Metales pesados en sedimentos contaminados: Variabilidad espacio-temporal en la ría de Bilbao

Abstract

Several samples ofsurficial sediments were collected in two polluted sites of the Bilbao estuary In order to study the spatial (on a metric scale) and temporal variability of the contents of heavy metals and As. A decline in concentrations between 1997 and 2001 has been observed in one of the sampling sites. This change may be caused by recent reduction in anthropogenic discharges related to improvement in effluent clean-up procedures and closure of polluting factories. To the contrary, a significant enrichment has been found in the other studied site. Remobilization of more polluted materials located inmediatly upstreams, due to recent dredgings, may be responsible for this unexpected increase