Xi, Hongyan. / "December 2010." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 163-176). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Le paludisme trouve dans la région amazonienne des conditions favorables à la transmission de la maladie, par un moustique vecteur qui est essentiellement l’Anophèles darlingi, se reproduisant en milieu aquatique. Ce moustique est connu pour sa grande adaptabilité aux conditions environnementales et en Amazonie, il est réputé être plus spécialement trouvé près des fleuves d’eau blanche (chargée en sédiments). La relation entre la présence du moustique et la couleur des eaux a été peu étudiée à l’échelle régionale. La présente étude a utilisé 11 années d’images MODIS à 250 m de résolution et un pas de temps mensuel, dont il a été extrait un indicateur de réflectance des eaux. D’autre part, ce travail de thèse exploite les données épidémiologiques du système de surveillance épidémiologique brésilien du paludisme. L’objectif principal est d’évaluer les corrélations entre la dynamique saisonnière de la réflectance des eaux et l’incidence parasitaire du paludisme sur différentes zones de l’État d’Amazonas afin notamment de comprendre l’influence de la couleur des eaux sur la présence du vecteur et donc la transmission du paludisme. Les résultats obtenus permettent de montrer que les notifications concernant le paludisme dans l’Etat d’Amazonas sont en effet corrélées aux eaux blanches, mais que les eaux noires ont aussi une corrélation avec l’incidence du paludisme, d’une façon sensiblement différente, à la fois dans le temps et dans l’espace. Ces résultats pourront être utiles à l’amélioration de notre compréhension des risques épidémiologiques dans cette région ainsi qu’à la mise en place de programme de surveillance plus efficaces, même si le facteur étudié, i.e. la couleur des eaux, n’est qu’un facteur parmi beaucoup d’autres qui influent sur le risque d’infection paludéen. / Malaria in the Amazon region finds favorable conditions for the transmission of the disease by the mosquito vector Anopheles darlingi, which breeds in water. This mosquito is known for its great adaptability to environmental conditions. In the Amazon it is deemed to be especially found near rivers of white water (loaded with sediments). The relationship between the presence of the mosquito and water color has been little studied regionally. This study used 11 years of MODIS 250 m resolution and a monthly time base, which enable extracting a reflectance index of water. Secondly, this thesis uses the epidemiological data of the Brazilian system of epidemiological surveillance of malaria. The main objective is to evaluate the correlation between the seasonal dynamics of the reflectance of water and parasite incidence of malaria on different areas of the State of Amazonas in particular to understand the influence of water color on the presence of the vector and therefore the transmission of malaria. The results obtained show that notifications of malaria in the state of Amazonas are indeed correlated with white water, but the black water also have a correlation with the incidence of malaria, a substantially different way, since in the former case, the correlation is related to the flood, while in the case of black water, the presence of Anopheles and the flood are disconnected. These results may be useful in improving our understanding of epidemiological risks in the region and the establishment of more effective compliance program, even if the factor of interest, ie the color of the water is one factor among many others that affect the risk of malaria infection.

Water is essential for life on earth. Human society is challenged to sustain sufficient water quantity of good quality. This objective is reflected in sustainable development goal 6, “clean water and sanitation”. Water monitoring is part of sustainable water management and aims to evaluate the physical, chemical and biological status of a water body. Regular monitoring in the catchment area of Indalsälven (Sweden) is conducted by the Indalsälven Water Conservation Association (IWCA). In this area counts of Escherichia coli (E. coli) between 0 and 500 colony forming units (CFU) were monitored from 1993 – 2022 at the closest monitoring station Enkroken. This implies that drinking water quality standards were exceeded during many occasions (≥10 E. coli CFU/100ml). It is known that survival of E. coli in aquatic environments is dependent on nutrient levels, turbidity, sedimentation, pH level, predation, microbial community composition, temperature, and solar radiation. Low water depth and clear water with poor nutrient level in Enan and Handölan, tributaries to Indalsälven, are believed to cause solar radiation to be the main driver for inactivation of E. coli. Inactivation behaviour of indicator bacteria for faecal contamination such as E. col, is assumed to reflect on other bacteria that were excreted in the same way. The objective of the research was to investigate to which extent river color and river depth under the influence of sunlight affected E. coli inactivation in pristine like conditions such as the upper catchment area of Indalsälven. In this study, conditions from the research area were mimicked in 4 laboratory experiments. Results showed that neither 10 nor 35µW/cm2 led to additional inactivation due to sunlight. In a following experiment the liquid depth was reduced, with as a result that the inactivation of bacteria started to be influenced by sunlight when the depth was reduced to 14.4cm or lower. A fourth experiment was conducted at 14.4cm depth and additional color concentration 50 and 100 mg/l Pt. Results indicated that inactivation influenced by sunlight was reduced at color level 50 or more to a level that was equal to no sunlight radiation. A median depth of 0.2 cm and median color level of 15 mg/l Pt in the catchment area of Indalsälven suggests that inactivation of E. coli is very likely influenced by the sun, upstream the measuring point Enkroken and at points where the river is as shallow 14.4cm or less. Sunlight radiation might be underestimated in the conducted laboratory experiments, therefore continuous on-site research is suggested. / <p>2022-06-19</p>

Indiana University-Purdue University Indianapolis (IUPUI) / Phytoplankton size classes (pico-plankton, nano-plankton, and micro-plankton) provide information about pelagic ocean ecosystem structure, and their spatiotemporal variation is crucial in understanding ocean ecosystem structure and global carbon cycling. Remote sensing provides an efficient approach to estimate phytoplankton size compositions on global scale. In the first part of this thesis, a global sensitivity analysis method was used to determine factors mainly controlling the variations of remote sensing reflectance and inherent optical properties inverse algorithms. To achieve these purposes, average mass-specific coefficients of particles were first calculated through Mie theory, using particle size distributions and refractive indices as input; and then a synthesis remote sensing reflectance dataset was created using Hydrolight. Based on sensitivity analysis results, an algorithm for estimating phytoplankton size composition was proposed in the second part. This algorithm uses five types of spectral features: original and normalized remote sensing reflectance, two-band ratios, continuum removed spectra, and spectral curvatures. With the spectral features, phytoplankton size compositions were regressed using support vector machine. According to validation results, this algorithm performs well with simulated and satellite Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS), indicating that it is possible to estimate phytoplankton size compositions through satellite data on global scale.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-05T11:47:35Z No. of bitstreams: 1 micheleferreiralima.pdf: 5915949 bytes, checksum: e395fbdd27769373c115eaa14346a8a6 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-10-05T13:55:58Z (GMT) No. of bitstreams: 1 micheleferreiralima.pdf: 5915949 bytes, checksum: e395fbdd27769373c115eaa14346a8a6 (MD5) / Made available in DSpace on 2016-10-05T13:55:58Z (GMT). No. of bitstreams: 1 micheleferreiralima.pdf: 5915949 bytes, checksum: e395fbdd27769373c115eaa14346a8a6 (MD5) Previous issue date: 2010-07-30 / A Modelagem Matemática é uma ferramenta de estudo ecológico que vêm sendo aplicada ao gerenciamento de ecossistemas aquáticos com foco nos compartimentos físico, químico e biológico. Esta dissertação tratou da aplicação de um modelo hidrodinâmico tridimensional (Elcom) no Lago dos Manacás, com o objetivo de obter uma representação realista da estrutura térmica do reservatório. Uma vez calibrado, o Elcom constitui-se em uma eficiente metodologia para análise rápida dos processos de mistura e estratificação da coluna d’ água. É sabido que a circulação da água influencia na dinâmica de nutrientes e de comunidades biológicas, assim como na ressuspensão do sedimento, que atua como uma fonte de material orgânico e inorgânico para o sistema. Dessa forma, este trabalho também objetivou versar sobre as influências físicas e climáticas na biogeoquímica e coloração do lago. Nossos dados demonstraram que o Elcom foi satisfatoriamente representado na superfície da água (epilímnio), apenas com a configuração a partir de dados climáticos locais. Porém, este resultado não foi obtido na região intermediária (metalímnio) e no fundo do lago (hipolímnio). Assim, foi relevante entender as forçantes que influenciam na circulação da água, que esteve associada com ventos predominantes (NE-E) e velocidade de 7,8 m s-1. A chuva atuou de forma indireta e significativa, aumentando a vazão de entrada e promovendo o escoamento superficial. Foi observado que durante dias chuvosos de dezembro o lago manteve-se misturado e com altos níveis de turbidez e material em suspensão, que influenciam de forma indireta na cor verdadeira da água. A nossa hipótese inicial era que o Carbono Orgânico Dissolvido (COD) influenciava na cor do lago, porém esta foi derrubada, uma vez que no período estudado este não influenciou na coloração. No geral, o Lago dos Manacás não é limitado por nitrogênio e fósforo, possui estratificação química e pH neutro; altas concentrações de Ferro Total (FT) no fundo, o qual esteve relacionado com o Fosfato (FOS), uma vez que as maiores médias de FOS foram presentes quando o FT foi menor. Esse trabalho tem como perspectiva futura a aplicação dos dados biogeoquímicos em uma modelagem Ecológica (Caedym), calibrando-a no Lago dos Manacás. Assim, a modelagem acoplada Elcom – Caedym poderá ser vislumbrada para estudos futuros. / The mathematical modeling is a tool for ecological studies that has been applied to management of aquatic ecosystems with focus on physical, chemical and biological compartments. This thesis aimed to apply a three-dimensional hydrodynamic model (Elcom) in Manacás Lake, with the purpose to obtain a realistic representation of the thermal reservoir structure. When calibrated, the Elcom is an efficient methodology that can be applied for rapid analysis of the water column mixing and stratification processes. It is known that the movement of water influences the nutrient dynamics and biological communities, as well as resuspension of sediment, which acts as a source of organic and inorganic material into the system. This study also aimed to relate the physical and climatic influences on the biogeochemistry and color of the water. Our data demonstrated that Elcom has been satisfactorily represented on the water surface (epilimnion), only with local climatic configuration. However, this result was not obtained in the intermediate region (metalimnion) and in the bottom (hypolimnion). Thus, it was important to understand the forces that influence the water movements, which was associated with predominant winds (NE-E) and velocity of 7.8 m s-1; the rain acted indirectly and significantly increasing the inflow and promoting the runoff. It was observed that during rainy days in December, the lake remained mixed, with high levels of turbidity and suspended solids, which indirectly influence the true color of water. Our initial hypothesis was overthrow failed, because the Dissolved Organic Carbon (COD) did not affect the color. Overall, Manacás Lake is not limited by nitrogen and phosphorus, it presented chemical stratification, has neutral pH and high concentrations of Total Iron (TI) on the bottom, which was related to the FOS, since higher values of phosphate ( FOS), were present when the TI was lower. This work has the prospect of future application of biogeochemical data in ecological model (Caedym) and to calibrate it in Manacás Lake. Thus, the coupled modeling Elcom - Caedym can be envisioned for future studies.