An evaluation of trace metal distribution, enrichment factors and risk in sediments of a coastal lagoon (Ria de Aveiro, Portugal)

This paper describes a sediment survey undertaken to unravel patterns of distribution and dispersion of trace metals in an Iberian Peninsula northwestern coastal lagoon (Ria de Aveiro). Cadmium, lead, chromium, copper and zinc were analyzed in bottom sediments. Geochemical normalization is performed and two different regression models for each metal versus aluminum are tested and compared using the respective enrichment factors (EF), an estimation of the relative importance of anthropogenic contributions to the studied sediments. Mean sediment quality guideline quotients (mSQGQ) are used to evaluate sediment quality and associated potential risk to biota with effects range low as empirical sediment quality guideline (SQG) in the basis for mSQGQ calculation. Additionally, the geoaccumulation index is calculated to compare studied sediment levels to global baseline levels. The application of SQGs revealed insufficient characterization capability, especially when contrasted to EF calculated from the regression methods. These pointed a mildly enriched system with localized “hot spot” areas. Therefore, it can be considered that bottom sediments in the Ria de Aveiro system are in their majority unpolluted, zinc being the only metal of concern, presenting enrichment in all four main channels. The major rivers outlets (Caster, Antuã, and Vouga) constitute point sources, thus presenting potential risk for biota. Yet, the strong tidal influence creates a damping effect by efficiently redistributing sediment bound metals.

Geochemistry Of Acid Mine Drainage From A Coal Mining Area And Processes Controlling Metal Attenuation In Stream Waters, Southern Brazil.

Acid drainage influence on the water and sediment quality was investigated in a coal mining area (southern Brazil). Mine drainage showed pH between 3.2 and 4.6 and elevated concentrations of sulfate, As and metals, of which, Fe, Mn and Zn exceeded the limits for the emission of effluents stated in the Brazilian legislation. Arsenic also exceeded the limit, but only slightly. Groundwater monitoring wells from active mines and tailings piles showed pH interval and chemical concentrations similar to those of mine drainage. However, the river and ground water samples of municipal public water supplies revealed a pH range from 7.2 to 7.5 and low chemical concentrations, although Cd concentration slightly exceeded the limit adopted by Brazilian legislation for groundwater. In general, surface waters showed large pH range (6 to 10.8), and changes caused by acid drainage in the chemical composition of these waters were not very significant. Locally, acid drainage seemed to have dissolved carbonate rocks present in the local stratigraphic sequence, attenuating the dispersion of metals and As. Stream sediments presented anomalies of these elements, which were strongly dependent on the proximity of tailings piles and abandoned mines. We found that precipitation processes in sediments and the dilution of dissolved phases were responsible for the attenuation of the concentrations of the metals and As in the acid drainage and river water mixing zone. In general, a larger influence of mining activities on the chemical composition of the surface waters and sediments was observed when enrichment factors in relation to regional background levels were used.

Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars III. Detection of lithium in the metal-poor bulge dwarf MOA-2010-BLG-285S

Context. To study the evolution of Li in the Galaxy it is necessary to observe dwarf or subgiant stars. These are the only long-lived stars whose present-day atmospheric chemical composition reflects their natal Li abundances according to standard models of stellar evolution. Although Li has been extensively studied in the Galactic disk and halo, to date there has only been one uncertain detection of Li in an unevolved bulge star. Aims. Our aim with this study is to provide the first clear detection of Li in the Galactic bulge, based on an analysis of a dwarf star that has largely retained its initial Li abundance. Methods. We performed a detailed elemental abundance analysis of the bulge dwarf star MOA-2010-BLG-285S using a high-resolution and high signal-to-noise spectrum obtained with the UVES spectrograph at the VLT when the object was optically magnified during a gravitational microlensing event (visual magnification A similar to 550 during observation). The Li abundance was determined through synthetic line profile fitting of the (7)Li resonance doublet line at 670.8 nm. The results have been corrected for departures from LTE. Results. MOA-2010-BLG-285S is, at [Fe/H] = -1.23, the most metal-poor dwarf star detected so far in the Galactic bulge. Its old age (12.5 Gyr) and enhanced [alpha/Fe] ratios agree well with stars in the thick disk at similar metallicities. This star represents the first unambiguous detection of Li in a metal-poor dwarf star in the Galactic bulge. We find an NLTE corrected Li abundance of log epsilon(Li) = 2.16, which is consistent with values derived for Galactic disk and halo dwarf stars at similar metallicities and temperatures. Conclusions. Our results show that there are no signs of Li enrichment or production in the Galactic bulge during its earliest phases. Observations of Li in other galaxies (omega Cen) and other components of the Galaxy suggest further that the Spite plateau is universal.

VLT-FLAMES analysis of 8 giants in the bulge metal-poor globular cluster NGC 6522: oldest cluster in the Galaxy? Analysis of 8 giants in NGC 6522

Context. NGC 6522 has been the first metal-poor globular cluster identified in the bulge by Baade. Despite its importance, very few high-resolution abundance analyses of stars in this cluster are available. The bulge metal-poor clusters may be important tracers of the early chemical enrichment of the Galaxy. Aims. The main purpose of this study is to determine metallicity and elemental ratios in individual stars of NGC 6522. Methods. High-resolution spectra of 8 giants of the bulge's globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with the FLAMES+GIRAFFE spectrograph. Multiband V, I, J, K(s) photometry was used to derive effective temperatures as reference values. Spectroscopic parameters were derived from Fe I and Fe II lines, and adopted for the derivation of abundance ratios. Results. The present analysis provides a metallicity [Fe/H] = -1.0 +/- 0.2. The alpha-elements oxygen, magnesium and silicon show [O/Fe] = +0.4 +/- 0.3, [Mg/Fe] = [Si/Fe] = +0.25 +/- 0.15, whereas calcium and titanium show shallower ratios of [Ca/Fe] = [Ti/Fe] = +0.15 +/- 0.15. The neutron-capture r-process element europium appears to be overabundant by [Eu/Fe] = +0.4 +/- 0.4. The neutron-capture s-elements lanthanum and barium are enhanced by [La/Fe] = +0.35 +/- 0.2 and [Ba/Fe] = +0.5 +/- 0.5. The large internal errors, indicating the large star-to-star variation in the barium and europium abundances, are also discussed. Conclusions. The moderate metallicity combined to a blue horizontal branch (BHB), are characteristics similar to those of HP 1 and NGC 6558, pointing to a population of very old globular clusters in the Galactic bulge. Also, the abundance ratios in NGC 6522 resemble those in HP 1 and NGC 6558. The ultimate conclusion is that the bulge is old, and went through an early prompt chemical enrichment.

A rapid selection/amplification procedure for high-level expression of recombinant protein in a metal-amplifiable mammalian expression system

We describe a strategy for the selection and amplification of foreign gene expression in Chinese hamster ovary (CHO) cells employing a metallothionein gene-containing expression vector. This report describes an amplification procedure that results in an enrichment of clones exhibiting high levels of recombinant protein production and reduces the labour required for screening recombinant cell lines.

Sonidos del metal : el bombardino en las formaciones de viento metal

Este proyecto tiene como objetivo el estudio de la relación que el bombardino tiene con las formaciones más importantes de viento metal. Para ello he creído necesario, antes de profundizar en este tema, dar a conocer su historia y evolución. Mi intención con este proyecto es contribuir al enriquecimiento del patrimonio de este maravilloso instrumento, que poco a poco, va ganando el respeto que se merece.

Reconstruction of metal pollution and recent sedimentation processes in Havana Bay (Cuba): A tool for coastal ecosystem management.

Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the (210)Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90s, which dismissed catchment erosion and pollution.

Uranium-enrichment in soils and plants in the vicinity of a pitchblende vein at La Creusaz-Les Marecottes (W of Martigny, Valais, Switzerland)

In the NE part of the Aiguilles Rouges Massif near Martigny, at the eastern contact of the Variscan Vallorcine granite to adjacent gneisses, a series of pitchblende (UO2)-veins occur. This paper determines the level of enrichment and mobility of uranium in soils situated in the vicinity of such a UO2-vein 7 km west of Martigny. Within an area of 50 x 100 m, situated on a relatively steep slope and characterized by a strong gramma-ray anomaly, six soil profiles including their plant cover and a reference soil profile outside the influence of the UO2-vein have been examined. The soil shows pH-values between 4 and 5 and is colluvial. The applied analytical methods for the metal contents include extraction methods, common for soil studies, and bulk analysis performed with X-ray fluorescence and ICP-MS. Uranium contents found in the uppermost 20 cm of the soil profiles vary from 2,500 ppm close to the vein to 15 ppm at the lowermost point of the study area. The reference soil has around 3 ppm uranium. At greater depth (20 to 40 cm) the U-content decreases to about half of the surface values, indicating a vertical transport of uranium within the soil profile. No systematic dependance of uranium-contents to grain size (amount of clay) nor to the amount of organic matter has been found. However, the good correlation between uranium and free iron oxide concentration suggests adsorption of uranium on iron oxy-hydroxides. The ashes of grass and mosses contain up to 90 ppm U, the blueberry and redwood only up to 3 ppm. Our observations suggest that at the surface the uranium is transported by downhill creep (solifluxion) of uranium-rich rock fragments. Liberated by oxidation of the uppermost fragments in a given soil column, the uranium migrates vertically until the conditions are favourable to adsorption onto Fe-oxy-hydroxides. However, as high U-contents of local surface water show, this adsorption does not lead to a significant retention of the uranium.

Genesis of the Jurassic carbonate-hosted Pb-Zn deposits of Jebel Ressas (North-eastern Tunisia): Evidence from mineralogy, petrography and trace metal contents and isotope (O, C, S, Pb) geochemistry

The Jebel Ressas Pb-Zn deposits in North-Eastern Tunisia occur mainly as open-space fillings (lodes, tectonic breccia cements) in bioclastic limestones of the Upper Jurassic Ressas Formation and along the contact of this formation with Triassic rocks. The galena-sphalerite association and their alteration products (cerussite, hemimorphite, hydrozincite) are set within a calcite gangue. The Triassic rocks exhibit enrichments in trace metals, namely Pb, Co and Cd enrichment in clays and Pb, Zn, Cd, Co and Cr enrichment in carbonates, suggesting that the Triassic rocks have interacted with the ore-bearing fluids associated with the Jebel Ressas Pb-Zn deposits. The delta(18)O content of calcite associated with the Pb-Zn mineralization suggests that it is likely to have precipitated from a fluid that was in equilibrium with the Triassic dolostones. The delta(34)S values in galenas from the Pb-Zn deposits range from -1.5 to +11.4%, with an average of 5.9% and standard deviation of 3.9%. These data imply mixing of thermochemically-reduced heavy sulfur carried in geothermal- and fault-stress-driven deep-seated source fluid with bacterially-reduced light sulfur carried in topography-driven meteoric fluid. Lead isotope ratios in galenas from the Pb-Zn deposits are homogenous and indicate a single upper crustal source of base-metals for these deposits. Synthesis of the geochemical data with geological data suggests that the base-metal mineralization at Jebel Ressas was formed during the Serravallian-Tortonian (or Middle-Late Miocene) Alpine compressional tectonics.

Formation and Control of Trace Metal Emissions in Co-Firing of Biomass, Peat, and Wastes in Fluidised Bed Combustors

Environmentally harmful consequences of fossil fuel utilisation andthe landfilling of wastes have increased the interest among the energy producers to consider the use of alternative fuels like wood fuels and Refuse-Derived Fuels, RDFs. The fluidised bed technology that allows the flexible use of a variety of different fuels is commonly used at small- and medium-sized power plants ofmunicipalities and industry in Finland. Since there is only one mass-burn plantcurrently in operation in the country and no intention to build new ones, the co-firing of pre-processed wastes in fluidised bed boilers has become the most generally applied waste-to-energy concept in Finland. The recently validated EU Directive on Incineration of Wastes aims to mitigate environmentally harmful pollutants of waste incineration and co-incineration of wastes with conventional fuels. Apart from gaseous flue gas pollutants and dust, the emissions of toxic tracemetals are limited. The implementation of the Directive's restrictions in the Finnish legislation is assumed to limit the co-firing of waste fuels, due to the insufficient reduction of the regulated air pollutants in the existing flue gas cleaning devices. Trace metals emission formation and reduction in the ESP, the condensing wet scrubber, the fabric filter, and the humidification reactor were studied, experimentally, in full- and pilot-scale combustors utilising the bubbling fluidised bed technology, and, theoretically, by means of reactor model calculations. The core of the model is a thermodynamic equilibrium analysis. The experiments were carried out with wood chips, sawdust, and peat, and their refuse-derived fuel, RDF, blends. In all, ten different fuels or fuel blends were tested. Relatively high concentrations of trace metals in RDFs compared to the concentrations of these metals in wood fuels increased the trace metal concentrations in the flue gas after the boiler ten- to hundred-folds, when RDF was co-fired with sawdust in a full-scale BFB boiler. In the case of peat, lesser increase in trace metal concentrations was observed, due to the higher initial trace metal concentrations of peat compared to sawdust. Despite the high removal rate of most of the trace metals in the ESP, the Directive emission limits for trace metals were exceeded in each of the RDF co-firing tests. The dominat trace metals in fluegas after the ESP were Cu, Pb and Mn. In the condensing wet scrubber, the flue gas trace metal emissions were reduced below the Directive emission limits, whenRDF pellet was used as a co-firing fuel together with sawdust and peat. High chlorine content of the RDFs enhanced the mercuric chloride formation and hence the mercury removal in the ESP and scrubber. Mercury emissions were lower than theDirective emission limit for total Hg, 0.05 mg/Nm3, in all full-scale co-firingtests already in the flue gas after the ESP. The pilot-scale experiments with aBFB combustor equipped with a fabric filter revealed that the fabric filter alone is able to reduce the trace metal concentrations, including mercury, in the flue gas during the RDF co-firing approximately to the same level as they are during the wood chip firing. Lower trace metal emissions than the Directive limits were easily reached even with a 40% thermal share of RDF co-firing with sawdust.Enrichment of trace metals in the submicron fly ash particle fraction because of RDF co-firing was not observed in the test runs where sawdust was used as the main fuel. The combustion of RDF pellets with peat caused an enrichment of As, Cd, Co, Pb, Sb, and V in the submicron particle mode. Accumulation and release oftrace metals in the bed material was examined by means of a bed material analysis, mass balance calculations and a reactor model. Lead, zinc and copper were found to have a tendency to be accumulated in the bed material but also to have a tendency to be released from the bed material into the combustion gases, if the combustion conditions were changed. The concentration of the trace metal in the combustion gases of the bubbling fluidised bed boiler was found to be a summary of trace metal fluxes from three main sources. They were (1) the trace metal flux from the burning fuel particle (2) the trace metal flux from the ash in the bed, and (3) the trace metal flux from the active alkali metal layer on the sand (and ash) particles in the bed. The amount of chlorine in the system, the combustion temperature, the fuel ash composition and the saturation state of the bed material in regard to trace metals were discovered to be key factors affecting therelease process. During the co-firing of waste fuels with variable amounts of e.g. ash and chlorine, it is extremely important to consider the possible ongoingaccumulation and/or release of the trace metals in the bed, when determining the flue gas trace metal emissions. If the state of the combustion process in regard to trace metals accumulation and/or release in the bed material is not known,it may happen that emissions from the bed material rather than the combustion of the fuel in question are measured and reported.

Development of a flotation method for preconcentration-separation of trace amounts of some metal ions in plant tissues prior to their FAAS determinations

An efficient flotation method based on the combination of flame atomic absorption spectrometry (FAAS) and separation and preconcentration step for determination of Cr3+, Cu 2+, Co2+, Ni2+, Zn2+, Cd 2+, Fe3+ and Pb2+ ions in various real samples by the possibility of applying bis(2-hydroxyacetophenone)-1,4-butanediimine (BHABDI) as a new collector was studied. The influence of pH, amount of BHABDI as collector, sample matrix, type and amount of eluting agent, type and amount of surfactant as floating agent, ionic strength and air flow rates i.e. variables affecting the efficiency of the extraction system was evaluated. It is ascertained that metal ions such as iron can be separated simultaneously from matrix in the presence of 0.012 mM ligand, 0.025% (w/v) of CTAB to a test sample of 750 mL at pH 6.5. These ions can be eluted quantitatively with 6 mL of 1.0 mol L-1 HNO3 in methanol which lead to the enrichment factor of 125. The detection limits for analyte ions were in the range of 1.3-2.4 ng mL-1. The method has been successfully applied for determination of trace amounts of ions in various real samples.

Enrichment of nutritional value of Phyllanthus emblica fruit juice using the probiotic bacterium, Lactobacillus paracasei HII01 mediated fermentation

The fermented herbal juices are capable of curing and preventing diseases and reducing the aging progress. The present study was performed to investigate the fermentation of Phyllanthus emblica fruit by Lactobacillus paracasei HII01 with respect to carbon sources, polyphenols, and antioxidant properties. The physical changes, for instance, color, odor, taste, turbidity and gas formation, throughout the fermentation process was manually monitored. The fermented product was rich in polyphenolic content. The acid content and pH of the product were under the norms of Thai community product standards. Antioxidant properties of the fermented product were proved using ABTS, and FRAP assays. Chelation based study suggested that fermented P. emblica fruit juices are healthy enough to stabilize the oxidized form of the metal ion. The optimum fermentation period was 15 days. All the results supported that studied carbon sources did not interfere with the quality of the product. This report is the prelude study on the use of probiotic starter culture for the production of P. emblica fruit based lactic acid bacteria fermented beverages (LAFB) enriched with bioactive compounds. Further research on the impact of different carbon sources and upstream processes on the quality of LAFB is currently in progress.

Metal oxides prepared through the nanocasting approach-mechanistic study, surface interactions and applications in separation

Mesoporous metal oxides are nowadays widely used in various technological applications, for instance in catalysis, biomolecular separations and drug delivery. A popular technique used to synthesize mesoporous metal oxides is the nanocasting process. Mesoporous metal oxide replicas are obtained from the impregnation of a porous template with a metal oxide precursor followed by thermal treatment and removal of the template by etching in NaOH or HF solutions. In a similar manner to the traditional casting wherein the product inherits the features of the mold, the metal oxide replicas are supposed to have an inverse structure of the starting porous template. This is however not the case, as broken or deformed particles and other structural defects have all been experienced during nanocasting experiments. Although the nanocasting technique is widely used, not all the processing steps are well understood. Questions over the fidelity of replication and morphology control are yet to be adequately answered. This work therefore attempts to answer some of these questions by elucidating the nanocasting process, pin pointing the crucial steps involved and how to harness this knowledge in making wholesome replicas which are a true replication of the starting templates. The rich surface chemistry of mesoporous metal oxides is an important reason why they are widely used in applications such as catalysis, biomolecular separation, etc. At times the surface is modified or functionalized with organic species for stability or for a particular application. In this work, nanocast metal oxides (TiO2, ZrO2 and SnO2) and SiO2 were modified with amino-containing molecules using four different approaches, namely (a) covalent bonding of 3-aminopropyltriethoxysilane (APTES), (b) adsorption of 2-aminoethyl dihydrogen phosphate (AEDP), (c) surface polymerization of aziridine and (d) adsorption of poly(ethylenimine) (PEI) through electrostatic interactions. Afterwards, the hydrolytic stability of each functionalization was investigated at pH 2 and 10 by zeta potential measurements. The modifications were successful except for the AEDP approach which was unable to produce efficient amino-modification on any of the metal oxides used. The APTES, aziridine and PEI amino-modifications were fairly stable at pH 10 for all the metal oxides tested while only AZ and PEI modified-SnO2 were stable at pH 2 after 40 h. Furthermore, the functionalized metal oxides (SiO2, Mn2O3, ZrO2 and SnO2) were packed into columns for capillary liquid chromatography (CLC) and capillary electrochromatography (CEC). Among the functionalized metal oxides, aziridinefunctionalized SiO2, (SiO2-AZ) showed good chemical stability, and was the most useful packing material in both CLC and CEC. Lastly, nanocast metal oxides were synthesized for phosphopeptide enrichment which is a technique used to enrich phosphorylated proteins in biological samples prior to mass spectrometry analysis. By using the nanocasting technique to prepare the metal oxides, the surface area was controlled within a range of 42-75 m2/g thereby enabling an objective comparison of the metal oxides. The binding characteristics of these metal oxides were compared by using samples with different levels of complexity such as synthetic peptides and cell lysates. The results show that nanocast TiO2, ZrO2, Fe2O3 and In2O3 have comparable binding characteristics. Furthermore, In2O3 which is a novel material in phosphopeptide enrichment applications performed comparably with standard TiO2 which is the benchmark for such phosphopeptide enrichment procedures. The performance of the metal oxides was explained by ranking the metal oxides according to their isoelectric points and acidity. Overall, the clarification of the nanocasting process provided in this work will aid the synthesis of metal oxides with true fidelity of replication. Also, the different applications of the metal oxides based on their surface interactions and binding characteristics show the versatility of metal oxide materials. Some of these results can form the basis from which further applications and protocols can be developed.