Bioavailability and ecological risks of trace metals in bottom sediments from Doce river continental shelf before and after the biggest environmental disaster in Brazil: The collapse of the Fundão dam.
J Environ Manage
; 272: 111086, 2020 Oct 15.
Article
em En
| MEDLINE
| ID: mdl-32854890
The present study deals with bioavailability of trace metals in the Doce river continental shelf, southeast of Brazil. The bottom sediments of the study area were firstly sampled a few weeks before the biggest environmental disaster of Brazil, the collapse of the Fundão dam in November of 2015. The disaster released around 40 Mm3 of iron ore tailings into Doce river basin and an estimate of 10 Mm3 reached the river delta, having the adjacent continental shelf as the final destination. One year and a half later, on April of 2017, the continental shelf was sampled again. A total of 48 stations were evaluated concerning concentrations of trace metals (Zn, Cu, Pb, Ni, Cr) and other ancillary variables before and after the accident. Trace metals were determined through fractionation in order to assess mobility and establish the ecological risk through RAC index. Before the accident, trace metals mobility was Pb > Ni > Cu > Zn > Cr, with Pb Cu, Ni and posing high ecological risk (RAC>30%) in many stations. Differences in concentrations of metal from pre to post accident were significant, and the increase of trace metals was observed. The mobility order after the accident changed to: Cu > Pb > Ni > Zn > Cr. Metal fractionation showed remarkable changes after the accident, with elements such as Cu, Ni and Zn highly associated with reducible fractions originated from the tailings composition. Despite the decrease of RAC to medium risk after the accident in most stations, the bioavilability of Cu, Pb, Ni and Zn increased as show by their higher accumulation in the bioavailable fractions.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Poluentes Químicos da Água
/
Metais Pesados
/
Desastres
Tipo de estudo:
Etiology_studies
/
Risk_factors_studies
País/Região como assunto:
America do sul
/
Brasil
Idioma:
En
Revista:
J Environ Manage
Ano de publicação:
2020
Tipo de documento:
Article
País de publicação:
Reino Unido