762 research outputs found

    Uptake of uranium by lettuce (Lactuca sativa L.) in natural uranium contaminated soils in order to assess chemical risk for consumers

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    Uranium mining activity in Cunha Baixa (Portugal) village has left a legacy of polluted soils and irrigation water. A controlled field experiment was conducted with lettuce (Lactuca sativa L.) in an agricultural area nearby the abandoned mine in order to evaluate uranium uptake and distribution in roots and leaves as well as ascertain levels of uranium intake by the local inhabitants from plant consuming. Two soils with different average uranium content (38 and 106 mg/kg) were irrigated with non-contaminated and uranium contaminated water (100 μg/l). A non-contaminated soil irrigated with local tap water (<1 μg/l uranium) was also used as a control. Uranium in lettuce tissues was positively correlated with soil uranium content, but non-significant differences were obtained from contaminated soils irrigated with different water quality. Uranium in plants (dry weight) growing in contaminated soils ranged from 0.95 to 6 mg/kg in roots and 0.32 to 2.6 mg/kg in leaves. Lettuce bioconcentration is more related to available uranium species in water than to its uranium concentration. Translocated uranium to lettuce leaves corresponds to 30% of the uranium uptake whatever the soil or irrigation water quality. A maximum uranium daily intake of 0.06 to 0.12 μg/kg bodyweight day was estimated for an adult assuming 30 to 60 g/day of lettuce is consumed. Although this value accounts for only 10% to 20% of the recommended Tolerable Daily Intake for ingested uranium, it still provides an additional source of the element in the local inhabitants’ die

    Potential use of Erica andevalensis and Erica australis in phytoremediation of sulphide mine environments: São Domingos, Portugal

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    The area around the São Domingos copper mine (Iberian Pyrite Belt) is subject of great environmental concern as acid mine water occurs several kilometres downstream of the mine. In addition thousands of tons of mine waste are present. Erica australis and Erica andevalensis, which are two spontaneous plant species of this area, have been studied with regard to their potential for phytostabilization. Soils and plants from São Domingos and from a reference site (Moreanes) were analysed for soil characteristics, chemical element content in soils (total and AB-DTPA bioavailable fraction) and in plants. Superficial and seepage water as well as waste material leachates were also analysed. Seepage water showed high redox potential (mean 481 mV), high conductivity (mean 4337 μS cm−1) and low pH values (mean 2.6), being classified as mining water. Leachate solutions possessed mainly high levels of Fe, Al and SO42−. Soils in the mining area were highly contaminated in Pb, As and Sb. Locally also high values of Cu and Zn were encountered and the soil available fraction of the majority of the elements showed also quite high values. E. andevalensis grows in soils with pH between 3 and 4, whereas E. australis was only found in soils with pH above 3.5. Both species grow spontaneously in soils, highly contaminated with Pb, As and Sb. These plants, even in the non contaminated soils, are Al-tolerant and Mn-accumulators. In contaminated soils these species are also As-tolerant. Considering the tolerant behaviour in extreme environmental conditions, these Erica species may be of major importance for the recovery of the sulphide mining areas, with climate conditions compatible with its breeding and growing, by physical and chemical stabilization of contaminated soils and even waste material

    Evaluation of amendments in the rehabilitation of sulfide mine tailings from São Domingos

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    RAMIRAN International ConferenceThe São Domingos mining area is located in the Iberian Pyrite Belt, SE Portugal, and represents a serious environmental hazard (Matos and Martins, 2006). Exploitation dated back to pre-roman and roman times with extraction of Ag, Au and Cu exploitation, mainly in the gossan (resulting from the ore weathering). The intense exploitation started in the middle of 19th century, both in the gossan and sulfide ore-containing Cu, Zn, As and Pb, and lasted until 1960, with the exhaustion of the ore (Quental et al., 2002). Different types of waste materials were left: gossan, host rocks (volcanic with shales, and shales), roman and modern slags, smelting ashes and brittle and blocks of pyrite (Matos, 2004; Álvarez-Valero et al., 2008). All sulfide mine wastes are typically heterogeneous and contain high amounts of trace elements, acidic pH and small contents of organic matter and nutrients. The large dumps containing pyrite and other metal sulfides generate, by oxidation, acidic mine drainage (AMD) which increases the availability of trace elements for microorganisms and plants in the surrounding soils. All of these characteristics contribute towards a system that is barely capable of supporting the establishment or survival of plants. The use of amendments and spontaneous colonization (vegetation) from mining areas (phytostabilization) are cost-effective and environmentally sustainable methods to rehabilitate these contaminated and degraded areas even in arid and semi-arid conditions (Tordoff et al., 2000; Mendez and Maier, 2008). Thus, the preparation of Technosols from mixtures of organic and inorganic wastes can be an attractive option to rehabilitate mining areas because they can improve physical, chemical and biological properties contributing, at the same time, towards a strategy of wastes valorisation (Macías, 2004). The use of mixtures composed of residues with different C:N ratios can be used to manipulate the rate of mineralization. Nevertheless, the amendments used should also promote other soil functions (Arbestain et al., 2008). The objective of this study was to evaluate the influence of cost-effective organic and inorganic amendments, available in the region, in the rehabilitation of sulfide materials from the São Domingos mine are

    Impacts on water, soil and plants from the abandoned Miguel Vacas copper mine, Portugal

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    Soil, water and plant geochemistry was studied around the Miguel Vacas copper mine (Alentejo, SE Portugal), which stopped its exploitation and processing activities in 1991. After closure waste-rock piles remained exposed to weathering. The copper ore was mainly composed of copper phosphates and carbonates. Remediation actions were insufficient to prevent the spreading of waste-rock materials to surrounding farmed fields. The latter caused contamination of soils and water. Based on overall characteristics water from wells and surface stream water mostly can be classified as of the sulphate magnesium type. The application of a chemical equilibrium model to the sampled water showed that copper, phosphate and sulphate concentrations are controlled by copper(II) secondary minerals (pseudomalachite, libethenite and malachite) and gypsum. Nevertheless, groundwater can be used for irrigation and cattle based on quality parameters. Soils and plants (Prunus domestica L., Olea europaea L. spp. europaea and Quercus ilex L.) were collected southeast of the open pit and the exploitation substructures. The soils located in the influence of drainage water that percolated through waste material or exploitation substructures were contaminated with Cu, and Ni was close to the maximum value allowed by Portuguese legislation. These soils, however, did not show elevated Zn and Mn concentrations. The trace element content in plants was within the normal range, with Q. ilex being able to accumulate Mn and to some extent also Ni. Dispersion of trace elements seemed to be limited to a distance 1500 m down from the waste dumps in southeastern direction

    Ti6Al4V-PEEK multi-material structures – design, fabrication and tribological characterization focused on orthopedic implants

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    Acknowledgements: This work was supported by FCT through the grants SFRH/BD/128657/2017 and SFRH/BPD/112111/2015, the project PTDC/EMSTEC/5422/2014 and also by project NORTE 01-0145_FEDER-000018. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.A multi-material concept that gathers Ti6Al4V and PEEK properties in a cellular structured component was designed, fabricated and investigated targeting hip implants. SLM and pressure assisted injection techniques were used to obtain Ti6Al4V-PEEK multi-material structures. Aiming to reproduce to some extension the tribological phenomena occurring during and after hip implant insertion, five tribological tests were outlined and performed. The obtained results showed that the presence of PEEK on the Ti6Al4V-PEEK cellular structures led to a substantial improvement on the wear resistance (62% reduction in the mass loss) when compared to the material currently available on market for hip implants. The multi-material solution here investigated shows a good compromise between the primary stability after implant insertion and the wear performance.info:eu-repo/semantics/publishedVersio

    Evaluation of trace elements mobility from soils to sediments between the Iberian pyrite belt and the Atlantic Ocean

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    An environmental study was conducted in 193 stream sediments and 355 soil samples collected in the lower section of Guadiana River Basin to evaluate the trace elements transfer from one compartment into another. The objective was to evaluate the dispersion of Pb, Cu, Zn and other chemical elements resulting from upstream mines into the lower N-S sector of the Guadiana River Basin to the Atlantic Ocean. The area partly includes the Iberian Pyrite Belt, a known volcanogenic massive sulphide (VMS) province with important mining activity history. Median concentrations of the elements Cu, Pb, Zn, Al, As, Ba, Br, Ca, Mg, Mn and Na are generally higher in the studied sediments than in soils. Soils are normally acidic and mobility of elements is in these conditions higher. When the relations between upstream soils and downstream sediments were established, median values were higher in the upstream soils only for elements such as Co, Ni, K, Pb, Mn and Ti, probably the less mobile, and the Cu, Zn, Al, As, Ba, Br, Ca, Cr, Fe, Mg and Na have highest concentrations in the downstream sediments. Lead was considered the less mobile element and Zn the highly mobile of the base metals in the mining area of the lower Guadiana River. Dispersion of the metals, considering the studied soil and sediment samples is partially restricted to the mining areas or downstream sediments but close to the mine sources, where ore tailings and acid waters occur. Near the mouth, concentrations of As, Cu, Pb and Zn increase in relation with mining and other pollution sources. Interaction with salt water forces chemical elements precipitation from water and subsequent increase of their concentration in sediments. This may be the reason for the increase of those chemical elements concentrations in the sediment

    Gene trio signatures as molecular markers to predict response to doxorubicin cyclophosphamide neoadjuvant chemotherapy in breast cancerpatients

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    In breast cancer patients submitted to neoadjuvant chemotherapy (4 cycles of doxorubicin and cyclophosphamide, AC), expression of groups of three genes (gene trio signatures) could distinguish responsive from non-responsive tumors, as demonstrated by cDNA microarray profiling in a previous study by our group. In the current study, we determined if the expression of the same genes would retain the predictive strength, when analyzed by a more accessible technique (real-time RT-PCR). We evaluated 28 samples already analyzed by cDNA microarray, as a technical validation procedure, and 14 tumors, as an independent biological validation set. All patients received neoadjuvant chemotherapy (4 AC). Among five trio combinations previously identified, defined by nine genes individually investigated (BZRP, CLPTM1,MTSS1, NOTCH1, NUP210, PRSS11, RPL37A, SMYD2, and XLHSRF-1), the most accurate were established by RPL37A, XLHSRF-1based trios, with NOTCH1 or NUP210. Both trios correctly separated 86% of tumors (87% sensitivity and 80% specificity for predicting response), according to their response to chemotherapy (82% in a leave-one-out cross-validation method). Using the pre-established features obtained by linear discriminant analysis, 71% samples from the biological validation set were also correctly classified by both trios (72% sensitivity; 66% specificity). Furthermore, we explored other gene combinations to achieve a higher accuracy in the technical validation group (as a training set). A new trio, MTSS1, RPL37 and SMYD2, correctly classified 93% of samples from the technical validation group (95% sensitivity and 80% specificity; 86% accuracy by the cross-validation method) and 79% from the biological validation group (72% sensitivity and 100% specificity). Therefore, the combined expression of MTSS1, RPL37 and SMYD2, as evaluated by real-time RT-PCR, is a potential candidate to predict response to neoadjuvant doxorubicin and cyclophosphamide in breast cancer patients

    PSD95 and nNOS interaction as a novel molecular target to modulate conditioned fear: relevance to PTSD

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    Stimulation of N-methyl-D-aspartic acid receptors (NMDARs) and the resulting increase of nitric oxide (NO) production are critical for fear memory formation. Following NMDAR activation, efficient production of NO requires linking the 95 kDa postsynaptic density protein (PSD95), a scaffolding protein to neuronal nitric oxide synthase (nNOS). A variety of previously studied NMDAR antagonists and NOS inhibitors can disrupt fear conditioning, but they also affect many other CNS functions such as motor activity, anxiety, and learning. We hypothesized that disrupting nNOS and PSD95 interaction in the amygdala, a critical site for fear memory formation, will reduce conditioned fear. Our results show that systemic treatment with ZL006, a compound that disrupts PSD95/nNOS binding, attenuates fear memory compared to its inactive isomer ZL007. Co-immunoprecipitation after fear conditioning showed a robust increase in the amygdala PSD95/nNOS binding, which was blocked by systemic pre-administration of ZL006. Treatment of amygdala slices with ZL006 also impaired long-term potentiation (LTP), a cellular signature of synaptic plasticity. Direct intra-amygdala infusion of ZL006 also attenuated conditioned fear. Finally, unlike NMDAR antagonist MK-801, ZL006 does not affect locomotion, social interaction, object recognition memory, and spatial memory. These findings support the hypothesis that disrupting the PSD95/nNOS interaction downstream of NMDARs selectively reduces fear memory, and highlights PSD95/nNOS interaction as a novel target for fear-related disorders, such as posttraumatic stress disorder

    Accumulation and translocation of trace elements in Cistus ladanifer L. from IPB portuguese mining areas

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    The accumulation and translocation of As, Cu, Pb and Zn in different Cistus ladanifer L. populations colonizing mine areas of Brancanes, Sao Domingos, Chanca and Caveira (Portuguese Iberian Pyrite Belt) and two control areas (Caldeirao and Pomarao) was evaluated. Soils from Sao Domingos and Caveira presented the greatest total concentrations of As, Cu and Pb. Brancanes and Chanca mine areas might be considered in natural attenuation processes relatively to the past mining activity that cessed about one century ago. Plants are, except those from Caveira mine area, Zn accumulators. The concentration of Pb in plants (aerial part) from the control and Sao Domingos areas are within the range considered phytotoxic. Trace elements concentrations in plants are below the domestic animal toxicity limits. Cistus ladanifer might be used in phytostabilization programs of other mine areas as trace elements concentrations in soils did not influence the behaviour of the different plant population

    Geochemical behavior of trace elements in the surroundings of Mina de S. Domingos, Alentejo: Tapada and Telheiro sites

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    Even thought the mining activity in S Domingos finished more than forty years ago, the mining site is still a source of polluting trace elements for soils and sediments downstream the open pit. The present work aims to evaluate the contamination of these soils and sediments. Therefore two sampling areas were selected: one, assumed as non-contaminated (Tapada), is used to access the reference values of the chemical variables for this region, and the other, downstream from the mining site, is affected by the mining activity (Telheiro). The soils and sediments were characterised on the <2 mm fraction, by pH (H2O), organic carbon and free iron oxides content. A total multi element analysis was done on the same fraction. Univariate and multivariate statistics were performed, as well as geochemical mapping using geostatistical interpolation methods. In Telheiro some samples had high levels of trace elements (mainly As, Pb, Sb, and Hg) and very low pH values (minimum 2.66), this is particularly obvious in the samples collected close to the acid mine drainage. In Tapada no contaminated soils were found. The multivariate analysis showed an association between As, Pb and Sb and between Cu and Z
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