130 resultados para ecossistemas lóticos
Resumo:
E utrophication in continental aquatic ecosystems and the following deterioration of water quality are some of the greatest problems to be solved in this century. Due to their own peculiarities reservoirs from semi - arid regions constitute a great challenge to water management because of their greater vulnerability to eutrophication process. I dentification of biolo gical community components that may be used as bioindicators is important to allow an early detection of adverse changes, and also to provide subsidies for management and conservation actions. The aim of the present study is to evaluate the potential of zo oplankton community as bioindicator of the trophic state of two reservoirs belonging to the Piranhas - Açu basin, RN, Brazil: Boqueirão de Parelhas and Passagem das Traíras. Monthly sampling s of both systems were carried out in both systems during the period of January to December. Measurements were performed for temperature, pH, dissolved oxygen and water electrical conductivity besides water samples collection for nutrients, suspended solids, chlorophyll - a and zooplankton analyses. T axonomic composition of zooplankton , density and biomass were analysed. Trophic state index, ABC curves , W statistic and the Calanoida: Cyclopoida ratio were also obtained. The results evidenced that Boqueirão de Parelhas reservoir was a mesotrophic sy stem, and Passagem das Traíras r eservoir was eutrophic. In both reservoirs zooplankton community had low species richness, mostly constituted by tolerant species which have wide geographical distribution, as well the dominance of the rotifers Brachionus havanaensis , B. calyciflo rus and Keratella tropica ; of the calanoid copepods Notodiaptomus cearensis and N. iheringi ; cyclopoid copepod Thermocyclops decipiens, and of the cladocerans Ceriodaphnia cornuta and Diaphanosoma spinulosum . Among the biological indices the ABC curves fo r the zooplankton community indicated a moderate dis turbance in both reservoirs, th e Calanoida: Cyclopoida ration indicated not impacted environments , e xcept during the end of the study to the reservoir Passagem das Traíras . It was concluded that the indices used are good indicators of disturbance and alteration in the community, however they are not good indicators for monitoring the trophic state of the studied reservoirs due to the simultaneous occurrence of other factors selecting species, as the c oncentration of ions and high turbidity, which are part of the reservoir characteristics of semiarid.
Resumo:
A major and growing problems faced by modern society is the high production of waste and related effects they produce, such as environmental degradation and pollution of various ecosystems, with direct effects on quality of life. The thermal treatment technologies have been widely used in the treatment of these wastes and thermal plasma is gaining importance in processing blanketing. This work is focused on developing an optimized system of supervision and control applied to a processing plant and petrochemical waste effluents using thermal plasma. The system is basically composed of a inductive plasma torch reactors washing system / exhaust gases and RF power used to generate plasma. The process of supervision and control of the plant is of paramount importance in the development of the ultimate goal. For this reason, various subsidies were created in the search for greater efficiency in the process, generating events, graphics / distribution and storage of data for each subsystem of the plant, process execution, control and 3D visualization of each subsystem of the plant between others. A communication platform between the virtual 3D plant architecture and a real control structure (hardware) was created. The goal is to use the concepts of mixed reality and develop strategies for different types of controls that allow manipulating 3D plant without restrictions and schedules, optimize the actual process. Studies have shown that one of the best ways to implement the control of generation inductively coupled plasma techniques is to use intelligent control, both for their efficiency in the results is low for its implementation, without requiring a specific model. The control strategy using Fuzzy Logic (Fuzzy-PI) was developed and implemented, and the results showed satisfactory condition on response time and viability
Resumo:
Heavy metals are present in industrial waste. These metals can generate a large environmental impact contaminating water, soil and plants. The chemical action of heavy metals has attracted environmental interest. In this context, this study aimed to test t he performance of electrochemical technologies for removing and quantifying heavy metals. First ly , the electroanalytical technique of stripping voltammetry with glassy carbon electrode (GC) was standardized in order to use this method for the quantificatio n of metals during their removal by electrocoagulation process (EC). A nalytical curves were evaluated to obtain reliability of the determin ation and quantification of Cd 2+ and Pb 2+ separately or in a mixture. Meanwhile , EC process was developed using an el ectrochemical cell in a continuous flow (EFC) for removing Pb 2+ and Cd 2+ . The se experiments were performed using Al parallel plates with 10 cm of diameter ( 63.5 cm 2 ) . The optimization of conditions for removing Pb 2+ and Cd 2+ , dissolved in 2 L of solution at 151 L h - 1 , were studied by applying different values of current for 30 min. Cd 2+ and Pb 2+ concentrations were monitored during electrolysis using stripping voltammetry. The results showed that the removal of Pb 2 + was effective when the EC pro cess is used, obtaining removals of 98% in 30 min. This behavior is dependent on the applied current, which implies an increase in power consumption. From the results also verified that the stripping voltammetry technique is quite reliable deter mining Pb 2+ concentration , when compared with the measurements obtained by atomic absorption method (AA). In view of this, t he second objective of this study was to evaluate the removal of Cd 2+ and Pb 2+ (mixture solution) by EC . Removal efficiency increasing current was confirmed when 93% and 100% of Cd 2+ and Pb 2+ was removed after 30 min . The increase in the current promotes the oxidation of sacrificial electrodes, and consequently increased amount of coagulant, which influences the removal of heavy metals in solution. Adsortive voltammetry is a fast, reliable, economical and simple way to determine Cd 2+ and Pb 2+ during their removal. I t is more economical than those normally used, which require the use of toxic and expensive reagents. Our results demonstrated the potential use of electroanalytical techniques to monitor the course of environmental interventions. Thus, the application of the two techniques associated can be a reliable way to monitor environmental impacts due to the pollution of aquatic ecosystems by heavy metals.
Resumo:
The Área de Proteção Ambiental de Jenipabu was created by Decreto 12,620/95, covering the beaches of Redinha Nova, Santa Rita and Jenipabu and Campina communities in the municipality of Extremoz, and Africa community fragment, in Natal. This protected area was created in the context of expansion of tourism in Rio Grande do Norte, in the 1990s, in which PRODETUR investments made possible the installation of infrastructure equipment, mainly in the Via Costeira and Ponta Negra beach in Natal by inserting it in the sun and sea tourism route to Northeast Brazil. In this context the beach Jenipabu in Extremoz, became one of the main attractions for those visiting Natal, due to the natural elements of its landscape, its dune field, which is offered to tourists the buggy ride. In December 1994 the excess buggy rides held in these dunes led to IBAMA ban their access to buggy for carrying out environmental study. This measure resulted in the creation of APAJ in 1995 with the goal of ordering the use and occupation to protect its ecosystems, especially the dunes, the disordered tourism. Given this context, this work aims to analyze the process of creating the APAJ and changes in the geographic space of its beaches, Redinha Nova, Santa Rita and Jenipabu, from the materialization of tourism process, as well as their implications for its residents. To this end, this paper presents a discussion of environmental currents that developed in the western portion of the globe, focusing on the need to regulate small areas of the national territory in protected areas, and an analysis of public policies that enabled the implementation tourism in APAJ as well as the laws and decrees governing the process of creation and management. Using the theory of circuits of urban economy of the Santos (2008) to analyze the territory used by tourism on the beaches of Redinha Nova, Santa Rita and Jenipabu, showing their dependent relationship with the territory used by the upper circuit on the Via Costeira and in the Ponta Negra beach and its influence on the APAJ urbanization process. Ending with the analysis of the influence of the materialization of tourism in the transformation of stocks ways of being-in-space and space-be of the Santa Rita and Jenipabu beaches in each geographical situation of APAJ among the first decades of the twentieth century to the 2014. Fieldwork was conducted between 2012 and 2014, performing actions of qualitative interviews with older residents of Santa Rita and Jenipabu beaches, interviews with structured questionnaire with merchants of APAJ and collecting GPS points trades, identifying and mapping the territory used by the lower circuit in APAJ beaches.
Resumo:
Industrial activities like mining, electroplating and the oil extraction process, are increasing the levels of heavy metals such as Cu, Fe, Mg and Cd in aquatic ecosystems. This increase is related to the discharge of effluents containing trace of this elements above the maximum allowed by law. Methods such as ion exchange, membrane filtration and chemical precipitation have been studied as a means of treatment of these metals contamination. The precipitation of metals using anionic surfactants derived from carboxylic acids emerged as an alternative for the removal of metals from industrial effluents. The reaction between bivalent ions and these types of surfactants in aqueous solution leads to the formation of metal carboxylates, which can precipitate in the form of flakes and are subsequently removed by a process of decantation or simple filtration. In this work the metals extraction is performed by using the surfactant sodium hexadecanoate as extracting agent. The main purpose was to study the effect of temperature, solution pH, and concentration of surfactant in the metal removal process. The statistical design of the process showed that the process is directly dependent to changes in pH and concentration of surfactant, but inversely proportional and somewhat dependent to temperature variation, with the latter effect being considered negligible in most cases. The individual study of the effect of temperature showed a strong dependence of the process with the Kraft point, both for the surfactant used as extracting agent, as for the surfactant obtained after the reaction of this surfactant with the metal. From data of temperatures and concentrations of the surfactant was possible to calculate the equilibrium constant for the reaction between sodium hexadecanoate and copper ions. Later, thermodynamic parameters were determined, showing that the process is exothermic and spontaneous.
Resumo:
Reservoirs are artificial ecosystems, intermediate between rivers and lakes, with diferent morphological and hydrological characteristics that can provide many important benefits to society. However, the use of this water for human consumption, watering livestock, leisure, irrigated agricultural production and pisciculture development, directly influence the increase loading of nutrients to aquatic environments and contribute to acceleration of eutrophication. Furthermore, global climate models are predicting a higher occurrence of extreme events such as floods and severe droughts, which will create hydrological stresses in lakes. In the semiarid northeast we can see the occurrence of these events, the drought of the years 2012, 2013 and 2014 was the worst drought in 60 years, according to the National Water Agency (ANA). Thus, this study aimed to evaluate the quality of the semiarid tropical water sources, identifying temporal patterns in periods with extreme hydrological events (floods and severe droughts). The study results showed that Gargalheiras and Cruzeta reservoirs presented significative changes in the limnological variables between rain and severe drought periods, with better appearance and in the most of the water quality variables in the rainy season and higher nutrientes concentrations and high electrical conductivity values in severe season, indicating decay of its quality. However, we found diferent behaviors between the reservoirs in severe drought. While Gargalheiras showed a typical behavior of the region, with high concentrations of algal biomass, indicating the worsening eutrophication, Cruzeta demonstrated a colapse in the total phytoplankton biomass, evidenced by the decrease in chla concentrations. This fact occurred because the low depth and proximity with the sediment facilited the inorganic solids resuspension and, consequently, resulted in turbid water column and light by limitation. In addition, the different behaviors between the reservoirs indicate that the responses of these environments problems such as extreme events must take into account factors such the region climate, size, depth of the reservoir and the basin characteristics.
Resumo:
The artifi cial eutrophication is one of the biggest t h reat for the quality of aquatic ecosystems in the whole world. The expectations for the future climatic scenarios in arid and semi - arid regions are intense and frequent droughts enhancing the risk of eutrophicati on and cyanobacterial blooms. Restoration techniques of eutrophic lakes were proposed to reduce nutrient loading and improve the water quality. A successful technique used in temperate regions is the biomanipulation by benthivorous fish removal . Our hypoth esis is that the benthivorous fish removal reduces phytoplankton total biomass and change the composition of phytoplankton functional groups, improving water quality. The aim of the study was evaluate the impact of biomanipulation on phytoplankton function al groups and in the water quality. We applied the technique of biomanipulation in the artificial lake ESEC, in a semi - arid region of Brazil and analyzed the physical and chemical variables and the dynamic of phytoplankton functional groups monthly during November 2012 to August 2013. With the removal of benthivorous fish we observed a significant increase of the euphotic depth, phytoplankton richness and the recruitment of green algae (groups F and J ), indicators of good water quality. However, we did not observe significant differences on total phosphorous concentration and on phytoplankton biomass and diversity. The drought effect in the region during the study was evident , promoting a drastic reduction on water level which influenced the availability of resource and affected phytoplankton community before the biomanipulation. To evaluate the effect of severe drought on the dynamic of phytoplankton functional groups and test if the drought periods are favorable to dominance of cyanobacterial groups, we stu died two artificial neighbors lakes (ESEC and Pocinhos) in a semi - arid tropical region during May 2012 to February 2013. We observed a temporal differentiation of biotic and abiotic variables caused by drought. Both lakes presented reduction of 2 meters of water level and increase on conductivity, turbidity, nutrients concentration and a reduction on water transparency, during the severe drought. The deeper lake (Pocinhos) increased phytoplankton total biomass and presented cyanobacterial functional group d ominance (group S N ) and the shallower lake (ESEC) reduced phytoplankton total biomass and presented dominance of mixotrophic and flagellate functional groups (groups W 1 e W 2 ). Summarizing, the knowledge of the effects of benthivorous fish removal in semi - a rid tropical lakes still unknown and this study had limitations caused by the impact of drought. Thus, it is necessary a long term monitoring to investigate the real effects of biomanipulation on the functioning of the studied ecosystems. Otherwise, period s of drought could have opposite effects (increase or reduction) on total biomass and composition of phytoplankton functional groups. Drought not always leads to dominance of cyanobacterial groups.
Resumo:
The coastal area of the city of Natal due to its location and natural potentialities has been an area where we have experienced big changes in its environment, at the expense of several forms of use and human occupation. On the coast of Via Costeira beach the process of use and land occupation was structured at the end of 1970s and early 1980s, as a result of the government policy which has developmental essence, based on the settlement of plenty big enterprises by the Parque das Dunas/Via Costeira Project. This project was created to install in Natal, capital of the state, infrastructure equipment on this stretch of coastline consisted of dune fields and many parts of ecosystems which have high natural relevance and fragility that used to present a semi-isolation in the urban city, for the development of tourist activities, which is considered as a viable economic solution capable of setting right serious socioeconomic problems that had persisted there. According to what was said so far, this study aimed to analyze the forms of use and land occupation besides the change of the landscape along the Via Costeira coast in the city of Natal/RN. These changes often take place without considering the complexity and fragility of natural ecosystems involved. The geoenvironmental study was based on the geosystemic theory, thus It was possible to analyze the human interventions in the superficial aspects of landscapes holistically. The practical procedures were contemplated with literature searches, followed by field work where were fulfilled the recognition and general characterization of the area in order to investigate and analyze the main types of land occupation and its use that have taken place there since big buildings began to come out, being supported by the legislation whose laws are about protection and conservation of coastal natural resources. The research also includes the identification and evaluation of the main types of negative impacts caused due to different forms of use that induce environmental and social conflicts nearby this shore. Thus, It was carried out a spatial and multitemporal analysis from orthophotos, aerial photographs and others taken during the field work besides satellite images too. The information which is taken out from these instruments was used to draw maps related to land occupation, spatial impacts and other thematic maps. We worked on a hypothesis that the implementation of mega enterprises on Via Costeira and many different forms of intensified use by human actions, has not considered the natural aspects and restrictions of use in this area, these ones would be the main factors that brought on the suppression and degradation in this environment and consequently the transformation of the natural landscape.
Resumo:
With the development and improvement of techniques for molecular studies and their subsequent application to the systematic, significant changes occurred in the classification of gasteroid fungi. The genus Morganella belongs to the family Lycoperdaceae, and is characterized mainly by lignicolous habit and presence of paracapilicium. Recent data demonstrate the discovery of new species for the group and the existence of a wide variety of species occurring in tropical ecosystems. However, the phylogenetic relationships of the genus, as well as the taxonomic classification, still require revisions to be better understood, the literature studies that address this issue are still very scarce. Thus, the objective of this study was to conduct studies of molecular phylogeny with species of the genus Morganella, to enhance understanding of the phylogeny of the group by including tropical species data. For this, the specimens used both for DNA extractions as for morphological review were obtained from Brazilian and foreign herbaria. For morphological analysis were observed characters relevant to the group's taxonomy. For phylogenetic analysis the Maximum Parsimony and Bayesian Analyzes were used, using the internal transcribed spacer (ITS) of nuclear ribosomal DNA. In phylogenetic analyzes, representatives from Morganella form a monophyletic clade with good support value and based on these results the genus should not be included as subgenus of Lycoperdon. The analysis indicated that M. pyriformis was not grouped with other representatives of Morganella, and therefore should not be included in the group as representative of Apioperdon subgenus because it is a Lycoperdon representative. Moreover, M. fuliginea, M. nuda, M. albostipitata, M. velutina, M. subincarnata are grouped with high support values within the genus Morganella. Morganella arenicola based on morphological and molecular studies does not aggregate in Morganella. Morganella nuda was grouped with M. fuliginea giving indications that can be treated as an intraspecific variation. The results of the analyzes favor to a better understanding of the species of Morganella. However, additional studies using a greater number of species, as well as other molecular markers are needed for a better understanding of the phylogenetic of Morganella.
Resumo:
O estudo dos efeitos que a diversidade de espécies pode causar nos processos ecossistêmicos tem crescido vertiginosamente nas últimas duas décadas. Diversos trabalhos experimentais realizados no mundo todo têm demonstrado que uma maior diversidade de plantas contribui para o aumento da produtividade de ecossistemas terrestres. Além disso, esse efeito pode influenciar processos em diversos níveis tróficos, contribuindo assim para a estabilidade dos processos ecossistêmicos a longo prazo. Paralelamente com os estudos do efeito da diversidade, muita atenção tem sido dada para desvendar o papel das características funcionais das espécies no funcionamento dos ecossistemas. Isto porque as características funcionais das espécies têm se mostrado importantes "peças" no entendimento dos efeitos que espécies individuais podem exercer nos ecossistemas e suas respostas ao ambiente. Nesta tese de doutorado eu explorei algumas lacunas de conhecimento dentro dessa área em crescente desenvolvimento conhecida na literatura ecológica como "biodiversidade e funcionamento dos ecossistemas". No primeiro capítulo, eu busquei evidências para mecanismos que podem explicar a relação positiva entre diversidade e funcionamento com foco em cinco mecanismos relacionados às interações entre plantas, tendo como parâmetro de funcionamento a produtividade primária. No segundo capítulo, eu utilizei técnicas para a estimativa de padrões de diversidade em escalas biogeográficas e bases de dados de satélites com longa duração para desvendar se a biodiversidade em escalas macroecológicas promove a estabilidade da produtividade dos ambientes terrestres no semiárido brasileiro. Por fim, o objetivo do terceiro capítulo foi entender como a perda da cobertura vegetal originária do uso da terra por comunidades tradicionais no semiárido brasileiro influenciaria os processos de interações entre plantas e o papel das características funcionais das espécies nessas interações. Acredito que a contribuição individual de cada capítulo preenche lacunas de conhecimento importantes dessa área da Ecologia que ainda se encontra em expansão.
Resumo:
Reservoirs are artificial ecosystems intermediate between rivers and lakes widely used in the Brazilian semiarid region as a way to provide water supply due to the said region’s water scarcity. The use of water from these supply sources for multiple uses, along with occupation and utilization of its riparian zone without proper management, directly influences the increased nutrient flow into aquatic environments, there with contributing to the acceleration of eutrophication. The semi-arid region is characterized by peculiar weather conditions, such as severe evaporation, high temperatures with little variation throughout the year and long water residence time, making it susceptible to prolonged drought occurrence, which tends to concentrate the nutrients in reservoirs, which favors the development of eutrophic conditions. Moreover, it is common soil use and occupation by carrying out activities with potential environmental impact on natural resources such as agriculture, livestock farming and lack of sanitation. The aim of this study is both to evaluate the water quality of the Cruzeta Reservoir, located in the semiarid region of Rio Grande do Norte, during a prolonged drought period, and assess the quality of its riparian zone soil under different uses, by monitoring physical-chemical variables. Along the prolonged drought, high levels of turbidity, suspended solids, nutrients and chlorophyll a were verified as present, therefore featuring low water quality. In the riparian zone of Cruzeta Reservoir, the areas under use of agriculture and livestock farming appeared as one of the main diffuse sources of nutrients to the said reservoir, featuring the highest levels of phosphorus and nitrogen in the soil, originated from decomposition of animal excreta and from the use of fertilizers, creating a tendency to increased eutrophication of such water supply source. The indicators of water and soil quality are useful for monitoring and evaluating the conservation status of natural resources, allowing the control and mitigation of the reservoir eutrophication process. This study confirmed the hypothesis that the reduction of water level, resulting from prolonged drought event, aggravates the symptoms of eutrophication; and also that using the soil under severalways modifies the physic chemical properties of the soil, having livestock farming and agriculture as the usages with greatest potential towards yielding P and N to the aquatic environment.
Resumo:
Organic dyes have been widely used in various branches of dyeing industries. These compounds are known to be very toxic, mutagenic, cancinogenic only cause aesthetic pollution and irreversible damage to aquatic ecosystems and human health. Are recalcitrant contaminants due to its high stability and resistance to photobleaching and bio. Given this context, the search for technologies that can minimize the effects of such pollutants is required. In recent decades the Electrochemical Oxidation Process Advanced (PEOAs) based on the generation of strongly oxidizing species (radicals ●OH) offer promising approaches for the prevention of problems caused by industrial effluents. This study analyzed the degradation and mineralization of textile dyes and the study of a real effluent in order to assess the feasibility of PEOAs: Electro-Fenton (EF), Photo Electro-Fenton (PEF) and anodic oxidation (AO), and these methods still was studied the Solar Fotoelectro-Fenton (SPEF) in a pre-pilot plant, in order to study the electrochemical treatment on an industrial scale. In the study has compared the effect of PEOAs in the removal of color, TOC and decay kinetics of degradation of the compounds, and also for using the Congo Red (CR) SPEF studies were performed mineralization current efficiency (MCE). The best results are given to the treatment of the PEF for all the studied dyes. From the results it was possible to choose the PEF as the most effective and promising for application of treatment when compared to other methods of treatment, and prove from SPEF that the process can be used in industrial scales, since this method PEF has been improved and solar irradiation replaced the UVA lamp.
Resumo:
Organic dyes have been widely used in various branches of dyeing industries. These compounds are known to be very toxic, mutagenic, cancinogenic only cause aesthetic pollution and irreversible damage to aquatic ecosystems and human health. Are recalcitrant contaminants due to its high stability and resistance to photobleaching and bio. Given this context, the search for technologies that can minimize the effects of such pollutants is required. In recent decades the Electrochemical Oxidation Process Advanced (PEOAs) based on the generation of strongly oxidizing species (radicals ●OH) offer promising approaches for the prevention of problems caused by industrial effluents. This study analyzed the degradation and mineralization of textile dyes and the study of a real effluent in order to assess the feasibility of PEOAs: Electro-Fenton (EF), Photo Electro-Fenton (PEF) and anodic oxidation (AO), and these methods still was studied the Solar Fotoelectro-Fenton (SPEF) in a pre-pilot plant, in order to study the electrochemical treatment on an industrial scale. In the study has compared the effect of PEOAs in the removal of color, TOC and decay kinetics of degradation of the compounds, and also for using the Congo Red (CR) SPEF studies were performed mineralization current efficiency (MCE). The best results are given to the treatment of the PEF for all the studied dyes. From the results it was possible to choose the PEF as the most effective and promising for application of treatment when compared to other methods of treatment, and prove from SPEF that the process can be used in industrial scales, since this method PEF has been improved and solar irradiation replaced the UVA lamp.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)