Browsing by Author "Candeias, Carla"
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- Acid mine drainage from the Panasqueira mine and its influence on Zêzere river (Central Portugal)Publication . Candeias, Carla; Ávila, Paula Freire; Silva, Eduardo Ferreira da; Ferreira, Adelaide; Salgueiro, Ana Rita; Teixeira, João PauloThe Panasqueira hydrothermal mineralization, located in central Portugal, is the biggest Sn–W deposit of the Western Europe. The main evidences of the mining exploitation and ore treatment operations are testified with huge tailings, mainly, in the Rio and Barroca Grande areas. The mining and beneficiation processes, at the site, produces metal rich mine wastes. Oxidation of sulfides tailings and flow from open impoundments are responsible for the mobilization and migration of metals from the mine wastes into the environment. Acid mine drainage (AMD) discharged from Rio tailing has a pH around 3 and high metal concentrations. In Zêzere river, Fe and As are the most rapidly depleted downstream from AMD once As adsorbs, coprecipitate and form compounds with iron oxyhydroxides. The Zêzere river waters are oversaturated with respect to kaolinite and goethite and ferrihydrite can precipitate on stream with a near-neutral pH. At sites having low pH the dissolved Fe species in the water, mainly, occur as sulfate complexes due to a high SO4 concentration. Melanterite (Fe2+(SO4)·7(H2O)) and minor amounts of rozenite (Fe2+(SO4)·4(H2O)) and szomolnokite (Fe2+(SO4)·(H2O)) were observed on Rio tailing basement.
- Assessment of Panasqueira mine surrounding soils through a contamination factorPublication . Candeias, Carla; Salgueiro, Ana Rita; Silva, Eduardo Ferreira da; Ávila, Paula Freire
- Assessment of potential health risk for inhabitants of S. Francisco de Assis living near Panasqueira mine (Portugal)Publication . Candeias, Carla; Melo, Rita; Ávila, Paula Freire; Ferreira, E.; Salgueiro, Ana Rita; Teixeira, João Paulo
- Assessment of the soil contamination by potentially toxic elements in Aljustrel mining area in order to implement soil reclamation strategiesPublication . Candeias, Carla; Silva, E. Ferreira da; Salgueiro, Ana Rita; Pereira, H. Garcia; Matos, João Xavier; Ávila, Paula Freire
- Avaliação do impacte da drenagem de água ácida na hidrogeoquímica do rio Zêzere : o caso de estudo da mina da Panasqueira, PortugalPublication . Ávila, Paula Freire; Ferreira, Adelaide; Salgueiro, Ana Rita; Candeias, Carla; Melo, Rita; Silva, Eduardo Ferreira daA mineralização hidrotermal da Panasqueira localiza-se no centro de Portugal e é o maior depósito de Sn-W da Europa Ocidental. A exploração mineira e as operações do tratamento do minério deram origem a escombreiras de grandes dimensões, principalmente, nas áreas do Cabeço do Pião (escombreira do Rio) e Barroca Grande. A exploração e beneficiação dos processos de tratamento no local geraram rejeitados ricos em metais. A oxidação dos sulfuretos existentes na escombreira e o escoamento pela barragem de contenção de lixiviados, são os responsáveis pela mobilização e migração dos metais a partir dos rejeitados da mina até ao meio ambiente. As descargas das drenagens de água ácida da escombreira do Rio possuem um valor baixo de pH (pH < 3) e elevadas concentrações em metais pesados. No Rio Zêzere, o Fe e o As são os elementos que apresentam o mais rápido decaimento de teores uma vez que o As é adsorvido/e ou coprecipita e forma compostos pouco solúveis com os óxidos e hidróxidos de ferro. Em locais com baixo pH as espécies de Fe dissolvidas ocorrem, principalmente, como sulfatos complexos devido à elevada concentração de SO4 2-. Melanterite (Fe2+(SO4).7(H2O)) e pequenas quantidades de rozenite (Fe2+(SO4).4(H2O)) e szomolnokite (Fe2+(SO4).(H2O)) foram observadas na base da escombreira do Rio.
- Caracterização de teores em cobre nos solos e sedimentos na envolvente à Mina de AljustrelPublication . Guimarães, T.; Almeida, J. A.; Brito, M. G.; Salgueiro, Rita; Silva, E.; Candeias, Carla; Ávila, Paula Freire
- Characterization of saline waters from Ria de Aveiro (Portugal) for potential use in SPA treatmentsPublication . Almeida, Lara; Rocha, Fernando; Candeias, CarlaABSTRACT: This study aims to characterize the properties of the saline waters from an old saltpan at the Ria de Aveiro, and assess its potential use in skin treatments. Eight water samples were collected from two different areas of an open-air salt SPA, during four different climatic seasons between 2020 and 2021. Physichochemical parameters of the waters revealed an alkaline pH and high electrical conductivity (EC), mainly in the area where salt production takes place (Area 2). Chemical analysis revealead an enrichment in potentially toxic elements (PTEs), namely Cu and Cr6+, in samples of Area 2, collected in the summer. MEV-EDE analysis of the total suspended matter (TSM) showed the presence of NaCl cubic particles, microorganisms (e.g., diatoms) and particles enriched in PTEs. The low concentrations of PTEs does not pose a risk to SPA users, allowing these waters to be used as a liquid phase in SPA treatments for skin diseases.
- Dust Characterization and Its Potential Impact during the 2014-2015 Fogo Volcano Eruption (Cape Verde)Publication . Candeias, Carla; Ávila, Paula Freire; Alves, Célia; Gama, Carla; Sequeira, Cristina; Silva, E. Ferreira da; Rocha, FernandoABSTRACT: Fogo (Fogo Island) is the youngest and most active volcano of Cape Verde. The last eruption occurred in 2014-2015. Aiming to assess the dust sources that impacted the air quality during the present study period, fresh lava samples were collected, while Saharan dust intrusions and transport were modeled. Rooftop dust was also collected on the island dwellings and a mineralogical and chemical characterization was undertaken. Air quality monitors were used to obtain concentrations of atmospheric particulate matter (PM) and gaseous pollutants. The mineralogical constitution was assessed by XRD and Electron Microprobe. The pseudototal chemical concentration was performed by XRF, ICP-MS and SEM; the latter includes particles morphology. During the study, WRF-CHIMERE results showed the intrusion of desert dust which affected the air quality. Lava was classified as tephritic to basanitic, with high potassium content. The Pollution Load Index for rooftop dust was > 1 in all samples, suggesting an enrichment. Higher values were found in dust size fraction < 63 mu m, with contamination factor pointing to high enrichment of As, Ni and Pb, and very high enrichment of Cd. The non-carcinogenic hazard estimated for children suggested that health problems may arise. The carcinogenic risk was above the target risk, mostly due to As > Pb > Co. Ingestion was the main exposure route. PM10 concentrations exceeded the 24-h mean of 50 mu g/m(3) recommended by WHO. Nevertheless, TVOCs displayed levels lower than guidelines. The highest levels of CO2 were recorded in more populated villages and farthest from the volcano.
- Geochemical, mineralogical and morphological characterisation of road dust and associated health risksPublication . Candeias, Carla; Vicente, Estela; Tomé, Mário; Rocha, Fernando; Ávila, Paula Freire; Alves, CéliaABSTRACT: Road dust resuspension, especially the particulate matter fraction below 10 mu m (PM10), is one of the main air quality management challenges in Europe. Road dust samples were collected from representative streets (suburban and urban) of the city of Viana do Castelo, Portugal. PM10 emission factors (mg veh(-1) km(-1)) ranging from 49 (asphalt) to 330 (cobble stone) were estimated by means of the United Stated Environmental Protection Agency method. Two road dust fractions (<0.074 mm and from 0.0074 to 1 mm) were characterised for their geochemical, mineralogical and morphological properties. In urban streets, road dusts reveal the contribution from traffic emissions, with higher concentrations of, for example, Cu, Zn and Pb. In the suburban area, agriculture practices likely contributed to As concentrations of 180 mg kg(-1) in the finest road dust fraction. Samples are primarily composed of quartz, but also of muscovite, albite, kaolinite, microcline, Fe-enstatite, graphite and amorphous content. Particle morphology clearly shows the link with natural and traffic related materials, with well-formed minerals and irregular aggregates. The hazard quotient suggests a probability to induce non-carcinogenic adverse health effects in children by ingestion of Zr. Arsenic in the suburban street represents a human health risk of 1.58 x 10(-4).
- Heavy metal pollution in mine-soil-plant system in S. Francisco de Assis - Panasqueira mine (Portugal)Publication . Candeias, Carla; Melo, Rita; Ávila, Paula Freire; Silva, Eduardo Ferreira da; Salgueiro, Ana Rita; Teixeira, João PauloThe active Panasqueira mine is a tin–tungsten (Sn–W) mineralization hosted by metasediments with quartz veins rich in ferberite. The economic exploitation has been focused on wolframite, cassiterite and chalcopyrite. The mineralization also comprises several sulphides, carbonates and silver sulphosalts. The mining and beneficiation processes produces arsenic-rich mine wastes laid up in huge tailings and open air impoundments that are the main source of pollution in the surrounding area, once the oxidation of sulphides can result in the mobilization and migration of trace metals/metalloids from the mining wastes into the environment, releasing contaminants into the ecosystem. A geochemical survey was undertaken, in order to investigate the environmental contamination impact on agricultural and residential soils in S. Francisco de Assis village due to the mining activities. Rhizosphere samples, vegetables (Solanum tubersum sava and Brassica olerácea L.) which constitute an important part of the local human diet), irrigation waters and road dusts were collected in private residences in S. Francisco de Assis village. According to the Ontario guidelines ( Ministry of Environment, 2011), the Arsenic contents in the rhizosphere soils exceed 20 times the reference value for agricultural soils (11 mg kg-1). The result obtained showed that some edible plants frequently used in the region could be enriched in these metals/metalloids and may represent a serious hazard if consumed. The potatoes tend to have a preferential accumulation in the leaves and roots while in cabbages most elements have a preferential accumulation in the roots. An index of the risk for residents, due to ingesting of these metals/metalloids, by consuming vegetables grown around the sampling area, was calculated and the result indicates that the inhabitants of S. Francisco de Assis village are probably exposed to some potential health risks through the intake of arsenic, cadmium and also lead via consuming their vegetables.
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