Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. James B. Cowart, Florida State University, College of Arts and Sciences, Dept. of Geological Sciences. Title and description from dissertation home page (viewed Oct. 1, 2003). Includes bibliographical references.

For presentation at the International Symposium on Brackish Water as a Factor in Development, by the Desert Research Institute at Sede-Boqer at the Ben-Gurion University of the Negev, Beer-Sheva, Israel, January 5-10, 1975. / Introduction: The Safford Valley area lies along the Gila River in the southeastern part of the State of Arizona. The portion of the valley being considered, see Figure 1, is an intermontane trough averaging about 15 miles (24.2 kilometers) in width and about 30 miles (48.3 kilometers) in length. The cultivated lands lie along the Gila River and are 0.5 to 3.5 miles (0.8 to 5.6 kilometers) from the river. The approximately 14,000 inhabitants of the valley are primarily located in the municipalities, and Safford, the largest of the towns, was founded in 1875. Agriculture and agriculture-dependent activities, however, provide the mainstay of the Safford Valley economy accounting for approximately 63 percent of the export employment (State of Arizona, 1971). Like many valleys in arid regions, the Safford Valley, because of an inadequate supply of good quality water, has been forced to depend on ground water of notoriously poor quality. The purpose of this paper is to show how the limitation of available good quality water and the need to use brackish water affects agricultural practices and industrial development in the Safford Valley.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 210-214). Also available on the World Wide Web.

Water scarcity for agriculture is one of the most important challenges to improve food security worldwide. In this thesis we study the potential to develop a low-cost controller for a small scale brackish desalination plant that consists of proven water treatment technologies, reverse osmosis, cation exchange, and nanofiltration to treat groundwater into two final products: drinking water and irrigation water. The plant is powered by a combination of wind and solar power systems. The low-cost controller uses Arduino Mega, and Arduino DUE, which consist of ATmega2560 and Atmel SAM3X8E ARM Cortex-M3 CPU microcontrollers. These are widely used systems characterized for good performance and low cost. However, Arduino also requires drivers and interfaces to allow the control and monitoring of sensors and actuators. The thesis explains the process, as well as the hardware and software implemented.

Abstract in English and German / The reported PhD research study was conceived from real water problems experienced by a rural community in South Africa (SA). Specifically, water quality in the Nandoni Dam situated in the Vhembe District, Limpopo Province, South Africa was assessed in order to determine its fitness for use, following complaints by community members using this water for drinking and domestic purposes. The dam supplies water to 55 villages with approximately 800 000 residents. At the inception of the study, there was little scientific information relating to the quality of the water in the dam. Water samples from various sites across the Nandoni Dam, a primary source of domestic water supply in the region, were collected through each season of the year over a period of 12 months to ascertain the concentrations of dissolved salts in the dam. Additionally, harmful polycyclic aromatic hydrocarbons (PAHs) and phenols were assessed. The concentrations of the ions contributing to water salinity were generally lower than the brackish water bracket (i.e. 500 – 30 000 mg/L) but too high for potable water. The concentration of the phenols was relatively higher than the threshold limit of drinking water. Therefore, the water sourced from the Nandoni Dam was found not suitable for human consumption and therefore required integrated water resource management, as well as robust and cost-effective water treatment especially since the salinity of the water was high even after treatment by a water treatment plant sourcing water from the dam. In an attempt to develop a suitable energy-efficient technology or system for complete removal of salts (desalination) from the salty water (including brackish water), electrospun polyvinylidene fluoride (PVDF) nanofibre membranes were synthesised and evaluated for removal of salts using the Direct Contact Membrane Distillation (DCMD) process. The nanofibre membranes were synthesised with combined high mechanical stability, porosity, and superhydrophobicity to prevent fouling and wetting while maintaining high salt rejection and water flux. Organically functionalised silica nanoparticles (f-SiO2NPs) were embedded on PVDF nanofibre membranes using an in-situ electrospinning technique for superhydrophobicity enhancement. These modified membranes displayed Young’s modulus of ~43 MPa and showed highly porous properties (~80% porosity, 1.24-1.41 μm pore sizes) with superhydrophobic surfaces (contact angle >150°). Membranes embedded with octadecyltrimethoxysilane (OTMS), and chlorodimethyl-octadecyl silane (Cl-DMOS), octadecyltrimethoxysilane (ODTS)-modified SiO2NPs were the most efficient; rejecting >99.9% of NaCl salt, with a water flux of approximately 30.7-34.2 LMH at 60°C, thus indicating their capacity to produce potable water. The superhydrophobic membranes were coated with a thin layer consisting of carboxylated multiwalled carbon nanotubes (f-MWCNTs) and silver nanoparticles (AgNPs) to reduce membrane fouling. The AgNPs and f-MWCNTs were uniformly distributed with size diameters of 28.24±1.15 nm and 6.7±2.1 nm respectively as evidenced by transmission electron microscopy (TEM) micrographs. The antibacterial AgNPs embedded in the PVDF nanofibre membranes inhibited the growth of Gram-positive Geobacillus stearothermophilus and Staphylococcus aureus as well as Gram-negative Pseudomonas aeruginosa and Klebsiella pneumoniae indicating their potential to prevent biofilm formation. Fouling tests were conducted using bovine serum albumin (BSA), sodium alginate, colloidal silica, and thermophilic bacteria effluent as model organic, inorganic, and bio-foulants, respectively, using DCMD. The uncoated membranes were characterised by a flux decays ranging from 30% to 90% and salt rejection decays ranging from 1.4% to 6.1%. Membrane coating reduced the flux and salt rejection decays to 10–24% and 0.07–0.75%, respectively. Although the initial flux decreased from 42 to  16 LMH when using coated membranes, the resistance of these coated membranes to water flux and salt rejection decays indicated that coating could be a suitable one-step solution for fouling mitigation in DCMD. The major challenge would be to design the MD membranes with architectures that allow a high-water flux to be maintained i.e., a highly porous layer. Furthermore, the volatile compounds bearing hydrophobic groups were pretreated to reduce their fouling capacity on PVDF nanofibre membranes. In this study, polyacrylonitrile (PAN) and polyethylene-imine (PEI) functionalised-PAN nanofibre membranes were synthesised and evaluated as a pretreatment for the removal of chlorophenol and nitrophenol from solutions. Under optimised experimental conditions, adsorption capacities ranging from 27.3 – 38.4 mg/g for PAN and PEI-modified nanofibres, respectively, were recorded. The PEI-functionalised nanofibres showed a high potential as a pretreatment step to be integrated to MD process. Ultimately an integrated water desalination system was developed. This involved a pretreatment filter (pore size ~100 μm) containing PEI-functionalised PAN nanofibre materials to reduce particulates and large molecules of dissolved organic/inorganic compounds from the water to be treated. In this research, it was observed that the pre-treatment step was not sufficient in removing all traces of compounds causing fouling of the superhydrophobic PDVF nanofibre membranes. As such, coating of the membranes with a thin hydrophilic layer and coupled with the filtration pretreatment step was found to provide fouling-resistance properties, high salt rejection, and low flux decays on brackish water collected at an estuary in Belgium and the Nandoni Dam in South Africa, demonstrating the potential of the MD separation process towards potable water recovery from brackish water. / Het onderzoek in dit proefschrift was gebaseerd op concrete waterproblemen die een landelijke gemeenschap in Zuid-Afrika (SA) ervaart. In het bijzonder werd de waterkwaliteit in het Nandoni-reservoir in het Vhembe-district in de provincie Limpopo in Zuid-Afrika onderzocht, om te bepalen of dit water geschikt is voor gebruik, na klachten van leden van de gemeenschap die dit water gebruiken als drinkwater en voor huishoudelijk gebruik. Het reservoir levert water aan 55 dorpen met ongeveer 800.000 inwoners. Bij het begin van het onderzoek was er weinig wetenschappelijke informatie over de kwaliteit van het water in het reservoir. Watermonsters van verschillende locaties in het reservoir, dat een primaire bron van drinkwater is in de regio, werden gedurende verschillende seizoenen van het jaar verzameld over een periode van 12 maanden, om de concentraties van de meest voorkomende ionen in het reservoir te bepalen. Bovendien werden de concentraties van schadelijke polycyclische aromatische koolwaterstoffen (PAK's) en fenolen gemeten. De concentraties van de ionen die bijdroegen aan het zoutgehalte van het water waren in het algemeen lager dan de drempel om het water als brak water te bestempelen (dat wil zeggen 500 – 30 000 mg/l), maar waren te hoog voor drinkwater. De concentratie van de fenolen was hoger dan de limiet voor drinkwater. Daarom bleek het water afkomstig van het Nandoni reservoir niet geschikt voor menselijke consumptie. Een beter geïntegreerd waterbeheer is dus nodig om deze bron voor drinkwater te beschermen, naast een robuuste en kosteneffectieve waterbehandeling. Deze waterbehandeling moet vooral het zoutgehalte van het water naar beneden halen, maar ook de concentraties van fenolen. In een poging om een geschikte energie-efficiënte technologie of een systeem voor de volledige verwijdering van zouten (~ontzilting) uit brak water te ontwikkelen, werden elektrisch gesponnen polyvinylideenfluoride (PVDF) nanovezelmembranen gesynthetiseerd en beoordeeld op verwijdering van zouten met behulp van Direct Contact Membraandestillatie (DCMD). De nanovezelmembranen hadden een gecombineerde hoge mechanische stabiliteit, porositeit en superhydrofobiciteit, die hielp om vervuiling (fouling) en vloeistofintrede in de poriën (wetting) te voorkomen, terwijl een hoge zoutverwijdering en hoge waterflux doorheen de membranen gehandhaafd bleven. Organische gefunctionaliseerde silica-nanodeeltjes (f-SiO2NP's) werden nadien geïncorporeerd in de PVDF nanovezelmembranen met behulp van een in-situ elektrospinning techniek om zo een nog grotere superhydrofobiciteit te bekomen. Deze gemodificeerde membranen hadden een degelijke treksterkte (Young's modulus van ~ 43 MPa) en waren zeer poreus (~ 80% porositeit, 1.24-1.41 μm poriegrootte). Het oppervlak van de membranen vertoonde inderdaad superhydrofobe eigenschappen (contacthoek met water > 150 °). De membranen ingebed met octadecyltrimethoxysilaan (ODTS) SiO2NP's waren het meest efficiënt: ze toonden een zoutretentie van> 99.9% voor NaCl, bij een waterflux van ongeveer 30.7-34.2 l/(m².h) bij 60 ° C (ten opzichte van 20°C in het permeaat), wat aangeeft dat ze in staat zijn om drinkbaar water te produceren. De superhydrofobe membranen werden nadien ook gecoat met een dunne laag bestaande uit gecarboxyleerde multiwall-carbon nanotubes (f-MWCNT's) en zilver nanodeeltjes (AgNP's), in een poging om membraanvervuiling te verminderen. De AgNP's en f-MWCNT’s hadden uniforme diameters van respectievelijk 28,24 ± 1,15 nm en 6,7 ± 2,1 nm (zoals bleek uit transmissie-elektronenmicroscopie (TEM)). De antibacteriële AgNP's ingebed in de PVDF-nanovezelmembranen remden de groei van Gram-positieve Geobacillus stearothermophilus en Staphylococcus aureus bacteriën, evenals Gram-negatieve Pseudomonas aeruginosa en Klebsiella pneumoniae bacteriën. Dit toont het potentieel van deze membranen om biofilmvorming te voorkomen. Vervuilingsproeven (in DCMD) werden uitgevoerd met behulp van runderserumalbumine (BSA), natriumalginaat, colloïdaal silica, en thermofiele bacteriën - als respectievelijk organische, anorganische en biologische vervuiling. De niet-gemodificeerde membranen werden gekenmerkt door een fluxverval, met een daling van de flux met 30% tot 90%, naast een daling van de zoutretentie met 1.4% tot 6.1%. Bij de gecoate membranen daalde de flux slechts met 10-24% en de zoutverwijdering slechts met 0.07-0.75% respectievelijk. Hoewel de initiële flux ook afnam (van 42 naar ± 16 l/(m².h)) bij het gebruik van gecoate membranen, toonde de hogere weerstand tegen vervuiling van deze gecoate membranen aan dat deze coating een geschikte oplossing zou kunnen zijn tegen vervuiling in DCMD. Bovendien kan de synthese in één stap verlopen. De grootste uitdaging zal echter zijn om MD-membranen te ontwerpen waarbij de coating de oorspronkelijke waterflux/de porositeit van de membranen niet teveel verlaagt. Daarnaast werden gemodificeerde PVDF nanovezels geproduceerd om de verwijdering van vluchtige, hydrofobe stoffen (zoals fenolen) door adsorptie aan deze vezels te verhogen. Er werden polyacrylonitril (PAN) en polyethyleen-imine (PEI) gefunctionaliseerde PAN nanovezels gesynthetiseerd, waarna deze geëvalueerd werden als adsorbens (en dus voorbehandeling voor de membraanstap) voor chloorfenol en nitrofenol. Onder geoptimaliseerde experimentele omstandigheden werden adsorptiecapaciteiten tussen respectievelijk 27.3 en 38.4 mg / g voor PAN- en PEI-gemodificeerde nanovezels gemeten. De PEI-gefunctionaliseerde nanovezels vertoonden een hoog potentieel als een voorbehandelingsstap voor de hierboven beschreven DCMD. Tenslotte werd ook een geïntegreerd waterontziltingssysteem ontwikkeld. Dit systeem bestond uit een voorbehandelingsstap met PEI-gefunctionaliseerde PAN-nanovezels (in de vorm van een membraan met poriegrootte ~100 μm), gevolgd door een gemodificeerde DCMD stap. De voorbehandeling diende om deeltjes en grote opgeloste organische verbindingen uit het te behandelen water te verwijderen voor de DCMD-stap. In dit onderzoek werd waargenomen dat de voorbehandelingsstap niet voldoende was om alle organische contaminanten te verwijderen die vervuiling veroorzaakten op de superhydrofobe PDVF nanovezelmembranen in de DCMD-stap. Toch bleek coating van de DCMD membranen met een dunne hydrofiele laag (gekoppeld aan de voorbehandelingsstap) een voldoende bescherming tegen vervuiling te bieden zodat de zoutretentie en waterflux van deze membranen hoog bleef. De combinatie van voorbehandeling – gemodificeerde DCMD werd succesvol getest op water uit de Schelde en uit het Nandoni reservoir, waarmee het potentieel van de technologie om drinkwater uit brak water te produceren werd aangetoond. / School of Science / Ph.D. (Applied Biological Science : Environmental Technology)

Made available in DSpace on 2016-08-31T13:24:11Z (GMT). No. of bitstreams: 1 ChristianoRC_DISSERT.pdf: 985774 bytes, checksum: 16a5bb519ba17167ab91e67bf421f7f6 (MD5) Previous issue date: 2011-03-30 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / In Brazil, mainly in the semiarid region, a major challenge is to promote the water supply to households in rural areas. Groundwater is identified as a viable alternative to ensure the access of rural communities in the northeast to water from public investment in drilling wells. However, these water sources in most cases have use restrictions for human consumption, because they present problems of salinity. The technology of reverse osmosis has been widely used for treatment of brackish water, with successful experiences in most locations where units have been deployed in water treatment by desalination. Many rural communities in Mossoró, RN, are supplied with water from the aquifer Jandaíra, high salt concentration, which is treated in desalination plants, allowing its use for human consumption. In these communities, the reject brine of the process of desalination is not receiving any treatment or proper disposal, being dumped straight into the ground and, when used in irrigation of crops there are no scientific-technical reasons for their use, causing problems of soil salinization. Due to the impacts caused by the use of brackish or reject brine for irrigation in the soil, to enable their use should always adopt some special practices of water management and soil for salinity control. As the majority of crops grown in the region classified as sensitive to moderately sensitive to salinity, there is the need to better characterize these waters, to establish the appropriate management of plants, soil and irrigation systems. As the majority of crops grown in the region are classified as sensitive to moderately sensitive to salinity, there is the need to better characterize these waters, to establish the appropriate management of plants, soil and irrigation systems. Thus, this study aimed to evaluate the quality of water for irrigation in rural communities of Mossoró, supplied with brackish water from tube wells equipped with desalination, providing this information as a tool to aid the proper management and use of these waters irrigation. 30 rural communities were selected to perform the collection of samples of water from the waste generated in the desalination, purified and in its natural form (brackish water of the well). In the collected samples were determined at electric conductivity (ECw), pH and concentrations of Na+, Ca2+, K+, Cl-, HCO3 - e CO3 2-, in addition, the sodium adsorption ratio (SAR). The Analyses of water samples were interpreted as to risk of salinity, sodicity, toxicity of ions and other quality parameters. The results show that water of the wells rural communities studied, have restrictions to their use in agriculture, as to risks of salinity and sodicity of the soil, especially the waters of the communities: São Romão, Boa Fé and Pau Branco. the reject brine of the desalination have high concentrations of salts, especially in communities of Boa Fé and Puxa Boi, compromising their use for irrigation, and, the desalinated water, although they have low concentrations of salts have restrictions on the problems of infiltration into the soil, if by chance, are employed in irrigation. / No Brasil, principalmente na região semiárida, um grande desafio é promover o abastecimento de água às famílias residentes nas áreas rurais. As águas subterrâneas são apontadas como uma alternativa viável para garantir o acesso das comunidades rurais do nordeste à água, a partir de investimentos públicos na perfuração de poços tubulares. Entretanto, essas fontes hídricas apresentam na maioria dos casos restrições de uso para dessedentamento humano, por apresentarem problemas de salinidade.A tecnologia da osmose reversa tem sido amplamente utilizada para o tratamento da água salobra, com experiências de êxito na maioria das localidades aonde têm sido implantadas as unidades de tratamento de água por dessalinização. Muitas comunidades rurais de Mossoró, RN, são abastecidas com água proveniente do aquífero Jandaíra, de elevada concentração de sais, a qual é tratada em dessalinizadores, possibilitando sua utilização para consumo humano. Nessas comunidades, o rejeito do processo da dessalinização não está recebendo qualquer tratamento ou destinação adequada, sendo despejado diretamente no solo e, quando utilizados na irrigação de culturas não há qualquer fundamentação técnico-científica para o seu uso, causando problemas de salinização nos solos. Devido aos impactos causados pelo uso de águas salobras ou de rejeito salino na irrigação no solo, para viabilizar a sua utilização deve-se sempre adotar algumas práticas especiais de manejo da água e do solo para o controle da salinidade. Sendo a maioria das culturas exploradas na região classificadas como sensíveis a moderadamente sensíveis à salinidade, surge a necessidade de melhor caracterizar essas águas, para se estabelecer o manejo adequado das plantas, solo e sistemas de irrigação. Assim, o presente trabalho objetivou avaliar a qualidade da água para fins de irrigação de comunidades rurais de Mossoró, abastecidas com águas salobras provenientes de poços tubulares, dotados de dessalinizadores, fornecendo estas informações como uma ferramenta de auxílio para o manejo adequado da utilização destas águas na irrigação. Foram selecionadas 30 comunidades rurais para realização das coletas de amostras das águas do rejeito gerado na dessalinização, purificadas e na sua forma natural (água salobra de poço). Nas amostras coletadas foram determinadas a condutividade elétrica da água (CEa), o pH e concentrações de Na+, Ca2+, K+, Cl-, HCO3 - e CO3 2-; além disso, a razão de adsorção de sódio (RAS). As análises das amostras de água foram interpretadas quanto aos riscos de salinidade, sodicidade, toxidade de íons e outros parâmetros de qualidade. Os resultados mostram que as águas dos poços das comunidades rurais estudadas possuem restrições para a sua utilização na agricultura, quanto aos riscos de salinização e sodificação do solo, principalmente as águas das comunidades: São Romão; Boa Fé e Pau Branco; as águas de rejeito da dessalinização possuem elevadas concentrações de sais, principalmente nas comunidades de Boa Fé e Puxa Boi, comprometendo a sua utilização para a irrigação e as águas dessalinizadas, embora possuírem baixos teores de sais têm restrições quanto a problemas de infiltração no solo, caso venham a ser empregadas para irrigação.

O Complexo Lagunar de Jacarepaguá, localizado no município do Rio de Janeiro, região sudeste do Brasil, é formado pelas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi. Estas lagunas estão interligadas ao mar pelo canal da Joatinga e têm como afluentes rios e canais que vertem dos maciços da Tijuca e da Pedra Branca. Recebem esgotos sanitários e efluentes industriais, além de contribuições difusas de águas de drenagem e circulação das massas de águas de várias origens, com elevada carga de poluição. A eutrofização cultural aliada aos processos de evolução de ecossistemas costeiros produziu um estado de degradação destas águas com constantes florações de cianobactérias potencialmente tóxicas. O presente estudo tem como objetivo avaliar a ocorrência das cianobactérias (Classe Cyanophyceae) no Complexo Lagunar de Jacarepaguá e corroborar a hipótese de serem boas indicadoras de qualidade ambiental de águas salobras. Foi realizado um monitoramento ambiental nas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi, nos anos de 2004 a 2006, sendo analisados parâmetros físicos, químicos e biológicos. Os resultados obtidos demonstraram a dominância e a persistência das cianobactérias em elevadas concentrações de nutrientes, caracterizando a hipereutrofização dessas lagunas. As estratégias ecológicas das cianobactérias garantiram sua dominância em quase todo o período amostral e demonstraram ser um refinado sensor das variáveis ambientais. A salinidade não foi um fator de limitação ao desenvolvimento desses microorganismos. Desta forma, este estudo, oferece subsídios para gestão de recursos hídricos, corroborando com a legislação CONAMA 357/05-MMA, na sugestão de indicação deste parâmetro de qualidade ambiental também para ambientes salobros na classe 1. / The Jacarepaguá Lagoon Complex, located in the state of the Rio of Janeiro, in Southeast of Brazil, is formed by the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi. These lagoons are interconnected to the sea by the Joatinga canal and receive contribution from tributary rivers and channels that come from Tijuca and Pedra Branca massifs. They receive industrial and domestic effluents, including diffuse contributions of the drainage basin, as well as water circulation from several origins, with a high pollution load. The cultural eutrophication associated with coastal ecosystems evolution processes, have produced a state of degradation of these waters with frequent waterblooms of potentially toxic cyanobacteria. The objective of the present study is to evaluate the presence of Cyanobacteria (Class Cyanophyceae) in the Jacarepaguá Lagoon Complex and also to corroborate the hypothesis of using them as a good bioindicators of environmental quality in brackish waters. An environmental monitoring program has been carried out in the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi from 2004 to 2006, including physical, chemical and biological parameters analysis. The results showed the dominance and persistence of Cyanobacteria at high concentrations of nutrients, characterizing the hypereutrofication of these lagoons. The ecological strategies of Cyanobacteria were responsible for their dominance in almost the whole period of study and demonstrated that they can be used as a good sensor of environmental variables. The salinity did not demonstrate to be a limiting factor to the development of these microorganisms. In this way, this study provides subsidies for water resources management, corroborating with Brazilian legislation (CONAMA 357/05- MMA) suggesting the inclusion of Cyanobacteria as a parameter of environmental quality in brackish environments classified as Class 1.

O Complexo Lagunar de Jacarepaguá, localizado no município do Rio de Janeiro, região sudeste do Brasil, é formado pelas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi. Estas lagunas estão interligadas ao mar pelo canal da Joatinga e têm como afluentes rios e canais que vertem dos maciços da Tijuca e da Pedra Branca. Recebem esgotos sanitários e efluentes industriais, além de contribuições difusas de águas de drenagem e circulação das massas de águas de várias origens, com elevada carga de poluição. A eutrofização cultural aliada aos processos de evolução de ecossistemas costeiros produziu um estado de degradação destas águas com constantes florações de cianobactérias potencialmente tóxicas. O presente estudo tem como objetivo avaliar a ocorrência das cianobactérias (Classe Cyanophyceae) no Complexo Lagunar de Jacarepaguá e corroborar a hipótese de serem boas indicadoras de qualidade ambiental de águas salobras. Foi realizado um monitoramento ambiental nas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi, nos anos de 2004 a 2006, sendo analisados parâmetros físicos, químicos e biológicos. Os resultados obtidos demonstraram a dominância e a persistência das cianobactérias em elevadas concentrações de nutrientes, caracterizando a hipereutrofização dessas lagunas. As estratégias ecológicas das cianobactérias garantiram sua dominância em quase todo o período amostral e demonstraram ser um refinado sensor das variáveis ambientais. A salinidade não foi um fator de limitação ao desenvolvimento desses microorganismos. Desta forma, este estudo, oferece subsídios para gestão de recursos hídricos, corroborando com a legislação CONAMA 357/05-MMA, na sugestão de indicação deste parâmetro de qualidade ambiental também para ambientes salobros na classe 1. / The Jacarepaguá Lagoon Complex, located in the state of the Rio of Janeiro, in Southeast of Brazil, is formed by the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi. These lagoons are interconnected to the sea by the Joatinga canal and receive contribution from tributary rivers and channels that come from Tijuca and Pedra Branca massifs. They receive industrial and domestic effluents, including diffuse contributions of the drainage basin, as well as water circulation from several origins, with a high pollution load. The cultural eutrophication associated with coastal ecosystems evolution processes, have produced a state of degradation of these waters with frequent waterblooms of potentially toxic cyanobacteria. The objective of the present study is to evaluate the presence of Cyanobacteria (Class Cyanophyceae) in the Jacarepaguá Lagoon Complex and also to corroborate the hypothesis of using them as a good bioindicators of environmental quality in brackish waters. An environmental monitoring program has been carried out in the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi from 2004 to 2006, including physical, chemical and biological parameters analysis. The results showed the dominance and persistence of Cyanobacteria at high concentrations of nutrients, characterizing the hypereutrofication of these lagoons. The ecological strategies of Cyanobacteria were responsible for their dominance in almost the whole period of study and demonstrated that they can be used as a good sensor of environmental variables. The salinity did not demonstrate to be a limiting factor to the development of these microorganisms. In this way, this study provides subsidies for water resources management, corroborating with Brazilian legislation (CONAMA 357/05- MMA) suggesting the inclusion of Cyanobacteria as a parameter of environmental quality in brackish environments classified as Class 1.