Suchergebnisse

The rare earth elements (REE) along with iron and manganese distribution in ochre-precipitates and wetland soils in a passive system for acid mine drainage treatment (Jales, Portugal) was studied. The results obtained by instrumental neutron activation analysis showed a higher incorporation of the light REE (particularly La and Ce) by the ochre-precipitates resulting from the mine water-limestone interaction. These fluffy materials influence the entrance of the first wetland where a correlation between Fe and La and Ce was found. Then Mn phases appear to play a more important role controlling REE distribution in the remaining area of the wetland soils. ; Thanks to EDM (Empresa de Desenvolvimento Mineiro, S.A.) for providing access to the water treatment plant, and to the staff of the Portuguese Research Reactor (RPI) of CTN/IST. C2TN authors gratefully acknowledge the FCT (the Portuguese Science and Technology Foundation) support through the UID/Multi/04349/2013. This work is co-funded by European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by FCT. ...

The main objectives of the present study were to (i) investigate the effects of mineralogy and solid-phase distribution on element bioaccessibility and (ii) perform a risk assessment to calculate the risks to human health via the ingestion pathway. Multiple discriminant analysis showed that the dust chemistry discriminates between indoor and outdoor samples. The solid-phase distribution of the elements in indoor dust indicated that a large proportion of zinc, nickel, lead, copper, and cobalt is associated with an aluminum oxy-hydroxides component, formed by the weathering of aluminum silicates. This component, which seems to influence the mobility of many trace elements, was identified for a group of indoor dust samples that probably had a considerable contribution from outdoor dust. An iron oxide component consisted of the highest percentage of chromium, arsenic, antimony, and tin, indicating low mobility for these elements. The bioaccessible fraction in the stomach phase from the unified BARGE method was generally high in zinc, cadmium, and lead and low in nickel, cobalt, copper, chromium, and antimony. Unlike other potentially toxic elements, copper and nickel associated with aluminum oxy-hydroxides and calcium carbonates were not extracted by the stomach solutions. These trace elements possibly form stable complexes with gastric fluid constituents such as pepsin and amino acid. Lead had a hazard quotient >1, which indicates the risk of non-carcinogenic health effects, especially for children. ; This research was by funded the LabexDRIIHM,Frenchprogramme"Investissementsd'Avenir"(ANR‐11‐LABX‐0010) which is managed by the ANR, and co‐funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), projects ICT UIDB/04683/2020 and UIDP/04683/2020, project GeoBioTec (UID/GEO/04035/2019) and national funds provided by the FCT ‐ Fundação para a Ciência e a ...

Mineral-water interaction in mine drainage often results in the formation of iron-rich precipitates, called ochre products. They often comprise particles in the nanoscale, known by their strong reactivity. The present study focuses on these nanoprecipitates formed in streams that receive water from a U-Ra mine. Water and the ochre-precipitates that cover the streambed were sampled for geochemical and mineralogical characterization. Results indicate low crystallinity and variety of morphology of the ochre product, which is mainly composed by ferrihydrite in coexistence with minor hematite. The work concludes by noting the potential relevance of these nanophases in fate and transport of elements that pose major environmental concern, namely in uranium-rich mine waters. ; This work was co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 - project ICT (UID/GEO/04683/2013) with reference POCI-01-0145- FEDER-007690 and project Nano-MINENV number 029259. The authors are grateful to the suggestions of the ...

The geochemical evolution of acid mine drainage results in secondary minerals that play a key role in the environmental behavior of the mine wastes. The present work is focused on these newly formed minerals at the Penedono waste dump, characterized by fine-grained tails with pyrite and arsenopyrite. Mineralogical study led to an inventory of secondary phases, comprising soluble sulfates, scorodite, and oxyhydroxysulfates. In addition, there is amorphous Fe, As rich-nanoprecipitates. Jarosite and scorodite are abundant minerals, acting as cement for encrusting tails in Fe and As-rich hardpans. These hard structures are relatively insoluble, retaining toxic elements, thereby contributing to natural attenuation of mining contamination associated with the sulphide wastes. ; European Union through the European Regional Development Fund, based on COMPETE 2020 - project ICT (UID/GEO/04683/2013) with reference POCI-01-0145- FEDER-007690 and project Nano-MINENV number ...