Copper, zinc and lead impact in SW Iberian shelf sediments: An assessment of recent historical changes in Guadiana river basin

Abstract

In the present study, lithogenic/biogenic and anthropogenic elements were determined in five sediment cores collected at the SW Iberian Continental Shelf in order to investigate the spatial and temporal heavy metal distribution and to associate them with specific continental influences/events.Elemental concentrations suggest a heavy metal (Cu, Zn and Pb) enrichment at the upper sections of all the cores. This enrichment is larger for cores localised closer to the coastline and probably exposed to a stronger continental influence. The geochemical regional background values for the studied elements are reached at ~25-30 cm for all the studied cores with one exception (core 8), which showed to be metal-enriched down to ~80 cm. It is worthnoting that core 8 is located closer to the coastal area, in a different fine sedimentary deposit, in which the deposition rates seem to be considerably higher. Enrichment factors (EF) calculated by using the natural background value determined at the deeper layers show that the EF values vary at the upper sections of cores, between 1.0 and 4.5 and the spatial distribution of the sediment cores show a similar behaviour in the heavy metal distribution patterns along this area of the continental shelf. Cu, Zn and Pb are heavy metals associated with mining exploitation along the Iberian Pyrite Belt, one of the most important mining areas of southwestern Europe, with massive orebodies of these metals. The combination of enrichment factors downcore profiles with sedimentation rate values signifies the beginning of heavy metal pollution in shelf sediments (~200-250 years ago) and is coincident with the mining exploitation reactivation during the XIX century.

Anthropogenic influences in a lagoonal environment: a multiproxy approach at the valo grande mouth, Cananéia-Iguape system (SE Brazil)

“…A comparison of our data with anthropogenically affected sediments in the Bilbao estuary, Spain (CEARRETA et al, 2002), the SW Iberian shelf (CORREDEIRA et al, 2008), and Santos bay and estuary, SE Brazil (TESSLER et al, 2006) revealed that the sediments from the core analyzed here are significantly poorer in heavy metals than those from the Iberian sediments. On the other hand, after the opening of the Valo Grande, levels of Pb, Cu, Zn and Cr were of the same order of magnitude as those from the highly polluted Santos estuary (Table 1).…”

“…Hornberger et al (1999) identified enrichment factors of about 20 in Hg concentrations in sediments of San Francisco Bay (USA), which were related to Au mining activities in the XIXth century. Corredeira et al (2008) also identified enrichment of Cu, Zn and Pb in the SW Iberian sediments associated with mining activities along the Iberian Pyrite Belt.…”

“…Due to their geomorphological and physicochemical properties, lagoons and estuaries are potential deposit areas for anthropogenic sediments, and the number of studies dealing with these subjects is increasing rapidly (JONES; TURKI, 1997;BIRCH;TAYLOR, 1999;CEARRETA et al, 2000CEARRETA et al, , 2002CUNDY et al, 2003;ELBERLING et al, 2003;PASTERNACK;BROWN, 2006;DONDERS et al, 2008;LEORRI et al, 2008). An important approach to the subject is related to the sedimentary record of this anthropogenic influence, which incorporates high resolution geochronology with proxies of different types so as to provide a reliable documentation of the contamination history of a given area (ALVE, 1991(ALVE, , 1995PLATER et al, 1998;APPEBY, 2004;LI et al, 2000;CHAN et al, 2001;CEARRETA et al, 2002;RUIZ-FERNÁNDEZ et al, 2007, among others).…”

“…An increase in the contamination by heavy metals, which began in the 1930s, and by DDT, starting in the 1960s, was identified. Dassenakis et al (1995) studied the sediments of the Acheloos Estuary (Greece) where diverse human activities, such as dams, agriculture and navigation, influenced the system. These human actions, in combination with hydrological patterns and both mineralogical and morphological factors, affected the chemical behavior and heavy metal distribution patterns of this estuary's sediment.…”

Distribution of heavy metals and pollution pathways in a shallow marine shelf: assessment for a future management

“…These inputs have caused the contamination by heavy metals (mainly Zn and Pb) in the river mouth and the adjacent zones (Corredeira et al 2008). Littoral drift currents will lead this pollutant flow toward the east in a direction nearly parallel to the coast, mainly between 10 and 18 m water depth (Fig.…”