Publicação

Rare-earth-element fractionation patterns in estuarine sediments as a consequence of acid mine drainage : a case study in SW Spain

Ver documento

Detalhes bibliográficos
Resumo:Processes of seawater dilution and acid neutralization cause significant effects upon REE fractionation between the aqueous solution and sediments. This study describes the results of a recent investigation into such processes in the sediments of the Tinto and Odiel estuary. The results show differences in behaviour between light REEs (LREEs) and middle and heavy REEs (MREEs and HREEs). A relative depletion in La is observed as a consequence of the low pH values, which prevents the separation of LREEs from solution to the suspended matter. When acid neutralization occurs, on the other hand, an increase in the La content is related to the preferential separation of LREEs compared to MREEs and HREEs. Under these conditions three main fractionation patterns were distinguished: the first shows a slightly MREE enriched shape in sediments deposited in the fluvial zone; the second displays significant depletion in LREEs and a nearly flat tendency in MREEs and HREEs towards the estuarine mixing zone; and the third is enriched in total REEs and shows a relative increase in LREEs and MREEs. The evolution of these patterns reveals that pH is the key variable controlling REE fractionation in environments affected by acid mine drainage.
Autores principais:López-González, N.
Outros Autores:Borrego, J.; Carro, B.; Grande, J. A.; De la Torre, M. L.; Valente, Teresa Maria Fernandes
Assunto:Acid and saline mixing Estuary Mining Rare-earth elements Sediments
Ano:2012
País:Portugal
Tipo de documento:artigo
Tipo de acesso:acesso restrito
Instituição associada:Universidade do Minho
Idioma:inglês
Origem:RepositóriUM - Universidade do Minho
Descrição
Resumo:Processes of seawater dilution and acid neutralization cause significant effects upon REE fractionation between the aqueous solution and sediments. This study describes the results of a recent investigation into such processes in the sediments of the Tinto and Odiel estuary. The results show differences in behaviour between light REEs (LREEs) and middle and heavy REEs (MREEs and HREEs). A relative depletion in La is observed as a consequence of the low pH values, which prevents the separation of LREEs from solution to the suspended matter. When acid neutralization occurs, on the other hand, an increase in the La content is related to the preferential separation of LREEs compared to MREEs and HREEs. Under these conditions three main fractionation patterns were distinguished: the first shows a slightly MREE enriched shape in sediments deposited in the fluvial zone; the second displays significant depletion in LREEs and a nearly flat tendency in MREEs and HREEs towards the estuarine mixing zone; and the third is enriched in total REEs and shows a relative increase in LREEs and MREEs. The evolution of these patterns reveals that pH is the key variable controlling REE fractionation in environments affected by acid mine drainage.