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Abstract Introduction: The sea urchin Diadema mexicanum, due to its bioerosion activity, is considered of ecological importance. This phenomenon could negatively or positively affect coral reef ecosystems. The bioerosion process varies according to the abundance and size of the sea urchin. Objective: Juvenile organisms possess different metabolic needs compared to adults, so knowing their stomach content according to size allows us to quantify the selection of substrate bioeroded. Methods: To determine this, D. mexicanum individuals were collected in 12 sites from January 2009 to September 2010 along the Eastern Tropical Pacific coast. The stomach content was categorized in Carbonated Fraction (CF), Non-Carbonated Fraction (NCF), and Organic Matter (OM). Stomach content was analyzed according to a) juvenile (< 2.5 cm) or adult (> 2.5 cm) stage and b) locality. Results: Juveniles presented the following stomach content average percentages: 20.7 % OM, 12 % NCF and 67.9 % CF; and adults: 11.4 % OM, 14.8 % NCF and 73.8 % CF. Based on a Wilcoxon test and a Kendall linear regression, the following results were obtained. The carbonated fraction in the stomach increased by 0.47 units on average for every cm of growth (p < 0.05). OM consumed by D. mexicanum increases only 0.05 units for every cm of growth (p < 0.05). We found a difference of stomach content depending on the site (p < 0.05) and life stage (p < 0.05). Localities like Huatulco and Coco presented significant differences that could be related to local oceanographic conditions. Conclusions: We relate these changes of the stomach fractions to the necessity of the juvenile sea urchins for nutrients to maintain their growth. The amount of OM is crucial for the development of early stages, meaning that there is a difference in substrate selection associated with growth.
Resumen Introducción: El erizo de mar Diadema mexicanum, por su actividad de bioerosión, es considerado de importancia ecológica. Este fenómeno podría afectar negativa o positivamente a los ecosistemas de arrecifes de coral. El proceso de bioerosión varía según la abundancia y el tamaño del erizo de mar. Objetivo: Los organismos juveniles poseen diferentes necesidades metabólicas en comparación con los adultos, por lo que conocer el contenido estomacal según el tamaño, nos permite cuantificar la selección de sustrato bioerosionado. Métodos: Para determinar esto, se recolectaron individuos de D. mexicanum en 12 sitios desde enero de 2009 hasta septiembre de 2010 a lo largo de la costa del Pacífico Tropical Oriental. El contenido estomacal se clasificó en Fracción Carbonatada (FC), Fracción No Carbonatada (NCF) y Materia Orgánica (MO). El contenido estomacal se analizó según a) estadio juvenil (< 3 cm) o adulto (> 3 cm) y b) localidad. Resultados: Los juveniles presentaron los siguientes porcentajes promedio del contenido estomacal: 20.7 % OM, 12 % NCF y 67.9 % CF; y adultos: 11.4 % OM, 14.8 % NCF y 73.8 % CF. Con base en una prueba de Wilcoxon y una regresión lineal de Kendall, se obtuvieron los siguientes resultados. La fracción carbonatada en el estómago aumentó en promedio 0.47 unidades por cada cm de crecimiento (p < 0.05). La MO consumida por D. mexicanum aumenta solo 0.05 unidades por cada cm de crecimiento (p < 0.05). Encontramos una diferencia en el contenido estomacal según el sitio (p < 0.05) y el estadio de vida (P < 0.05). Localidades como Huatulco y Coco presentaron diferencias significativas que podrían estar relacionadas con las condiciones oceanográficas locales. Conclusiones: Relacionamos estos cambios de la composición porcentual del contenido estomacal con la necesidad de los erizos de mar juveniles de nutrientes para mantener su crecimiento. La cantidad de MO es crucial para el desarrollo de las primeras etapas, lo que significa que existe una diferencia en la selección de sustrato asociada con el crecimiento.
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Indonesia is a tropical area with high rainfall, the area on land is connected by around 472 large and small rivers that flow into the sea. The estuary area is the meeting area of ??rivers or fresh water streams with the ocean. Transportation of organic matter, minerals and sediments from upstream to the estuary and from the sea containing minerals, hence estuarine waters are more fertile than other areas. In addition, estuary areas are important habitats for several types of marine and freshwater organisms to fulfill their life cycles, which are used as spawning, foraging, and nursery grounds. This study aimed to determine the total organic contents, total Nitrogen, and Phosphorus in the estuary waters of Maros as a source of brackish water for fish pond aquaculture in Maros Regency. The research was conducted in the estuary waters of Maros for three months from September to November 2020. Sampling was conducted four times with an interval of once every 15 days. Sampling was carried out at five stations based on water movements to the estuary, station A was located at the seawater, station B was located in the pond wastewater locations, station C was water sources from residential waste, station D was located in the river, and station E was the estuarine water. The results showed that the dominant water quality parameters affecting estuarine water quality were salinity, total organic matter, nitrogen content, either in the form of ammonia, nitrate, or nitrite, and phosphorus content, especially phosphate. Water entering the estuary has an impact on high concentrations of total organic matter, increased concentrations of Total N, and phosphorus. The results of water quality analysis in estuaries showed that salinity, organic matter, ammonia, nitrite and nitrate, and phosphate exceed the standard threshold for water quality standards for fish pond aquaculture. Thus, the waters of the Maros estuary are not suitable for aquaculture, especially for the 5 observed stations (A, B, C, D and E).
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El herbicida ácido 2,4 - diclorofenoxiacético (2,4-D) es un ácido selectivo y sistémico que, desde 1940, es ampliamente utilizado en suelo agrícolas, de todo el mundo. Su uso radica a su selectividad entre la vegetación de hoja ancha y cultivos de gramíneas y como regulador del crecimiento vegetal; sin embargo, este herbicida se puede acumular en el ambiente y, adicionalmente, puede ser transportado por lixiviación, a través del suelo, llegando a contaminar aguas subterráneas, lo que genera un alto riesgo para el ambiente y la salud del ser humano. El estudio de la movilidad del 2,4-D en suelos con alto contenido de materia orgánica permitió conocer, que no solo la materia orgánica se correlaciona indirectamente con la movilidad de este compuesto, sino que, también, influye la humedad, al reducir la lixiviación y el potencial de contaminación del recurso hídrico subterráneo, mientras que la conductividad hidráulica se relaciona, de manera directa, con la lixiviación de este herbicida.
The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is a selective and systemic acid that has been widely used in agricultural soils since 1940. Its use lies in its selectivity between broadleaf vegetation and grass crops, and as a regulator of plant growth. However, this herbicide can accumulate in the environment, and additionally, it can be transported by leaching through the soil, contaminating groundwater, which generates a high risk for the environment and human health. In this study, the mobility of 2,4-D in organic-matter-rich soils was assessed. The results revealed that not only the organic material is indirectly correlated with the mobility of this compound but also influences humidity and reduces leaching and potential pollution of groundwater resources, whereas hydraulic conductivity is directly related to herbicide leaching.
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Introducción: La materia orgánica particulada gruesa originada en la vegetación ribereña es la fuente principal de energía en muchas cuencas de cabecera. Sin embargo, la transferencia de dicha materia es alterada por la destrucción de los bosques. Objetivo: Evaluar diferencias en la materia orgánica en quebradas con bosques y con pastizales. Métodos: Comparar las entradas, el almacenamiento y la exportación de esta materia orgánica en el cauce de quebradas con bosques y con pastizales, en la región central de los Andes de Colombia. En cada quebrada, se midieron los aportes verticales y laterales de hojarasca con canastas; hojarasca del lecho de las quebradas con cuadrantes, y la exportación de material con redes de deriva, con un alcance de 100 m. Resultados: Las quebradas con bosques ribereños recibieron un promedio anual de 915 g m-2 de materia orgánica particulada gruesa, exportando un total de 334 g m-3 y almacenando 732 g m-2, valores que fueron significativamente más altos que en quebradas con pastizales, donde los valores correspondientes fueron: 125.4 g m-2; 128 g m-3 y 205.5 g m-2. Conclusiones: La remoción de cobertura boscosa de la zona ribereña reduce la materia orgánica en estas cuencas de cabecera en Colombia.
Introduction: Coarse particulate organic matter originated in riparian vegetation is the main source of energy in many headwater streams. However, the transfer of such material is altered by the destruction of forests. Objective: To assess flow differences of this organic matter in streams with forests and grasslands. Methods: We compared input, storage and export of this organic matter in the riparian belts of streams with forests, and streams with grasslands, in the central Andean region of Colombia. For each stream, we measured vertical and lateral litter with baskets; stream bed litter with a quadrant, and matter export with drift nets, in a 100 m reach. Results: The streams with riparian forest received an average of 915 g m-2 of coarse particulate organic matter annually, exported a total of 334 g m-3 and stored 732 g m-2, values that were significantly higher than in grassland streams, where the corresponding values were: 125.4 g m-2; 128 g m-3 and 205.5 g m-2. Conclusions: The removal of tree cover from the riparian zone reduced the organic matter in these headwater streams of Colombia.
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Conservación de los Recursos Naturales , Ríos , Crianza de Animales Domésticos , Colombia , Materia OrgánicaRESUMEN
Pastures cover, in Brazil, around 165 million ha, most of them are at some degradation level. Recovering these pastures is essential. The objective of this study was to evaluate the sensibility of soil organic matter (SOM) and its physical attributes in pasture soil at different degradation levels (1 to 4), Capoeiras (1 and 2) and secondary Forest (Control). Samples were collected at four depths (0.00-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m). We verified higher values for SOM and hydraulic conductivity (Ko) in Forest, especially in the most superficial layer (0.00-0.05). We noted low values for macroporosity in this area. In all areas under Pastures lower values for Ko were observed in the superficial layer (0.00-0.05 m) when compared to layers 0.05-0.10 and 0.10-0.20 m, which indicates that the pasture management and cattle trampling negatively affect the physical quality of the pastures. For field capacity and wilting point the average values were observed in Pasture 4 (more degraded), which caused higher values for water availability. According to the principal components analysis, except for SOM at 0.20-0.40 m, all variables studied presented correlation above 0.6. From grouping analysis, we separated 3 groups: Forest; Capoeiras 1 and Capoeira 2 and Pastures 1 to 4.
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Calidad del Suelo , Características del SueloRESUMEN
The purpose of this study was to evaluate doses of sulfur applied at topdressing, with and without organic compost supply at planting, in the production, physiological quality and content of macronutrients in lettuce seeds. Ten treatments were evaluated in a 5x2 factorial scheme (five sulfur doses at topdressing x with and without application of organic compost at planting). The experimental design was a randomized block design, with four replicates. The sulfur doses applied at topdressing fertilization were 50, 100, 150 and 200 kg ha-1 of S, in addition to the control treatment (dose zero). Regarding the treatments with organic compost, the dose of 70 t ha-1 of compost (wet basis) was supplied at planting. The following characteristics were evaluated: seed production (mass and number of seeds per plant), seed quality (mass of one thousand seeds, first count of the standard germination test, germination percentage, and germination speed index) and content of macronutrients and mineral accumulation. The organic compost supply at planting increased seed production by 43% compared to the treatment without the application of organic compost, while the doses of sulfur did not affect the production of lettuce seeds. The supply of organic compost increased the accumulation of a great part of the macronutrients, except for the accumulation of calcium. The lettuce seeds quality was not affected by both the main treatments, the sulfur doses at topdressing and the organic compost supply at planting. The descending order of nutrients accumulated in the lettuce seeds was nitrogen> potassium> phosphorus> magnesium> calcium> sulfur.
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Semillas , Nutrientes , Lactuca , Materia OrgánicaRESUMEN
RESUMO Estudos recentes vêm demonstrando que a aplicação de cloro poderia levar à formação de trihalometanos (THM), que ocorre quando o cloro reage com a matéria orgânica natural, também denominada de precursora de THM e presente em águas naturais. A United States Environmental Protection Agency (USEPA) classificou os THM como prováveis carcinogênicos para humanos. Com o objetivo de avaliar os níveis de THM na água destinada ao abastecimento público na cidade de Cáceres/MT, foram coletadas amostras de água em três pontos distintos: P1 na água bruta, P2 na saída do reservatório e P3 na rede de abastecimento, por um período de um ano (agosto de 2018 a junho de 2019), com frequência bimestral. Além dos THM, foram monitorados os parâmetros de turbidez, cor, pH e cloro residual livre. Os resultados de água bruta demonstraram que o fenômeno natural denominado "decoada" aumentou as concentrações de turbidez e cor aparente no período enchente/cheia pelo intenso processo de decomposição que ocorre nesse momento, elevando os níveis de matéria orgânica na água bruta. Quanto à água tratada, valores de turbidez fora do preconizado foram detectados. Os níveis de THMs chegaram próximo (0,09518 mg.L-1 - P2) de atingir o VMP de 0,1 mg.L-1 em consequência da presença de precursores. Os valores de THM foram maiores em P2 pelo fato de esse ponto apresentar medição maior de cloro residual livre em relação a P3. Todavia, notou-se uma forte correlação entre THM e turbidez (p < 0,05 e R² = 0,67), o que demonstra que o parâmetro de turbidez pode ser um indicativo da presença de precursores de THM.
ABSTRACT Recent studies have shown that the application of chlorine could lead to the formation of trihalomethanes (THM), which occurs when chlorine reacts with natural organic matter (NOM), also known as precursors of THM, present in natural waters. The United States Environmental Protection Agency (USEPA) has classified THM as probable carcinogens for humans. In order to assess the levels of trihalomethanes in water destined for public supply in the city of Cáceres, state of Mato Grosso, Brazil, water samples were collected from three different points: P1, at raw water; P2, at the outlet of the reservoir; and P3, at the supply network, for a period of one year (from August 2018 to June 2019), with bimonthly frequency. In addition to THM, the parameters of turbidity, color, pH, and free residual chlorine were monitored. The results of raw water demonstrated that the natural phenomenon called "decoada" increased the concentrations of turbidity and apparent color in the flood/spate period, due to the intense decomposition process that occurs in this period, increasing the levels of organic matter in raw water. As for treated water, turbidity values outside the recommended values were detected. THM levels (0.09518 mg.L-1 - P2) almost reached the MPV of mg.L-1, as a result of the presence of precursors. The THM values were higher in P2 because this point presents a higher concentration of free residual chlorine in relation to P3. However, there was a strong correlation between THM and turbidity (p < 0.05 and R² = 0.67), thus demonstrating that the turbidity parameter may be indicative of the presence of THM precursors.
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RESUMO Os wetlands construídos (WC) são uma ecotecnologia aplicável para o tratamento descentralizado de esgotos notadamente em pequenas comunidades, em razão de sua simplicidade operacional. Existem vários arranjos e combinações de WC possíveis, destacando-se o arranjo tanque séptico (TS), seguido da modalidade de WC de escoamento vertical (WCV) com recirculação do efluente do WCV de volta para o TS, como proposta para possibilitar a remoção de nitrogênio presente no esgoto afluente. Entretanto, no Brasil, essa configuração e suas implicações operacionais e de desempenho são pouco exploradas. Diante disso, o objetivo deste trabalho foi avaliar o desempenho de um sistema de TS seguido de um WCV com recirculação no tratamento descentralizado de esgoto doméstico. O sistema empregado no tratamento de esgoto de um equivalente populacional de dez habitantes é composto de um TS (4,7 m3 de volume útil), seguido de um WCV (24,5 m2 de área superficial) preenchido com brita e plantado com Canna spp. O monitoramento, que compreendeu um período de nove meses, teve início após um ano e cinco meses de operação do sistema. Utilizando taxa de 50% de recirculação, taxa de aplicação hidráulica no WCV de 85 mm d-1 e carga de 47 g DQO m-2.d-1, foram obtidas boas eficiências para remoção conjunta de demanda química de oxigênio — DQO (80%), sólidos em suspensão totais — SST (85%) e nitrogênio total —NT (42%), mesmo com elevadas cargas orgânicas. Além das boas eficiências apresentadas, o sistema demonstrou ser robusto e de operação simples e representa uma alternativa tecnológica com potencial para o tratamento descentralizado de esgotos de empreendimentos habitacionais.
ABSTRACT Constructed wetland (CW) is an applicable eco-technology for decentralized wastewater treatment, notably in small communities, due to its operational simplicity. CW has several possible arrangements and combinations, among which the septic tank (ST) stands out, followed by the vertical flow constructed wetland (VFCW), with treated effluent recirculation back to the ST to enable nitrogen removal. However, in Brazil, this configuration and its operational and performance implications are little explored. Therefore, this study aimed to evaluate the performance of an ST system, followed by a VFCW with recirculation in the decentralized treatment of domestic wastewater. The wastewater treatment system for 10 inhabitants consists of an ST (4.7 m3 of useful volume), followed by a VFCW (24.5 m2 of surface area) planted with Canna spp. The monitoring, which covered a period of nine months, started after one year and five months of system operation. Using a 50% recirculation rate, VFCW hydraulic loading rate of 85 mm d-1, and organic load of 47 g COD m-2 d-1, good efficiencies were obtained for the joint removal of chemical oxygen demand — COD (80%), total suspended solids — TSS (85%), and total nitrogen — TN (42%), even with high organic loads. In addition to the good efficiencies presented, the system proved to be robust and easy to operate, representing a technological alternative with potential for the decentralized wastewater treatment of housing developments.
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Ammonium quaternary compounds are widely used in poultry and swine production as disinfectants in the control of pathogens. They act on gram-positive bacteria, gram-negative bacteria, enveloped fungi and viruses. However, in some conditions of pH and presence of organic matter can be inactivated. This study evaluated the action of ammonium quaternary compounds at 1:1,000 and 1:2,000 dilutions against Salmonella enterica serovarTyphimurium and Salmonella enterica serovar Enteritidis in the presence of three different organic matter simulators, fetal bovine serum, skim milk and whole milk concentration of 1, 3, 5, and 7% and at pH 6 and 9, with 15 min of contact. It was possible to verify that the organic matter simulators adjusted in the same conditions of contact time and percentage, in the in vitro tests, presented different results and the fetal bovine serum did not inactivate the disinfectant. However, the best result against S. Typhimurium and S. Enteritidis was obtained at pH 6 at the dilution of 1:1,000 in all organic matter simulators.
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Salmonella enteritidis , Contención de Riesgos Biológicos , Salmonella enterica , Materia Orgánica , Compuestos de Amonio Cuaternario , Porcinos , Aves , Técnicas In Vitro , Albúmina Sérica Bovina , Leche , Desinfectantes , Bacterias Gramnegativas , Bacterias GrampositivasRESUMEN
Polyhydroxyalkanoates (PHA) synthesis by activated sludge using volatile fatty acids (VFAs) in fermentation liquid of excess sludge as carbon source is a hotspot in the field of environmental biotechnology. However, there is no unified conclusion on the effects of non-VFAs, mainly dissolved organic matter (DOM), on PHA production. Thus, this critical review mainly introduces the main characteristics and common analysis methods of DOM in anaerobic fermentation liquid. The effects of DOM on PHA production are analyzed from the aspects of microbiology, metabolic regulation and sludge properties. The results of different studies showed that high concentration of DOM is bad for PHA production, but an appropriate amount of DOM is conducive to the stability of sludge properties, reducing the final PHA purification cost. Finally, suitable strategies were proposed to regulate the PHA synthesis by activated sludge with DOM for PHA production by anaerobic fermentation liquid.
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Anaerobiosis , Reactores Biológicos , Ácidos Grasos Volátiles , Fermentación , Polihidroxialcanoatos , Aguas del AlcantarilladoRESUMEN
Systems of soil cultivation and use directly influence crop yield by interfering with the soil chemical, physical, and biological attributes. This study aimed to evaluate the correlation between maize grain yield, soil chemical and biological attributes, and the occurrence of nematodes in maize crops grown in the off-season, in the state of Mato Grosso do Sul. Soil samples from 21 off-season maize crops were collected in 2015. The samples were used to identify and quantify nematodes, determine biomass carbon and microbial activity, and for chemical analysis. The attributes were clustered based on the variables evaluated using the mean Euclidean distance and Ward's clustering method. The interrelationship between the variables was analyzed by correlations, and its unfolding in the cause and effect investigations was evaluated by the path analysis. Organic matter and microbial biomass carbon positively influence grain yield. Magnesium negatively influences the population of Pratylenchulus spp. in maize crops. The potential acidity and organic matter are related to the presence of Rotylenchulus spp.
Sistemas de cultivo e uso do solo influenciam diretamente o rendimento das culturas, interferindo nos atributos químicos, físicos e biológicos do solo. Este trabalho teve como objetivo avaliar a correlação entre a produtividade de grãos de milho, os atributos químicos e biológicos do solo e a ocorrência de nematoides em milho cultivado no período de entressafra, no estado do Mato Grosso do Sul. Amostras de solo de 21 safras de milho fora de temporada foram coletadas em 2015. As amostras foram usadas para identificar e quantificar os nematóides, determinar a atividade microbiana e o carbono da biomassa, e para análises químicas. Os atributos foram agrupados com base nas variáveis avaliadas usando a distância euclidiana média e o método de agrupamento de Ward. A inter-relação entre as variáveis foi analisada por meio de correlações, e seu desdobramento nas investigações de causa e efeito foi avaliado pela análise de trilha. A matéria orgânica e o carbono da biomassa microbiana influenciam positivamente o rendimento de grãos. O magnésio influencia negativamente a população de Pratylenchulus spp. nas culturas de milho. A acidez potencial e a matéria orgânica estão relacionadas à presença de Rotylenchulus spp.
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Suelo , Zea mays , NematodosRESUMEN
The ruderal babassu palm (Attalea speciosa) is expanding on large areas of degraded Amazon landscapes. Decomposition of leaves and roots is in the center of plant:soil interactions. We evaluated decomposition and nutrient concentrations of leaves and fine roots of babassu in comparison with two exotic reference species, Acacia mangium (slow degradability) and Leucaena leucocephala (fast degradability), in a 138-day litterbag assay carried out in secondary forest stands of different age and babassu abundance. We chose 4-mm over 2-mm mesh litterbags based on a pilot study. Babassu leaves degraded slower than leaves of A. mangium and L. leucocephala, and also had lower nitrogen, phosphorus and calcium concentrations in all stages of decomposition. By contrast, potassium concentrations in babassu leaves were higher than in both reference species at 0 and 50 days. Roots of all three species decomposed slower than leaves. Compared to the leaves, both biomass loss and nutrient concentrations differed less between babassu and reference-species roots, except for lower nitrogen concentration in babassu roots. Leaf-litter decomposition of all three species was significantly faster in old than in young secondary forest, suggesting an acceleration of decomposition along succession. Babassu leaves decomposed faster in old babassu-dominated than non-dominated secondary forest, pointing to the existence of specialized decomposer communities in babassu-dominated stands. (AU)
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Suelo , Nutrientes , Ecosistema Amazónico , Acacia , Materia OrgánicaRESUMEN
Avaliar, por microscopia eletrônica de varredura (MEV), o efeito do uso individual e combinado do etidronato 18% (HEBP) na remoção da smear layer do canal radicular. Métodos: Trinta dentes humanos unirradiculares foram utilizados. As raízes foram preparadas com instrumentos rotatórios do Sistema ProTaper Universal e divididas aleatoriamente em três grupos, de acordo com o protocolo de irrigação empregado: G1 = hipoclorito de sódio 2,5% (NaOCl) e ácido etilenodiaminotetracético 17% (EDTA); G2 = NaOCl 2,5% e HEBP 18%; e G3 = NaOCl 2,5% + HEBP 18%, misturados em partes iguais. As raízes foram seccionadas longitudinalmente e metalizadas, para análise em MEV. As fotomicrografias obtidas dos terços cervical, médio e apical foram avaliadas por três examinadores calibrados, que atribuíram escores de 1 a 5 às imagens. Os grupos experimentais foram comparados usando o teste de Kruskal-Wallis e o teste de Student-New- man-Keuls. Os terços radiculares foram comparados pelo teste de Friedman. O nível de significância foi estabelecido em 5%. Resultados: A capacidade de remoção da smear layer com NaOCl 2,5% e 18% HEBP (G2) foi semelhante à obtida com NaOCl 2,5% e EDTA 17% (G1) no terço médio e cervical da raiz; o nível de limpeza do terço apical foi semelhante, independentemente do protocolo de irrigação utilizado. Conclusão: HEBP é uma solução promissora para uso em tratamentos endodônticos (AU).
Introduction: We evaluated the effect of individual and combined use of 18% etidronate (HEBP) in root canal smear layer removal using scanning electron microscopy (SEM). Methods: Thirty human single-rooted teeth were used. The roots were prepared with ProTaper Universal System rotary files and randomly divided into three groups according to the irrigation protocol used. G1: 2.5% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA); G2: 2.5% NaOCl and 18% HEBP; and G3: 2.5% NaOCl + HEBP 18%, mixed in equal parts. The roots were sectioned longitudinally and metallized for SEM analysis. The photomicrographs obtained from the cervical, middle, and apical thirds were evaluated by three calibrated examiners, who assigned scores from 1 to 5 to the images. The experimental groups were compared using the Kruskal-Wallis test and the Student-Newman-Keuls test. Root thirds were compared by the Friedman test. The level of significance was set at 5%. Results: The capacity for removal of the smear layer by 2.5% NaOCl and 18% HEBP (G2) was similar to that achieved with 2.5% NaOCl and 17% EDTA (G1) in the cervical and middle thirds of the root; the cleansing level of the apical third was similar, regardless of the irrigation protocol used. Conclusion: HEBP is a promising solution for use in endodontic treatments (AU).
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Humanos , Microscopía Electrónica de Rastreo , Ácido Etidrónico , Elevación , Cavidad Pulpar , Soluciones , Eficacia , Disolución , Materia OrgánicaRESUMEN
RESUMO Matéria orgânica natural (MON) é uma complexa matriz de compostos orgânicos originados de fontes naturais que estão presentes em corpos hídricos. A MON é comprovada precursora de subprodutos da desinfecção (SPD), além de afetar processos de tratamento de água, tais como a coagulação, a desinfecção, a oxidação, a adsorção em carvão ativado e a filtração em membranas. Por essas razões, a redução da MON no tratamento de água para consumo humano é importante. Vários métodos são usados para caracterizar e quantificar a MON, tais como adsorção em resinas e parâmetros de massa. Carbono orgânico total (COT), carbono orgânico dissolvido (COD), absorção na região do ultravioleta (UV254) e absorbância específica de luz ultravioleta (AEUV) são usualmente utilizados como parâmetros de massa. O fracionamento rápido é uma técnica que usa diferentes resinas para separar frações da MON. Nesse contexto, este trabalho teve como objetivo geral caracterizar a matéria orgânica dissolvida (MOD) em processos de tratamento de água para consumo humano usando o método do fracionamento rápido e os parâmetros COD, UV254 e AEUV. Também foram analisados as variáveis turbidez, cor, pH e alcalinidade. Foram avaliados os efeitos dos processos de coagulação, sedimentação, filtração e adsorção em carvão ativado nas frações que formam a MON. Ácidos muito hidrofóbicos (AMH) constituíram a principal fração da MOD na água estudada, havendo redução de 89% entre a água bruta e o efluente do filtro de carvão ativado granular (CAG). A segunda fração predominante foi de ácidos levemente hidrofóbicos (ALH), reduzidos em 83% ao longo do tratamento. Na água bruta, as frações de matérias hidrofílicas carregadas (MHC) e de neutras (MHN) apresentaram concentrações de 0,11 mg L-1 e 0,04 mg L-1, não sendo removidas pelo tratamento.
ABSTRACT Natural organic matter (NOM) is a complex matrix of organic compounds originated from natural sources that are present in water bodies. NOM is a known precursor of disinfection by-products (DBP) and affects drinking water treatment processes such as coagulation, disinfection, oxidation, activated carbon adsorption, and membrane filtration. For these reasons, the reduction of NOM in water treatment is important. Several methods are used to characterize and quantify NOM, such as resin adsorption and mass parameters. The latter include total organic carbon (TOC), dissolved organic carbon (DOC), ultraviolet absorption at 254 nm (UV254), and specific UV absorption (SUVA). Rapid fractionation is a technique that uses different resins to separate NOM fractions. The objective of this study was to characterize dissolved organic matter (DOM) in drinking water treatment processes using rapid fractionation and the parameters DOC, UV254, and SUVA. Turbidity, color, pH, and alkalinity were also analyzed. The effects of coagulation, sedimentation, filtration, and adsorption processes on the fractions forming the NOM were evaluated. Very hydrophobic acids (VHA) constituted the main fraction of DOM in the studied water, with a reduction of 89% between raw water and granular activated carbon filter (GAC) respect to raw water. The second predominant fraction consisted of slightly hydrophobic acids (SHA), reduced by 83% throughout the treatment processes. In raw water, the hydrophilic charged (MHC) and neutral (MHN) fractions showed concentrations of 0.11 and 0.04 mg L-1, which were not removed during treatment.
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Abstract The occupation of sandy soils in Brazil has occurred with poor adoption of management technology, which has caused its degradation. The recovery of organic matter, particularly when growing annual plants and cover crops, with mulch residue allows the maintenance of the productive potential of these soils. Thus, the shoot dry mass production (SDMP) of winter cover crops was evaluated in an Ultisol under no-tillage system and in rotation with soybean and maize using 0, 2, 4 and 8 t ha-1 year-1 of poultry litter, mineral fertilizer exclusively and 2 t ha-1 year-1 of poultry litter associated with a half-dose of mineral fertilizer. The experimental design included randomized blocks with four replicates. The use of poultry litter increased the SDMP of the cover crops; the production was relatively high when high doses of poultry litter were applied; on the other hand, the yield of SDMP and grain was limited by the exclusive use of mineral fertilizer. Organic matter and nutrient status improvement by cover crops were one of the reasons for the increase in soybean and maize grain yields.
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Humanos , Animales , Nutrientes , Suelos Arenosos/análisis , Agricultura/métodos , Materia Orgánica , Fertilizantes , Minerales , Glycine max , Productos Agrícolas , Zea maysRESUMEN
Abstract The no-tillage system associated with crops rotation affects the dynamics of soil organic matter, influencing the formation, reorganization and stabilization of aggregates and the carbon content (C) into soil aggregates. The aim of this study was to evaluate the effect of crop rotations under no-tillage system on C content and soil aggregation. The experiment was conducted at the Paraná Agronomic Institute in Ponta Grossa, PR, Brazil. The treatments consisted of six crop rotations, in a 3-year cycle, arranged in a randomized block design with four replications. Soil samples were collected at layers of 0-5, 5-10 and 10-20 cm. The aggregate classification was determined by the wet sieving methodology, and the Weighted Mean Diameter (WMD), Geometric Mean Diameter (GMD) and Aggregate Stability Index (ASI) were calculated. The C content in the aggregates was determined by wet oxidation. The results were submitted to analysis of variance and Tukey test at 5% probability. There was no difference among crop rotations for aggregate classes and aggregation indexes, but were higher in surface, decreasing in depth. The carbon content in the aggregates did not differ among crop rotations, but presented stratification in the soil profile, decreasing in depth. The cycle of three years with crop rotation was insufficient to express possible changes in soil C content and aggregation.
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Humanos , Suelo/química , Carbono/química , Fertilizantes , Brasil , Productos Agrícolas , Modelos TeóricosRESUMEN
Abstract This study assessed the performance of two pilot units, a conventional activated sludge (CAS) and an Integrated Fixed-Film Activated Sludge (IAS), in the treatment of leachate from sanitary landfill combined with domestic sewage, with the aim of removing organic substances. In order to assess the possible impacts on treatment, three experimental phases were designed using influent leachate contributions of 5%, 10%, and 20% of the total BOD load. Overall, the results showed that no significant changes in the behavior of biological processes. The IAS unit presented average BOD removal efficiencies of above 88%, 87% and 80% for the three leachate load contributions of 5%, 10% and 20% studied. The CAS unit presented lower average efficiency with a 5% leachate contribution (64%), but displayed a similar performance to the IAS unit in the other phases (82% and 80%); similar quantitative aspects were observed for both treatment processes with regards to biomass composition analysis. The kinetic coefficients related to heterotrophic metabolism did not indicate negative effects on treatment efficiency as a result of the increase in leachate addition, with values of 2.8; 2.8 and 2.7 d-1 obtained respectively for each phase with the CAS unit, and 2.0; 1.5 and 1.6 d-1 with the IAS unit, representing similar values to those found in the literature (1.5 a 5.0 d-1). The results reinforced the conclusion that the leachate load introduced did not cause inhibition or significant alterations to heterotrophic metabolism, and, therefore, to the removal of organic matter.
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Humanos , Animales , Contaminantes Químicos del Agua/metabolismo , Líquido Percolado , Lodos Activados , /métodos , Biomasa , Proyectos Piloto , Reactores Biológicos , Bacterias Heterotróficas , Materia OrgánicaRESUMEN
RESUMO Neste trabalho, teve-se como objetivo avaliar o desempenho de Sistemas Alagados Construídos de Escoamento Horizontal Subsuperficial (SAC-EHSS) cultivados com Mentha aquatica, submetidos a diferentes tempos de detenção hidráulica (TDH), na remoção de matéria orgânica, nutrientes e bactérias do grupo coliformes presentes em esgoto sanitário efluente de tanque séptico. Quatro SACs-EHSS de 24,0 × 1,0 × 0,35 m foram construídos e preenchidos com brita #0, como meio suporte, até a altura de 0,20 m. Em dois SAC-EHSS, foi cultivada a espécie Mentha aquatica, permanecendo os outros dois sem vegetação como tratamento controle. O experimento foi realizado em duas etapas: na primeira, de 20 de junho a 24 de agosto de 2011, avaliaram-se os TDH de 6,0 e 4,5 dias; e, na segunda, de 31 de agosto a 09 de novembro de 2011, foram analisados os TDH de 3,0 e 1,5 dias. Para avaliação do desempenho dos sistemas, foram quantificadas as variáveis: demanda química de oxigênio (DQO), demanda bioquímica de oxigênio (DBO5), concentrações totais de nitrogênio (N), fósforo (P), potássio (K) e sódio (Na), coliformes totais e Escherichia coli. As eficiências médias na remoção de DQO variaram entre 71,3 e 91,4% e as de DBO5, entre 75,3 e 91,0%. As remoções médias de nutrientes foram de 29,5 a 77,2% do N total; de 12,8 a 58,3% do P total; de 20,4 a 63,3% do K total; e de 17,5 a 53,4% do Na total. As reduções na contagem de coliformes totais foram de 1,29 a 3,41 unidades logarítmicas e as de E. coli, de 1,13 a 3,46 unidades logarítmicas. Maiores eficiências na remoção de matéria orgânica, nutrientes e bactérias do grupo coliformes foram observadas nos SAC-EHSS cultivados que operaram com maiores TDH.
ABSTRACT This work was conducted to evaluate the performance of horizontal subsurface flow constructed wetlands (HSSF-CWs) cultivated with Mentha aquatica, subjected to different hydraulic retention times (HRTs), in the removal of organic matter, nutrients and coliform bacteria in sewage effluent from septic tank. Four HSSF-CWs measuring 24.0 × 1.0 × 0.35 m were built and filled with gravel # 0, as a support medium, up to the height of 0.20 m. In two HSSF-CWs, Mentha aquatica was cultivated, the other two remained without vegetation, as control treatment. The experiment was conducted in two stages: in the first, from 06/20 to 08/24/2011, HRTs of 6.0 and 4.5 days were evaluated, and in the second stage, from 08/31 to 11/09/2011, HRTs of 3.0 and 1.5 days were evaluated. To evaluate the systems performance, the following variables were quantified: chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen, phosphorus, potassium, sodium, total coliforms and Escherichia coli. Average removal efficiencies of COD ranged from 71.3 to 91.4% and of BOD5 from 75.3 to 91.0%. With respect to nutrients, average removals ranged from 29.5 to 77.2% total N; 12.8 to 58.3% total P; 20.4 to 63.3% total K and 17.5 to 53.4% total Na. Reductions in total coliform counts ranged from 1.29 to 3.41 log units and 1.13 to 3.46 log units in E. coli. Improved efficiencies in the removal of organic matter, nutrients and coliform bacteria were observed in cultivated HSSF-CWs that operated at higher HRT.
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Aim: This study was aimed at determining the physicochemical characteristics (such as pH, dissolved oxygen, biological oxygen demand, nitrogen, phosphorus, chloride, iron, lead, magnesium etc.) of the effluent sludge from a sewage oxidation pond and the receiving stream before and after exposure to solar energy. This is to gain a better understanding on how ultraviolet radiations from sunlight alters the physicochemical parameters inherent in the sludge and the stream. Methods and Results: Effluent sludge samples and water samples from the receiving stream were collected and exposed to solar energy over a twenty-day period. Physicochemical parameters were measured using standard methods. Results revealed that mean values of dissolved oxygen and pH increased whereas those of biological oxygen demand, ammonia nitrogen, chloride, phosphorus, iron, lead zinc and magnesium reduced over the period study. Conclusion: The findings from this study suggest that the addition of solar energy to the chains of processes in sewage treatment will produce effluents with minimal content of nutrients from organic matter and heavy metals and these will ultimately protect the receiving stream from contamination, thus contributing to human health protection.
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This work focuses on analyzing of physico-chemical properties of sediment affected by frequent floods along the eastern shore of the Bandama River in the department of Niakaramadougou. Sampling was from 4 excavated graves at two positions of studied area, one near the stream and the other one far away from the stream.. Samples collected were analyzed, including texture with granulometric analysis made by the Robinson pipette, and standard sediment analysis methods for measuring organic carbon (OC), nitrogen (N), and other chemical properties including pH, organic matter (OM), and C/N ratio. Statistical analyses were carried out to assess the differences between the physico-chemical parameters at different sampling areas. Differences are significant when comparing areas that are highly affected by floods and areas that are less affected by floods, especially for concentrations of OM, OC and nitrogen. Results show that successive floods are influencing directly the dynamic of physico-chemical properties of the sediments along the shore.