Macroalgal beds provide the ecological foundations for most shallow reef ecosystems in temperate environments. With distinctive canopies primarily of brown laminarian algae (northern hemisphere), or laminarian or fucalean algae (southern hemisphere), in many areas these habitats are at risk from human activity. Overexploitation, pollution, and other effects of coastal activities have resulted in significant habitat loss in coastal ecosystems, and human-induced climate change is now seen as a major threat to ecosystem health in marine systems. Understanding the impact of climate change is particularly important for habitat-forming ecosystem engineers like kelps, as these species form the basis of hierarchically organised communities and play a fundamental role in determining community structure and ecological processes. South eastern Australia has experienced increases in marine temperatures at nearly four times the global average, and there is now evidence that, in some locations, macroalgae communities are retreating in a manner consistent with ocean warming. Successful management of marine systems requires understanding ecosystem processes, particularly the patterns and magnitude of production. Macroalgal communities often show relatively low resistance to disturbance, yet rapid recovery once disturbances are removed, hence they are generally highly dynamic in response to environmental perturbations. As a result, macroalgae are likely to play an increasingly important role in buffering the short term/dynamic effects of climate change on temperate reef communities.Knowledge of the productivity of seaweed-dominated temperate reef systems is largely a synthesis from studies conducted over small spatial scales utilising a variety of methods that generally measure different characteristics of both individual seaweeds and collectively. As a result of the diversity of measurement methods, estimates of gross primary productivity (GPP), production potential, and macroalgal biomass for temperate reefs are numerous and variable. This can lead to challenges for ecologists attempting to amalgamate research findings to facilitate long-term, broad-scale perspectives or compare short-term research between spatially separated communities. However, to date there has been relatively little research to compare measurement approaches and quantify differences in productivity estimates across the different techniques.The present research provides a unique investigation into some of the techniques and methodology involved in measuring primary productivity in marine systems, particularly kelp forests, using the macroalgae Ecklonia radiata, Phyllospora comosa and Macrocystis pyrifera as study species. The work is based on both field and laboratory exploration of productivity measurements and associated parameters. In situ measurements of primary productivity (diel oxygen modelling, benthic oxygen exchange chambers) or PSII electron transport (PAM fluorometry) are compared, and the possibility of using acoustics as a means of quantifying oxygen production at large scales is explored, as has already been applied in seagrass beds. This thesis also provides an in depth investigation of the effect of variability in sampling methodology with regards to interpretation of PAM fluorometry-derived parameters. Chapter 2 investigates the acoustic properties of Ecklonia radiata. The density, sound speed and resulting adabiatic compressibility of E. radiata tissue were investigated in the laboratory. Four methods were developed and trialled to determine the intrinsic sound speed of Ecklonia radiata tissue based on measurement of the time of flight of an ultrasonic pulse, while compressibility was calculated from density measurements. The results show that Ecklonia radiata sound speed and density are higher, and compressibility lower, than that of seawater. Properties varied according to size and tissue type and the variation likely reflected differences in cell type, packing and structure as well as the concentrations of alginates and other carbohydrates. These are important considerations for acoustic propagation and the results provide valuable inputs for future acoustic work. Chapter 3 focuses on the acoustic modelling of different scenarios of primary production in a shallow water rocky reef environment of Fortescue Bay (Canoe Bay), Tasmania, where E. radiata dominates the canopy. In February 2012, the environment was continuously probed by acoustic signal transmission and monitored by a comprehensive set of oceanographic sensors with the aim to assess the potential for acoustics to quantify excess oxygen production in bubble form. Ray-theory acoustic modelling results indicate that ecologically-significant void fractions of oxygen in the canopy layer from production would be clearly seen in diel variation of propagation features such as the energy decay rate of the medium impulse response. The model can then be used to invert empirical data for retrieving void fraction. However, comparative analysis of part of FORTES 12 data and model suggests that no large excess of bubbles was produced by photosynthesis under the present environmental conditions, in contrast to earlier observations made in seagrasses. As a result, the use of acoustics as a means of measuring primary productivity in kelp could not be further explored during the course of this research.Chapter 4 provides a unique comparison of the estimates of photosynthetic O2 production rates in an Ecklonia radiata dominated community using three different measurement methods: diel oxygen GPP models, benthic oxygen exchange chambers, and electron transport rate from PAM fluorometry which is usually interpreted as a measure of production potential. All three methods were run concurrently in situ in Fortescue Bay, Tasmania. The first diel oxygen model was fitted to in situ measures of dissolved oxygen (DO) in the environment and demonstrated a good fit, however, a consequence of this approach is that large variation in oxygen production was predicted at low PAR levels. A second model was created which utilised an explicit relationship between DO production and PAR, but it didn’t represent DO at the surface as well as the first model. Importantly, the two models indicate similar daily production rates of the seaweed bed (all species combined) that are ~ 2 times that predicted for the kelp alone based on incubations in the benthic chambers and scaling for the average size of adult kelp sporophytes and their population density. Oxygen evolution from incubation of sporophytes in benthic chambers and PAM fluorometry derived electron transport rates showed similar patterns, but the results indicate that the latter method may overestimate potential photosynthesis. The results suggest that diel oxygen modelling, benthic oxygen exchange chambers and PAM fluorescence can all provide good indications of productivity in shallow water marine environments. However, care must be taken in interpretation of results as each method differs in the type of productivity estimates it provides. As a direct measure of total seaweed production per unit area of reef, estimates from models based on empirical measures of environmental DO have much to recommend them.Chapter 5 details a final analysis investigating the effects of diurnal, seasonal and latitudinal variability in ambient light on PAM-derived parameters, as well as possible effects associated with depth, within- and between-alga variation in PSII performance, and latitudinal effects unrelated to the light climate. This research was based on field measurements undertaken in Tasmania, Western Australia and New South Wales, Australia in both summer and winter during 2012 and 2013, focussing on Ecklonia radiata, Macrocystis pyrifera and Phyllospora comosa. Photosynthetic characteristics of all species were highly dependent on the time of day, depth, latitude/region, season, and part of the thallus from which measurements were taken. Patterns dependent on time-of-day, depth and thalli placement varied with season and/or geographic region, and the nature of these patterns varied between species. It is clear from this work that efforts to standardise approaches to taking measurements of seaweeds using PAM fluorometry will be essential if measurements are to be compared meaningfully across studies.The key findings of this thesis are: (1) a first determination of the acoustic properties of E. radiata tissue which enable the development of scattering models to interpret scientific echosounder data collected in kelp beds; (2) a Gaussian beam/finite element beam code (Bellhop) with detailed environmental input and a huge number of beams can predict the acoustic character of a shallow water rocky reef and bubble layers with low-frequency effective sound speed; (3) the model allows prediction of the acoustic energy decay rates due to various scenarios of ecologically-relevant photosynthetic O2 production rates; (4) day vs night acoustic measurement and model data comparisons challenge void fraction predictions made from well established measurements and methods; (5) diel oxygen modelling, benthic oxygen exchange chambers and PAM fluorescence can all provide good indications of productivity, however, understanding the limitations of each method is essential when interpreting the results as the measurements they provide are not directly comparable; and (6) applying a consistent sampling methodology is a key consideration when planning research utilising PAM fluorometry as diurnal, seasonal, and latitudinal variability, as well as effects associated with depth and within- and between-alga variation in PSII performance will have significant impact on PAM-derived parameters. The results of this work give valuable insight into the advantages and disadvantages involved with several main techniques currently utilised to measure production of macroalgal/seagrass beds, and the challenges faced by ecologists attempting to interpret results and compare research between methods and across studies. Last but not least, this study provides important and relevant information on the potential use of acoustics as a future means of determining productivity of benthic habitat on large scales in marine environments. The work presented herein will assist in both development and interpretation of future study of productivity in marine systems. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

O rio Uberabinha, localizado na região do Triângulo Mineiro, em Minas Gerais, compõe a sub-bacia do rio Araguari, afluente da bacia do rio Paranaíba, na região hidrográfica do rio Paraná. Mede, da sua nascente no município de Uberaba à foz no rio Araguari, aproximadamente 150 km, percorrendo cerca de 135 km no município de Uberlândia. Drena uma bacia de cerca de 2.190 km2, onde se localizam as captações da água que abastece uma população que hoje se aproxima de meio milhão de habitantes. Os esgotos produzidos pela cidade são também todos descarregados no rio. O trabalho consistiu na análises de pH, temperatura, oxigênio dissolvido e demanda bioquímica de oxigênio em amostras coletadas em cinco pontos do rio Uberabinha, a partir de uma seção a montante da cidade, até cerca de 20,5 km a jusante do último ponto de lançamento de esgoto, abrangendo uma extensão de aproximadamente 42 km. Neste trecho, o relevo passa de medianamente dissecado para intensamente dissecado, com presença de inúmeras corredeiras e cachoeiras. As amostras foram coletadas de junho de 1999 a maio de 2000 e a vazão também foi medida nos dois pontos extremos de coleta. Os resultados mostram que os teores de OD sofrem uma redução ao receber a carga de poluição e gradativamente tendem a recuperar sua taxa de saturação. Em contrapartida, a DBO segue uma curva inversa, denotando a atuação do fenômeno da autodepuração, embora dentro do trecho estudado não se verifique ainda a completa remoção da carga orgânica. / The Uberabinha River, located in the region of Triângulo Mineiro, in the state of Minas Gerais, Brazil, is part of the Araguari River sub-basin. From its head in the city of Uberaba to its mouth in the Araguari River, it measures approximately 150 km, spanning about 135 km in the municipality of Uberlândia. The river drains a watershed of about 2.190 km2, from which water is collected to supply a population that approaches half a million inhabitants. Later, the sewage produced by the city is also discharged directly into the river. This research consisted in the analyses of pH, temperature, dissolved oxygen and biochemical oxygen demand of samples collected in five points of the Uberabinha River, from a section starting upstream of the urban area down to 20.5 km downstream the last point of sewage discharge, encompassing approximately 42 km. In this river section, the landforms go from low to medium hills with many rapids and waterfalls. The samples were collected from June 1999 to May 2000 and the water flow was measured on the two extremes of the studied river section. The results show that the dissolved oxygen values are reduced when receiving the sewage and it tends to slowly return to its normal saturation rate. On the other hand, the biochemical oxygen demand follows a reverse path, as a result of the natural phenomenon of self-restoration even though the organic material is not yet completely removed from the studied river section. / Dissertação (Mestrado)

The Trinity River flows through the Dallas-Ft. Worth Metroplex in north central Texas where it receives effluents from numerous point sources including seven large regional wastewater treatment facilities. Historically, the Trinity River has been impacted by massive wastewater loadings which often constitute > 80% of the total river discharge during low flow periods. Normally, high mass loadings correspond to the summer months, compounding the effects of a naturally stressful period, characterized by high temperatures and low dissolved oxygen concentrations. Samples from 12 stations were collected quarterly over an 18 month period from the Trinity River and two tributaries. Water samples were analyzed for a variety of water quality variables, including metals, priority pollutants, pesticides, and general water quality parameters. Water samples were also tested for acute and subchronic effects with several test species. Fish were collected at each station and assemblages were characterized using traditional classification techniques and the Index of Biotic Integrity. In addition, sediment samples were assessed for toxic effects which could have adversely impacted fish recruitment and in situ biomonitoring experiments were performed. Quantitative habitat characterization analyses were performed to gain additional information that could possibly explains differences in fish assemblage structure related to habitat variability. Data were analyzed using regression, univariate, multivariate, and descriptive statistical techniques and new approaches for analyzing impact assessment data were discussed. Results indicated that the most substantial impacts on fish assemblages were confined to a segment of the river where a sequence of point sources, in close proximity to each other, were overloading the river's capacity to sufficiently dilute and/or detoxify the effluent. Data also indicated the presence of episodic toxicity from nonpoint sources. In addition, toxic effects in sediment samples and differences in habitat were detected and may have contributed to measured differences among fish assemblages in the Trinity River.

No description available.

The object of the study was the pharmaceutical substance TRIAZID of the newest Russian antiviral drug azolo-azinovogo series containing nitro group. Objective: development and validation of the methodology for voltammetric determination of triazide in the pharmaceutical substance TRIAZID on a glassy carbon electrode. Analysis of literature data showed that in the case of biologically active nitro compounds, the most useful for quantitative determination is the electroreduction signal of the nitro group. The advantages of the signal include both the large amount of current generated per mole of the electroactive connection and the relatively low energy requirement for the reduction of the nitro group. This makes it possible to obtain a high current / concentration ratio at low recovery potentials. The conditions for obtaining an analytical signal of triazide on a glassy carbon electrode are optimized. A simple and expressive method for eliminating the interfering effect of dissolved oxygen with the help of sodium sulphite is proposed. / Объектом исследования служила фармацевтическая субстанция ТРИАЗИД новейшего российского противовирусного препарата азоло-азинового ряда, содержащего нитрогруппу. Цель работы: разработка и валидация методики вольтамперометрического определения триазида в фармацевтической субстанции ТРИАЗИД на стеклоуглеродном электроде. Анализ литературных данных показал, что в случае биологически активных нитросоединений наиболее полезным для количественного определения является сигнал электровосстановления нитрогруппы. К преимуществам сигнала можно отнести как большое количество тока, вырабатываемое на моль электроактивного соединения, так и относительно низкую потребность в энергии для восстановления нитрогруппы. Это позволяет получать высокое отношение ток / концентрация при низких потенциалах восстановления. Оптимизированы условия получения аналитического сигнала триазида на стеклоуглеродном электроде. Предложен простой и экспрессный способ устранения мешающего влияния растворенного кислорода с помощью сульфита натрия. Разработана и валидирована по актуальным требованиям Государственной Фармакопеи РФ XIII издания вольтамперометрическая методика определения триазида в фармацевтической субстанции ТРИАЗИД. Контроль содержания триазида по разработанной методике удовлетворяет заявленным критериям приемлемости, не требует дорогостоящего оборудования, привлечения высококвалифицированного персонала, отличается коротким временем анализа. При условии включения в фармстатью предприятия разработанный метод может применяться испытательными лабораториями предприятия в процессе производства препарата.

The present study evaluates the surface water quality in the canals of An Giang province in the period from 2009 to 2016. The results showed that surface water of the canals was contaminated by organic matter and microorganisms which makes it not suitable for water supply and conservation of aquatic life. The water quality parameters such as dissolved oxygen (DO), biological oxygen demand (BOD), total suspended solids (TSS), orthophosphate (P-PO43-) and coliforms levels in the wet season were found to be higher than those in the dry season. The problem of organic and microorganic pollution over a long period of time without solutions leads to declines in water quality and then quantity as well. Agriculture is the main activity contributing to pollution of surface water in interior canals along with the activities of daily life, industry and services. This causes pollution of the surface water on Hau River due to its exchange of water with the connected canals. Good agricultural practices should be implemented to limit the pollution of surface water resources of the Mekong Delta. / Nghiên cứu này nhằm đánh giá diễn biến chất lượng nước mặt trong các kênh rạch nội đồng của tỉnh An Giang trong giai đoạn 2009 – 2016. Kết quả cho thấy nước mặt tại các kênh rạch nội đồng đã ô nhiễm hữu cơ và vi sinh vật. Nguồn nước không phù hợp cho mục đích cấp nước sinh hoạt và bảo tồn thực vật thủy sinh. Các chỉ tiêu như hàm lượng oxy hòa tan (DO), nhu cầu oxy sinh hóa (BOD), tổng chất rắn lơ lửng (TSS), orthophosphate (P-PO43-) và coliforms trong mùa mưa cao hơn mùa khô. Vấn đề ô nhiễm hữu cơ và vi sinh vật diễn ra trong thời gian dài và chưa có giải pháp xử lý làm cho chất lượng nước suy giảm dẫn đến suy giảm về trữ lượng. Nông nghiệp là hoạt động chính góp phần làm ô nhiễm nguồn nước mặt trong các kênh rạch nội đồng bên cạnh các hoạt động sinh hoạt, công nghiệp và dịch vụ. Điều này dẫn đến nước mặt trên sông Hậu cũng có đặt tính ô nhiễm tương tự do trao đổi nước với các kênh rạch nội đồng. Thực hành sản xuất nông nghiệp thân thiện môi trường cần sớm được triển khai để hạn chế ô nhiễm nguồn nước mặt quan trọng của khu vực đồng bằng sông Cửu Long.

Maintaining dissolved oxygen concentrations under different operating schemes (constant, manual or automated aeration control) was evaluated in 20 earthen catfish ponds ranging from 0.04 to 0.07 hectares in size. Ponds were assigned to treatments based on achieving equal distribution of biomass among treatments. Catfish weighing approximately 0.11 kg each were stocked at a rate of 14,820 catfish/hectare and were fed, to satiation, a 36% crude protein floating feed for the first week and switched to a 32% crude protein floating feed for the remainder of the study. Percentage weight gain, FCR and survival were calculated but did not differ among treatments. A partial enterprise budget analysis was generated to determine comparative value of different aeration techniques relative to production costs. Mean partial net returns did not differ among treatments. Complete comparison was not possible due to failure of automated monitors to record DO and to operate aerators under designed protocols.

No description available.

<p>An electro-optical sensor module was designed to monitor the level of dissolved oxygen (DO) using the method of frequency domain fluoroscopy. Frequency domain fluoroscopy is an optical method that detects the concentration of an analyte by indirectly monitoring the fluorescent lifetime decay. A planar film containing oxygen sensitive fluorophores interacts with a liquid solution, where the percent DO dictates the fluorescent lifetime decay. Amplitude modulated LED emission is created using an electrically implemented oscillator, exciting the oxygen sensitive fluorophores. The emission light from the fluorophores is detected by a photodiode and conditioned. The timing characteristics of the excitation and emission light waveforms are interpreted by a microcontroller. Time delay values have been correlated to actual percent DO values experimentally, and appropriate data modeling has been implemented for calibration purposes. This design is appropriate for application in bioreactors, presenting a functional and cost effective design. Future research can be performed to extrapolate the microcontroller platform to host a pH module, cell number module and glucose module, providing sufficient feedback to an automated bioreactor systems.</p> / Master of Applied Science (MASc)

From the Proceedings of the 1978 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 14-15, 1978, Flagstaff, Arizona / Algal growth and oxygen evolution at the soil -water interface of soil recharge basins intermittently flooded with secondary sewage effluent (SSE) produced diurnal fluxes in dissolved oxygen (DO) in the SSE and redox potentials (Eh) in the SSE and the surface soil of the basin. The maximum daily DO-% saturation in the SSE during flooding ranged from 30 to 450 %, depending on the length of flooding and seasonal effects of temperature and solar radiation. Diurnal cycles of Eh in the SSE and the top 0 to 2 cm of soil indicated that oxygen production by algae and bacterial nitrifying and denitrifying reactions at the soil-water interface are occurring daily for limited periods during flooding and that these reactions might contribute to the net-N removal and renovation of SSE by soil filtration.