Zinc, chromium, vanadium and iron in the Mediterranean Sea (original) (raw)
Related papers
Trace metal enrichments in the Mediterranean Sea
Earth and Planetary Science Letters, 1985
Copper, nickel, and cadmium occur at higher concentrations in the surface waters of the Mediterranean than in nutrient-depleted waters of the open ocean. Trace metal profiles have been taken on both sides of the Strait of Gibraltar to constrain a mass balance. Deep Mediterranean waters have trace metal levels comparable to surface waters in regions of Mediterranean deep water formation, implying a minimal role for vertical transport by biological activity. Excess trace metals are not present in open-Atlantic source waters, but a detailed map of trace metal distributions in the Alboran Sea (immediately east of the Strait) reveals a metal-enriched plume with concentrations as high as copper, 3.6 nmol/kg; nickel, 2.8 nmol/kg; and cadmium, 120 pmol/kg. A substantial enrichment in trace metal concentrations therefore can occur in transit from the open Atlantic through the coastal zone into the Strait. This trace metal enrichment may derive either from river inflow (masked by evaporation), diffusion out of continental shelf sediments, eolian particulate fallout, or anthropogenic sources. Metal sources (fluvial, sedimentary, or atmospheric; natural or anthropogenic) are difficult to discern from the large-scale oceanographic distributiofi. Metal retention in nutrient-depleted surface waters is not due to unusual metal fluxes relative to nutrients, but instead is a consequence of less frequent recycling of nutrients in the Mediterranean compared to the open ocean. Metal enrichments would be expected before human intervention, with anthropogenic input reflected in proportion to the relative augmentation of inputs over natural levels. Mediterranean water produces small trace metal anomalies in the outflow core (positive for Ni, negative for Cd). Present observations are consistent with this prediction, but high precision data would be necessary to observe these at distance from Gibraltar.
AIMS Environmental Science
Coastal areas are sites of discharge of anthropogenic compounds, such as trace metals. In seawater, trace metals have a strong affinity for particulate organic matter or clay mineral and tend to accumulate in sediments. However, natural events and human activities can cause disturbances in surface sediments involving modification of chemical balances and contamination of surrounding waters. Here, we investigated the dynamics of trace metals in the Sfax coastal area (Gulf of Gabès, southern Mediterranean Sea), a shallow coastal ecosystem impacted by tides and submitted to urban/industrial effluents. We presented the spatial distribution of trace metals concentrations, their potential mobility in sediments and evaluated the potential sources of target elements in surface waters. The highest concentration levels in surficial sediments (3.51 µg/g) and surface waters (0.25 µg/L) were found for Cd. The latter showed a great affinity (50%) for the exchangeable phase while other elements (Cu, Cr and Ni) were found in most residual phases, reducing the environmental risk. Pb and Zn, associated Fe/Mn oxyhydroxides revealed potential inputs from urban and industrial effluents. Multivariate statistical analysis suggested that dissolved trace metals in surface waters were probably derived from effluents/wadis but also from sediment resuspension processes, induced by natural (tides, hydrodynamics) or anthropogenic (dredging) events. Overall, this study highlights the importance of the interactions between sediment and water column for the trace metal dynamics in very shallow coastal environments with an exacerbated pattern for Cd.
Marine Chemistry, 2010
Atmospheric deposition (wet and dry) of major and trace metals (V, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb) was monitored at a remote location in the eastern Mediterranean Sea from January 2005 through December 2006. A comparison of atmospheric deposition fluxes with sediment traps data (simultaneously collected) highlighted the significance of atmospheric inputs to the biogeochemical cycling of trace elements. V, Cr, Fe and Pb were mainly associated with the particulate form (64-98%), whilst for Mn, Zn, Cu and Cd the soluble fraction represents 60-70% of the total input. The solubility of all studied metals in both wet and dry deposition was found to decrease with increasing pH values and increasing dust mass. Cr, Mn and Cu fluxes were higher during the dry season compared to those measured during the wet season. For the remaining metals the opposite trend is valid, whilst Fe and Zn are removed from the atmosphere almost equally by wet and dry deposition. Atmospheric deposition of major and trace metals in the eastern Mediterranean Sea was sufficient to balance metals in the water column, indicating the predominant role of atmospheric deposition as an external source of trace elements in the area.
Vertical export flux of metals in the Mediterranean Sea
Deep Sea Research Part I: Oceanographic Research Papers, 2014
We examined metal (Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb) and particulate organic carbon (OC) concentrations of the marine vertical export flux at the DYFAMED time-series station in the Northwestern Mediterranean Sea. We present here the first data set of natural and anthropogenic metals from sediment trap moorings deployed at 1000 m-depth between 2003 and 2007 at the DYFAMED site. A highly significant correlation was observed between most metal concentrations, whatever the nature and emission source of the metal. Cu, Zn and Cd exhibit different behaviors, presumably due to their very high solubility and complexation with organic ligands. The observed difference of atmospheric and marine fluxes in terms of temporal variability and elemental concentration suggests that dense water convection and primary production and not atmospheric deposition control the marine vertical export flux. This argument is strengthened by the fact that significant Saharan dust events did not result in concomitant marine vertical export fluxes nor did they generate significant changes in metal concentrations of trapped particles.
Research Square (Research Square), 2023
The alteration of marine sediments plays a key role in the global health of the seas as consequence of anthropogenic pollution in highly populated coastal areas. This research analyses the concentration and distribution of heavy metals in coastal and marine sediments of the Mediterranean Sea. Research has highlighted that Hg, Ni and Cu are present in very high concentrations in sediments, while Cr, Zn, Cd, Ba and V have slightly more moderate values. Sediment quality guidelines and the pollution indexes (Igeo and Geochemical Signal Type-GST) have been used to evaluate the trace element results, revealing a general trend of decreasing concentrations from the littoral coast to the open sea. Principal component analysis (PCA) indicates that the chemistry of metals in sediments is mainly regulated by the sequence Cu, Pb, Zn, Ba, and Cr. This study suggests that heavy metals distribution patterns are related to strong pressured tourist areas and management strategies are needed to ensure the health of the Mediterranean Sea.
Trace metal distributions in shelf waters of the northwestern Black Sea
Continental Shelf Research, 2001
Measurements of dissolved and leachable particulate trace metals (Mn, Fe, Co, Pb, Cd, Zn, Cu and Ni) and total particulate Mn and Fe were made on seawater samples collected from the northwestern Black Sea during the EROS 2000 expedition conducted in July-August 1995. The investigation concentrated on waters of the shelf and shelf edge, but included one deeper water (1440 m) station. In the oxic layer of the deep station, the suspended particulate fractions of Mn and Fe were a major part of the total metal mass, consistent with the presence of the ''Fine Particle Layer'' which forms on the shelf and spreads all over the Black Sea with intensities decreasing from the coast. Dissolved and total particulate concentrations were, respectively, Mn, 0.69-9.6, 1.2-29; Fe, 0.79-3.03, 2.3-7.4 nM. Dissolved Cu and Ni concentrations were relatively high (1-8 and 8-12 nM, respectively), and did not show any depletion in surface oxic waters, possibly as a result of strong organic complexation. Dissolved Pb concentrations (100-200 pM) were higher than were generally found on the shelf. This was attributed to atmospheric inputs combined with less efficient scavenging of metals in these low SPM waters. The distribution of dissolved Co closely resembled that of dissolved Mn reflecting coupling through oxidation of Mn. Concentrations of dissolved Cd and Zn were low in surface water (0.07-0.09 and 0.9-2.0 nM, respectively), and increases in concentrations with depth were sharply reversed around the top of the redoxcline. For most metals (Mn, Fe, Co, Pb, Cu, Cd, Zn) dissolved concentrations were low in the anoxic layers as a result of solubility by formation of, or association with, solid sulphide phases. Dissolved Ni was not affected by sulphide precipitation. At most of the shelf stations there were clear enhancements of dissolved Mn and Fe in the deepest waters, consistent with other evidence that significant benthic fluxes of these metals arise through the redox conditions in the region of the sediment-water interface. In the shelf water column, dissolved Mn and Fe concentrations *Corresponding author. : S 0 2 7 8 -4 3 4 3 ( 0 1 ) 0 0 0 1 3 -9 ranged between 1.2 and 1350 and between 0.4 and 181 nM, respectively; the highest concentrations were found near the bottom. Particulate concentrations of Mn and Fe were high, implying high oxidation rates of Mn(II) and Fe(II) and/or high supply rates from rivers. Total particulate concentrations of Mn and Fe were 0.7-1050 and 2.3-2650 nM, respectively; the highest concentrations were found in surface and bottom waters. The distributions of particulate Mn and Fe were consistent with the isopycnal transport of Mn and Fe oxyhydroxides from the shelf by the coastal circulation. Distributions of other trace metals (Co, Pb, Cu, Ni, Cd, Zn) were considerably influenced by riverine inputs. Relatively high dissolved and available particulate metal concentrations were generally found in surface waters at stations directly influenced by the Danube River. Some trace metals (Co, Ni, Cd and Zn) were influenced by Mn and Fe cycling and increases in their dissolved concentrations occurred at a number of stations near the sediment-water interface. Dissolved and available particulate metal concentrations (nM) at stations on the shelf were, respectively: 0.171-1.80, 0.003-0.437 (Co); 0.014-0.614, 0.010-1.48 (Pb); 7.6-28.8, 0.048-3.75 (Cu); 11.0-17.5, 0.018-2.10 (Ni); 0.033-0.161, 0.003-0.063 (Cd); 1. . #
Environmental Earth Sciences, 2009
The present study investigates the distribution of trace metals (Zn, Hg, Cd, Cu, and Pb), as indicators of pollution, in the surficial offshore shelf sediments along the northern coast of Heraklion Prefecture (Crete, Mediterranean Sea). The concentrations and the spatial distribution of the different trace metals, in relation to the sedimentological characteristics and the water circulation pattern of the entire continental shelf, are associated with human inshore sources of pollutants located along the coastline of the study area. Although the trace metal concentrations measured are higher than the background values, they are not considered to be dangerous to human health, as they are lower than the standard values given by the World Health Organisation, with only a few localised exceptions. Furthermore, results reveal the important role of local hydrodynamism that moves fine-grained material and associated trace metals offshore (seawards to wave breaking zone) and then transports them eastwards by entrapping them in the prevailing offshore shelf-water circulation.
Marine Geology, 1996
The concentrations of major (Al, Mg, Fe, and Mn) and trace (Zn, Cr, Ni, Co, Cu, and Pb) elements as well as carbonate, organic carbon, and grain size distributions have been determined in surface sediments collected at 73 stations from the Gulf of iskenderun. The shelf sediments of the Gulf of Jskenderun are largely muds but sediments with higher contents of sand and gravel also occur due to the presence of high biogenic CaCO, contents (up to 80%) in the samples. The abundance and regional distributions of elements in the surface sediments of the Gulf are largely controlled by differences in grain size and in the level of dilution by skeletal/shell remains, and by the variation in composition of source materials. Mg, Ni, Cr, Co, and to a lesser extent Zn and Pb, are significantly enriched relative to their average crustal abundances. These metal enrichments are found especially in the eastern part along the SW-NEtrending areas of the Gulf and are mostly consistent with the chemical and mineralogical compositions of the major basic and ultrabasic source rocks present on the adjacent coast and hinterland. There is strong evidence that suggest that aluminosilicates, Fe and Mn compounds (possibly oxyhydroxides), and organic matter act as the most effective carriers for transfer of available metals (Zn, Cr, Ni, Co, and Cu) to the sediments.