The relevance of defining trace metal baselines in coastal waters at a regional scale: The case of the Portuguese coast (SW Europe)

Abstract

The Water Framework Directives aims a reduction in concentration of hazardous substances in the marine environment. Consequently, there is a need to distinguish between anthropogenically influenced metal concentrations from natural background levels. To better achieve this goal in the Portuguese coast, dissolved and particulate trace metal (TM) concentrations along the Portuguese coast were determined in 46 sites distance 1-3 km from the shoreline. Dissolved values ranged within the following intervals: 0.01-0.89 nM for Cd, 0.01-3.37 nM for Co, 0.90-45.4 nM for Cu, 3.30-140 pM for Hg, 1.88-15.1 nM for Ni, 0.01-0.15 nM for Pb and 1.40-62.0 nM for Zn. Whereas Cd, Co, Cu, Ni and Zn were enhanced in the southern coast, while Pb values were higher in the central part of the western coast. Mercury concentrations showed punctual increases all along the coast. Values of trace metals in suspended particulate matter varied in a broad range: 36-2902 μmol g(-1) for Al, 0.10-15.1 nmol g(-1) for Cd, 1.50-165 nmol g(-1) for Co, 50.0-990 nmol g(-1) for Cu, 2.80-76.4 nmol g(-1) for Hg, 22-1471 nmol g(-1) for Ni, 10.0-347 nmol g(-1) for Pb and 416-10,981 nmol g(-1) for Zn. Higher values for Al, Ni and Co were found in the central part of the western coast. However, Cd, Cu, Pb and Zn increased their levels from the north coast towards the central and south areas. The variability of both dissolved and particulate metals appears to be mainly associated with oceanographic conditions and continental inputs at North and central areas of the coast, and in the south coast to geological features rather than to anthropogenic pressures. On the basis of these results, regional baseline concentrations are proposed for the three typologies in Portuguese coastal waters defined under the Water Framework Directive.

Effect of phytoplankton size classes on bio-optical properties of phytoplankton in the Western Iberian coast: Application of models

“…Muacho et al, 2013) and suspended particulate matter (e.g. Oliveira et al, 1999;Santos-Echeandia, Caetano, Brito, Canário & Vale, 2012) have also been reported for specific locations of the Portuguese coast. Cells experiencing high light levels tend to have less chlorophyll-a molecules per cell, compared with low-light adapted cells.…”

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.…”

“…Most of these studies were not particularly devoted to the effect of upwelling upon the distribution of the metals. Like in other coasts, metal concentrations along the Portuguese coast tend to be lower offshore than at the coast, particularly where estuaries outflow (Cotté-Krief et al, 2000;Santos-Echeandía et al, 2012;Prego et al, 2013). At Cape São Vicente there is no significant river runoff contribution, so it is assumed that the recorded metal concentrations are mainly derived by upwelling, where metal concentrations are higher than in nonupwelling open-ocean areas.…”

Trace metal variability, background levels and pollution status assessment in line with the water framework and Marine Strategy Framework EU Directives in the waters of a heavily impacted Mediterranean Gulf

“…Note: All results shown here are anti-log values. treatment as the present study for Basque coastal waters, while Santos-Echeandía et al (2012) report baseline concentrations for Portuguese coastal waters as the concentration interval for the 20% of the lowest concentrations for each metal. In Table 5 we have included for comparison reasons, the results found by these authors for the water bodies with typological characteristics more or less similar to those of the Saronikos Gulf.…”