Aerosol inorganic composition at a tropical site: Discrepancies between filter-based sampling and a semi-continuous method

The concentrations of the water-soluble inorganic aerosol species, ammonium (NH4+), nitrate (NO3-), chloride (Cl-), and sulfate (SO42-), were measured from September to November 2002 at a pasture site in the Amazon Basin (Rondnia, Brazil) (LBA-SMOCC). Measurements were conducted using a semi-continuous technique (Wet-annular denuder/Steam-Jet Aerosol Collector: WAD/SJAC) and three integrating filter-based methods, namely (1) a denuder-filter pack (DFP: Teflon and impregnated Whatman filters), (2) a stacked-filter unit (SFU: polycarbonate filters), and (3) a High Volume dichotomous sampler (HiVol: quartz fiber filters). Measurements covered the late dry season (biomass burning), a transition period, and the onset of the wet season (clean conditions). Analyses of the particles collected on filters were performed using ion chromatography (IC) and Particle-Induced X-ray Emission spectrometry (PIXE). Season-dependent discrepancies were observed between the WAD/SJAC system and the filter-based samplers. During the dry season, when PM2.5 (D-p <= 2.5 mu m) concentrations were similar to 100 mu g m(-3), aerosol NH4+ and SO42- measured by the filter-based samplers were on average two times higher than those determined by the WAD/SJAC. Concentrations of aerosol NO3- and Cl- measured with the HiVol during daytime, and with the DFP during day- and nighttime also exceeded those of the WAD/SJAC by a factor of two. In contrast, aerosol NO3- and Cl- measured with the SFU during the dry season were nearly two times lower than those measured by the WAD/SJAC. These differences declined markedly during the transition period and towards the cleaner conditions during the onset of the wet season (PM2.5 similar to 5 mu g m(-3)); when filter-based samplers measured on average 40-90% less than the WAD/SJAC. The differences were not due to consistent systematic biases of the analytical techniques, but were apparently a result of prevailing environmental conditions and different sampling procedures. For the transition period and wet season, the significance of our results is reduced by a low number of data points. We argue that the observed differences are mainly attributable to (a) positive and negative filter sampling artifacts, (b) presence of organic compounds and organosulfates on filter substrates, and (c) a SJAC sampling efficiency of less than 100%.

Compressible Sherrington-Kirkpatrick spin-glass model

We introduce a Sherrington-Kirkpatrick spin-glass model with the addition of elastic degrees of freedom. The problem is formulated in terms of an effective four-spin Hamiltonian in the pressure ensemble, which can be treated by the replica method. In the replica-symmetric approximation, we analyze the pressure-temperature phase diagram, and obtain expressions for the critical boundaries between the disordered and the ordered (spin-glass and ferromagnetic) phases. The second-order para-ferromagnetic border ends at a tricritical point, beyond which the transition becomes discontinuous. We use these results to make contact with the temperature-concentration phase diagrams of mixtures of hydrogen-bonded crystals.

Aminoacetone, a putative endogenous source of methylglyoxal, causes oxidative stress and death to insulin-producing RINm5f cells

Aminoacetone (AA), triose phosphates, and acetone are putative endogenous sources of potentially cytotoxic and genotoxic methylglyoxal (MG), which has been reported to be augmented in the plasma of diabetic patients. In these patients, accumulation of MG derived from aminoacetone, a threonine and glycine catabolite, is inferred from the observed concomitant endothelial overexpression of circulating semicarbazide-sensitive amine oxidases. These copper-dependent enzymes catalyze the oxidation of primary amines, such as AA and methylamine, by molecular oxygen, to the corresponding aldehydes, NH4+ ion and H2O2. We recently reported that AA aerobic oxidation to MG also takes place immediately upon addition of catalytic amounts of copper and iron ions. Taking into account that (i) MG and H2O2 are reportedly cytotoxic to insulin-producing cell lineages such as RINm5f and that (ii) the metal-catalyzed oxidation of AA is propagated by O-2(center dot-) radical anion, we decided to investigate the possible pro-oxidant action of AA on these cells taken here as a reliable model system for pancreatic beta-cells. Indeed, we show that AA (0.10-5.0 mM) administration to RINm5f cultures induces cell death. Ferrous (50-300 mu M) and Fe3+ ion (100 mu M) addition to the cell cultures had no effect, whereas Cu2+ (5.0-100 mu M) significantly increased cell death. Supplementation of the AA- and Cu2+-containing culture medium with antioxidants, such as catalase (5.0 mu M), superoxide dismutase (SOD, 50 U/mL), and N-acetylcysteine (NAC, 5.0 mM) led to partial protection. mRNA expression of MnSOD, CuZnSOD, glutathione peroxidase, and glutathione reductase, but not of catalase, is higher in cells treated with AA (0.50-1.0 mM) plus Cu2+ ions (10-50 mu M) relative to control cultures. This may imply higher activity of antioxidant enzymes C, in RINm5f AA-treated cells. In addition, we have found that AA (0.50-1.0 mM) Plus Cu2+ (100 mu M) (i) increase RINm5f cytosolic calcium; (ii) promote DNA fragmentation; and (iii) increase the pro-apoptotic (Bax)/antiapoptotic (Bcl-2) ratio at the level of mRNA expression. In conclusion, although both normal and pathological concentrations of AA are probably much lower than those used here, it is tempting to propose that excess AA in diabetic patients may drive oxidative damage and eventually the death of pancreatic beta-cells.

On the energy transfer from a polymer host to the rhenium(I) complex in OLEDs

Photoluminescence and electroluminescence of PVK films doped with fac-[ClRe(CO)(3)(bpy)], bpy=2,2`-bipyridine, are investigated. Photoluminescence spectra of spin-coated PVK films (lambda(exc)=290 nm) exhibit a broad band centered at 405 nm. As the concentration of dopant increases, the polymer emission is quenched and a band at 555 nm appears (isosbestic point at 475 nm). In OLEDs with ITO/PEDOT:PSS/PVK/butylPBD/Al architecture doped with fac-[ClRe(CO)(3)(bpy)], the polymer host emission is completely quenched even at the lowest concentration of dopant. The electroluminescence spectra of the devices show that there is an efficient energy transfer from the host to the dopant, which exhibits a very intense emission at 580 nm. (C) 2009 Elsevier B.V. All rights reserved.

Copper hexacyanoferrate nanoparticles modified electrodes: A versatile tool for biosensors

Copper hexacyanoferrate nanoparticles of about 30 nm in size have been prepared by the sonochemical irradiation of a mixture of aqueous potassium ferricyanide and copper chloride solutions. The nanoparticles were immobilized onto fluorine doped tin oxide (FTO) electrodes by using the electrostatic deposition layer-by-layer technique (LbL), obtaining electroactive films with electrocatalytic properties towards H2O2 reduction, providing higher currents than those observed for electrodeposited bulk material, even in electrolytes containing NH4+, Na+ and K+. The nanoparticles assembly was used as mediator in a glucose biosensor by immobilizing glucose oxidase enzyme by both, cross-linking and LbL. techniques. Sensitivities obtained were dependent on the immobilization method ranging from 1.23 mu A mmol(-1) L cm(-2) for crosslinking to 0.47 mu A mmol(-1) L cm(-2) for LbL; these values being of the same order than those obtained with electrodes where the amount of enzyme used is much higher. Moreover, the linear concentration range where the biosensors can operate was 10 times higher for electrodes prepared with the LbL immobilization method than with the conventional crosslinking one. (C) 2008 Elsevier B.V. All rights reserved.

Sensing hazardous metal ions using a fluoroionophore calix[4]arene species containing two 8-oxyquinoline groups

The interaction of a calix[4]arene-based species containing two 8-oxyquinoline chromophore pendants with hazardous metal ions has been investigated using optical absorption and fluorimetric techniques. In the presence of Hg(2+), Cd(2+), and Pb(2+) ions, there is only a small decrease of the calixarene absorption band at 283 nm. The main changes are associated with the absorption band of the 8-oxyquinoline group at 315 nm, undergoing a systematic bathochromic shift to above 350 nm. In addition, a systematic decrease of the oxyquinoline emission at lambda(em) = 392 nm (lambda(exc) = 315 nm) has been observed. These observations are consistent with the coordination of the metal ions to the quinoline groups attached to the calixarene ligand, providing a useful fluoroinophore species for analytical purposes.

Adsor����o em flocos de materiais adsorventes pulverizados e uso em reator de leito expandido/fluidizado

O presente trabalho descreve estudos relativos �� valida����o e aperfei��oamento de uma nova t��cnica de adsor����o em flocos de materiais adsorventes pulverizados e seu uso em reator de leito expandido/fluidizado. A t��cnica consiste na utiliza����o de pol��meros aquo-sol��veis para a flocula����o de suspens��es aquosas de materiais adsorventes pulverizados, baseando-se no baixo custo dos mesmos e no fato de que a capacidade de adsor����o dos flocos resultantes n��o �� afetada significativamente pelo pol��mero floculante. O uso da t��cnica em reator de leito expandido/fluidizado possibilita ainda a vantagem de uni��o dos processos de adsor����o e separa����o s��lido-l��quido em uma ��nica etapa. Os estudos foram realizados a partir da flocula����o de carv��o ativado e ze��lita natural pulverizados, separados e em mistura, para a adsor����o de fenol e nitrog��nio amoniacal (separados e misturados). Foi realizada uma adequada caracteriza����o dos materiais particulados, incluindo a determina����o de distribui����o granulom��trica, ��rea superficial espec��fica, potencial zeta, dentre outros. Estudos em escala de bancada foram realizados com ambos os poluentes e materiais adsorventes a fim de obter par��metros de processo (capacidade de adsor����o, cin��tica e concentra����o de floculante). Estudos em escala semipiloto com um reator de leito expandido/fluidizado de geometria cil��ndrico-c��nica foram realizados para estudar a adsor����o dos poluentes em leito de flocos dos materiais adsorventes (separados e misturados), assim como a regenera����o/reciclo do mesmo. A caracteriza����o dos materiais apresentou propriedades semelhantes para ambos (distribui����o granulom��trica, potencial zeta) e outras distintas para cada um deles (massa espec��fica, ��rea superficial espec��fica) A capacidade de troca cati��nica da ze��lita natural foi determinada em 1,02 meq NH4 +.g-1 (ap��s homoioniza����o com NaCl). Este material, proveniente do Chile, mostrou um significativo potencial de aplica����o como adsorvente de corantes (como o azul de metileno) e, principalmente, de nitrog��nio amoniacal. O floculante utilizado na gera����o dos flocos adsorventes, separados e misturados, foi do tipo poliacrilamida cati��nica e sua concentra����o ��tima foi de 4 e 5 mg.g-1, respectivamente. Os resultados obtidos nos estudos em escala de bancada (batelada) mostraram elevada cin��tica (valor m��dio de 0,3 min-1) e alta capacidade (valor m��dio de 13,4 mg NH3-N.g-1) em pH neutro (aproximadamente 6) para a adsor����o de nitrog��nio amoniacal em ze��lita natural pulverizada e floculada. No caso da adsor����o de fenol em carv��o ativado pulverizado e floculado, foram obtidas uma alta cin��tica (valor m��dio de 0,8 min-1) e elevada capacidade (156 mg.g-1). Os dados cin��ticos e de equil��brio foram adequadamente descritos por um modelo cin��tico para rea����es revers��veis de primeira ordem e pelas isotermas de Langmuir e Freundlich, respectivamente. Tanto a cin��tica quanto a capacidade de adsor����o n��o mostraram-se afetadas de forma significativa pelo uso do pol��mero floculante, sendo observada uma aus��ncia de sinergismo na adsor����o dos poluentes devido �� mistura dos dois materiais adsorventes, tanto pulverizados quanto floculados. Os resultados obtidos nos estudos em escala semipiloto validaram a utiliza����o de flocos de ze��lita natural e carv��o ativado pulverizados (n��o- misturados) em reator de leito expandido/fluidizado na adsor����o de nitrog��nio amoniacal (11 mg NH3-N.g-1) e fenol (132 mg.g-1), respectivamente, dentro das condi����es experimentais estabelecidas (taxas de aplica����o de 38 e 19 m.h-1, respectivamente) A regenera����o/reciclo do leito saturado de flocos mostrou-se vi��vel para o caso da adsor����o de nitrog��nio amoniacal em ze��lita natural, sendo insatisfat��ria para o leito de carv��o ativado saturado em fenol. O uso de leitos mistos mostrou-se eficaz e com vantagens tais como a adsor����o de m��ltiplos poluentes em uma ��nica etapa e a possibilidade de aumento da taxa de aplica����o no uso de materiais adsorventes menos densos (carv��o ativado) misturados com materiais adsorventes de maior massa espec��fica (ze��lita natural). Uma pr��-avalia����o dos custos operacionais envolvidos na t��cnica para uso em reator de leito expandido/fluidizado foi realizada, sendo estimados entre 0,32 e 1,48 US$.m-3 (volume de solu����o sint��tica de poluente tratada at�� o ponto de exaust��o do leito). Finalmente, s��o discutidas as potencialidades, vantagens/desvantagens e a viabilidade da nova t��cnica como processo f��sico-qu��mico alternativo de adsor����o em materiais adsorventes pulverizados.

Caracteriza����o das rela����es entre Araucaria angustifolia e nitrog��nio inorg��nico

A despeito da import��ncia ecol��gica e econ��mica da Araucaria angustifolia (Bertol.) Kuntze e da import��ncia do nitrog��nio (N) para o crescimento vegetal, existem poucos estudos que caracterizam as rela����es desse nutriente com ela. Os presentes estudos visaram caracterizar a prefer��ncia de plantas da esp��cie a diferentes formas de N inorg��nico e descrever a estrutura da varia����o espacial de N inorg��nico em tr��s s��tios de ocorr��ncia de Araucaria angustifolia no Brasil subtropical. No primeiro estudo, a abordagem experimental incluiu o uso de solu����es nutritivas. No segundo, as ferramentas geoestat��sticas, semivariogramas e krigeagem, foram utilizadas para a descri����o da varia����o espacial de NH4 +, NO3 - e NH4 + + NO3 -, em dois per��odos do ano, ver��o e inverno. Os s��tios escolhidos foram uma ��rea de mata nativa, uma de campo nativo e uma planta����o de Pinus elliottii. Os resultados de crescimento do primeiro estudo demonstraram que a esp��cie prefere am��nio como fonte de N. Nitrato, quando fornecido sozinho, induziu sintomas de defici��ncia de N, quando comparado a outras fontes de N: maiores raz��o raiz:parte a��rea, ramifica����o radicular e massa foliar por ��rea, engrossamento dos ��pices caulinares e ainda, menores conte��dos de clorofilas e N por unidade de massa em folhas jovens. A nutri����o �� base de nitrato tamb��m afetou a distribui����o de N no corpo da planta, com as folhas jovens acumulando menos N e maior raz��o C:N do que as folhas maduras (um padr��o n��o observado nos outros tratamentos). Aparentemente, o nitrato �� um importante fator a regular a parti����o de C e N entre diferentes partes da planta. A atividade nitrato redutase (ANR) seguiu um padr��o de parti����o raiz:parte a��rea esperado para con��feras de clima temperado. Entretanto, a ANR mesmo sob nutri����o de NH4 + sozinho, indica que a planta pode apresentar n��veis constitutivos de atividade da enzima, ou que quantidades baixas de NO3 - (formado pela poss��vel contamina����o dos meios de cultivo) podem induzir a ANR foliar. Em reflorestamentos, deve ser assegurado que o am��nio seja a forma de N predominante ou que esteja presente em quantidades suficientes para um adequado desenvolvimento das plantas. Ambientes que n��o satisfa��am estas necessidades podem limitar o desenvolvimento da esp��cie. Os resultados do segundo estudo mostraram que o NH4 +n��o foi a forma de N predominante na mata nativa, em ambos os per��odos do ano. Nesse s��tio o NO3 - ocorreu em propor����o similar �� do NH4 + nos demais s��tios (campo e planta����o de Pinus) A heterogeneidade na disponibilidade de N �� maior na mata nativa do que nos outros s��tios no ver��o. Desta forma, �� necess��ria uma maior plasticidade na habilidade de explora����o radicular do N do solo por parte das plantas que se estabelecem neste s��tio do que nos demais, durante esta esta����o. A planta����o de Pinus e o campo, al��m de terem mais am��nio que a mata nativa, s��o mais homog��neos na distribui����o deste, e podem, ent��o, constituir locais mais favor��veis, em termos de disponibilidade de N, para o estabelecimento do pinheiro brasileiro. O inverno imp��e um cen��rio bastante diferente. O aumento significativo da disponibilidade de N inorg��nico e a perda da estrutura espacial (�� exce����o da ��rea de campo) tornam os s��tios, teoricamente, menos hostis ao desenvolvimento vegetal.

Avalia����o do processo de compostagem de res��duos s��lidos urbanos

A crescente produ����o de res��duos s��lidos urbanos e a escassez de ��reas para uma destina����o final tecnicamente adequada, via implanta����o de aterros sanit��rios, faz com que tome import��ncia a t��cnica de tratamento de res��duos s��lidos org��nicos atrav��s das compostagem/vermicompostagem. Nesta pesquisa, foi realizada a avalia����o destes processos, tendo sido observadas principalmente a influ��ncia da aera����o e da umidade no desempenho destas t��cnicas de tratamento, em leiras de pequenos e grandes volumes. Nos experimentos, com leiras de pequenos volumes, realizados no IPH (Instituto de Pesquisas Hidr��ulicas) da UFRGS, utilizou-se res��duos s��lidos de poda (res��duos verdes, com alta concentra����o de carbono) codispostos (misturados em peso) com res��duos vegetais da CEASA (Companhia Estadual de Abastecimento Sociedade An��nima) e lodos provenientes de esta����es de tratamento de esgotos sanit��rios. Nos experimentos, com leiras de grandes volumes, realizados na UTC ��� Unidade de Triagem e Compostagem de Porto Alegre, utilizou-se res��duos org��nicos domiciliares codispostos com os mesmos res��duos utilizados nos primeiros experimentos. Paralelamente aos experimentos de compostagem, avaliou-se os lixiviados produzidos nos sistemas. Na compostagem de grandes volumes, tamb��m foi observado o desempenho de banhados constru��dos de fluxo subsuperficial para o tratamento desses efluentes l��quidos. com teores de res��duos verdes menores que 35 %, o que se justifica pela maior concentra����o de res��duos de caracter��stica facilmente biodegrad��vel e de maior palatabilidade para os vermes. Em todos os experimentos de compostagem, verificou-se que o controle efetivo do processo pode ser realizado atrav��s da avalia����o sistem��tica das temperatura e umidade das leiras. Evidenciou-se tamb��m que para regi��es de clima similar ao de Porto Alegre, com elevadas precipita����es principalmente no inverno, �� necess��rio adotar dimens��es adequadas ao sistema de compostagem ���windrow��� para ��reas descobertas. Comprovou-se tamb��m a necessidade de manuten����o da umidade na faixa entre 50% e 70 %, inclusive com reposi����o desta, mesmo na situa����o de inverno. A avalia����o dos lixiviados da compostagem demonstrou que, com os substratos utilizados nos experimentos, as concentra����es de DBO5, DQO e de outras vari��veis s��o elevadas ao in��cio do processo de decomposi����o, devido �� solubiliza����o dos compostos org��nicos e inorg��nicos presentes na mat��ria org��nica. Os lixiviados da compostagem possuem baixas concentra����es de condutividade, DBO5, NH4 +, entre outros, quando comparados aos lixiviados de aterros sanit��rios. tratamento destes efluentes. Os resultados obtidos nos banhados constru��dos para baixas cargas hidr��ulicas (1cm/d) e concentra����es de DBO5 do afluente abaixo de 150 mg/L apontaram uma efici��ncia m��dia de remo����o de 52,02%. No que se refere a nitrog��nio (todas as formas), f��sforo, metais, potencial redox e s��lidos totais, as efici��ncias foram vari��veis, com melhores resultados para nitrog��nio amoniacal e f��sforo. A compostagem pode ser considerada uma alternativa vi��vel de tratamento de res��duos org��nicos, utilizando-se o processo ���windrow��� com revolvimento mec��nico, mesmo em p��tios descobertos em climas subtropicais. Neste caso, sugere-se que os lixiviados gerados nos primeiros dias de compostagem (30 dias aproximandamente) sejam recirculados e o excedente tratado em ETE. Pode-se, tamb��m, utilizar o sistema de banhados constru��dos como complementa����o, principalmente para a remo����o de nitrog��nio e f��sforo.

Estudo comparativo de dois tipos de cultivo: monocultivo (camar��es) versus cultivo integrado (algas/camar��es)

The integrated culture of seaweed and aquatic animals is an ancient practice in Asian countries. The expansion of this practice to western countries is consequence of the recognition of this system as a sustainable alternative that allows economical diversification and mitigation of environmental impacts generated by effluents of aquaculture. This study evaluated the growth of the seaweed Gracilaria caudata and of the shrimp Litopenaeus vannamei in monoculture (shrimps) and integrated culture (shrimps and algae) systems, and accessed the effect of the seaweed in the water quality. There were two treatments in the experiment: monoculture (shrimps) and integrated culture (shrimps/ algae). The organisms were cultured in 6 aquaria (10L) filled with seawater (35.0��0.0 PSU and 28.1��0.4��C) for 28 days. The nutrients of water (PO43-, NH4+, NO2-, NO3- and DIN), the biomass and the relative growth rate (RGR, % day-1) of seaweed and shrimps were measured weekly. The parameters pH, temperature, salinity and dissolved oxygen were measured daily. The concentration of NH4+ in integrated culture (62.8��25.2��M) was lower (Mann-Whitney p<0.001) than in monoculture (85.6��24.3��M). The mean of PO4- in monoculture (10.4��4.6��M) was markedly higher (Mann-Whitney; p=0.024) than that in integrated culture (8.7��4.1��M). The level of dissolved oxygen in integrated culture (6.0��0.6mg/L) was higher (t-Student; P=0.014) than that in shrimp monoculture (5.8��0.6mg/L). The mean values of the parameters pH, NO2-, NO3- and DIN were 7.5��0.2, 10.1��12.2��M, 24.5��3.2��M and 120.17��30.76��M in monoculture, and 7.5��0.2, 10.5��13.2��M, 27.4��3.5��M and 100.76��49.59��M in integrated culture. There were not differences in these parameters between treatments. The biomass and RGR of seaweed reached 15.0��1.9g and 7.4��2.8% day-1 at the end of the experiment. The performance of shrimp was favorable in monoculture (1.5��0.8g; 5.7��1.6% dia-1) and in integrated culture (1.5��0.7g; 5.2��1.2% dia-1), and the rate of survival was 100% in both treatments. The tolerance and favorable performance of Gracilaria caudata suggest that this seaweed might be integrated into shrimp (Litopenaeus vannamei) culture systems

Efeito dos nutrientes (nitrog��nio e f��sforo) sobre o desenvolvimento da Gracilaria birdiae: crescimento e poss��vel uso como biofiltro

Marine shrimp farming has grown exponentially during the last years in Brazil. In spite of the promising economical situation, this activity is facing an increasing criticism due to its environmental impact. Thus, the necessity of alternatives to mitigate environmental degradation caused by this activity. An alternative that is being studied is the policulture that is the integrated culture of two or more organisms, normally one of them a filtering organism. Among filtering organisms, macroalgae are very practicable because they are efficient in the removal of the exceeding nutrients of the water and do not leave residues in the water. Besides, the integrated culture with macroalgae allows the economical exploration of the seaweed (for the manufacture of jelly and jam, for the dairy industry, pharmaceuticals, etc.) along with possibility of a sustainable aquaculture. In the present experiment, the development of the seaweed Gracilaria birdiae, the influence and tolerance of this species to the environmental parameters, and its absorption efficiency in relation with the three kinds of macronutrients (NH4+, NO3- and PO4-3) found in the effluents of marine shrimp farming was studied. The experiment was divided in two parts: a laboratorial part and one part carried under natural conditions. The water used in the laboratory trial was collected in the shrimp ponds of Tecnar��o farm and distributed in aquaria containing 20 g of G. birdiae. In the field trial, 0.5 kg of G. birdiae was inserted in PVC cages cultivated in the farm. The results of the study showed a modest growth of G. birdiae, probably due to its low tolerance to highly eutrophicated environments. However, the removal of nutrients was very expressive. Ammonia was reduced in approximately 34 %. Ortho-phosphate showed a reduction of 93.5 %. The capacity of biofiltration of the NO3- by the macro algae was of 100 %, showing that G. birdiae is a seaweed-filtered with a high level of removal for this nutrient under laboratorial conditions. In spite of the low growth of the macro algae in the experiment, the results in relation to the removal of nutrients of the water was encouraging, suggesting that this species can be an efficient biofilter and thus, a strong candidate to be used in a sustainable aquaculture

Estudo do crescimento, efici��ncia de biofiltra����o e cin��tica de absor����o de nutrientes (N-NH, N-NO e P-PO4��) da macroalga Gracilaria cervicornis (Turner) J. Agardh

The objective of this study was to examine the growth of Gracilaria cervicornis cultured in a shrimp (Litopenaeus vannamei) pond and to determine the absorption efficiency and the kinetics parameters (Vmax, Ks e Vmax:Ks) of this macroalgae for the nutrients N-NO3-, N-NH4+ and P-PO4-3, aiming at its use as bioremediatory of eutrophicated environments. For this study, two experiments (field and laboratory) were developed. In the field study, the seaweed was examined in relation to the growth and the biomass. In the laboratory experiment, the absorption efficiency of G. cervicornis was measured through the monitoring of the concentration of the three nutrients (N-NO3-, N-NH4+ e P-PO4-3) during 5 hours and the kinetic parameters were determined through the formula of Michaelis-Menten. The results obtained in this study demonstrated that G. cervicornis benefited from the available nutrients in the pond, increasing 52.4% of its biomass value after 30 days of culture. It was evidenced that the variability of the biomass could be explained through the salinity, availability of light (transparency and solid particle in suspension) and concentration of N-NO3- in the environment. In the laboratory experiment, the highest absorption efficiency was found in the treatments with low concentration (5 ��mol.L-1), being evidenced a reduction of up to 85,3%, 97,5% and 81,2% of N-NH4+, N-NO3- and P-PO43-, respectively. Regarding the kinetic parameters, G. cervicornis presented better ability in absorbing N-NH4+ in high concentrations (Vmax = 158,5 ��mol g-1 dry wt h-1) and P-PO43- in low concentrations (Ks = 5 ��mol.L-1 e Vmax:Ks = 10,3). The results of this study show that G. cervicornis could be cultivated in shrimp ponds, presents a good capacity of absorption for the tested nutrients and is a promising candidate for biorremediation in shrimp pond effluent

Kinetic Analysis of Gill (Na+,K+)-ATPase Activity in Selected Ontogenetic Stages of the Amazon River Shrimp, (Decapoda, Palaemonidae): Interactions at ATP- and Cation-Binding Sites

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Solubilization of CaHPO4 and AlPO4 by Aspergillus niger in culture media with different carbon and nitrogen sources

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Crescimento e esporula����o de isolados de Verticillium lecanii sob diferentes condi����es nutricionais

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)