidos no processo de interpolação influencia a aplicação e utilização da AP. Um conjunto de dados referentes a 55 amostras de atributos químicos do solo e 130 amostras de produtividade de soja, safra 2010/2011, foram analisados com o objetivo de comparar três métodos de interpolação (inverso da distância, inverso do quadrado da distância e krigagem ordinária) na construção de mapas temáticos. Foram comparados mapas de dez atributos químicos do solo e duas amostragens da produtividade, utilizando os índices Kappa, Tau e CDR. Constatou-se variação nos resultados e que a influência do interpolador depende do atributo e da frequência dos dados. Porém, a krigagem e o inverso do quadrado da distância foram considerados os métodos que geraram mapas com menor dispersão dos dados

Com o avanço da agricultura de precisão, em que a variabilidade da produtividade entre os diversos pontos de uma determinada área é levada em consideração, é necessário aprimorar, cada vez mais, o sistema de coleta de dados, para que os resultados possam ser confiáveis. Dentre outros, faz-se necessário conhecer o desempenho dos sensores localizados nas colhedoras, para que se saiba o nível de acurácia dos dados de campo para a geração dos mapas de produtividade. O objetivo do presente trabalho foi caracterizar o desempenho, sob condições controladas, de um equipamento comercial, especialmente o sensor de fluxo de volume e suas interações com os sensores de inclinação, de velocidade de deslocamento da máquina e de grau de umidade dos grãos, destinados à mensuração da produtividade de culturas de grãos em geral. Foi montada uma bancada de ensaio constituída de um tanque alimentador com comporta de abertura variável, que escoa grãos a um condutor helicoidal, que são transportados para um elevador de taliscas de uma colhedora comercial. Os grãos transportados pelo elevador passam através dossensores de fluxo de volume e grau de umidade e, em seguida, são descarregados num tanque superior suspenso por uma célula de carga com capacidade de 2.000kg (desprezando a variação da gravidade com relação ao nível do mar) para que os dados de massa sejam comparados com os registrados pelo sensor de fluxo de volume. O monitor de produtividade foi ensaiado na bancada para simulações de fluxos constantes e variados em três diferentes posições transversais do elevador. Os resultados mostraram que a bancada de ensaio mostrou-se eficiente para os tipos de ensaios propostos. Sua estrutura é resistente e a variação da angulação do elevador é de fácil manejo. A geometria da construção do tanque de alimentação mostrou-se eficiente para fornecer vazões uniformes com o tempo, obtendo-se taxas de fluxo constantes dentro dos limites de 2,0 a 8,0kg.s-1. O sensor de velocidade apresentou erro médio relativo de 0,31% e o de grau de umidade, erro médio em módulo de 5,01% para as condições estudadas. Quanto mais afastado do fluxo médio de calibração, pior é a estimativa do fluxo pelo monitor de produtividade. O erro médio geral dos ensaios com taxas de fluxo constantes foi de -5,31%, com desvio padrão de 4,14. O monitor propiciou, em 70% dos ensaios, erros pontuais menores que 6% para ensaios com fluxo constante. Suas leituras superestimaram valores menores do que o ponto da taxa de fluxo média de calibração e subestimaram valores para taxas de fluxo maiores que este ponto. As leituras do monitor responderam imediatamente as variações impostas ao fluxo processado pelo elevador de grãos. O clinômetro ou o algoritmo que considera a inclinação é eficiente para compensar as inclinações transversais da máquina, mesmo em condições de taxas de fluxo variadas. O erro médio geral dos ensaios com taxas de fluxo variadas, calculado a partir do erro médio em módulo de cada ensaio foi, 4,84%. O erro médio global encontrado do monitor de produtividade para as leituras com taxas de fluxo constantes e variadas, foi 5,12%. / With the progress of the precision agriculture where spatial yield variability is taken into account, it is necessary to improve data collection so the results can be more reliable. It is necessary to understand how yield sensor used on combines works in order to know the accuracy of the field data for generation of the yield maps. This work aims to characterize the performance, under controlled conditions, of a commercial equipment, its yield sensor and interactions with the hillside sensor, forward speed sensor and grain moisture sensor. A test bench with a tank feeder was built with a variable opening floodgate, which drains grains to the foot of the paddle elevator of a commercial combine. The grain flow transported by the elevator pass through the yield and moisture sensor and is unloaded in a superior tank hold by a load cell with capacity of 2.000kg (desconsidering the variation of the gravity) so that the mass data is compared with that registered by the monitor. The monitor was tested on simulations of constant and variable flow rates in three different transverse positions of the elevator. The results showed that the test bench was shown efficient for the types of proposed tests. Its structure is resistant and the variation of the angle of the elevator is of easy handling. The geometry of the feeding tank was shown efficient to supply uniform flow rates, between 2,0 and 8,0kg.s-1. The speed sensor showed relative mean error of 0,31% and the moisture sensor presented a module mean error of 5,01%. Flow estimation got worst increasing or decreasing the flow rate apart from calibration region. Main mean error of the test with constant flow rates was of -5,31%, with standard deviation of 4,14. On 70% of the test monitor, readings resulted in erros less than 6,00% with constant flow. Its readings overestimated flow values under the mean flow rate of calibration and underestimated flow above it. The readings of the yield monitor responded to the variations imposed to the flow through by the elevator immediately. The hillside sensor and the algorithm that considers the inclination are efficient for compensating the transverse inclinations of the machine, even in conditions of varied flow rates. The general mean error test with varied flow rates, was 4,84%. The global mean error shown by the yield monitor for the readings with varied and constant flow rates was 5,12%.

The overall goals of this dissertation are: 1) to better quantify the spatial heterogeneity of coarse particulate matter (PM10-2.5) and its chemical composition; and 2) to evaluate the performance (accuracy and precision) of passive samplers analyzed by computer-controlled scanning electron microscopy with energy-dispersive X-ray spectroscopy (CCSEM-EDS) for PM10-2.5. For these goals, field studies were conducted over multiple seasons in Cleveland, OH and were the source of data for this dissertation. To achieve the first goal, we characterized spatial variability in the mass and composition of PM10-2.5 in Cleveland, OH with the aid of inexpensive passive samplers. Passive samplers were deployed at 25 optimized sites for three week-long intervals in summer 2008 to characterize spatial variability in components of PM10-2.5. The size and composition of individual particles were determined using CCSEM-EDS. For each sample, this information was used to estimate PM10-2.5 mass and aerosol composition by particle class. The highest PM10-2.5 means were observed at three central industrial urban sites (35.4 Μg m-3, 43.4 Μg m-3, and 47.6 Μg m-3), whereas lower means were observed to the west and east of this area with the lowest means observed at outskirt suburban background sites (12.9 Μg m-3 and 14.7 Μg m-3). Concentration maps for PM10-2.5 and some compositional components of PM10-2.5 (Fe oxide and Ca rich) show an elongated shape of high values stretching from Lake Erie south through the central industrial area, whereas those for other compositional components (e.g., Si/Al rich) are considerably less heterogeneous. The findings from the spatial variability of coarse particles by compositional class analysis, presented in Chapter II of this dissertation, show that the concentrations of some particle classes were substantially more spatially heterogeneous than others. The data suggest that industrial sources located in The Flats district in particular may contribute to the observed concentration variability and heterogeneity. Lastly, percent relative spatial heterogeneity (SH%) is more consistent with spatial heterogeneity as visualized in the concentration surface maps compared to the coefficient of divergence (COD). The second goal was achieved by assessing the performance of passive samplers analyzed by CCSEM-EDS to measure PM10-2.5 (Chapter III) and investigating potential sources of variability in the measurement of PM10-2.5 with passive samplers analyzed by CCSEM-EDS (Chapter IV). Data for these analyses were obtained in studies conducted in summer 2009 and winter 2010. The precision of PM10-2.5 measured with the passive samplers was highly variable and ranged from a low coefficient of variation (CV) of 2.1% to a high CV of 90.8%. Eighty percent of the CVs were less than 40%. This assessment showed the CV for passive samplers was greater than that recommended by the United States Environmental Protection Agency (EPA) guidelines for the Federal Reference Method (FRM). Several CV values were high, exceeding 40% indicating substantially dissimilar results between co-located passive samplers. The overall CV for the passive samplers was 41.2% in 2009 and 33.8% in 2010. The precision when high CVs > 40% (n = 5 of 25) were excluded from the analysis was 24.1% in 2009 and 18.2% for 2010. Despite issues with precision, PM10-2.5 measured with passive samplers agreed well with that measured with FRM samplers with accuracy approaching EPA Federal Equivalent Method (FEM) criteria. The intercept was 1.21 and not statistically significant (p = 3.88). The passive to FRM sampler comparison (1:1) line fell within the 95% confidence interval (CI) for the best-fit linear regression and was statistically significant (p < 0.05). However, several data points had large standard deviations resulting in high variability between co-located passive samplers (n = 3), which extend outside of the 95% CI's. The passive sampler limit of detection (LOD) for the CCSEM method was 2.8 Μg m-3. This study also showed certain samples had higher CVs and that further investigation was needed to better understand the sources of variability in the measurement of PM10-2.5 with passive samplers. Sources of variability observed in the measurement of PM10-2.5 with passive samplers analyzed by CCSEM were explored in Chapter IV of this dissertation. This research suggests mass concentrations greater than 20 Μg m-3 for week long samples are needed on the passive sampler substrate to obtain overall CVs by mass less than 15%. It also suggests that greater than 55 particle counts within a compositional class are needed to reduce analytical CVs to less than 15%. Another finding from this study was increasing the concentration from 6.2 to 10.6 Μg m-3 increases the CCSEM analytical precision by mass 38% and by number 75% for random orientation. Also certain compositional classes appeared problematical for precision of passive sampler measurements. For example, the presence of salt plus moisture introduces challenges for CCSEM analysis through the wetting of salt crystalline particles which dissolve creating a displaced dry deposition pattern of particles upon subsequent evaporation. This process can falsely elevate or reduce the particle count and alter its distribution on the sampling media.

<p>Summer blooms of filamentous, diazotrophic cyanobacteria are typical of the Baltic Sea Proper, and are dominated by <i>Aphanizomenon </i>sp<i>.</i> and the toxic <i>Nodularia spumigena.</i> Although occurring every summer, the blooms vary greatly in timing and spatial distribution, making monitoring difficult and imprecise. This thesis studies how the spatial variability of Baltic cyanobacterial blooms influences estimates of abundance, vertical and horizontal distribution and N₂-fixation. Implications for sampling and monitoring of cyanobacterial blooms are also discussed.</p><p>The results of the thesis confirm the importance of diazotrophic cyanobacteria in providing N for summer production in the Baltic Proper. It also highlights the large spatial and temporal variation in these blooms and argues that improved spatial coverage and replication could make monitoring data more useful for demonstrating time trends, and for identifying the factors regulating the blooms. The vertical distribution of <i>Aphanizomenon</i> and <i>Nodularia</i> was found to be spatially variable, probably as a combination of species-specific adaptations and ambient weather conditions. Vertical migration in <i>Aphanizomenon</i> was more important towards the end of summer, and is probably regulated by a trade-off between P-availability and light and temperature.</p>

Polythermal glaciers, i.e. glaciers with a combination of ice at and below the freezing point, are widespread in arctic and subarctic environments. The polythermal structure has major implications for glacier hydrology, ice flow and glacial erosion. However, the interplay of factors governing its spatial and temporal variations such as net mass balance, ice advection and water content in the ice is poorly investigated and as yet not fully understood. This study deals with a thorough investigation of the polythermal regime on Storglaciären, northern Sweden, a small valley glacier with a cold surface layer in the ablation area. Extensive field work was performed including mapping of the cold surface layer using ground-penetrating radar, ice temperature measurements, mass balance and ice velocity measurements. Analyses of these data combined with numerical modelling were used specifically to investigate the spatial and temporal variability of the cold surface layer, the spatial distribution of the water content just below the cold surface layer transition, the effect of radar frequency on the detection of the surface layer, and the sensitivity of the cold surface layer to changes in forcing. A comparison between direct temperature measurements in boreholes and ground-penetrating surveys shows that the radar-inferred cold-temperate transition depth is within ±1 m from the melting point of ice at frequencies above ~300 MHz. At frequencies below ~155 MHz, the accuracy degrades because of reduced scattering efficiency that occurs when the scatterers become much smaller compared to the wavelength. The mapped spatial pattern of the englacial cold-temperate transition boundary is complex. This pattern reflects the observed spatial variation in net loss of ice at the surface by ablation and vertical advection of ice, which is suggested to provide the predominant forcing of the cold surface layer thickness pattern. This is further supported by thermomechanical modeling of the cold surface layer, which indicates high sensitivity of the cold surface layer thickness to changes in vertical advection rates. The water content is the least investigated quantity that is relevant for the thermal regime of glaciers, but also the most difficult to assess. Spatial variability of absolute water content in the temperate ice immediately below the cold surface layer on Storglaciären was determined by combining relative estimates of water content from ground-penetrating radar data with absolute determination from temperature measurements and the thermal boundary condition at the freezing front. These measurements indicate large-scale spatial variability in the water content, which seems to arise from variations in entrapment of water at the firn-ice transition. However, this variability cannot alone explain the spatial pattern in the thermal regime on Storglaciären. Repeated surveys of the cold surface layer show a 22% average thinning of the cold surface layer on Storglaciären between 1989 and 2001. Transient thermomechanical modeling results suggest that the cold surface layer adapts to new equilibrium conditions in only a few decades after a perturbation in the forcing is introduced. An increased winter air temperature since mid-1980s seems to be the cause of the observed thinning of the cold surface layer. Over the last decades, mass balance measurements indicate that the glacier has been close to a steady state. The quasi-steady state situation is also reflected in the vertical advection, which shows no significant changes during the last decades. Increased winter temperatures at the ice surface would result in a slow-down of the formation of cold ice at the base of the cold surface layer and lead to a larger imbalance between net loss of ice at the surface and freezing of temperate ice at the cold-temperate transition.

Summer blooms of filamentous, diazotrophic cyanobacteria are typical of the Baltic Sea Proper, and are dominated by Aphanizomenon sp. and the toxic Nodularia spumigena. Although occurring every summer, the blooms vary greatly in timing and spatial distribution, making monitoring difficult and imprecise. This thesis studies how the spatial variability of Baltic cyanobacterial blooms influences estimates of abundance, vertical and horizontal distribution and N2-fixation. Implications for sampling and monitoring of cyanobacterial blooms are also discussed. The results of the thesis confirm the importance of diazotrophic cyanobacteria in providing N for summer production in the Baltic Proper. It also highlights the large spatial and temporal variation in these blooms and argues that improved spatial coverage and replication could make monitoring data more useful for demonstrating time trends, and for identifying the factors regulating the blooms. The vertical distribution of Aphanizomenon and Nodularia was found to be spatially variable, probably as a combination of species-specific adaptations and ambient weather conditions. Vertical migration in Aphanizomenon was more important towards the end of summer, and is probably regulated by a trade-off between P-availability and light and temperature.