<p>The hypothetical assumption that chloride is conservative in the soil has been debated for the last decade. The results of the recent years of study in chlorine biogeochemistry show that chloride is non-conservative but rather participates in complex biogeochemical reactions in the soil. These interactions in nature inform the development of simplified hydrochemical model of chloride dynamics in the soil that is driven on soil routine component of HBV hydrological model. This novel attempt affords the opportunity to explore chlorine biogeochemistry further by evaluating the biological processes such as microbial biomass that predominate chlorine cycles in the same order of magnitude as earlier studied abiotic factors. Data from soil lysimeter experiment with different inputs treatments were used in the calibration and validation of both the hydrological and biogeochemical model. The results show that (1) model efficiency reduces with decreasing water residence and with increasing soil organic matter. (2) Longer water residence time (low water input), high chloride and high nitrogen input loads relatively enhance maximum biomass accumulation in a shorter time span. (3) Chloride retention time reduces with increasing chloride loads under short water residence. (4) Microbial biomass growth rate is highest under high chloride input treatments. (5) Biomass death rates shows reducing trend under short water residence (High water input). Further researches are therefore suggested for possible model expansion and to make the results of this model plausible under field conditions.</p>

The hypothetical assumption that chloride is conservative in the soil has been debated for the last decade. The results of the recent years of study in chlorine biogeochemistry show that chloride is non-conservative but rather participates in complex biogeochemical reactions in the soil. These interactions in nature inform the development of simplified hydrochemical model of chloride dynamics in the soil that is driven on soil routine component of HBV hydrological model. This novel attempt affords the opportunity to explore chlorine biogeochemistry further by evaluating the biological processes such as microbial biomass that predominate chlorine cycles in the same order of magnitude as earlier studied abiotic factors. Data from soil lysimeter experiment with different inputs treatments were used in the calibration and validation of both the hydrological and biogeochemical model. The results show that (1) model efficiency reduces with decreasing water residence and with increasing soil organic matter. (2) Longer water residence time (low water input), high chloride and high nitrogen input loads relatively enhance maximum biomass accumulation in a shorter time span. (3) Chloride retention time reduces with increasing chloride loads under short water residence. (4) Microbial biomass growth rate is highest under high chloride input treatments. (5) Biomass death rates shows reducing trend under short water residence (High water input). Further researches are therefore suggested for possible model expansion and to make the results of this model plausible under field conditions.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Potentially toxic cyanobacterial blooms have been frequent in Brazilian lakes and reservoirs, causing economic issues as well as public health risks. In Rio Grande do Sul, a series of five reservoirs in the high course of the River Jacuí form a cascade system. One of the reservoirs, Passo Real, mainly accumulates water for hydroelectrical power generation and also regulates water flow to downstream reservoirs, amongst other uses. Blooms of cyanobacteria have been frequently recorded in this water body, possibly due to the long water residence time, associated to weather conditions and nutrient runoff from intense agricultural activities in the surrounding area. The study described herein aimed to: a) verify patterns of climatic, hydrological and limnological conditions, as well as their relationship with blooms of cyanobacteria; b) describe the yearly circulation regime, and thermal stratification of the water column; c) define the most favourable environmental conditions for the incidence of both dispersive and surface accumulative blooms, and also which species are adapted to each bloom type. 60 phytoplankton samples were taken from Passo Real reservoir between October 2009 and January 2013. Cyanobacteria species were identified and counted to estimate specific density and specific biovolume. Each bloom was assigned to a class: dispersive or surface accumulative. Measurements of solar radiation availability, solar shine, air temperature, rainfall, direction, and velocity of wind were taken, and also weather conditions for the sampling period were recorded. Hydrological (inflow, outflow, altitude, usable volume and residence time) and limnological (transparency, water temperature, pH, electric conductivity, total dissolved solids and chlorophyll-a) variables were also measured. The most influential variables favouring bloom formation were: intense rainfall (>20mm) up to ten days before sampling; air temperature mainly above 15ºC thirty days before sampling; low wind speed (<2m·s-1); high inflow caused by intense rainfall, coinciding with agricultural off season; long water residence time, 132 days on average on months with blooms; warmer temperatures and thermal stratification of the water between October and March. The reservoir was classified as warm monomictic, with only one complete vertical circulation in the winter and thermal stratification in the summer. Dispersive blooms were found when wind speed was above 7,9m·s-1, and surface accumulative blooms occurred when wind speed was below 5,5m·s-1. Species of the genus Dolichospermum were more adapted to produce dispersive blooms, mainly D. crassum and D. circinalis. On the other hand, species of Microcystis were better adapted to surface accumulative blooms, namely M. aeruginosa and M. panniformis, which were also indicator species for this type of bloom. / A ocorrência de florações de cianobactérias potencialmente tóxicas tem sido frequente em lagos e reservatórios no Brasil, ocasionando problemas econômicos e riscos à saúde pública. No Rio Grande do Sul há uma série de cinco reservatórios formando um sistema em cascata no Alto Curso do Rio Jacuí. O reservatório Passo Real compõe esse sistema e tem como principal função acumular água para a geração de energia elétrica e regular vazões para os reservatórios a jusante, servindo também aos demais usos múltiplos da água. Florações de cianobactérias têm sido registradas com frequência neste reservatório, possivelmente pelo longo tempo de residência da água, associado às condições meteorológicas e ao aporte de nutrientes, decorrente da intensa atividade agrícola sobre sua bacia de drenagem. Diante do exposto, objetivouse, neste trabalho: a) verificar a ocorrência de padrões nas condições meteorológicas, hidrológicas e limnológicas e a relação destes com as florações de cianobactérias; b) caracterizar o regime anual de circulação e estratificação térmica da água; e c) determinar quais as condições ambientais para a ocorrência de florações dispersivas e acumulativas em superfície e quais as espécies adaptadas a cada uma das florações. Para isto foram coletadas 60 amostras de fitoplâncton no reservatório Passo Real, entre outubro de 2009 e janeiro de 2013. As cianobactérias foram identificadas, estimada a densidade e o biovolume de cada espécie e as florações foram classificadas como dispersivas ou acumulativas em superfície. Foram determinadas as disponibilidades de radiação solar, brilho solar, temperatura do ar, precipitação pluviométrica, direção e velocidade do vento, assim como as variáveis meteorológicas do período coletado. Variáveis hidrológicas (vazão afluente e defluente, cota altimétrica, volume útil e tempo de residência) e limnológicas (Transparência, temperatura da água, pH, condutividade elétrica, total de sólidos dissolvidos e clorofila-a) foram caracterizadas. Dentre as variáveis meteorológicas, hidrológicas e limnológicas analisadas no período estudado, aquelas que tiveram uma influência favorável para a ocorrência das florações foram: precipitações pluviométricas elevadas (>20mm), registradas até 10 dias antes das coletas; ocorrência de temperatura média do ar diária acima de 15°C nos trinta dias que antecederam as coletas; baixa velocidade do vento (<2m·s-1) nos dias que antecederam as coletas com florações; elevadas vazões afluentes, decorrentes das precipitações elevadas, coincidentes com os períodos de entressafra dos cultivos agrícolas; longo tempo de residência da água, média de 132 dias durante os meses com florações; temperaturas elevadas e estratificação térmica da água no período de outubro a março. O reservatório Passo Real foi classificado como monomítico quente, com apenas uma circulação vertical completa no inverno e estratificação térmica no verão. Florações dispersivas ocorreram em condições de velocidade do vento acima de 7,9m·s-1. Florações acumulativas de superfície ocorreram em condições de velocidade do vento abaixo de 5,5m·s-1. Espécies do gênero Dolichospermum estão melhores adaptadas a formar florações dispersivas, principalmente as espécies D. crassum e D. circinalis. Já espécies do gênero Microcystis estão melhor adaptadas a formar florações acumulativas em superfície, com destaque para M. aeruginosa e M. panniformis, indicadoras deste tipo de floração.

タンデトロン加速器質量分析計業績報告

In urban areas, stormwater management ponds (SWPs) are built to mitigate polluted runoff. Although these ponds are increasing in numbers, their ecology is not well understood. Physical and chemical characteristics of 17 SWPs in the City of Ottawa were measured to determine the drivers of phytoplankton biomass (Chl. a) and primary production (PP). While total phosphorus was the best predictor of algal biomass in the ponds (as in lakes), the imperviousness of the catchment could also predict Chl. a. Planktonic PP in two ponds measured seasonally was more closely related to water residence time than to nutrient concentrations with rates approaching at times the theoretical maximum for aquatic systems. In one pond, whole ecosystem metabolism, estimated using diel changes in dissolved oxygen and δ18O-O2, suggested that these hypereutrophic systems were net sinks for carbon in the summer but likely sources to the atmosphere at other times of the year.

In urban areas, stormwater management ponds (SWPs) are built to mitigate polluted runoff. Although these ponds are increasing in numbers, their ecology is not well understood. Physical and chemical characteristics of 17 SWPs in the City of Ottawa were measured to determine the drivers of phytoplankton biomass (Chl. a) and primary production (PP). While total phosphorus was the best predictor of algal biomass in the ponds (as in lakes), the imperviousness of the catchment could also predict Chl. a. Planktonic PP in two ponds measured seasonally was more closely related to water residence time than to nutrient concentrations with rates approaching at times the theoretical maximum for aquatic systems. In one pond, whole ecosystem metabolism, estimated using diel changes in dissolved oxygen and δ18O-O2, suggested that these hypereutrophic systems were net sinks for carbon in the summer but likely sources to the atmosphere at other times of the year.

In urban areas, stormwater management ponds (SWPs) are built to mitigate polluted runoff. Although these ponds are increasing in numbers, their ecology is not well understood. Physical and chemical characteristics of 17 SWPs in the City of Ottawa were measured to determine the drivers of phytoplankton biomass (Chl. a) and primary production (PP). While total phosphorus was the best predictor of algal biomass in the ponds (as in lakes), the imperviousness of the catchment could also predict Chl. a. Planktonic PP in two ponds measured seasonally was more closely related to water residence time than to nutrient concentrations with rates approaching at times the theoretical maximum for aquatic systems. In one pond, whole ecosystem metabolism, estimated using diel changes in dissolved oxygen and δ18O-O2, suggested that these hypereutrophic systems were net sinks for carbon in the summer but likely sources to the atmosphere at other times of the year.

Applying mathematical models to dynamic contrast enhanced MRI (DCE MRI) data to perform quantitative tracer kinetic analysis enables the estimation of tissue characteristics such as vascular permeability and the fractional volume of plasma in a tissue. However, it is unclear to what extent modeling assumptions, particularly regarding water exchange between tissue compartments, impacts parameter estimates derived from clinical DCE MRI data. In this work, a new model is developed which includes water exchange effects, termed the water exchange modified two compartment exchange model (WX-2CXM). Two boundaries of this model (the fast and no exchange limits) were used to analyse a clinical DCE MRI bladder cancer dataset. Comparisons with DCE CT, which is not affected by water exchange, suggested that water exchange may have affected estimates of vp, the fractional volume of plasma. Further investigation and simulations led to the development of a DCE MRI protocol which was sensitised to water exchange, in order to further evaluate the water exchange effects found in the bladder cancer dataset. This protocol was tested by imaging the parotid glands in eight healthy volunteers, and confirmed evidence of water exchange effects on vp, as well as flow Fp and the fractional volume of extravascular extracellular space ve. This protocol also enabled preliminary estimates of the water residence times in parotid tissue, however, these estimates had a large variability and require further validation. The work presented in this thesis suggests that, although water exchange effects do not have a large effect on clinical data, the effect is measurable, and may lead to the ability to estimate of tissue water residence times. Results do not support a change in the current practise of neglecting water exchange effects in clinical DCEMRI acquisitions.