Avaliação da sorção de Cu (II) e Hg (II) pela Sargassum sp modificado com epicloridrina

É crescente o aumento da preocupação do homem com a contaminação de ambientes aquáticos uma vez que da subsistência dos mesmos depende o bem estar de todos. Ao mesmo tempo em que cresce a preocupação tem aumentado a quantidade de pesquisas em busca de tecnologias alternativas ao tratamento e remediação de efluentes aquosos contaminados pelas mais diversas substâncias incluindo os metais pesados. Nas últimas décadas, tem crescido o número de trabalhos avaliando a capacidade de sorção e a viabilidade da utilização de biossorventes de baixo custo na captação de íons metálicos e um desses materiais são as biomassas de algas pardas. Dentre os vários gêneros existentes no planeta o território brasileiro é rico na macroalga do gênero Sargassum. Muito embora a composição dessas biomassas varie o principal constituinte das mesmas é o ácido algínico e seus sais alcalinos na forma de um copolímero linear, homopolimérico, com unidades do ácido manurônico, (M), (1-4)-β-D- ligado e seu epímero em C-5 nos resíduos α-L-gulurônicos, (G), respectivamente, covalentemente ligados entre si em sequencias diferenciadas ou em blocos. Os monômeros podem aparecer em blocos homopoliméricos consecutivos, resíduos G (unidades G), resíduos consecutivos M (unidades M), pequenas unidades alternadas M e G (blocos MG), ou em blocos aleatoriamente organizados. A proposta dessa dissertação é realizar a modificação do copolímero existente na biomassa com epicloridrina, avaliar e comparar a captação de íons Cu (II) e Hg (II) pela biomassa da alga Sargassum sp., com a biomassa não modificada e resultados publicados na literatura

Fish zoning of some watercourses in Normandy [Translation from: Verhandlungen der Internationalen Vereinigung fuer Theoretische und Angewandte Limnologie 18, 1135-1146, 1972]

The identification of fish zones in western and central Europe has been the objective some major studies. This paper concerns a stream in Normandy specially studied by the author in 1969 and 1970 in the framework of a study on the role of the mean temperature in fish zoning. The paper propounds the comparative study of the morphodynamic and occasionally physico-chemical characteristics, as well as the results of previous sampling by electric fishing of the fish populations of two other streams of the higher Cretaceous layer and supplied by ”chalky” water in Normandy and Picardy.

Remoção de compostos sulfurados e nitrogenados de diesel hidrotratado por adsorção em argila, alumina e sílica-alumina, impregnadas com metais de transição

Na matriz energética brasileira, o óleo diesel tem lugar de destaque, porém ainda é comercializado com teores de compostos sulfurados e nitrogenados considerados altos para as legislações ambientais que entrarão em vigor nos próximos anos. Tradicionalmente, a remoção desses compostos de enxofre de correntes de petróleo é realizada por processos de hidrotratamento (HDT). No entanto, devido as características do diesel brasileiro, se faz necessária maior severidade para atingir as novas especificações dos combustíveis. Isto implica em investimentos e custos operacionais crescentes para atender a demanda que se instala. Neste contexto, a adsorção está sendo estudada para a purificação da corrente de óleo diesel oriunda da etapa de hidrotratamento como polimento final para alcançar as especificações mais exigentes. Sabe-se que os adsorventes comerciais apresentam limitações na remoção destes contaminantes e uma alternativa que tem se mostrado promissora é a incorporação de metais de transição na estrutura do sólido. No presente trabalho foram modificados adsorventes comerciais, tais como aluminas, sílica-aluminas e argilas pela introdução dos elementos níquel, colbalto e molibdênio e testado o desempenho dessas modificações frente à adsorção de compostos sulfurados e nitrogenados presentes em um diesel hidrotratado. Foram feitas caracterizações químicas, físicas, texturais e morfológicas dos sólidos com e sem incorporação de metais de transição na estrutura original. Os experimentos de adsorção foram realizados a 40C. Avaliando todos os sólidos, o adsorvente que mostrou o melhor desempenho na remoção de compostos sulfurados e nitrogenados por massa de adsorvente foi a sílica-alumina sem modificações, que foi capaz de remover em torno de 90% de compostos nitrogenados e 55 % de sulfurados para 2 g de sólido / 10 mL de diesel. Para os materiais modificados, observou-se que a incorporação dos metais de transição ocasionou redução da sua área superficial e do volume total de poros. Desta maneira, os efeitos esperados pelas interações entre o sítios metálicos e os compostos de nitrogênio e enxofre foram reduzidos

Ecological study of the River Lambourn. Report for the period October 1970 to September 1973

Few detailed studies have been made on the ecology of the chalk streams. A complex community of plants and animals is present and much more information is required to achieve an understanding of the requirements and interactions of all the species. It is important that the rivers affected by this scheme should be studied and kept under continued observation so that any effects produced by the scheme can be detected. This need has been recognised by the Thames Conservancy and the Water Resources Board who jointly sponsored this investigation on one of the chalk streams involved in the scheme. The present investigation has two main objectives both of which depend on obtaining a detailed picture of the ecology of the river at the present time. First, it will provide basic information on the state of the river prior to the development of the pumping scheme which will be available for comparison at any later date. Secondly, it may be possible to use some of the data to predict the ecological changes which may occur if the flow of the river is altered by the pumping scheme. The study covers suspended solids, invertebrates, fish.This report is part of a series of fives studies on the River Lambourn which were undertaken between 1970 and 1979. [PDF contains 24 pages]

Ecological study of chalk and limestone stream. Annual report October 1975 to September 1976

Few detailed studies have been made on the ecology of the chalk streams. A complex community of plants and animals is present and much more information is required to achieve an understanding of the requirements and interactions of all the species. It is important that the rivers affected by this scheme should be studied and kept under continued observation so that any effects produced by the scheme can be detected. The report gives a brief synopsis of work carried out during the third year of a four year ecological study sponsored jointly by the Thames Water Authority and the Central Water Planning Unit. It assumes . It assumes some familiarity with the investigations carried out on the River Lambourn during the preceding three years which was sponsored jointly by the Thames Conservancy and Water Resources Board (immediate predecessors of the present sponsoring organisations). (PDF contains 35 pages)

Information collected in Teesdale concerning free-swimming stages of brown trout (Salmo trutta L.)

During 1978 and 1979, electrofishing surveys were made in Teesdale - both to provide background information for ecological work on the streams, and to provide data so that the influence of discharge regime on the fish population densities could be examined. The discharge regimes of the different streams were compared using the Base Flow Index (BFI) as developed by the Institute of Hydrology. (PDF contains 30 pages)

Survival of intragravel stages of brown trout (Salmo trutta L.) in Teesdale

A study has been undertaken on several streams in Teesdale (UK)in order to examine survival rates of intragravel stages of brown trout and the factors influencing survival. Although all the becks contained brown trout spawning areas, some were utilised by more spawning trout than others. The best spawning sites as judged by this criterion were Thorsgill and Great Eggleshope becks where the research effort was therefore concentrated. There were two different spawning areas in Eggleshope, namely Great Eggleshope beck itself and Great Eggleshope spring fed tributary (Esft), data from these two areas are analysed separately in most parts of the text.

Mechanics of sediment transport and bedrock erosion in steep landscapes

Erosion is concentrated in steep landscapes such that, despite accounting for only a small fraction of Earth’s total surface area, these areas regulate the flux of sediment to downstream basins, and their rugged morphology records transient changes (or lack thereof) in geologic and climatic forcing. Steep landscapes are geomorphically active; large sediment fluxes and rapid landscape evolution rates can create or destroy habitat for humans and wildlife alike, and landslides, debris flows, and floods common in mountainous areas represent a persistent natural and structural hazard. Despite the central role that steep landscapes play in the geosciences and in landscape management, the processes controlling their evolution have been poorly studied compared to lower-gradient areas. This thesis focuses on the basic mechanics of sediment transport and bedrock incision in steep landscapes, as these are the fundamental processes which set the pace and style of landscape evolution. Chapter 1 examines the spatial distribution of slow-moving landslides; these landslides can dominate sediment fluxes to river networks, but the controls on their occurrence are poorly understood. Using a case-study along the San Andreas Fault, California, I show that slow-moving landslides preferentially occur near the fault, suggesting a rock-strength control on landslide distribution. Chapter 2 provides the first field-measurements of incipient sediment motion in streams steeper than 14% and shows a large influence of slope-dependent flow hydraulics and grain-scale roughness on particle motion. Chapter 3 presents experimental evidence for bedrock erosion by suspended sediment, suggesting that, in contrast to prevailing theoretical predictions, suspension-regime transport in steep streams can be the dominant erosion agent. Steep streams are often characterized by the presence of waterfalls and bedrock steps which can have locally high rates of erosion; Chapters 4 and 5 present newly developed, experimentally validated theory on sediment transport through and bedrock erosion in waterfall plunge pools. Finally, Chapter 6 explores the formation of a bedrock slot canyon where interactions between sediment transport and bedrock incision lead to the formation of upstream-propagating bedrock step-pools and waterfalls.

Ecological study of the River Lambourn. Report for the period October 1973 to September 1977

The investigations described in this report were carried out to fulfill three distinct but interrelated objectives. In 1973 the Thames Conservancy were making plans for a second stage of their groundwater scheme which would take water from the chalk aquifers in the valley of the Kennet and they wanted basic information on the ecological state of this river and its upper tributaries. Little appeared to be known about limestone streams and a preliminary study of one of the streams in this area was desirable as a basis for planning more detailed studies if these were needed later. At a progress meeting held in March 1976 the problems and opportunities presented by the developing drought conditions were considered. It was concluded that the ecological effects of the exceptionally low natural flows should be studied and that it would be important to assess the ecological impact of the groundwater scheme if it was brought into operation that year. This could only be done on the Lambourn and the Winterbourne and it was decided that considerable effort should be diverted there for this purpose and that the field observations should be extended to cover any recovery period after the end of the drought. To make this possible it was agreed that the studies of invertebrates and detritus on the Kennet should be reduced considerably and that the proposed study of the limestone stream should be abandoned. The revised objectives were as follows: A detailed ecological study of several sites on the Kennet and its tributaries above Kintbury, extending over at least two years and involving observations on wate r weeds , invertebrates, fish, detritus and the trophic relationships within the river community. Quantitativ e and qualitative sampling of water weeds and invertebrates during one year at a number of sites on several chalk streams to determine whether the patterns and relationships found in the Lambourn are also found at the other sites. Observations on the Lambourn at Bagnor were to continue for most of the period to look for long-term fluctuations and to enable these sites to act as controls with which the other sites could be compared. Further detailed studies on the Lambourn and the Winterbourne to assess the impact of low flows, trial pumping and the operation of the groundwater scheme.

Aspects of the washout of salmonid eggs. 1. Observations on the physical characteristics of real and artificial eggs, their rate of fall in a water column and their pattern of settlement in an experimental channel

When salmonid redds are disrupted by spates, the displaced eggs will drift downstream. The mean distance of travel, the types of locations in which the eggs resettle and the depth of reburial of displaced eggs are not known. Investigation of these topics under field conditions presents considerable practical problems, though the use of artificial eggs might help to overcome some of them. Attempts to assess the similarities and/or differences in performance between real and artificial eggs are essential before artificial eggs can validly be used to simulate real eggs. The present report first compares the two types of egg in terms of their measurable physical characteristics (e.g. dimensions and density). The rate at which eggs fall in still water will relate to the rate at which they are likely to resettle in flowing water in the field. As the rate of fall will be influenced by a number of additional factors (e.g. shape and surface texture) which are not easily measured directly, the rates of fall of the two types of egg have been compared directly under controlled conditions. Finally, comparisons of the pattern of settlement of the two types of egg in flowing water in an experimental channel have been made. Although the work was primarily aimed at testing the value of artificial eggs as a simulation of real eggs, several side issues more directly concerned with the properties of real eggs and the likely distance of drift in natural streams have also been explored. This is the first of three reports made on this topic by the author in 1984.

Composition and bulk properties of Dorset river gravels

Considerable interest has been expressed in the composition of the stream gravels, the movement of bed materials and the relationship of sediment composition, packing and siltation of void space to invertebrate ecology. In the autumn of 1982, freeze-samples of gravel were obtained in Dorset streams. Data were required on the depth of salmonid egg pocke and were part of a broader investigation of regional variation in the independent variables of salmonid fish length, gravel size, current velocity and the resultant dependent variable ~egg burial depth. The Dorset river gravels examined are bimodal. The grain size distribution may be resolved into two near-normal frequency distributions interpreted as representing a primary framework or lattice of gravel particles into which a secondary matrix population of sand particles has penetrated.

Progress on the salmon investigation

An article detailing some of the conclusions of the salmon investigation undertaken by the author, on the River Eden and its tributaries, for the previous few years. It is proposed that seasonal changes in young salmon growth are related to water temperature variation. A figure is included showing length of fish compared to the average temperature of water in the River Eden over a two year duration. The article describes comparative work undertaken to date between three streams within the Thurso watershed and the River Eden. A table is included showing the average size of fish in each of the watercourses compared. Laboratory experiments on the effects of temperature on young salmon are outlined, as well as investigative work undertaken into the realtionship between fish scales and fish length.

Effects of injection nozzle configuration on secondary injection into supersonic flow

Gaseous nitrogen and argon were injected into a primary stream of air moving at Mach 2.56. The gases were injected at secondary to primary total pressure ratios from 3.2 to 28.6 through four different nozzles. Two nozzles, one sonic and one supersonic (M = 3.26), injected normal to the primary stream; and two sonic nozzles injected at 45° angles to the primary flow, one injecting upstream and the other downstream. Data consisted of static pressure measurements on the wall near the injector, total pressure profiles in the wake of the injectant plume, and concentration measurements downstream of the flow. Scale parameters were calculated based upon an analytical model of the flow field and their validity verified by experimental results. These scale heights were used to compare normalized wall side forces for the different nozzles and to compare the mixing of the two streams.

On the transport properties of fluid-particle flow

The hydrodynamic forces acting on a solid particle in a viscous, incompressible fluid medium at low Reynolds number flow is investigated mathematically as a prerequisite to the understanding of transport processes in two-phase flow involving solid particles and fluid. Viscous interaction between a small number of spherical particles and continuous solid boundaries as well as fluid interface are analyzed under a “point-force” approximation. Non-spherical and elastic spherical particles in a simple shear flow area are then considered. Non-steady motion of a spherical particle is briefly touched upon to illustrate the transient effect of particle motion.

A macroscopic continuum description of particle-fluid flow is formulated in terms of spatial averages yielding a set of particle continuum and bulk fluid equations. Phenomenological formulas describing the transport processes in a fluid medium are extended to cases where the volume concentration of solid particles is sufficiently high to exert an important influence. Hydrodynamic forces acting on a spherical solid particle in such a system, e.g. drag, torque, rotational coupling force, and viscous collision force between streams of different sized particles moving relative to each other are obtained. Phenomenological constants, such as the shear viscosity coefficient, and the diffusion coefficient of the bulk fluid, are found as a function of the material properties of the constituents of the two-phase system and the volume concentration of solid. For transient heat conduction phenomena, it is found that the introduction of a complex conductivity for the bulk fluid permits a simple mathematical description of this otherwise complicated process. The rate of heat transfer between particle continuum and bulk fluid is also investigated by means of an Oseen-type approximation to the energy equation.

Biological environments of larger UK rivers: progress report 1987

This interim progress report for the 9 months from January 1987 to September 1987 aims to provide insights into the mechanisms by which populations of particles (in this instance, phytoplankton) behave in relation to fluvial flow and, thus, to better model the dispersive properties of rivers and the ecological principles governing the distribution of potamoplankton generally. The author has been able to show with dye-tracers that significant water retention in pool reaches occurs within the range of (low) discharges obtaining, in accord with the Aggregated Dead Zone model and to an extent comparable with streams and small rivers investigated previously.