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The Petawatt Aquitaine Laser (PETAL) facility was designed and constructed by the French Commissariat à l'énergie atomique et aux énergies alternatives (CEA) as an additional PW beamline to the Laser MegaJoule (LMJ) facility. PETAL energy is limited to 1 kJ at the beginning due to the damage threshold of the final optics. In this paper, we present the commissioning of the PW PETAL beamline. The first kJ shots in the amplifier section with a large spectrum front end, the alignment of the synthetic aperture compression stage and the initial demonstration of the 1.15 PW @ 850 J operations in the compression stage are detailed. Issues encountered relating to damage to optics are also addressed.
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Mangrove forests play an important role in biogeochemical cycles of metals, nutrients, and C in coastal ecosystems. However, these functions could be strongly affected by the mangrove soil degradation. In this study, we performed an intensive sampling characterizing mangrove soils under different types of environment (lagoon/gulf) and vegetation (Rhizophora/Avicennia/dead mangrove) in the Venezuelan coast. To better understand the spatial heterogeneity of the composition and characteristics of the soils, a wide range of the soil attributes were analyzed. In general, the soils were anoxic (Eh < 200 mV), with a neutral pH and low concentration in toxic metals; nevertheless, they varied widely in the soil and its quality-defining parameters (e.g., clay contents, total organic carbon, Fe, Al, toxic trace metals). It is noteworthy that the mangroves presented a low FePyrite content due to a limitation in the Fe oxyhydroxide contents, especially in soils with higher organic C content (TOC > 15%). Finally, the dead mangrove showed significantly lower amounts of TOC and fibers (in comparison to the well-preserved mangrove forest), which indicates that the C pools in mangrove soils are highly sensitive also to natural impact, such as ENSO.
Assuntos
Avicennia/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Florestas , Rhizophoraceae/crescimento & desenvolvimento , Solo , Áreas Alagadas , Avicennia/química , Metais/análise , Rhizophoraceae/química , Solo/química , Solo/normas , Oligoelementos/análise , VenezuelaRESUMO
Different types of crystalline carbon nanomaterials were used to reinforce polyaniline for use in electromechanical bilayer bending actuators. The objective is to analyze how the different graphitic structures of the nanocarbons affect and improve the in situ polymerized polyaniline composites and their subsequent actuator behavior. The nanocarbons investigated were multiwalled carbon nanotubes, nitrogen-doped carbon nanotubes, helical-ribbon carbon nanofibers and graphene oxide, each one presenting different shape and structural characteristics. Films of nanocarbon-PAni composite were tested in a liquid electrolyte cell system. Experimental design was used to select the type of nanocarbon filler and composite loadings, and yielded a good balance of electromechanical properties. Raman spectroscopy suggests good interaction between PAni and the nanocarbon fillers. Electron microscopy showed that graphene oxide dispersed the best, followed by multiwall carbon nanotubes, while nitrogen-doped nanotube composites showed dispersion problems and thus poor performance. Multiwall carbon nanotube composite actuators showed the best performance based on the combination of bending angle, bending velocity and maximum working cycles, while graphene oxide attained similarly good performance due to its best dispersion. This parallel testing of a broad set of nanocarbon fillers on PAni-composite actuators is unprecedented to the best of our knowledge and shows that the type and properties of the carbon nanomaterial are critical to the performance of electromechanical devices with other conditions remaining equal.
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Wastewater discharge from shrimp farming is one of the main causes of eutrophication in mangrove ecosystems. We investigated the phosphorus (P) geochemistry in mangrove soils affected by shrimp farming effluents by carrying out a seasonal study of two mangrove forests (a control site (CS); a site affected by shrimp farm effluents (SF)). We determined the soil pH, redox potential (Eh), total organic carbon (TOC), total phosphorus (TP), and dissolved P. We also carried out sequential extraction of the P-solid phases. In SF, the effluents affected the soil physicochemical conditions, resulting in lower Eh and higher pH, as well as lower TOC and higher TP than in CS. Organic P forms were dominant in both sites and seasons, although to a lesser extent in SF. The lower TOC in SF was related to the increased microbial activity and organic matter decomposition caused by fertilization. The higher amounts of P oxides in SF suggest that the effluents alter the dominance of iron and sulfate reduction in mangrove soils, generating more reactive Fe that is available for bonding to phosphates. Strong TP losses were recorded in both sites during the dry season, in association with increased amounts of exchangeable and dissolved P. The higher bioavailability of P during the dry season may be attributed to increased mineralization of organic matter and dissolution of Ca-P in response to more oxidizing and acidic conditions. The P loss has significant environmental implications regarding eutrophication and marine productivity.
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Aquicultura , Monitoramento Ambiental , Fósforo/análise , Poluentes do Solo/análise , Solo/química , Poluentes Químicos da Água/análise , Áreas Alagadas , Animais , Brasil , Crustáceos , Eutrofização , Oxirredução , Estações do Ano , Águas Residuárias/análise , Águas Residuárias/químicaRESUMO
A full-scale passive treatment plant using barium carbonate (BaCO3), the mineral witherite, as a Dispersed Alkaline Substrate (DAS) for strongly contaminated acid mine drainage was implemented for the first time globally at Mina Concepción, located in the Iberian Pyrite Belt (SW Spain). The plant was monitored over a 105-day period, covering the wettest months of the hydrological year and with a mean flow around 4 L s-1. The AMD treated in the plant exhibits a high strength, with an average sulfate concentration around 1500 mg L-1 and net acidity close to 1000 mg L-1 as CaCO3 equivalent. According to the above, the loading rate for SO4 and Fe was around 400 and 80 kg day-1, respectively. The treatment process produced an alkaline effluent with low metal content. Nearly complete removal of most metal(loid)s was achieved, with significant sulfate decrease to below 500 mg L-1 in the alkaline outflow of the barium carbonate tank. Barium carbonate demonstrated superior performance compared to magnesia, particularly in enhancing alkalinity and lowering net acidity and concentrations of sulfate and manganese. The high efficiency attained by the plant after the barium carbonate treatment is evidenced by compliance with environmental water quality standards for most contaminants.
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Bacterial and archaeal community structures and diversity of three different sedimentary environments (BH1A, BH2A and BH3A) in the acid pit lake of a chalcopyrite mine at Touro (Spain) were determined by 16S rRNA gene PCR-DGGE and sequencing of clone libraries. DGGE of bacterial and archaeal amplicons showed that the sediments harbor different communities. Bacterial 16S rRNA gene sequences were assigned to Acidobacteria, Actinobacteria, Cyanobacteria, Planctomycetes, Proteobacteria, Chloroflexi and uncultured bacteria, after clustering into 42 operational taxonomic units (OTUs). OTU 2 represented approximately 37, 42 and 37 % of all sequences from sediments BH1A, BH2A and BH3A, respectively, and was phylogenetically related to uncultured Chloroflexi. Remaining OTUs were phylogenetically related to heterotrophic bacteria, including representatives of Ferrithrix and Acidobacterium genera. Archaeal 16S rRNA gene sequences were clustered into 54 OTUs. Most of the sequences from the BH1A sediment were assigned to Euryarchaeota, whereas those from BH2A sediment were assigned to Crenarchaeota. The majority of the sequences from BH3A sediment were assigned to unclassified Archaea, and showed similarities to uncultured and unclassified environmental clones. No sequences related to Acidithiobacillus and Leptospirillum, commonly associated with acid mine drainage, were detected in this study.
Assuntos
Archaea/isolamento & purificação , Bactérias/isolamento & purificação , Cobre/análise , Sedimentos Geológicos/química , Lagos/microbiologia , Microbiota , Archaea/classificação , Archaea/genética , Bactérias/classificação , Bactérias/genética , Concentração de Íons de Hidrogênio , Lagos/química , RNA Ribossômico 16S/genéticaRESUMO
The effectiveness of a combination of soil solarization and poultry manure (raw or pelletized) amendments for the control of root-knot nematode (Meloidogyne incognita) was tested in carnation (Dianthus caryophyllus) crops grown in in-ground beds under plastic-covered greenhouse conditions in southern Spain. Our trials demonstrated that soil solarization alone did not provide sufficient control of root-knot nematode, because the carnation growing season in this region only partly coincides with the most effective period for solarization, resulting in an insufficient duration of treatment during a key period for effectiveness. Chemical fumigation with 1,3-dichloropropene + chloropicrin prior to planting was effective in reducing nematode population densities in soil. Its effects spanned 9 months after planting, resulting in acceptable crop yields. In comparison, the combination of soil solarization and raw or pelletized poultry manure was slightly less effective than chemical fumigation for control of this pathogen but crop yields after 9 months were similar. However, the higher root gall indices observed after 9 months, in comparison with chemically fumigated plots, indicated the need for a reapplication of the organic manure treatment at the start of each successive growing season.
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BACKGROUND: Treatment with GH promotes linear growth and decreases body fat in patients with isolated GH deficiency (GHD). However, few studies have analyzed how GH replacement modifies ghrelin levels and the adipokine profile and the relationship of these modifications with the metabolic changes. AIMS: To analyze the eventual differences between serum levels of leptin, leptin soluble receptor (sOBR), resistin, adiponectin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), total (TG) and acylated ghrelin (AG) and lipid and glycemic profiles in children with GHD, as well as to determine the effect of GH replacement on these parameters during the first year of therapy. SUBJECTS AND METHODS: Thirty pre-pubertal (Tanner stage I) GHD children and 30 matched controls were enrolled. Children with GHD were studied before and after 6 and 12 months of GH treatment. Weight, height, BMI, fasting glucose, insulin, lipid profile and serum levels of adipokines and ghrelin were studied at every visit. Adi - pokines, insulin and ghrelin levels were determined by using commercial radio- and enzymoimmunoassays. RESULTS: At baseline children with GHD had significantly higher sOBR (p<0.01) and adiponectin (p<0.01) levels than controls. Treatment with GH resulted in a decline in leptin (p<0.05) and TG (p<0.001) levels, an increase of homeostasis model assessment index and restored IGF-I levels (p<0.001). CONCLUSIONS: These data indicate that GH replacement has a negative effect on leptin levels and may also produce a slight unfavorable effect on carbohydrate metabolism. In addition, the changes observed in the adipokine profile appear to be independent of body mass index.
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Adiponectina/sangue , Grelina/sangue , Hormônio do Crescimento/administração & dosagem , Hormônio do Crescimento Humano/deficiência , Interleucina-6/sangue , Leptina/sangue , Resistina/sangue , Fator de Necrose Tumoral alfa/sangue , Antropometria , Glicemia/metabolismo , Índice de Massa Corporal , Metabolismo dos Carboidratos/efeitos dos fármacos , Criança , Hormônio do Crescimento/farmacologia , Humanos , Estudos Prospectivos , Receptores para Leptina/metabolismoRESUMO
The present study was carried out to test the viability of a method of reductive dehalogenation of α-, ß-, γ-, and δ-hexachlorocyclohexane (HCH) in soil slurry systems. The soil slurries were maintained under anaerobic conditions, with titanium(III) citrate as a reducing agent and hydroxocobalamin (vitamin B(12a)) as a catalyzing agent. Experiments were carried out with two soil samples with markedly different characteristics (particularly regarding organic matter content), at a small scale and larger reactor scale. HCH concentration was monitored throughout the 24 h duration of the tests. In the low organic matter soil HCH isomers degraded rapidly, in both the small scale and reactor systems, and undetectable levels (<0.5%) were reached within 5 h. However, complete degradation of HCH isomers was not achieved in soil with high organic matter content, and there were differences between the results obtained in the small scale and reactor systems. In the small scale system, the levels of degradation reached 93, 88, 94, and 91%, for α-, ß-, γ-, and δ-HCH, respectively, and the nondegraded HCH was sorbed in the soil. In the reactor system, the reaction stopped after two hours (no more than 65% of any of the isomers was degraded).
Assuntos
Halogenação , Hexaclorocicloexano/química , Hidroxocobalamina/química , Esgotos/química , Solo/química , Isomerismo , Oxirredução , Fatores de TempoRESUMO
In May 2017, a spill from La Zarza pit lake (SW Spain) resulted in the release of approximately 270,000â¯m3 of extremely acidic waters to the Odiel River. Around 780â¯×â¯103â¯kg of Fe, 170â¯×â¯103â¯kg of Al, 2.15â¯×â¯103â¯kg of As and high amounts of other trace metals and metalloids were spilled. The purpose of this study is to explain the causes, consequences and impacts of the mine spill on the receiving water bodies. To this end, an extensive sampling along the mine site, river and estuary as well as a hydrological model of the pit lake was performed. Around 53â¯km of the Odiel River's main course, which was already contaminated by acid mine drainage (AMD), were affected. The mine spill resulted in an incremental impact on the Odiel River water quality. Thus, dissolved concentrations of some elements increased in the river up to 450 times; e.g. 435â¯mg/L of Fe and 0.41â¯mg/L of As. Due to low pH values (around 2.5), most metals (e.g., Cu, Zn, Mn, Cd) were transported in the dissolved phase to the estuary, exhibiting a conservative behavior and decreasing their concentration only due to dilution. However, dissolved concentrations of Fe, Cr, Pb, Se, Sb, Ti, V and especially As decreased significantly along the river due to Fe precipitation and sorption/coprecipitation processes. At the upper zone of the estuary, a noticeable increment of metal concentrations (up to 77 times) was also recorded. The water balance illustrates the existence of groundwater inputs (at least 16% of total) to the pit lake, due probably to local infiltration of rainwater at the mining zone. The probable existence of an ancient adit connected to the pit lake indicates that potential releases could occur again if adequate prevention measures are not adopted.
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Ácidos/análise , Monitoramento Ambiental/métodos , Lagos/química , Metais/análise , Mineração , Rios/química , Poluentes Químicos da Água/análise , Ácidos/toxicidade , Estuários , Ferro/análise , Espanha , Sulfetos/análise , Qualidade da ÁguaRESUMO
Mixtures of wastes were prepared to improve on the characteristics of the individual ingredients as Technosols, with special attention given to heavy metal extractability. An anaerobic digested sewage sludge and a CaO-treated aerobic sludge were used. A mixture of the two sludges (50:50 DW basis) was also prepared to provide a third type of sludge. The residues were mixed with other types of waste, such as fly ash, Linz-Donowitz slag, foundry sand, shot blasting machine scrap, fettling and barley straw. Extractability of Cu, Cr, Ni, and Zn by 0.01 M CaCl(2) extraction (Me(CACI(2)) was carried out, and leachability of these elements was estimated by acidification of an aqueous suspension of the mixtures with 0.5 N acetic acid (Me(acetic)). The total concentrations of the metals were also determined (Me(T)). The Me(CACI(2)/Me(T) ratios for Cu and Ni (means: 4.0% and 3.1%) were higher than those for Cr and Zn (means: 0.07% each). The mean Me(acetic)/Me(T) ratios followed the order Ni, Zn, Cu, and Cr (19.5%, 4.1%, 3.7%, and 0.09%, respectively). The results highlight the existence of complex interactions among organic matter solubility, pH and heavy metal extractability.
Assuntos
Metais Pesados/química , Esgotos/química , Aerobiose , Anaerobiose , Cloreto de Cálcio/química , Concentração de Íons de Hidrogênio , Solubilidade , Fatores de TempoRESUMO
AIM: Clinical and capillaroscopic evaluation of an association of Ruscus aculeatus, hesperidin methylchalcone (HMC) and ascorbic acid in chronic venous insufficiency METHODS: A prospective, multicenter and open clinical study. Chronic venous insufficiency patients were studied using clinical, etiological, anatomical, physiological classification (CEAP) symptom scale. Symptomatology, CEAP scale, and baseline, 2-, 4-, 6- and 8-week skin capillaroscopy were assessed. Treatment consisted of two capsules per day of Ruscus aculeatus 150 mg/HMC 150 mg/ascorbic acid 100 mg during 8 weeks. RESULTS: A total of 124 patients were studied, 109 female (89.28%), with a mean age of 52.5 (33-80+9.8). Initial intense reports were 79% pain, 85% heaviness, 74% cramps, 82% edema, decreasing to 20%, 12%, 8% and 14%, respectively, within two weeks, and symptomatology being absent at the end of treatment. Capillaroscopy changes at treatment completion were: 98% to 20% inter-capillary fluid decrease; 80% to 20% efferent loop thickening; 5% to 2% peri-capillary bed, and 5% to 4% mega-capillaries. CONCLUSION: Severe symptom decrease started from the second week until there were no symptoms at the end of treatment. It is the first time morphologic changes were observed in chronic venous insufficiency through capillaroscopy following a pharmacological intervention. Capillary-level effect was proportional to symptom decrease. Improvement was seen from the second week of treatment.
Assuntos
Antioxidantes/uso terapêutico , Ácido Ascórbico/uso terapêutico , Chalconas/uso terapêutico , Hesperidina/análogos & derivados , Fitoterapia , Extratos Vegetais/uso terapêutico , Ruscus , Insuficiência Venosa/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Doença Crônica , Feminino , Hesperidina/uso terapêutico , Humanos , Perna (Membro)/irrigação sanguínea , Masculino , Angioscopia Microscópica , Pessoa de Meia-Idade , Insuficiência Venosa/complicações , Insuficiência Venosa/patologiaRESUMO
Mangrove forests play an important role in biogeochemical cycle of C, storing large amounts of organic carbon. However, these functions can be controlled by the high spatial heterogeneity of these intertidal environments. In this study were performed an intensive sampling characterizing mangrove soils under different type of vegetation (Rhizophora/Avicennia/dead mangrove) in the Venezuelan coast. The soils were anoxic, with a pH~7; however other soil parameters varied widely (e.g., clay, organic carbon). Dead mangrove area showed a significant lower amounts of total organic carbon (TOC) (6.8±2.2%), in comparison to the well-preserved mangrove of Avicennia or Rhizophora (TOC=17-20%). Our results indicate that 56% of the TOC was lost within a period of 10years and we estimate that 11,219kgm-2 of CO2 was emitted as a result of the mangrove death. These results represent an average emission rate of 11.2±19.17tCO2ha-1y-1.
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Avicennia , Carbono/análise , Solo/química , Áreas Alagadas , Monitoramento Ambiental , Florestas , RhizophoraceaeRESUMO
Calculations of critical loads of acidity within Europe have shown Galicia to be one of the regions in Spain with the highest risk of soil acidification by deposition of atmospheric pollutants. We used the simple mass balance method (SMB) to derive critical loads of sulphur and nitrogen for forest soils in Galicia using available site-specific information. Exceedance of acidic deposition was calculated using the deposition levels of N and S registered in 2001. Most forest ecosystems analysed can support acid loads of more than 2000 eq N ha(-1) year(-1). The lowest critical loads of acidity (1483 eq ha(-1) year(-1)) occurred in coniferous forest stands growing on shallow soils developed on slates, in the interior zone. The highest critical load values (9386 eq ha(-1) year(-1)) were observed in coniferous stands in zones with elevated precipitation rates, in the littoral area. The critical load for acidity was exceeded in 5% of the forest soils. Such exceedances were mainly caused by deposition of nitrogen compounds. The contribution of sulphur deposition to acid exceedance was important in the surroundings of the city of A Coruña. Analysis of rainfall bulk composition revealed that N deposition in Galicia was mainly due to ammonium emissions, probably derived from agricultural and cattle breeding activities.
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Chuva Ácida/análise , Nitrogênio/análise , Poluentes do Solo/análise , Enxofre/análise , Agricultura , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Centrais Elétricas , Espanha , Árvores , Emissões de VeículosRESUMO
The behaviour of the organochlorine pesticide hexachlorocyclohexane (HCH) is investigated. The concentrations of alpha-, beta-, gamma-, and delta-HCH isomers were measured in soils, rhizosphere and vegetation in a contaminated area in Galicia (NW Spain). The total concentration of HCH in soils reached values close to 20,000 mgkg(-1). The plants analysed (Avena sativa L., Chenopodium spp., Solanum nigrum L., Cytisus striatus (Hill) Roth, and Vicia sativa L.) accumulated HCH, especially the beta-HCH isomer, in their tissues. The most likely mechanisms of HCH accumulation in plants were sorption of soil HCH on roots and sorption of volatilized HCH on aerial plant tissues. The concentrations of HCH obtained from the bulk and rhizosphere soils of selected plant species suggest that roots tend to reduce levels of the HCH isomers in the rhizosphere. The results reflect the importance of vegetation in the distribution of organochlorine compounds in the soil-plant system.
Assuntos
Monitoramento Ambiental/métodos , Hexaclorocicloexano/química , Inseticidas/química , Plantas/metabolismo , Poluentes do Solo/química , Absorção , Biodegradação Ambiental , Ecossistema , Interações Hidrofóbicas e Hidrofílicas , Isomerismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Espanha , VolatilizaçãoRESUMO
Underground mine drainages are extremely difficult to study due to the lack of information about the flow path and source proximity in relation to the outflow adit. Geochemical processes controlling metals and acidity fluxes in a complex anthropogenic mine aquifer in SW Spain during the dry and rainy season were investigated by geochemical and statistical tools. High concentrations of acidity, sulfate, metals and metalloids (e.g. Fe, Cu, Zn, As, Cd, Ni, Co) were observed due to intense sulfide oxidation processes. The high residence time inside the anthropogenic aquifer, around 40days, caused the release of significant quantities of metals linked to host rocks (e.g. Al, Ca, Ge, Li, Mg, REE). The most outstanding characteristic of the acid mine drainage (AMD) outflows is the existence of higher Fe/SO4 molar ratios than those theoretical of pyrite (0.50) during most of the monitored period, due to a fire which occurred in 1949 and remained active for decades. Permanent and temporal retention mechanisms of acidity and metals were observed in the galleries. Once released from sulfide oxidation, Pb and As are sorbed on Fe oxyhydroxysulfate or precipitated as low solubility minerals (i.e. anglesite) inside the galleries. The precipitation of evaporitic sulfate salts during the dry season and the subsequent re-dissolution after rainfall control the fluxes of acidity and main metals (i.e. Fe, Mg, Al) from this anthropogenic aquifer. Some elements, such as Cd, Cu, Ni, REE and Zn, are retained in highly soluble sulfate salts while other elements, such as Ge, Pb and Sc, have a lower response to washout processes due to its incorporation in less soluble sulfate salts. In this way, metal concentration during the washout processes would be controlled by the proportion and solubility of each type of evaporitic sulfate salt stored during the dry season. The recovery of metals of economic interest contained in the AMD could help to self-finance the remediation of these waters in derelict mines worldwide.
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Água Subterrânea/química , Metais/análise , Mineração , Sulfatos/análise , Poluentes Químicos da Água/análise , Precipitação Química , Recuperação e Remediação Ambiental , Ferro/análise , Minerais/análise , Solubilidade , Espanha , Sulfetos/análise , Movimentos da ÁguaRESUMO
Scarcity of waters is the main limiting factor of economic development in most arid and semi-arid regions worldwide. The construction of reservoirs may be an optimal solution to assure water availability if the drainage area shows low disturbances. This is the quandary of mining areas where economic development relies on water accessibility. Water acidification trends were investigated in the Sancho Reservoir (SW Spain) in the last 20 years. The acidity (pH3-5) and high dissolved metal concentrations (e.g., 4.4 mg/L of Al, 2.1mg/L of Mn, 1.9 mg/L of Zn) observed in the Sancho, together with the large volume stored (between 37 and 55 Mm(3)), makes this reservoir an extreme case of surface water pollution worldwide. A progressive acidification has been observed since 2003, as evidenced by decreasing pH values and increasing dissolved metal concentrations, especially noticeable after 2007. The increase in the net acidity in the reservoir originates from the higher input of metals and acidity due to the rebound effect after the mining closure in 2001. This trend was not detected in the river feeding the reservoir due to its great hydrological and hydrochemical variability, typical of the Mediterranean climate. Chemical analysis and absolute dating of sediments identified a progressive enrichment in S and metals (i.e., Fe, Zn Cu, Ni, Co and Cd) in the upper 20 cm, which reinforce the year 2002/03 as the onset of the acidification of the reservoir. The decrease of pH values from 4-5 to 3-4 occurred later than the increase in sulfate and metals due to pH-buffering by Al. The acid mine drainage (AMD) pressure has caused an increment of dissolved Fe and other metals, as well as a change in the pH buffering role, exerted now by Fe. These processes were simulated by PHREEQC, which confirms that the acidification trend will continue, causing pH values to reach 2.5 if AMD pressure persists.
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Laser Doppler scattering from Tl(I) ions moving synchronously through an ensemble of gramicidin channels in a bilayer membrane gives their intrachannel velocity distribution. The observed velocity distributions are unimodal indicating that ion flow through some region or regions of the channels is relatively steady. Average intrachannel velocities range from 3.75 x 10(-2) m/s to 2.38 x 10(-1) m/s for transmembrane potentials between 10 mV and 150 mV, respectively.
Assuntos
Gramicidina/química , Canais Iônicos , Bicamadas Lipídicas , Íons , Cinética , Fluxometria por Laser-Doppler/instrumentação , Fluxometria por Laser-Doppler/métodos , Potenciais da Membrana , Modelos Biológicos , Potenciometria , TálioRESUMO
The trace elements present at highest concentrations were Cr and Zn, which probably originated from the dumping of effluent from a tanning factory. High proportions of these two elements were associated with the residual fraction. Biodeposits and sediments showed high concentrations of Cd and Pb in the reactive fraction, with a high proportion of the concentration in the reactive fraction being associated with carbonates. Nickel showed a higher degree of pyritization than the previous elements, although most of the Ni was associated with the residual and reactive fractions. Arsenic, Hg and Cu showed high degrees of pyritization, particularly below a depth of 5 cm. The results demonstrate that those elements with a high degree of pyritization may be released into the water through oxidation of the metal sulphides that they form when in suspension in oxic sea water, with the subsequent risk of increased bioavailability to benthic fauna.
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Bivalves/química , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Oligoelementos/análise , Poluentes Químicos da Água/análise , Animais , Arsênio/análise , Cromo/análise , Cobre/análise , Resíduos Industriais , Ferro/análise , Manganês/análise , Mercúrio/análise , Oxirredução , Rios , Espanha , Espectrofotometria Ultravioleta , Curtume , Zinco/análiseRESUMO
Fungicidal activity of 36 natural and synthetic sesquiterpene lactones with guaianolide, trans, trans-germacranolide, cis, cis-germacranolide, melampolide, and eudesmanolide carbon skeletons was evaluated against the phytopathogenic fungi Colletotrichum acutatum, C. fragariae, C. gloeosporioides, Fusarium oxysporum, Botrytis cinerea, and Phomopsis sp. Dose-response data for the active compounds dehydrozaluzanin C, dehydrocostuslactone, 5alpha-hydroxydehydrocostuslacone, costunolide, and zaluzanin C are presented. A new 96-well microbioassay procedure for fast and easy evaluation of antifungal activity was used to compare these compounds with commercial fungicide standards. Some structure-activity conclusions are also presented.