Contribution of N Species and P Fractions to Stream Water Quality in Agricultural Catchments

The contribution from agricultural catchments to stream nitrogen and phosphorus concentrations was assessed by evaluation of the chemical composition of these nutrients in agricultural runoff for both surface and subsurface flow pathways. A range of land uses (grazed and ungrazed grassland, cereals, roots) in intensive agricultural systems was studied at scales from hillslope plots (0.5m2) to large catchment (>300km2). By fractionating the total nutrient load it was possible to establish that most of the phosphorus was transported in the unreactive (particulate and organic) fraction via surface runoff. This was true regardless of the scale of measurement. The form of the nitrogen load varied with land use and grazing intensity. High loads of dissolved inorganic nitrogen (with >90% transported as NH4-N) were recorded in surface runoff from heavily grazed land. In subsurface flow from small (2km2) subcatchments and in larger (>300 km2) catchments, organic nitrogen was found to be an important secondary constituent of the total nitrogen load, comprising 40% of the total annual load.

Malonato complexes of oxidovanadium(IV): synthesis, structural characterization and exploration of their insulin mimetic properties

Several bis-malonatooxidovanadium(IV) complexes of the general type [M(2)(H2(O))(n)][VO(mal)(2)(H(2)O)] (where M = Li(1), Na(2), K(3), Cs(4) and NH4(5); n = 3.5, 1, 3, 1 and 1, respectively) were isolated in good yield and high purity. These complexes were fully characterized by various physicochemical techniques (elemental analysis, UV- Vis, IR, EPR, CV, etc.) complexes 1, 2 and 3 were structurally characterized by single crystal X- ray diffraction technique. In vivo antidiabetic properties of bis- malonato complexes 1, 2, 3 and 5 have been studied using Streptozotocin induced diabetic rats. Significant lowering of blood sugar level has been noticed. At the same time these complexes were found to regulate secondary pathophysiological complications like liver damage and lowering of the total antioxidant status (TAS) in diabetic rats. Results of these study are expected to a expand the possibility of designing new oxidovanadium(IV) complexes of O, O chelating ligands with significant antidiabetic properties

Structural complexity in indium selenides prepared using bicyclic amines as structure-directing agents

The synthesis and characterization of five new indium selenides, [C9H17N2]3[In5Se8+x(Se2)1���x] (1���2), [C6H12N2]4[C6H14N2]3[In10Se15(Se2)3] (3), [C6H14N2][(C6H12N2)2NaIn5Se9] (4) and [enH2][NH4][In7Se12] (5), are described. These materials were prepared under solvothermal conditions, using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO) as structure-directing agents. Compounds 1���4 represent the first examples of ribbons in indium selenides, and 4 is the first example of incorporation of an alkali metal complex. Compounds 1, 2 and 4 contain closely related [In5Se8+x(Se2)1���x]3��� ribbons which differ only in their content of (Se2)2��� anions. These ribbons are interspaced by organic countercations in 1 and 2, while in 4 they are linked by highly unusual [Na(DABCO)2]+ units into a three-dimensional framework. Compound 3 contains complex ribbons, with a long repeating sequence of ca. 36 ��, and 4 is a non-centrosymmetric three-dimensional framework, formed as a consequence of the decomposition of DABCO into ethylenediamine (en) and ammonia.

Utilization of organic nitrogen by ectomycorrhizal fungi (Hebeloma spp.) of arctic and temperate origin

Arctic and temperate strains of Hebeloma spp. were grown in axenic culture on glutamic acid, alanine, lysine and NH4+ as sole sources of nitrogen (N), with excess carbon (C) or deficient C (supplied as glucose). Their ability to utilize seed protein as a natural N source was also assessed. All strains tested had the capacity to assimilate amino acids and generally utilized alanine and glutamic acid more readily than NH4+. Some strains were able to utilize amino C when starved of glucose C, and could mineralize amino-N to NH3-N. Arctic strains, in particular, appeared to be pre-adapted to the utilization of seed protein N and glutamic acid N, which is often liberated in high concentrations after soil freezing. The results are discussed in relation to their possible ecological importance.

Comparative growth of ectomycorrhizal fungi (Hebeloma spp.) on organic and inorganic nitrogen

In the largely organic soils in which ectomycorrhizas are commonly found, a preference for absorbing organic nitrogen over mineral forms is likely to be an advantage, especially where mineralisation rates are low. To determine rates of both independent and preferential growth of ectomycorrhizal basidiomycetes on organic and inorganic nitrogen, strains of Hebeloma were grown on nutrient agar media containing either NH4+ or glutamic acid as the sole source of nitrogen, on both single medium and split plate Petri dishes. Growth rates on the split plate Petri dishes, where the fungi had access to both nitrogen sources, were generally greater than on the single medium dishes. Growth on glutamic acid was at least equal to, and usually greater than, that on NH4+. In some cases growth on NH4+ alone appeared severely inhibited, a condition that was partially alleviated by access to glutamic acid on the split plates Petri dishes. This highlights a potential pitfall of single nitrogen source growth studies. The greater growth of most strains on glutamic acid suggests an adaptation to organic nitrogen utilisation in these strains. If this is so in soils with low mineralisation rates, direct uptake of amino acids by ectomycorrhizal plants could by-pass the bottle neck that requires mineral nitrogen to be made available for plant uptake.

Season changes in water quality and Sargassum biomass in Southwest Australia

Sargassum C. Agardh is one of the most diverse genera of marine macro-algae and commonly inhabits shallow tropical and sub-tropical waters. This study aimed to investigate the effect of seasonality and the associated water quality changes on the distribution, canopy cover, mean thallus length and the biomass of Sargassum beds around Point Peron, Shoalwater Islands Marine Park, Southwest Australia. Samples of Sargassum and seawater were collected every three months from summer 2012 to summer 2014 from four different reef zones. A combination of in situ observations and WorldView-2 satellite remote-sensing images were used to map the spatial distribution of Sargassum beds and other associated benthic habitats. The results demonstrated a strong seasonal variation in the environmental parameters, canopy cover, mean thallus length, and biomass of Sargassum, which were significantly (P < 0.05) influenced by the nutrient concentration (PO43-, NO3-, NH4+) and rainfall. However, no variation in any studied parameter was observed among the four reef zones. The highest Sargassum biomass peaks occurred between late spring and early summer (from September to January). The results provide essential information to guide effective conservation and management, as well as sustainable utilisation of this coastal marine renewable resource.

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.

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.

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