Historical trend in heavy metals pollution in the sediments of Cienfuegos bay, defined by and geochronology

Abstract

Investigations on the concentration level of heavy metals in the sediments of Cienfuegos bay (Cuba) have been carried out, to reconstruct their “depositional history” by using radionuclide geochronology, to highlight the major changes occurred in the last century and to draw hypotheses on their origin. During two sampling campaigns (1999 and 2001) sediment cores and surface grab samples have been collected in the two basins of the bay. In this paper results on the horizontal and vertical distribution of arsenic, nickel and vanadium are discussed, along with data on concentrations of natural (excess ) and anthropogenic () radionuclides, used as tools to “date” the sediment horizons. Results evidenced that important changes in the sedimentation regime of the bay occurred in the last forty years, in relation to changes in land uses and to the effects of some extreme meteorological events. The distribution of the heavy metals shows the influence of the recent industrialization of the area, as revealed by both the spatial and vertical concentration within the sediment horizons.