Evaluation of sample processing methods for the polar contaminant analysis of sewage sludge using liquid chromatography - mass spectrometry (LC/MS)

Monitoring of sewage sludge has proved the presence of many polar anthropogenic pollutants since LC/MS techniques came into routine use. While advanced techniques may improve characterizations, flawed sample processing procedures, however, may disturb or disguise the presence and fate of many target compounds present in this type of complex matrix before analytical process starts. Freeze-drying or oven-drying, in combination with centrifugation or filtration as sample processing techniques were performed followed by visual pattern recognition of target compounds for assessment of pretreatment processes. The results shown that oven-drying affected the sludge characterization, while freeze-drying led to less analytical misinterpretations.

Root exudation of imazapyr by eucalypt, cultivated in soil

Imazapyr has been used to control stump sprouting in stand of Eucalyptus plantations, where herbicide is applied to the tree trunk before cutting. The herbicide is applied exclusively on the stump to be killed, but little is known about the final fate of the molecule. Imazapyr exudation via roots of eucalypt grown in soil as the substrate was evaluated under greenhouse conditions. Different herbicide doses (0.000, 0.375, 0.750, 1.125, 1.500, and 3.000 kg ha-1 a.i.) were applied on the aerial parts of 8-month-old Eucalyptus grandis clonal seedlings, cultivated in pots with 18.0 dm³ of soil. Forty days after this treatment, the eucalypt plants were cut and a lateral opening in the containers was made and the plants inclined 90º, with plants sensitive to herbicide presence (sorghum and cucumber) sown into the openings along the exposed soil surface. After 15-day sowing, toxicity symptoms on the shoots as well as the shoot and root system dry biomass of the bio-indicators were evaluated. The results suggest that eucalypt roots do exude imazapyr, and/or its metabolites, at concentrations high enough to cause toxicity to the bio-indicators. Toxicity effects were observed in all plants sown along the exposed soil profile of the container, with higher intensity at higher doses.

Targeting and translocation of endothelial nitric oxide synthase

This review explores advances in our understanding of the intracellular regulation of the endothelial isoform of nitric oxide synthase (eNOS) in the context of its dynamically regulated subcellular targeting. Nitric oxide (NO) is a labile molecule, and may play important biological roles both within the cell in which it is synthesized and in its interactions with nearby cells and molecules. The localization of eNOS within the cell importantly influences the biological role and chemical fate of the NO produced by the enzyme. eNOS, a Ca2+/calmodulin-dependent enzyme, is subject to a complex pattern of intracellular regulation, including co- and post-translational modifications and interactions with other proteins and ligands. In endothelial cells and cardiac myocytes eNOS is localized in specialized plasmalemmal signal-transducing domains termed caveolae; acylation of the enzyme by the fatty acids myristate and palmitate is required for targeting of the protein to caveolae. Targeting to caveolae facilitates eNOS activation following receptor stimulation. In resting cells, eNOS is tonically inhibited by its interactions with caveolin, the scaffolding protein in caveolae. However, following agonist activation, eNOS dissociates from caveolin, and nearly all the eNOS translocates to structures within the cell cytosol; following more protracted incubations with agonists, most of the cytosolic enzyme subsequently translocates back to the cell membrane. The agonist-induced internalization of eNOS is completely abrogated by chelation of intracellular Ca2+. These rapid receptor-mediated effects are seen not only for "classic" eNOS agonists such as bradykinin, but also for estradiol, indicating a novel non-genomic role for estrogen in eNOS activation. eNOS targeting to the membrane is labile, and is subject to receptor-regulated Ca2+-dependent reversible translocation, providing another point for regulation of NO-dependent signaling in the vascular endothelium.

Tracer studies in the coffee plant (Coffea arabica L.)

Due to the great importance of coffee to the Brazilian economy, a good deal of the work carried out in the "Laboratório de Isótopos", E. E. A. "Luiz de Queiroz", Piracicaba, S. Paulo, Brazil, was dedicated to the study of some problems involving that plant. The first one was designed to verify a few aspects of the control of zinc deficiency which is common in many types of soils in Brazil. An experiment conducted in nutrient solution showed that the leaf absorption of the radiozinc was eight times as high as the root uptake; the lower surface of the leaves is particularly suited for this kind of absorption. Among the heavy metal micronutrients, only iron did not affect the absorption of the radiozinc; manganese, copper, and molybdenum brought about a decrease of fifty per cent in total uptake. In another pot experiment in which two soils typical of the coffee growing regions were used, namely, a sandy soil called "arenito de Bauru" and a heavy one, "terra roxa", only O.l and 0.2 per cent of the activity supplied to the roots was recovered", respectively. This indicates that under field conditions the farmer should not attempt to correct zinc deficiency by applying zinc salts to the soil: leaf sprays should be used wherever necessary. In order to find out the most suitable way to supply phosphatic fertilizers to the coffee plant, under normal farm conditions, an experiment with tagged superphosphate was carried out with the following methods of distribution of this material: (1) topdressed in a circular area around the trees; (2) placed in the bottom of a 15 cm deep furrow made around the plant; (3) placed in a semicircular furrow, as in the previous treatment; (4) sprayed directly to the leaves. It was verified that in the first case, circa 10 per cent of the phosphorus in the leaves came from the superphosphate; for the other treatments, the results ware, respectively: 2.4, 1.7, and 38.0 per cent. It is interesting to mention that the first and the last methods of distribution were those less used by the farmers; now they are being introduced in many coffee plantations. In a previous trial it was demonstrated that urea sprays were an adequate way to correct nitrogen deficiency under field conditions. An experiment was then set up in which urea-C14 was used to study the metabolism of this fertilizer in coffee leaves. In was verified that in a 9 hours period circa 95 per cent of the urea supplied to the leaves had been absorbed. The distribution of the nitrogen of the urea was followed by standard chemical procedures. On the other hand the fate of the carbonic moiety was studied with the aid of the radiochromatographic technique. Thus, the incorporation of C14 in aminoacids, sugars and organic acids was ascertained. Data obtained in this work gave a definite support to the idea that in coffee leaves, as in a few other higher plants, a mechanism similar to the urea cycle of animals does exist.

Bacillus sphaericus mosquito pathogens in the aquatic environment

The fate of Bacillus sphaericus spores in the aquatic environment was investigated by suspending spores in dialysis bags in fresh and seawater. Spore viability was lost more rapidly in seawater. Neither B. sphaericus nor B. thuringiensis israelensis (B.t.i.) spores mixed with pond sediment appeared to attach to the sediment. However, rapid decrease in B.t.i. toxicity suggested attachment of parasporal bodies to sediment. B. sphaericus toxin settled more slowly and less completely. B. sphaericus spores fed to larvae of four aquatic invertebrates were mostly eliminated from the animal gut in less than one week. An exception was the cranefly (Tipula abdominalis) where spores persisted in the posterior gut for up to five weeks.

Viral diseases and human evolution

The interaction of man with viral agents was possibly a key factor shaping human evolution, culture and civilization from its outset. Evidence of the effect of disease, since the early stages of human speciation, through pre-historical times to the present suggest that the types of viruses associated with man changed in time. As human populations progressed technologically, they grew in numbers and density. As a consequence different viruses found suitable conditions to thrive and establish long-lasting associations with man. Although not all viral agents cause disease and some may in fact be considered beneficial, the present situation of overpopulation, poverty and ecological inbalance may have devastating effets on human progress. Recently emerged diseases causing massive pandemics (eg., HIV-1 and HCV, dengue, etc.) are becoming formidable challenges, which may have a direct impact on the fate of our species.

Fertilizer 15N balance in a coffee cropping system: a case study in Brazil

Knowledge about the fate of fertilizer nitrogen in agricultural systems is essential for the improvement of management practices in order to maximize nitrogen (N) recovery by the crop and reduce N losses from the system to a minimum. This study involves fertilizer management practices using the 15N isotope label applied in a single rate to determine the fertilizer-N balance in a particular soil-coffee-atmosphere system and to deepen the understanding of N plant dynamics. Five replicates consisting of plots of about 120 plants each were randomly defined within a 0.2 ha coffee plantation planted in 2001, in Piracicaba, SP, Brazil. Nine plants of each plot were separated in sub-plots for the 15N balance studies and treated with N rates of 280 and 350 kg ha-1 during 2003/2004 and 2004/2005, respectively, both of them as ammonium sulfate enriched to a 15N abundance of 2.072 atom %. Plant shoots were considered as separate parts: the orthotropic central branch, productive branches, leaves of productive branches, vegetative branches, leaves of vegetative branches and fruit. Litter, consisting of dead leaves accumulated below the plant canopy, was measured by the difference between leaves at harvest and at the beginning of the following flowering. Roots and soil were sampled down to a depth of 1.0 at intervals of 0.2 m. Samples from the isotopic sub-plots were used to evaluate total N and 15N, and plants outside sub-plots were used to evaluate dry matter. Volatilization losses of NH3 were estimated using special collectors. Leaching of fertilizer-N was estimated from deep drainage water fluxes and 15N concentrations of the soil solution at 1 m soil depth. At the end of the 2-year evaluation, the recovery of 15N applied as ammonium sulfate was 19.1 % in aerial plant parts, 9.4 % in the roots, 23.8 % in the litter, 26.3 % in the fruit and 12.6 % remaining in the 0_1.0 m soil profile. Annual leaching and volatilization losses were very small (2.0 % and 0.9 %, respectively). After two years, only 6.2 % N were missing in the balance (100 %) which can be attributed to other non-estimated compartments and experimental errors. Results show that an enrichment of only 2 % atom 15N allows the study of the partition of fertilizer-N in a perennial crop such as coffee during a period of two years.

Nickel incorporation in Fe(II, III) hydroxysulfate Green Rust: effect on crystal lattice spacing and oxidation products

Ni(II)-Fe(II)-Fe(III) layered double hydroxides (LDH) or Ni-containing sulfate green rust (GR2) samples were prepared from Ni(II), Fe(II) and Fe(III) sulfate salts and analyzed with X ray diffraction. Nickel is readily incorporated in the GR2 structure and forms a solid solution between GR2 and a Ni(II)-Fe(III) LDH. There is a correlation between the unit cell a-value and the fraction of Ni(II) incorporated into the Ni(II)-GR2 structure. Since there is strong evidence that the divalent/trivalent cation ratio in GR2 is fixed at 2, it is possible in principle to determine the extent of divalent cation substitution for Fe(II) in GR2 from the unit cell a-value. Oxidation forms a mixture of minerals but the LDH structure is retained if at least 20 % of the divalent cations in the initial solution are Ni(II). It appears that Ni(II) is incorporated in a stable LDH structure. This may be important for two reasons, first for understanding the formation of LDHs, which are anion exchangers, in the natural environment. Secondly, this is important for understanding the fate of transition metals in the environment, particularly in the presence of reduced Fe compounds.

NITROGEN LOSS BY EROSION FROM MECHANICALLY TILLED AND UNTILLED SOIL UNDER SUCCESSIVE SIMULATED RAINFALLS

The description of the fate of fertilizer-derived nitrogen (N) in agricultural systems is an essential tool to enhance management practices that maximize nutrient use by crops and minimize losses. Soil erosion causes loss of nutrients such as N, causing negative effects on surface and ground water quality, aside from losses in agricultural productivity by soil depletion. Studies correlating the percentage of fertilizer-derived N (FDN) with soil erosion rates and the factors involved in this process are scarce. The losses of soil and fertilizer-derived N by water erosion in soil under conventional tillage and no tillage under different rainfall intensities were quantified, identifying the intervening factors that increase loss. The experiment was carried out on plots (3.5 × 11 m) with two treatments and three replications, under simulated rainfall. The treatments consisted of soil with and soil without tillage. Three successive rainfalls were applied in intervals of 24 h, at intensities of 30 mm/h, 30 mm/h and 70 mm/h. The applied N fertilizer was isotopically labeled (15N) and incorporated into the soil in a line perpendicular to the plot length. Tillage absence resulted in higher soil losses and higher total nitrogen losses (TN) by erosion induced by the rainfalls. The FDN losses followed another pattern, since FDN contributions were highest from tilled plots, even when soil and TN losses were lowest, i.e., the smaller the amount of eroded sediment, the greater the percentage of FDN associated with these. Rain intensity did not affect the FDN loss, and losses were greatest after less intense rainfalls in both treatments.

A técnica de dispersão de taylor para estudos de difusão em líquidos e suas aplicações

This paper describes the theoretical basis and the experimental requirements for the application of the Taylor dispersion technique for measurements of diffusion coefficients in liquids, emphasizing its simplicity and accuracy in comparison to other usual techniques. Some examples are discussed describing the use of this methodology on studies of solute-solvent interactions, solute aggregation, solute partitioning into macromolecular systems and on the assessment of nanoparticles sizes.

Dióxido de estanho nanoestruturado: síntese e crescimento de nanocristais e nanofitas

The objectives of this work are to supply a basic background on nanostructured materials and also to report about the obtaining of nanoparticles, mainly, tin dioxide nanocrystalline particles (obtained by using the polymeric precursor method) presenting a high stability against particle growth due to the usage of a metastable solid solution. The synthesis and growth of SnO2 nanoribbons by a carbothermal reduction process are also discussed.

Nanoparticle-coated organic-inorganic microparticles: experimental design and gastrointestinal tolerance evaluation

The influences of the spray-drying parameters and the type of nanoparticles (nanocapsules or nanospheres) on the characteristics of nanoparticle-coated diclofenac-loaded microparticles were investigated by using a factorial design 3². Gastrointestinal tolerance following oral administration in rats was evaluated. Formulations were selected considering the best yields, the best encapsulation efficiencies and the lowest water contents, presenting surfaces completely coated by nanostructures and a decrease in the surface areas in relation to the uncoated core. In vitro drug release demonstrated the influence of the nanoparticle-coating on the dissolution profiles of diclofenac. Nanocapsule-coated microparticles presented a protective effect on the gastrointestinal mucosa.

Mercúrio total em solos de manguezais da Baixada Santista e Ilha do Cardoso, estado de São Paulo

Total Hg content in soils of Baixada Santista, affected by different sources of pollution, and Cardoso Island, which is almost free of anthropogenic activities, were determined by CVAAS. To explain the fate of Hg in the ecosystem, pH, Eh, AVS, Stotal and Total Organic Carbon were also obtained throughout the soil profiles. With the exception of two sampling sites the average content of Hg in samples obtained for Baixada Santista was 0.34 ± 0.20 mg kg-1, which was close to the average data at Cardoso Island (0.30 ± 0.21 mg kg-1). Both of them were below the limit established by CETESB - 0.50 mg kg-1.

Interferentes endócrinos no ambiente

Although the hypothesis that environmental chemicals may exhibit endocrine disrupting effects is not new, the issue has been a growing level of concern due to reports of increased incidences of endocrine-related disease in humans, including declining male fertility, and more significantly, to adverse physiological effects observed in wildlife where cause and effect relationships are more evident. The list of endocrine disrupting chemicals (EDCs) includes a range of anthropogenic compounds, phytoestrogens, naturally occurring sex steroids and synthetic estrogens. Within the aquatic environment, the presence of EDCs has concerned many scientists and water quality regulators. Discharge of effluents from treatment facilities is likely to be a significant source of input of contaminants to many systems, and the potential for concentration of hydrophilic compounds and transformation products within sludges has implications for their disposal. Then, understanding the processes and the fate of EDCs on the environment, as well as the mechanisms of endocrine disruption, may facilitate controlling or limiting exposure of both humans and the environment to these compounds.

Efeito da associação do herbicida clomazone a nanoesferas de alginato/quitosana na sorção em solos

Agrochemicals constitute the class of products most commonly found in water resources. Their high level of concentration is due to the fact that less than 0.1% of pesticides applied to crops reach their target. The present work aims to study the sorption of clomazone herbicide (associated or not with nanoparticles). The sorption tests, performed with the 2(4) factorial design, showed that the form of herbicide is the main factor for sorption of clomazone. The application of nanoparticles as delivery system for agrochemicals is a pressing area of study and can contribute for decrease in effects of clomazone in the environment.