O reservatório da UHE Lajeado-TO localiza-se na região central do estado do Tocantins e possui condições propícias a atividades de lazer. Suas margens apresentam um elevado potencial recreacional, portanto, as condições sanitárias necessárias às atividades de contato primário devem ser asseguradas à população. Indicadores de balneabilidade devem ser avaliados em ambientes com fins recreacionais com o objetivo de prever e evitar efeitos adversos à saúde humana e à biota aquática. O presente trabalho realizou a avaliação do parâmetro indicador de contaminação fecal, Escherichia coli, para a classificação da balneabilidade em quatro praias na capital do Estado do Tocantins, Palmas. São elas as Praias do: Caju, Prata, Graciosa e das Arnos. Para tal, foram realizadas a detecção e contagens de Escherichia coli pela técnica do substrato cromogênico, de amostras coletas em cinco semanas, entre os anos de 2012 e 2015. As águas apresentaram baixas contagens de Escherichia coli, que permitiram a classificação como muito boa ou excelente balneabilidade, conforme a Resolução CONAMA Nº 274/2000. Dessa forma, o trabalho contribui para assegurar as atividades de lazer com segurança, e construir um banco de dados importante sobre as condições microbiológicas das praias pertencentes ao reservatório. INTRODUÇÃOOs corpos hídricos exercem papel essencial dentro de uma sociedade [1]. Diante do novo cenário mundial, em que a preocupação ambiental torna-se cada vez mais acentuada, os países em desenvolvimento, incluindo o Brasil, ainda
Here we use a top-down and bottom-up approach in landscape ecology to analyze the active microbes processing methane fluxes (FCH4) in seasonally flooded-forest (FOR) andtraditional farming systems (TFS) in Amazonian floodplains flooded with black, white, and clear water. Our results revealed higher CH4 emissions from water-atmosphere interface in clear water floodplain, followed by black and white water floodplain, respectively. Active methanogenic and methanotrophic taxa were ubiquitous at 0-15 and 15-30 cm soil layer in FOR and TFS, with differences among the water types with respect to the richness, evenness and diversity of the methanogenic communities. These ecological results were not generalizable regarding to FOR and TFS sites, soil layers, and non-flooded and flooded periods. Despite the predominant oxidation of CH4 in the non-flooded period, higher richness and diversity of methanotrophs were revealed for FOR and TFS in the flooded period. In turn, the structure of the methanogenic and methanotrophic communities and their variation were influenced mainly by soil physicochemical factors, water type, soil depth and the presence of nitrifiers, as Nitrososphaera and Nitrospira. Our study reveals a signature across methanotrophic communities in soils from Amazon floodplain with different water types, with a putative disproportionate role of NC10 phylum in CH4 mitigation in natural and agricultural Amazonian floodplains. These findings open the possibilities to explore the role of NC10 phylum in the carbon cycling in Amazon.
Microorganisms play an essential role in ecosystem functions. An increasingly used method for conducting functional analyses of a soil microbial community is based on the physiological profile at the community level. This method allows the metabolic capacity of microorganisms to be assessed based on patterns of carbon consumption and derived indices. In the present study, the functional diversity of microbial communities was assessed in soils from seasonally flooded-forest (FOR) and -traditional farming systems (TFS) in Amazonian floodplains flooded with black, clear, and white water. The soils of the Amazon floodplains showed differences in the metabolic activity of their microbial communities, with a general trend in activity level of clear water floodplain > black water floodplain > white water floodplain. The redundancy analysis (RDA) indicated that soil moisture (flood pulse) was the most important environmental parameter in determining the metabolic activity of the soil microbial communities in the black, clear, and white floodplains. In addition, the variance partitioning analysis (VPA) indicated that the microbial metabolic activity of the soil was more influenced by water type (41.72%) than by seasonality (19.55%) and land use type (15.28%). The soil microbiota of the white water floodplain was different from that of the clear water and black water floodplains in terms of metabolic richness, as the white water floodplain was mainly influenced by the low substrate use during the non-flooded period. Taken together, the results show the importance of considering soils under the influence of flood pulses, water types, and land use as environmental factors when recognizing functional diversity and ecosystem functioning in Amazonian floodplains.
Amazon floodplain ecosystems include open water and intermittent flood forest and agricultural systems with different water types. They are a significant natural source of methane (CH 4) in the tropics. When soils are flooded and become anoxic, CH 4 is produced by methanogenesis, while microbially mediated aerobic and anaerobic oxidation of CH 4 serves as the primary biological sink of this greenhouse gas. Measurements of rates and controls on CH 4 production and emission in the Amazon basin mainly come from studies on individual wetlands and floodplain lakes. Similarly, microbial communities in those Amazon floodplain habitats have been studied on individual lakes based on sequence-specific DNA analysis. Existing biogeochemical ecosystem models of CH 4 from the Amazon floodplains focus on soil properties or involve factors such as pH, redox potentials, or substrates. None of these models incorporate appropriate seasonal inundation; neither the microbiota does it as a component. In this sense, our chapter will highlight how the important efforts already contributed to understand the CH 4 emission and its connections with abiotic and biotic factors in Amazon floodplains, as well as emphasize the need of encouraging cooperation and exchange of experience between research teams by using different approaches and scientific methods.
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