Trace metals in the NE Atlantic coastal zone of Finisterre (Iberian Peninsula): Terrestrial and marine sources and rates of sedimentation

Abstract

Abstract. The biogeochemical patterns of bioactive metals (Cd, Co, Cu, Ni, V and Zn) and Pb were studied in the Corcubión Sound, an area close to Cape Finisterre (NW Iberian Peninsula). Seasonal patterns of dissolved and particulate trace metals in the freshwater and seawater, as well as in the phytoplankton were determined during three upwelling events in the winter, late spring and summer of 2005. Metals were also analysed in the surface and to 1 m-depth in the sediments. Upwelling patterns permit the discrimination between those of the outer Sound and Corcubión Inlet. Dissolved trace metals concentrations in the seawater of the outer Sound were in the range of those reported for the Northeast Atlantic Ocean. Mean values of dissolved metals concentrations in the upwelled ENACW were: 0.07±0.03 nMCd, 0.11±0.02 nMCo, 2.6±1.6 nMCu, 4.6±0.6 nMNi, 0.20±0.10 nMPb, 31±2 nMV and 3.8±2.3 nMZn. Higher values for dissolved Co, Cu and Zn were measured in two inflowing streams and in the Inlet. A severe-moderate contamination of these metals and Pb was detected in the sediments of the Inlet. Three different sediment layers were observed in cores located at the outer-Inlet boundary. The most recent showed the highest mass accumulation rates, mainly of Cu (e.g. 428 mgCu m -2 yr -1 ), Pb and Zn, during the last decade. The intermediate unit corresponds to the 20 th century (e.g. 39 mgCu m -2 yr -1 ) and the deeper layer from the 19 th to 14 th centuries can be regarded as representing the pre-industrial period, and show the lowest rates of metal accumulation (e.g. 7 mgCu m -2 yr -1 ). Diatoms were the main autochthonous source of metals in the sediments. The genus Chaetoceros, Lauderia dominates in the overlaying seawater during winter and Pseudonitzschia and Leptocylindrus were typical of summer blooms whilst in the sediments Chaetoceros, Paralia, Leptocylindrus and Thalassionema were the main diatoms genera. The comparison of the normalized metal vs. Si in the phytoplankton and vs Si in the biogenic opal of the sediment shows a prevailing lithogenic-anthropogenic origin of metals such as Cu, Fe, Ni, Pb and V while the upwelling was the main source for Cd in the sediments because of settling of diatoms. The continental influence and metal contamination is restricted to the innermost part of Sound during the last century where the anthropogenic activities supply Cd, Cu, Pb and Zn. Seasonally, dissolved trace metals concentrations in the outer Sound are within the normal range measured in the north-eastern Atlantic Ocean. The Sound system is pristine compared with the neighbouring and anthropogenically disturbed Rias, and may be a good reference of natural trace metal levels along the north-eastern Atlantic coast.

Anthropogenic Signatures of Lead in the Northeast Atlantic

“…Our surface water DPb concentration of 40.2 ± 7.5 pmol kg À1 (n = 109) along the shelf break in 2014-2015 showed at least a fourfold decrease compared to previous reports for the region (Figure 2e and Table S2) (Brügmann et al, 1985;Cotté-Krief et al, 2002;Helmers & Van der Loeff, 1993;Lambert et al, 1991;Muller et al, 1994) and were generally lower in comparison to other European shelf waters over the last 4 decades (Kremling & Streu, 2001;Laumond et al, 1984;Monteiro et al, 2015;Pohl et al, 2011;Prego et al, 2013;Waeles et al, 2008). The diminishing DPb concentrations over the last two decades form a success of the phaseout process of leaded gasoline.…”

Influence of an upwelling filament on the distribution of labile fraction of dissolved Zn, Cd and Pb off Cape São Vicente, SW Iberia

“…The number of studies reported in the literature regarding metals concentrations in the Iberian Peninsula coast are limited (e.g. van Geen et al, 1991;Leal et al, 1997;Cotté-Krief et al, 2000;Caetano and Vale, 2003;Cánovas et al, 2007;Santos-Echeandía et al, 2012;Prego et al, 2013; Table 2, this paper). Most of these studies were not particularly devoted to the effect of upwelling upon the distribution of the metals.…”

“…Particularly in some species of diatoms it is involved in the carbonic anhydrase (CA) activity (Morel and Price, 2003) and in one coccolithophore species, it regulates the alkaline phosphatase activity (Shaked et al, 2006). Despite the controversial ϲ opinions about Cd behaviour (Morel et al, 1991;European Commission, 2002;Prego et al, 2013), some authors agree about Cd biological functions, which include competition with Zn bioavailability in CA activity under Zn-limited conditions (Morel et al, 1991;Morel and Price, 2003). Both metals have a nutrient-type distribution in the ocean (Bruland and Lohan, 2003;Wyatt et al, 2014), often strongly correlated with the phosphate, nitrate and silicic acid (Bruland and Lohan, 2003;Croot et al, 2011;Wyatt et al, 2014).…”

“…Conversely, Pb is a non-essential metal to organisms, with no biological function, which turn it an excellent element to trace anthropogenic inputs to the ocean, since its presence in the ocean is originated by anthropogenic influence. Lead above certain amounts/concentrations may represent an environmental threat by its toxicity (European Commission, 2002;Prego et al, 2013). Zinc, Cd and Pb depicting different behaviours in the ocean were selected for this study to characterise their contribution in an area where upwelling events are recurrent.…”

Metals impact into the Paranaguá Estuarine Complex (Brazil) during the exceptional flood of 2011

“…Contents were lower than in highly polluted places such as the Mar Chiquita Lagoon, Argentina (BELTRAME et al, 2009) and the Dakar Coast (DIOP et al 2014); moderately polluted estuaries like the Scheldt Estuary (ZWOLSMAN; VAN ECK, 1999) and the Changjiang Estuary, China (HSU; LIN, 1998), and comparable to well preserved systems such as Jaguaripe Estuary, Bay of Santos, Brazil (HATJE et al, 2012) and Corcunbion Sound, Iberian Peninsula (PREGO et al, 2013).…”