991 resultados para NH4
Resumo:
Compost, vermicompost and biochar amendments are thought to improve soil quality and plant yield. However, little is known about their long-term impact on crop yield and the environment in tropical agro-ecosystems. In this study we investigated the effect of organic amendments (buffalo manure, compost and verrnicompost) and biochar (applied alone or with vermicompost) on plant yield, soil fertility, soil erosion and water dynamics in a degraded Acrisol in Vietnam. Maize growth and yield, as well as weed growth, were examined for three years in terrestrial mesocosms under natural rainfall. Maize yield and growth showed high inter-annual variability depending on the organic amendment. Vermicompost improved maize growth and yield but its effect was rather small and was only significant when water availability was limited (year 2). This suggests that vermicompost could be a promising substrate for improving the resistance of agrosystems to water stress. When the vermicompost biochar mixture was applied, further growth and yield improvements were recorded in some cases. When applied alone, biochar had a positive influence on maize yield and growth, thus confirming its interest for improving long-term soil productivity. All organic amendments reduced water runoff, soil detachment and NH4+ and NO3- transfer to water. These effects were more significant with vermicompost than with buffalo manure and compost, highlighting that the beneficial influence of vermicompost is not limited to its influence on plant yield. In addition, this study showed for the first time that the combination of vermicompost and biochar may not only improve plant productivity but also reduce the negative impact of agriculture on water quality. (C) 2015 Elsevier B.V. All rights reserved.
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Sediments are an important location in determining the fate of nutrients entering the estuary. Role of sediments needs to be incorporated into water quality models. Purpose of this study was to estimate the portion of sediment oxygen consumption (SOC) and sediment ammonium (NH4+) release directly attributable to benthic invertebrates via the respiratory use of oxygen and catabolic release of ammonium. Samples were collected at 8 locations from August 1985 through November 1988. (PDF contains 45 pages)
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A physical model is presented to describe the kinds of static forces responsible for adhesion of nano-scale copper metal particles to silicon surface with a fluid layer. To demonstrate the extent of particle cleaning, Received in revised form equilibrium separation distance (ESD) and net adhesion force (NAF) of a regulated metal particle with different radii (10-300 nm) on the silicon surface in CO2-based cleaning systems under different pressures were simulated. Generally, increasing the pressure of the cleaning system decreased the net adhesion force between spherical copper particle and silicon surface entrapped with medium. For CO2 + isopropanol cleaning system, the equilibrium separation distance exhibited a maximum at temperature 313.15 K in the Equilibrium separation distance regions of pressure space (1.84-8.02 MPa). When the dimension of copper particle was given, for example, High pressure 50 nm radius particles, the net adhesion force decreased and equilibrium separation distance increased with increased pressure in the CO2 + H2O cleaning system at temperature 348.15 K under 2.50-12.67 MPa pressure range. However, the net adhesion force and equilibrium separation distance both decreased with an increase in surfactant concentration at given pressure (27.6 or 27.5 MPa) and temperature (318 or 298 K) for CO2 + H2O with surfactant PFPE COO-NH4+ or DiF(8)-PO4-Na+. (C) 2008 Elsevier B.V. All rights reserved.
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<p>Superprotonic phase transitions and thermal behaviors of three complex solid acid systems are presented, namely Rb3H(SO4)2-RbHSO4 system, Rb3H(SeO4)2-Cs3H(SeO4)2 solid solution system, and Cs6(H2SO4)3(H1.5PO4)4. These material systems present a rich set of phase transition characteristics that set them apart from other, simpler solid acids. A.C. impedance spectroscopy, high-temperature X-ray powder diffraction, and thermal analysis, as well as other characterization techniques, were employed to investigate the phase behavior of these systems.</p> <p>Rb3H(SO4)2 is an atypical member of the M3H(XO4)2 class of compounds (M = alkali metal or NH4+ and X = S or Se) in that a transition to a high-conductivity state involves disproportionation into two phases rather than a simple polymorphic transition [1]. In the present work, investigations of the Rb3H(SO4)2-RbHSO4 system have revealed the disproportionation products to be Rb2SO4 and the previously unknown compound Rb5H3(SO4)4. The new compound becomes stable at a temperature between 25 and 140 C and is isostructural to a recently reported trigonal phase with space group P3m of Cs5H3(SO4)4 [2]. At 185 C the compound undergoes an apparently polymorphic transformation with a heat of transition of 23.8 kJ/mol and a slight additional increase in conductivity.</p> <p>The compounds Rb3H(SeO4)2 and Cs3H(SeO4)2, though not isomorphous at ambient temperatures, are quintessential examples of superprotonic materials. Both adopt monoclinic structures at ambient temperatures and ultimately transform to a trigonal (R3m) superprotonic structure at slightly elevated temperatures, 178 and 183 C, respectively. The compounds are completely miscible above the superprotonic transition and show extensive solubility below it. Beyond a careful determination of the phase boundaries, we find a remarkable 40-fold increase in the superprotonic conductivity in intermediate compositions rich in Rb as compared to either end-member.</p> <p>The compound Cs6(H2SO4)3(H1.5PO4)4 is unusual amongst solid acid compounds in that it has a complex cubic structure at ambient temperature and apparently transforms to a simpler cubic structure of the CsCl-type (isostructural with CsH2PO4) at its transition temperature of 100-120 C [3]. Here it is found that, depending on the level of humidification, the superprotonic transition of this material is superimposed with a decomposition reaction, which involves both exsolution of (liquid) acid and loss of H2O. This reaction can be suppressed by application of sufficiently high humidity, in which case Cs6(H2SO4)3(H1.5PO4)4 undergoes a true superprotonic transition. It is proposed that, under conditions of low humidity, the decomposition/dehydration reaction transforms the compound to Cs6(H2-0.5xSO4)3(H1.5PO4)4-x, also of the CsCl structure type at the temperatures of interest, but with a smaller unit cell. With increasing temperature, the decomposition/dehydration proceeds to greater and greater extent and unit cell of the solid phase decreases. This is identified to be the source of the apparent negative thermal expansion behavior.</p> <p>References</p> <p>[1] L.A. Cowan, R.M. Morcos, N. Hatada, A. Navrotsky, S.M. Haile, Solid State Ionics 179 (2008) (9-10) 305.</p> <p>[2] M. Sakashita, H. Fujihisa, K.I. Suzuki, S. Hayashi, K. Honda, Solid State Ionics 178 (2007) (21-22) 1262.</p> <p>[3] C.R.I. Chisholm, Superprotonic Phase Transitions in Solid Acids: Parameters affecting the presence and stability of superprotonic transitions in the MHnXO4 family of compounds (X=S, Se, P, As; M=Li, Na, K, NH4, Rb, Cs), Materials Science, California Institute of Technology, Pasadena, California (2003).</p>
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<p>This study proposes a wastewater electrolysis cell (WEC) for on-site treatment of human waste coupled with decentralized molecular H<sub>2</sub> production. The core of the WEC includes mixed metal oxides anodes functionalized with bismuth doped TiO<sub>2</sub> (BiO<sub>x</sub>/TiO<sub>2</sub>). The BiO<sub>x</sub>/TiO<sub>2</sub> anode shows reliable electro-catalytic activity to oxidize Cl- to reactive chlorine species (RCS), which degrades environmental pollutants including chemical oxygen demand (COD), protein, NH4<sup>+</sup>, urea, and total coliforms. The WEC experiments for treatment of various kinds of synthetic and real wastewater demonstrate sufficient water quality of effluent for reuse for toilet flushing and environmental purposes. Cathodic reduction of water and proton on stainless steel cathodes produced molecular H2 with moderate levels of current and energy efficiency. This thesis presents a comprehensive environmental analysis together with kinetic models to provide an in-depth understanding of reaction pathways mediated by the RCS and the effects of key operating parameters. The latter part of this thesis is dedicated to bilayer hetero-junction anodes which show enhanced generation efficiency of RCS and long-term stability.</p> <p>Chapter 2 describes the reaction pathway and kinetics of urea degradation mediated by electrochemically generated RCS. The urea oxidation involves chloramines and chlorinated urea as reaction intermediates, for which the mass/charge balance analysis reveals that N<sub>2</sub> and CO<sub>2</sub> are the primary products. Chapter 3 investigates direct-current and photovoltaic powered WEC for domestic wastewater treatment, while Chapter 4 demonstrates the feasibility of the WEC to treat model septic tank effluents. The results in Chapter 2 and 3 corroborate the active roles of chlorine radicals (Cl/Cl<sub>2</sub><sup>-</sup>) based on iR-compensated anodic potential (thermodynamic basis) and enhanced pseudo-first-order rate constants (kinetic basis). The effects of operating parameters (anodic potential and [Cl<sup>-</sup>] in Chapter 3; influent dilution and anaerobic pretreatment in Chapter 4) on the rate and current/energy efficiency of pollutants degradation and H<sub>2</sub> production are thoroughly discussed based on robust kinetic models. Chapter 5 reports the generation of RCS on Ir<sub>0.7</sub>Ta<sub>0.3</sub>O<sub>y</sub>/Bi<sub>x</sub>Ti<sub>1-x</sub>O<sub>z</sub> hetero-junction anodes with enhanced rate, current efficiency, and long-term stability compared to the Ir<sub>0.7</sub>Ta<sub>0.3</sub>O<sub>y</sub> anode. The effects of surficial Bi concentration are interrogated, focusing on relative distributions between surface-bound hydroxyl radical and higher oxide.</p>
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Os gestores de recursos hdricos esto encarregados da gesto de longo prazo, a regulao e a proteo dos recursos hdricos. No entanto, reconhece-se que a estes gestores devem levar em conta a multiplicidade de usos dos recursos hdricos que so apresentadas pelas partes interessadas, tais como agricultores, fornecedores de gua e grupos de ambientalistas. Dada a complexidade do sistema hidrolgico, o desenvolvimento e a utilizao de modelos matemticos so muitas das vezes necessrios. Neste contexto a modelagem ambiental frequentemente realizada para avaliar os impactos da degradao do ecossistema devido ao humana. Essa aplicao orientada a investigaes proporciona um importante meio pelo qual os cientistas podem interagir e influenciar nas polticas a nvel local, regional, nacional e internacional. No Mato Grosso, durante a implantao da hidroeltrica de Aproveitamento Mltiplo de Manso foram adotadas medidas de mitigao dos impactos socioeconmicos causados. Essas medidas geram uma tendncia de aumento populacional associado a uma mudana das caractersticas scio-econmicas, para toda a regio do entorno do Reservatrio, o que agrava o problema de poluio por nutrientes e denota que existe uma necessidade proeminente de estudos do impacto que estas cargas causariam no ecossistema do reservatrio. Utilizando o modelo hidrodinmico e termodinmico tridimensional ELCOM, associado ao modelo biogeoqumico Caedym, este trabalho tem a finalidade de criar uma modelagem representativa das cargas dos principais nutrientes causadores da eutrofizao cultural, sendo eles: a amnia (NH4), o nitrato (NO3) e o Ortofosfato (PO4), com a finalidade de estudar os efeitos das dinmicas espaciais e temporais destas cargas no estado trfico deste reservatrio no em torno dos pontos de lanamento de esgoto e na sua totalidade.
Resumo:
Telhados verdes so uma alternativa interessante para mitigar o risco de enchentes dada a enorme rea de telhados no utilizada das superfcies impermeveis nas reas urbanas. Graas a sua capacidade de armazenagem de gua, os telhados verdes podem reduzir significativamente o pico de escoamento dos eventos de maior pluviosidade. Investigaes sobre a composio de substratos baseados em materiais locais e projetos adequados para regies climticas tropicais so menos frequentes. Vegetao e substrato so elementos de um telhado verde que precisam ser adaptados para cada microclima e no universalizados. O objetivo deste estudo foi avaliar o desempenho de diferentes composies de substratos baseados em solo local, biomassa de coco, condicionador de solo e componentes comerciais, com a finalidade de maximizar a capacidade de reteno da gua de chuva e diminuir necessidades de manuteno. Um pr-ensaio de colunas avaliou a capacidade de reteno hdrica e a relao peso seco x peso mido de 15 composies de substrato. As composies com melhores resultados constituram os substratos S1(15% solo + 55% coco + 30%componentes comerciais), S2 (30% solo + 40% coco + 30%componentes comerciais) e S3 (60% solo + 10% coco + 30%componentes comerciais). A caracterizao fsico-qumica dos substratos, solo e fibra de coco foi realizada. Em seguida um teste de colunas avaliou a capacidade de reteno hdrica dos substratos sob duas condies de precipitao: uma leve (8,77 mm/h); e outra mais forte (42,0 mm/h). Os resultados apontaram que os substratos S2 e S3 apresentaram melhores resultados de reteno para ambas as intensidades de precipitao. Observou-se que S1, que apresentou melhor capacidade de reteno no pr-ensaio, teve desempenho inferior aos demais o que pode ser atribudo maior concentrao de fibra de coco na sua composio e o consequente surgimento de caminhos preferenciais ao longo do perfil da coluna, por onde a gua escoou mais rapidamente. Em eventos de precipitao mais leve, os substratos reteram de 60 a 100% do total aplicado. Quando se aplicou uma intensidade de precipitao mais forte, a faixa de reteno ficou entre 40% e 59%. No entanto, as variveis analisadas para avaliar a qualidade da gua de escoamento dos substratos (pH, CE, P, NO3, NH4, Ca, Mg, Cu, Fe, Mn, Zn, Cr, Co, Ni) ficaram acima dos valores comumente encontrados na literatura, indicando que as composies aqui adotadas para os substratos podem implicar em uma fonte de poluio hdrica. Os substratos para uso em telhados verdes apresentados neste estudo atenderam seu objetivo quanto reteno hdrica, mas a qualidade da gua percolada torna seu uso invivel at o momento. Verificou-se a necessidade de estudar mais profundamente a qualidade da gua lixiviada por cada componente dos substratos, individualmente, a fim de identificar as fontes dos elementos que presentes em concentraes elevadas tornam-se poluentes. Pode ser considerada a remoo de algum (s) dos componentes presentes na composio para se atingir um nvel satisfatrio de qualidade da gua de escoamento.
Catalisadores base de Mg/La e de Al/La para a produo de biodiesel a partir de leos refinados e cidos
Resumo:
A crescente preocupao com a preservao do meio ambiente aliada s perspectivas de esgotamento das fontes de energia obtidas dos combustveis fsseis tem impulsionado a indstria a desenvolver combustveis alternativos a partir de recursos renovveis e processos ambientalmente no agressivos. O biodiesel, uma mistura de steres de cidos graxos obtida pela transesterificao cataltica de leos vegetais com lcoois de cadeia curta (metanol ou etanol) um combustvel alternativo importante, pelo fato das suas propriedades (ndice de cetano, contedo energtico e viscosidade) serem similares s do diesel obtido a partir do petrleo. No presente trabalho, a transesterificao do leo de soja com metanol para a produo de biodiesel foi estudada em presena de catalisadores slidos base de Mg/La e Al/La com propriedades cido-bsicas. Catalisadores de Mg/La com uma relao molar Mg/La igual a 9:1 foram preparados por coprecipitao utilizando trs mtodos que se diferenciavam quanto ao tipo de agente precipitante e a temperatura de calcinao. O catalisador preparado com (NH4)2CO3/NH4OH como agente precipitante e calcinado a 450 C apresentou as melhores caractersticas fsico-qumicas e catalticas. Catalisadores base de Mg/La e Al/La com diferentes composies qumicas foram sintetizados nas condies de preparo selecionadas. O comportamento cataltico destes materiais foi investigado frente reao de transesterificao do leo de soja com metanol. O catalisador de Al/La com uma relao molar Al/La igual a 9:1 mostrou o melhor desempenho cataltico (rendimento em steres metlicos igual a 84 % a 180 C) e pode ser reutilizado por pelo menos trs ciclos de reao. Tambm foram realizados testes catalticos na presena do leo de soja com 10 % de cido oleico verificando-se que os catalisadores utilizados possuem stios capazes de catalisar as reaes de transesterificao e esterificao
Resumo:
1.6-BA 2.24-D6-BA; 3.ZTKT6-BA0.5mg/l NAA 4.; 5; 6 7.NAA4mgl 6-BA2mgl GAsNAA 8.10-16 9. 10. 11.NH4+410mg/l NH4+1%; 12. ;
Resumo:
17;; 0.2% Onozuka RS + 1% Hemicellulase + 0.1% Pectolyase8-16N6;NO3-NH4+;L-2,4-D1.0 mg/l 174-5;153-4%10% 5%DMSO0.55 M1 /40 340 30-40%8-10%5-6;5-10% 70-80%
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Psammochloa mongokcaKlebsiella oxytoca SA-2 K.oxytoca SA-2NH4+;N03 - 60K.oxytoca SA-2K.oxytoca SA-2K.oxytoca SA-2 K.oxytoca SA-221l06 cfu/gFWrootK.oxytoca SA-2 Oryza sativaK.oxytoca SA-2K.oxytoca SA-2K.oxytoca SA-2K.oxytoca SA-2K.oxytoca SA-2 K.oxytoca SA-2 21K.oxytoca SA-2K.oxytoca SA-2NH4+K.oxytoca SA-2K.oxytoca SA-2 K.oxytoca SA-2 K.oxytoca SA-2K.oxytoca SA-2NH4+
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";; 1Cryptococcus laurentiiimazalil25g/mlkresoxim-methyl50g/mlAlternaria alternataMonilinia fructicola 2Pichia membranefaciensC. laurentii NH4-Mo5 mmol/LNaHCO32%M. fructicolain vitroNH4-MoNaHCO3M. fructicola 3C. laurentiiRhodotorula glutinisNa2SiO3Penicillium expansumM. fructicolaP. expansumA. alternatain vitroNa2SiO3Na2SiO3PALPPOPOD 4R. glutinisSA0.5mmol/LP. expansumA. alternataSAin vitroSASA 5C. laurentiiR. glutinisControlled atmospheres, CAP. expansumA. alternata 6C. laurentii R. glutinisC. laurentiiCA"
Resumo:
(Saussurea medusa Maxim),, 1/2MS:NH4+NO3-30 mmol/L;NH4+/NO3-5:25;2 %3 %;0.5 mg/L GA30.5 mg/L IBA;pH 5.8;18 h/d3500 Lux;24;100 rpm21 d12.8 g/LDW1922 mg/L15 %25 MJSAMJ;SA0.02 mmol/LMJ 849 mg/L633 mg/L34.1 %;0.03 mmol/LSA968 mg/L633 mg/L52.9 %0.02 mmol/LMJ 0.03 mmol/LSA1125 mg/L633 mg/L77.7 % -2.453 %3.391 %
Resumo:
, C4C3 1nifAdctnifA37dct;dct40nifA 2108/ mL5 mmol/L (NH4)2SO430 mmol/L (NH4)2SO4 3150mol photons m-2s-115mol photons m-2s-177; 4PEPCPCRpmi
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lNNNH4+-NNo3--NNNH4+-30CmNO3--NPp KNaCaMgFeAI6K30cm N0~lOcm10~20cm20cmNNH4+-pP0^lOcm1020Cm KNaCaMgFeAI6KCaKCaO1OcmlO-20cm NNH4+-NpP)1800cm2300m120m1500mNH4+-NPNH4+-Np 3030 l100mI500m 2NNNO3-NNS p K;ScaMgAIAI(622)CaMg NPKCaMgSN NNNONNON NNO-Nl3L;NN03-Nl2mgLNN03-N 3691- 0391 - 0291 - 04)6 1161.Ol.4em0.2~O.9cm (D)(H)DH6DHD Y=a-be 45( D<0.5cm)43%k2.713x10370%k6.234xl0-3/. 3.5%6%;-15%7%;583%56%2.5%1%3% Olson5.693xl0-32.461x10-3/2.352xl0-3 OlsoKNaMnCpNMgZnCaCu KeNpNaMnMgCaCaCuZnOlson 56(199l~1997)1994 KMgCaNPAIS KMg
