Estimation using 18O of the water residence time in small watersheds

From the 18O hydrograph separation method, it was found that groundwater contribution is the principal component of the total discharge produced by these two catchment areas. The weighted mean of the 18O concentration in the precipitation, obtained for a four year period, was close to -6.0‰, with a variation in range of +2.3‰ to -16.3‰. For Bufalos stream water the weighted mean of 18O values during the same period (1984-1987) was -6.3‰, with a variation from -2.5‰ to -10.1‰, whereas for Paraiso this mean was -6.4‰, with extreme values of -3.1‰ and -9.8‰. From these values it was found that the amplitude damping (Ariver/Aprecipitation) was 0.41 for the Bufalos watershed and 0.36 for Paraiso. Using the appropriate equation to estimate the mean residence time of water in the subsurface reservoir of the Bufalos and Paraiso watersheds, the results of 4.3 and 5.0 months, respectively, were obtained. -from Authors

Estimation of water transit time in soils under Amazon forest cover using variations in sigma18O values.

In an attempt to estimate the soil-water transit time using the variation in 18O values, a statistical model was used. This model is based on linear regression analysis applied to the values observed for soil water and rain water. The time obtained from these correlations represents the mean time necessary for the water to run from one collecting point to the next.-from Authors

Environment and dispersal paths override life strategies and residence time in determining regional patterns of invasion by alien plants

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dynamics of some limnological characteristics in pacu (Piaractus mesopotamicus) culture tanks as function of handling

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization and evaluation of the impact of feed management on the effluents of Nile tilapia (Oreochromis niloticus) culture

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Itaipu reservoir limnology: eutrophication degree and the horizontal distribution of its limnological variables

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Use of grass carp (ctenopharyngodon idella) as a biological control agent for submerged aquatic macrophytes

This study aimed to evaluate feed preference and control efficacy of grass carp (Ctenopharyngodon idella) on the aquatic macrophytes Ceratophyllum demersum, Egeria densa and Egeria najas. An experiment was carried out at mesocosms conditions with 2,000 liters capacity and water residence time of 2.8 days. C. demersum, E. densa e E. najas biomasses were offered individually with sixty g and coupled in similar quantities of 30 g of each species, evaluated during 81 days, envolving 6 treatments. (1 - C. demersum, 2 - E. najas, 3 - E. densa, 4 - C. demersum + E. najas, 5 - C. demersum + E. densa and 6 - E. najas + E. densa). When offered individually, E. najas and C. demersum presented the same predation rate by grass carp, which was higher than E. densa predation rate. When plants were tested in pairs, the order of feed preference was C. demersum > E. najas > E. densa. E. najas and C. demersum percentage control ranged from 73 to 83%. No relation between biomass consumption and grass carp body weight gain was observed, probably due to differences in nutritional quality among macrophyte species according to fish necessities. Therefore, it is concluded that the use of grass carp is one excellent technique to control submersed macrophytes in Brazil.

Heterogeneidade espacial e temporal da comunidade zooplanctônica do sistema Cantareira, São Paulo, Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Water quality and zooplankton in tanks with larvae of Brycon Orbignyanus (Valenciennes, 1949)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biochemical and physiological responses of sugarcane cultivars to soil water deficiencies

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Surfactant systems for nasal zidovudine delivery: structural, rheological and mucoadhesive properties

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of water storage and heat treatment on the cytotoxicity of soft liners

Objective: To evaluate the effect of water storage time on the cytotoxicity of soft liners.Methods: Sample discs of soft liners Dentusoft, Dentuflex, Trusoft, Ufi-Gel-P and denture base acrylic resin Lucitone-550 were prepared and divided into four groups: GN: No treatment, G24: Stored in water at 37 degrees C for 24 h; G48: Stored in water at 37 degrees C for 48 h, GHW: Immersed in water at 55 degrees C for 10 min. To analyse the cytotoxic effect, three samples of each group were placed in tubes with Dubelcco's Modified Eagle Mediums and incubated at 37 degrees C for 24 h. During this period, the toxic substances were leached to the culture medium. The cytotoxicity was analysed quantitatively by the incorporation of radioactivity H-3-thymidine checking the number of viable cells (synthesis of DNA). The data were statistically analysed using two-way ANOVA and Tukey's honestly significant difference tests (alpha = 0.05).Results: Treatments did not reduce the cytotoxicity effect of the soft liners (p > 0.05). It was found that Ufi-Gel-P had a non-cytotoxic effect, Trusoft had a slightly cytotoxic effect, Dentuflex had a moderated cytotoxic effect, Dentusoft alternated between slightly and non-cytotoxic effect, and Lucitone-550 had non-cytotoxic effect when stored in water for 48 h.Conclusion: The effect of water storage and the heat treatment did not reduce the cytotoxicity of the soft liners.

Permian non-marine bivalves of the Falkland Islands and their palaeoenvironmental significance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Heat budgets, thermal structure and dissolved oxygen in Brazilian reservoirs

A comparison of the thermal regime and oxygen distribution patterns of some Brazilian reservoirs was made. A strong latitudinal dependence of surface temperature, annual mean and annual range was found. Except for Tucurui Reservoir, a reservoir of the Equatorial zone, the lowest surface temperature of the year in the other compared reservoirs was observed from June to August while the highest extended from October to February. The decreasing trend of annual mean temperatures and thermal ranges was due to the increasing seasonal variability of insolation with the latitude. A positive relationship between the increase on thermal surface-bottom differences and the depth of water column was found for reservoirs of similar latitudes. A long thermal stratification (around four months) was evidenced in the lacustrine zone of reservoirs with a residence time higher than 40 days. Low fluctuation (<2%) of the annual variability of heat contents was observed for the Tucurui Reservoir, while in das Garcas Reservoir a manmade lake located in the frontier between tropical and temperate regions, the annual coefficient of variation attained 13%. Concerning the heat budgets, the value for the Tucurui Reservoir was two times higher than in das Garcas Reservoir. Both the morphometric and climatological factors affected the heat contents of the two compared reservoirs. In deep eutrophic reservoirs, a significant reduction on the oxygen concentrations in the hypolimnetic zone was frequently observed. In some oligotrophic stratified reservoirs, a decrease on oxygen with depth occurred when the temperature of the hypolimnion was higher than 20 degrees C and caused a biochemical oxygen demand. In das Garcas Reservoir, the actual oxygen deficits ranged from 0.40 to 1.52 mg.O-2.cm(-2) and appear to be linked to oxygen consumption after the senescence of Microcystis aeruginosa populations in the spring. But, other factors such as the allochthonous loads of organic matter also had an important role on the oxygen balance of das Garcas Reservoir.

Electrocoagulation/flotation followed by fluidized bed anaerobic reactor applied to tannery effluent treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)