Histological alterations in liver and testis of Astyanax aff. bimaculatus caused by acute exposition to zinc

This study investigated the effect of acute exposition to zinc (Zn) on histology of the liver and testes of yellow tail lambari (Astyanax aff. bimaculatus). The exposure consisted of six concentrations of Zn (0, 3, 5, 10, 15, and 20 mg/L) for 96 hours of exposure. Fragments of liver and testis were routinely processed and embedded in plastic resin based on glycol methacrylate. Fragments of bones, muscles, liver and testis were dehydrated and digested to quantify the absorption levels of Zn in the tissue. Acute exposure to concentrations above 10mg/L has produced structural changes in the liver and gonads. The changes found in the liver were vascular congestion; decrease of cellular volume; displacement of the hepatocyte nucleus; necrosis; disarrangement of cordon structure; leukocyte infiltrate and vacuolization. The changes found in the gonads were ruptured cyst, delayed development of germ cells, pyknotic nucleus, cell cluster, displacement of cyst wall and vacuolization. The histological changes observed were compatible with the increasing concentration of zinc in environment, compromising liver and reproductive functions, because there was an increase in relative frequency of hepatocytes and reduced sperm production

Neutron activation analysis of wheat samples

The deficiency of essential micronutrients and excess of toxic metals in cereals, an important food items for human nutrition, can cause public health risk. Therefore, before their consumption and adoption of soil supplementation, concentrations of essential micronutrients and metals in cereals should be monitored. This study collected soil and two varieties of wheat samples–Triticum aestivum L. (Jordão/bread wheat), and Triticum durum L. (Marialva/durum wheat) from Elvas area, Portugal and analyzed concentrations of As, Cr, Co, Fe, K, Na, Rb and Zn using Instrumental Neutron Activation Analysis (INAA) to focus on the risk of adverse public health issues. The low variability and moderate concentrations of metals in soils indicated a lower significant effect of environmental input on metal concentrations in agricultural soils. The Cr and Fe concentrations in soils that ranged from 93–117 and 26,400–31,300 mg/kg, respectively, were relatively high, but Zn concentration was very low (below detection limit <22 mg/kg) indicating that soils should be supplemented with Zn during cultivation. The concentrations of metals in roots and straw of both varieties of wheat decreased in the order of K>Fe>Na>Zn>Cr>Rb>As>Co. Concentrations of As, Co and Cr in root, straw and spike of both varieties were higher than the permissible limits with exception of a few samples. The concentrations of Zn in root, straw and spike were relatively low (4–30 mg/kg) indicating the deficiency of an essential micronutrient Zn in wheat cultivated in Portugal. The elemental transfer from soil to plant decreases with increasing growth of the plant. The concentrations of various metals in different parts of wheat followed the order: Root>Straw>Spike. A few root, straw and spike samples showed enrichment of metals, but the majority of the samples showed no enrichment. Potassium is enriched in all samples of root, straw and spike for both varieties of wheat. Relatively to the seed used for cultivation, Jordão presented higher transfer coefficients than Marialva, in particular for Co, Fe, and Na. The Jordão and Marialva cultivars accumulated not statistically significant different concentrations of different metals. The advantages of using INAA are the multielementality, low detection limits and use of solid samples (no need of digestion).

Removal of Cd(II), Zn(II) and Pb(II) from aqueous solutions by brown marine macro algae: kinetic modelling

Specific marine macro algae species abundant at the Portuguese coast (Laminaria hyperborea, Bifurcaria bifurcata, Sargassum muticum and Fucus spiralis) were shown to be effective for removing toxic metals (Cd(II), Zn(II) and Pb(II)) from aqueous solutions. The initial metal concentrations in solution were about 75–100 mg L−1. The observed biosorption capacities for cadmium, zinc and lead ions were in the ranges of 23.9–39.5, 18.6–32.0 and 32.3–50.4 mg g−1, respectively. Kinetic studies revealed that the metal uptake rate was rather fast, with 75% of the total amount occurring in the first 10 min for all algal species. Experimental data were well fitted by a pseudo-second order rate equation. The contribution of internal diffusion mechanism was significant only to the initial biosorption stage. Results indicate that all the studied macro algae species can provide an efficient and cost-effective technology for eliminating heavy metals from industrial effluents.

Optimization of a microplate-based assay to assess esterase activity in the alga Pseudokirchneriella subcapitata

The present work describes the optimization of a short-term assay, based on the inhibition of the esterase activity of the alga Pseudokirchneriella subcapitata, in a microplate format. The optimization of the staining procedure showed that the incubation of the algal cells with 20 μmolL−1 fluorescein diacetate (FDA) for 40 min allowed discrimination between metabolic active and inactive cells. The shortterm assay was tested using Cu as toxicant. For this purpose, algal cells, in the exponential or stationary phase of growth, were exposed to the heavy metal in growing conditions. After 3 or 6 h, cells were subsequently stained with FDA, using the optimized procedure. For Cu, the 3- and 6-h EC50 values, based on the inhibition of the esterase activity of algal cells in the exponential phase of growth, were 209 and 130 μg L−1, respectively. P. subcapitata cells, in the stationary phase of growth, displayed higher effective concentration values than those observed in the exponential phase. The 3- and 6-h EC50 values for Cu, for cells in the stationary phase, were 443 and 268 μgL−1, respectively. This short-term microplate assay showed to be a rapid endpoint for testing toxicity using the alga P. subcapitata. The small volume required, the simplicity of the assay (no washing steps), and the automatic reading of the fluorescence make the assay particularly well suited for the evaluation of the toxicity of a high number of environmental samples.

A comunidade metálica portuguesa no ciberespaço. Da comunidade física à comunidade online

Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Ciências da Comunicação

ABCC Subfamily Vacuolar Transporters are Involved in Pb (Lead) Detoxification in Saccharomyces cerevisiae

The present work has as objective to contribute for the elucidation of the mechanism associated with Pb detoxification, using the yeast Saccharomyces cerevisiae as a model organism. The deletion of GTT1 or GTT2 genes, coding for functional glutathione transferases (GST) enzymes in S. cerevisiae, caused an increased susceptibility to high Pb concentrations (500-1000 μmol L(-1)). These results suggest that the formation of glutathione-Pb conjugate (GS-Pb), dependent of GSTs, is important in Pb detoxification. The involvement of ATP-binding cassette (ABC) vacuolar transporters, belonging to class C subfamily (ABCC) in vacuolar compartmentalization of Pb, was evaluated. For this purpose, mutant strains disrupted in YCF1, VMR1, YBT1 or BPT 1 genes were used. All mutants tested, without vacuolar ABCC transporters, presented an increased sensitivity to 500-1000 μmol L(-1) Pb comparative to wild-type strain. Taken together, the obtained results suggest that Pb detoxification, by vacuolar compartmentalization, can occur as a result of the concerted action of GSTs and vacuolar ABCC transporters. Pb is conjugated with glutathione, catalysed by glutathione transferases and followed to the transport of GS-Pb conjugate to the vacuole by ABCC transporters.

The two-component system of a novel copper resistant operon of Marinobacter hydrocarbonoclasticus

Dissertation for the Master’s Degree in Structural and Functional Biochemistry

The main leachate emissions of uncontrolled landfills

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, Perfil de Engenharia Sanitária

Analysis of chromium behaviour and speciation during the electrodialytic process

The interest in chromium (Cr) arises from the widespread use of this heavy metal in various industrial processes that cause its release as liquid, solid and gaseous waste into the environment. The impact of Cr on the environment and living organisms primarily depends on its chemical form, since Cr(III) is an essential micronutrient for humans, other animals and plants, and Cr(VI) is highly toxic and a known human carcinogen. This study aimed to evaluate if the electrodialytic process (ED) is an appropriate treatment for Cr removal, through a critical overview of Cr speciation, before and after the ED experiments, to assess possible Cr(III)-Cr(VI) interconversions during the treatment. ED was the treatment technique applied to two types of matrices containing Cr: chromate copper arsenate (CCA) contaminated soil and municipal solid waste incineration (MSWI) fly ash. In order to study Cr remediation, three EDR set-ups were used: a new set-up, the combined cell (2/3C or 3/2C), with three compartments, alternating current between two anodes and different initial experimental conditions, one set-up with three compartments (3C cell) and the other set-up with two compartments (2C cell). The Cr removal rates obtained in this study were between 10-36% for the soil, and 1-13% for the fly ash. The highest Cr removal rates were achieved in the 26 days experiments: 36% for the soil, 13% for the fly ash. Regarding the 13 days experiments, the highest Cr removal rates were attained with the 2/3C set-up: 24% for the soil, 5% for the fly ash. The analysis of Cr(VI) was performed before and after ED experiments to evaluate eventual changes in Cr speciation during the treatment. This analysis was conducted by two methods: USEPA Method 3060A, for the extraction of Cr(VI); and Hach Company Method 8023, for the detection of Cr(VI). Despite the differences in Cr total concentration, both matrices presented a similar speciation, with Cr(III) being the main species found and Cr(VI) less than 3% of Cr total, before and after the treatment. For fly ash, Cr(VI) was initially below the detection limit of the method and remained that way after the treatment. For soil, Cr(VI) decreased after the treatment. Oxidation of Cr(III) to Cr(VI) did not occur during the ED process since there was no increase in Cr(VI) in the matrices after the treatment. Hence, the results of this study indicate that ED is an appropriate technique to remediate matrices containing Cr because it contributes to Cr removal, without causing Cr(III)-Cr(VI) interconversions.

Spatio-temporal modelling of environmental data

Programa Doutoral em Matemática e Aplicações.

Preferência musical e risco de suicídio entre jovens

OBJETIVOS: Considerando-se que vários estudos internacionais indicam que a preferência musical, especialmente pelo heavy metal, correlaciona-se ao suicídio, objetivou-se na presente pesquisa conhecer as relações entre preferência musical e risco de suicídio. MÉTODOS: Participaram 200 estudantes universitários de diversos cursos de uma universidade pública da cidade de João Pessoa, PB, com idade média de 22 anos (DP = 4,77). Estes responderam à Escala Abreviada de Preferência Musical, que visa mensurar a preferência musical com relação a 14 gêneros musicais, e o Inventário de Razões para Viver (RFL), que objetiva aferir as razões que as pessoas têm para viver. RESULTADOS: De acordo com os resultados, verificaram-se correlações entre a pontuação total da RFL e os gêneros musicais convencional (positiva) e alternativo (negativa). Pôde-se ainda verificar que a preferência musical pelo estilo convencional foi um preditor de menor risco de suicídio entre jovens. CONCLUSÕES: Esta pesquisa demonstra a importância de mais uma variável, no caso a preferência musical, para entender o risco de suicídio entre jovens. Mas outros estudos devem ser realizados no contexto brasileiro para que se possa entender melhor essa relação.

Vermiculite bio-barriers for Cu and Zn remediation: an eco-friendly approach for freshwater and sediments protection

The increase in heavy metal contamination in freshwater systems causes serious environmental problems in most industrialized countries, and the effort to find ecofriendly techniques for reducing water and sediment contamination is fundamental for environmental protection. Permeable barriers made of natural clays can be used as low-cost and eco-friendly materials for adsorbing heavy metals from water solution and thus reducing the sediment contamination. This study discusses the application of permeable barriers made of vermiculite clay for heavy metals remediation at the interface between water and sediments and investigates the possibility to increase their efficiency by loading the vermiculite surface with a microbial biofilm of Pseudomonas putida, which is well known to be a heavy metal accumulator. Some batch assays were performed to verify the uptake capacity of two systems and their adsorption kinetics, and the results indicated that the vermiculite bio-barrier system had a higher removal capacity than the vermiculite barrier (?34.4 and 22.8 % for Cu and Zn, respectively). Moreover, the presence of P. putida biofilm strongly contributed to fasten the kinetics of metals adsorption onto vermiculite sheets. In open-system conditions, the presence of a vermiculite barrier at the interface between water and sediment could reduce the sediment contamination up to 20 and 23 % for Cu and Zn, respectively, highlighting the efficiency of these eco-friendly materials for environmental applications. Nevertheless, the contribution of microbial biofilm in open-system setup should be optimized, and some important considerations about biofilm attachment in a continuous-flow system have been discussed.

Investigation into the potential for establishing a self-sustainable wetland ecosystem over pyritic mine tailings

Research was conducted to investigate the potential for ecologically engineering a sustainable wetland ecosystem over pyritic mine tailings to prevent the generation of acid mine drainage. Ecological engineering is technology with the primary goal being the creation of self-sustainable ecological systems. Work involved the design and construction of a pilot-scale wetland system comprising three wetland cells, each covering 100 m2. Approximately forty tonnes of pyritic mine tailings were deposited on the base of the first cell above a synthetic liner, covered with peat, flooded and planted with emergent wetland macrophytes Typha latifolia, Phragmites australis, and Juncus effusus. The second cell was constructed as a conventional free water surface wetland, planted identically, and used as a reference wetland/experimental control. Wetland monitoring to determine long-term sustainability focused on indicators of ecosystem health including ecological, hydrological, physico-chemical, geochemical, and biotic metrics. An integrated assessment was conducted that involved field ecology in addition to ecological risk assessment. The objective of the field ecology study was to use vegetative parameters as ecological indicators for documenting wetlands success or degradation. The goal of the risk assessment was to determine if heavy-metal contamination of the wetland sediments occurred through metal mobilisation from the underlying tailings, and to evaluate if subsequent water column chemistry and biotic metal concentrations were significantly correlated with adverse wetland ecosystem impacts. Data were used to assess heavy metal bioavailability within the system as a function of metal speciation in the wetland sediments. Results indicate hydrology is the most important variable in the design and establishment of the tailings wetland and suggest a wetland cover is an ecologically viable alternative for pyritic tailings which are feasible to flood. Ecological data indicate that in terms of species richness and diversity, the tailings-wetland was exhibiting the ecological characteristics of natural wetlands within two years. Ata indicate that pH and conductivity in the tailings-wetland were not adversely impacted by the acid-generating potential or sulphate concentration of the tailings substrate and its porewater. Similarly, no enhanced seasonal impacts from sulphate or metals in the water column, nor adverse impacts on the final water quality of the outflows, were detected. Mean total metal concentrations in the sediments of the tailings-wetland indicate no significant adverse mobilisation of metals into the peat substrate from the tailings. Correlation analyses indicate a general increase in sediment metal concentration in this wetland with increasing water depth and pH, and a corresponding decrease in the metal concentrations of the water column. Sediment extractions also showed enrichment of Cd, Fe, Pb and Zn in the oxidisable fraction (including sulphides and organic matter) of the tailings-wetland sediments. These data suggest that adsorption and coprecipitation of metals is occurring from the water column of the tailings wetland with organic material at increasing depths under reducing conditions. The long-term control of metal bioavailability in the tailings wetland will likely be related to the presence and continual build-up of organic carbon binding sites in the developing wetland above the tailings. Metal speciation including free-metal ion concentration and the impact of physico-chemical parameters particularly pH and organic matter, were investigated to assess ecotoxicological risk. Results indicate that potentially bioavailable metals (the sum of the exchangeable and reducible fractions) within the tailings wetland are similar to values cited for natural wetlands. Estimated free-metal ion concentrations calculated from geochemical regression models indicate lower free-metal ion concentrations of Cd in the tailings wetland than natural wetlands and slightly higher free-metal ion concentrations of Pb and Zn. Increased concentrations of metals in roots, rhizomes and stems of emergent macrophytes did not occur in the tailings wetland. Even though a substantial number of Typha latifolia plants were found rooting directly into tailings, elevated metals were not found in these plant tissues. Phragmites also did not exhibit elevated metal concentrations in any plant tissues. Typha and Phragmites populations appear to be exhibiting metal-tolerant behaviour. The chemistry of the water column and sediments in Silvermines wetland were also investigated and were much more indicative of a wetland system impacted by heavy metal contamination than the tailings-wetland. Mean Dc, Fe, Mn, Pb and Zn concentrations in the water column and sediments of Silvermines wetlands were substantially higher than in the pilot wetlands and closely approximate concentrations in these matrices contaminated with metals from mining. In addition, mean sulphate concentration in Silvermines wetland was substantially higher and is closer to sulphate concentrations in waters associated with mining. Potentially bioavailable metals were substantially elevated in Silvermines wetland in comparison to the pilot wetlands and higher than those calculated for natural rive sediments. However, Fe oxy-hydroxide concentrations in Silvermines sediments are also much higher than in the pilot wetlands and this significantly impacts the concentration of free-metal ions in the sediment porewater. The free-metal ion concentrations for Pb and Zn indicate that Silvermines wetland is retaining metals and acting as a treatment wetland for drainage emanating from Silvermines tailings dam.

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.

Cadmium hyperaccumulation and genetic differentiation of Thlaspi caerulescens populations

Although the knowledge on heavy metal hyperaccumulation mechanisms is increasing, the genetic basis of cadmium (Cd) hyperaccurnulation remains to be elucidated. Thlaspi caerulescens is an attractive model since Cd accumulation polymorphism observed in this species suggests genetic differences between populations with low versus high Cd hyperaccumulation capacities. In our study, a methodology is proposed to analyse at a regional scale the genetic differentiation of T. caerulescens natural populations in relation to Cd hyperaccumulation capacity while controlling for different environmental, soil, plant parameters and geographic origins of populations. Twenty-two populations were characterised with AFLP markers and cpDNA polymorphism. Over all loci, a partial Mantel test showed no significant genetic structure with regard to the Cd hyperaccumulation capacity. Nevertheless, when comparing the marker variation to a neutral model, seven AFLP fragments (9% of markers) were identified as presenting particularly high genetic differentiation between populations with low and high Cd hyperaccurnulation capacity. Using simulations, the number of outlier loci was showed to be significantly higher than expected at random. These loci presented a genetic structure linked to Cd hyperaccumulation capacity independently of the geography, environment, soil parameters and Zn, Pb, Fe and Cu concentrations in plants. Using a canonical correspondence analysis, we identified three of them as particularly related to the Cd hyperaccumutation capacity. This study demonstrates that populations with low and high hyperaccurnulation capacities can be significantly distinguished based on molecular data. Further investigations with candidate genes and mapped markers may allow identification and characterization of genomic regions linked to factors involved in Cd hyperaccumulation.