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Paiva I, Marques R, Santos M, Reis M, Prudêncio MI, Waerenborgh JC, Dias MI, Russo D, Cardoso G, Vieira BJC, Carvalho E, Rosa C, Lobarinhas D, Diamantino C, Pinto R. Naturally occurring radioactive material and risk assessment of tailings of polymetallic and Ra/U mines from legacy sites. CHEMOSPHERE 2019; 223:171-179. [PMID: 30776762 DOI: 10.1016/j.chemosphere.2019.02.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 01/25/2019] [Accepted: 02/10/2019] [Indexed: 06/09/2023]
Abstract
Old mine tailings from Northern and Central Portugal were studied in order to perform a radiological and chemical characterization. The evaluation of massic activity of natural radionuclides and concentrations in tailings of polymetallic and Ra/U mines was performed by gamma spectrometry and neutron activation analysis. Iron speciation was carried out by Mössbauer spectroscopy. In polymetallic tailings with physical ore processing (Cumieira and Verdes - exploited for Sn, Nb-Ta) higher contents of Th, 228Ra and 226Ra in the coarser materials occur, probably due to their presence in host rock and ore fragments. In finer tailings, washing may explain the lower 226Ra and 210Pb massic activity. In tailings with physical/chemical ore processing (Covas - exploited for W and Sn) high U contents and a tendency for higher 226Ra and 210Pb massic activity in the fine materials is observed, probably due to their incorporation in nano-sized particles of iron oxides. A high variation of the 210Pb/226Ra ratio occurs in polymetallic tailings; a deficit of 210Pb can be observed particularly in deposits of settling tanks drained from dumps of chemically treated ore. In Ervideira-Mestras tailings (Ra/U exploitation) where no ore process in situ was performed, a near equilibrium between 210Pb and 226Ra occurs. Dose risk assessment was carried out by calculating external outdoor Annual Effective Dose Rate; the dose rates in air due to terrestrial gamma radiation are low for the polymetallic tailings (<47 nGy/h), and higher for tailings of Ra/U (up to 4130 nGy/h), in the worst scenario.
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Affiliation(s)
- Isabel Paiva
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal; Laboratório de Protecção e Segurança Radiológica (LPSR), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Rosa Marques
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Marta Santos
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal; Laboratório de Protecção e Segurança Radiológica (LPSR), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Mário Reis
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal; Laboratório de Protecção e Segurança Radiológica (LPSR), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Maria Isabel Prudêncio
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - João Carlos Waerenborgh
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Maria Isabel Dias
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Dulce Russo
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Guilherme Cardoso
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Bruno J C Vieira
- Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, EN 10 (km 139.7), 2695-066, Bobadela, Portugal.
| | - Edgar Carvalho
- Empresa de Desenvolvimento Mineiro, SA. (EDM), Rua Sampaio e Pina, nº 1, 7º, 1070-248, Lisboa, Portugal.
| | - Carlos Rosa
- Faculdade de Ciências, Universidade de Lisboa, IDL - Instituto Dom Luiz, Ed. C6, Campo Grande, 1749-016, Lisboa, Portugal.
| | - Daniela Lobarinhas
- Empresa de Desenvolvimento Mineiro, SA. (EDM), Rua Sampaio e Pina, nº 1, 7º, 1070-248, Lisboa, Portugal.
| | - Catarina Diamantino
- Empresa de Desenvolvimento Mineiro, SA. (EDM), Rua Sampaio e Pina, nº 1, 7º, 1070-248, Lisboa, Portugal.
| | - Rui Pinto
- Empresa de Desenvolvimento Mineiro, SA. (EDM), Rua Sampaio e Pina, nº 1, 7º, 1070-248, Lisboa, Portugal.
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