Patterns of trace metal bioaccumulation and trophic transfer in a phytoplankton-zooplankton-small pelagic fish marine food web.

Trace metal contamination in the European sardine and anchovy food web was investigated in the Gulf of Lions, NW Mediterranean Sea, including seawater and size fractions of plankton. The results highlighted: i) higher and more variable concentrations in the smaller plankton size classes for all metals except cadmium; ii) higher concentrations in anchovy versus sardine for all elements except lead; iii) different patterns of metal bioaccumulation through the food web: cobalt, nickel, copper, silver, lead and zinc displayed continuously decreasing concentrations (with the exception of increased zinc in fish only), while mercury concentrations dropped considerably in larger plankton size classes and rose significantly in fish. Lastly, cadmium concentrations were found to be highest in intermediate plankton size classes, with very low levels in fish. The need to efficiently characterize the biological composition of plankton in order to fully identify its role in the mobilization and transfer of metals was highlighted.

Platinum in sediments and mussels from the northwestern Mediterranean coast: Temporal and spatial aspects.

Platinum (Pt) is considered a Technology Critical Element (TCE) and an emerging metallic contaminant with increasing release into the environment. Gaps in knowledge and understanding of environmental levels, fate and effects of Pt still exist, especially in the marine environment. This work presents Pt concentrations in the northwestern Mediterranean coast including: (i) temporal variability from sediment cores and farmed mussels in the Toulon Bay (historically affected by intense human activities) and (ii) spatial distribution from recent wild mussels collected along ∼ 700 km coastline with contrasting ecosystems (including natural reserves), quantified using voltammetry and inductively coupled plasma-mass spectrometry. The historical (>100 years) record of Pt in sediments from the Toulon Bay suggests the existence of non-negligible Pt sources older than those related to vehicle emission devices, such as petrol industry and coal-fired activities. A strong Pt increase in more recent sediments (from ∼12 to 16 ng g-1) and mussels (8-fold increase from ∼0.12 to 0.80 ng g-1) covering the past 25 years reflect the overall evolution of Pt demand in Europe (∼20-fold increase for vehicle catalysts in 20 years). Spatial biomonitoring of Pt in mussels along the northwestern Mediterranean coast is assumed to reflect inter-site differences of Pt exposure (0.09-0.66 ng g-1) despite seasonal effect on tissue development. This study highlights the need for thorough and regular monitoring of Pt levels in sediments and biota from urbanized coastal areas in order to better assess the environmental impact of this TCE, including potential risks for marine organisms.

Carbon and nitrogen elemental and isotopic ratios of filter-feeding bivalves along the French coasts: An assessment of specific, geographic, seasonal and multi-decadal variations.

Primary consumers play a key role in coastal ecosystems by transferring organic matter from primary producers to predators. Among them, suspension-feeders, like bivalve molluscs are widely used in trophic web studies. The main goal of this study was to investigate variations of C and N elemental and isotopic ratios in common bivalves (M. edulis, M. galloprovincialis, and C. gigas) at large spatial (i.e. among three coastal regions) and different temporal (i.e. from seasonal to multi-decadal) scales in France, in order to identify potential general or specific patterns and speculate on their drivers. The observed spatial variability was related to the trophic status of the coastal regions (oligotrophic Mediterranean Sea versus meso- to eutrophic English Channel and Atlantic ocean), but not to ecosystem typology (estuaries, versus lagoons versus bays versus littoral systems). Furthermore, it highlighted local specificities in terms of the origin of the POM assimilated by bivalves (e.g., mainly continental POM vs. marine phytoplankton vs. microphytobenthic algae). Likewise, seasonal variability was related both to the reproduction cycle for C/N ratios of Mytilus spp. and to changes in trophic resources for δ13C of species located close to river mouth. Multi-decadal evolution exhibited shifts and trends for part of the 30-year series with decreases in δ13C and δ15N. Specifically, shifts appeared in the early 2000's, likely linking bivalve isotopic ratios to a cascade of processes affected by local drivers.

Evidencing the Impact of Coastal Contaminated Sediments on Mussels Through Pb Stable Isotopes Composition.

Heavily contaminated sediments are a serious concern for ecosystem quality, especially in coastal areas, where vulnerability is high due to intense anthropogenic pressure. Surface sediments (54 stations), 50 cm interface cores (five specific stations), river particles, coal and bulk Pb plate from past French Navy activities, seawater and mussels were collected in Toulon Bay (NW Mediterranean Sea). Lead content and Pb stable isotope composition have evidenced the direct impact of sediment pollution stock on both the water column quality and the living organisms, through the specific Pb isotopic signature in these considered compartments. The history of pollution events including past and present contaminant dispersion in Toulon Bay were also demonstrated by historical records of Pb content and Pb isotope ratios in sediment profiles. The sediment resuspension events, as simulated by batch experiments, could be a major factor contributing to the high Pb mobility in the considered ecosystem. A survey of Pb concentrations in surface seawater at 40 stations has revealed poor seawater quality, affecting both the dissolved fraction and suspended particles and points to marina/harbors as additional diffuse sources of dissolved Pb.

210Po and 210Pb trophic transfer within the phytoplankton-zooplankton-anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea).

The transfer of (210)Po and (210)Pb in the food web of small pelagic fishes (from phytoplankton and zooplankton to anchovy Engraulis encrasicolus and sardine Sardina pilchardus) is investigated in the Gulf of Lion (GoL). We present original data of (210)Po and (210)Pb activity concentrations, C and N stable isotope ratios, measured (i) from different size classes of phytoplankton and zooplankton during spring and winter in different environments of the GoL, and (ii) in two fish species. Significant spatial patterns based on (210)Po, (210)Pb activity concentrations and (210)Po/(210)Pb ratios in the different plankton size classes are evidenced by hierarchical clustering, both in spring and winter. This variability, also observed for C and N stable isotopes ratios, is connected to local specific pelagic habitats and hydrodynamics. The sampling strategy suggests that (210)Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while (210)Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and (210)Po activity concentrations measured in anchovies and sardines, we evidence (210)Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes.

Assessment of heavy metal and organic contaminants levels along the Libyan coast using transplanted mussels (Mytilus galloprovincialis).

Within the framework of the MYTIOR project in 2009, heavy metals and organic compounds contaminations were assessed in transplanted mussels in 16 different stations along the coasts of Libya. These stations were located at miles offshore industrial/urban sources but in open sea providing original results related to the background contamination rather than linked to a specific coastal source of pollutants. Results indicated mercury (Hg, 0.045-0.066 mg/kg dry weight (dw)), lead (Pb, 0.44-0, 71 mg/kg dw) and copper (Cu, 3.56-4.21 mg/kg dw) were in the same range or at lower value than control for all stations. Chromium (Cr) in Meleta (3.08 mg/kg dw) and Bomba (3.80 mg/kg dw) and Cadmium values in all stations (1.21-2.41 mg/kg dw) were above control. Meleta, stations from the gulf of Syrt and the three eastern stations were the most affected stations by nickel (max at 5.83 mg/kg dw in Syrt) when zinc was in the same range (141-197 mg/kg dw) and above the control (92 mg/kg dw) at all stations. Polycyclic aromatic hydrocarbon (PAH) levels were found in the range of 16.8-42.8 mg/kg (dry weight) indicating low levels along the Libyan coast with acenaphthene and benzo (a, b, k) pyrenes detected mainly in western Libya. The study of PAH ratios indicated a mixed petrogenic/pyrolytic origin. The only polychlorinated biphenyls (PCBs) found in Libya were PCB 101 in one location and PCB 153 in Tripoli, Garrapoli, Syrt, Ras Lanuf and Benghazi (1.2-1.9 µg/kg dw). Insecticides were lower than control in all stations except DDT, only detected in Misratah (3.5 µg/kg dw). Overall, the results indicated a low background contamination and a low pollution extent according to the environmental pressure occurring offshore the Libyan coast.

Long-term records of cadmium and silver contamination in sediments and oysters from the Gironde fluvial-estuarine continuum - evidence of changing silver sources.

The Gironde fluvial estuarine system is impacted by historic metal pollution (e.g. Cd, Zn, Hg) and oysters (Crassostrea gigas) from the estuary mouth have shown extremely high Cd concentrations for decades. Based on recent work (Chiffoleau et al., 2005) revealing anomalously high Ag concentrations (up to 65 mg kg(-1); dry weight) in Gironde oysters, we compared long-term (~1955-2001) records of Ag and Cd concentrations in reservoir sediment with the respective concentrations in oysters collected between 1979 and 2010 to identify the origin and historical trend of the recently discovered Ag anomaly. Sediment cores from two reservoirs upstream and downstream from the main metal pollution source provided information on (i) geochemical background (upstream; Ag: ~0.3 mg kg(-1); Cd: ~0.8 mg kg(-1)) and (ii) historical trends in Ag and Cd pollution. The results showed parallel concentration-depth profiles of Ag and Cd supporting a common source and transport. Decreasing concentrations since 1986 (Cd: from 300 to 11 mg kg(-1); Ag: from 6.7 to 0.43 mg kg(-1)) reflected the termination of Zn ore treatment in the Decazeville basin followed by remediation actions. Accordingly, Cd concentrations in oysters decreased after 1988 (from 109 to 26 mg kg(-1), dry weight (dw)), while Ag bioaccumulation increased from 38 up to 116 mg kg(-1), dw after 1993. Based on the Cd/Ag ratio (Cd/Ag~2) in oysters sampled before the termination of zinc ore treatment (1981-1985) and assuming that nearly all Cd in oysters originated from the metal point source, we estimated the respective contribution of Ag from this source to Ag concentrations in oysters. The evolution over the past 30 years clearly suggested that the recent, unexplained Ag concentrations in oysters are due to increasing contributions (>70% after 1999) by other sources, such as photography, electronics and emerging Ag applications/materials.

Trace metal concentrations in the North-western Mediterranean atmospheric aerosol between 1986 and 2008: seasonal patterns and decadal trends.

Climatic and anthropogenic changes are able to engender modifications in the aerosol composition at different geographical and temporal scales. The present study addresses this question for the trace metal concentrations (TM=Al, Fe, Mn, Co, Ni, Cu, Pb, Cd and Zn) of aerosol from the North-western Mediterranean coast of France (Cap Ferrat, nearby Nice) between 1986 and 2008. From seasonal variations (2006-08) and decadal trends (1986-2008) of TM concentrations, three groups of elements can be distinguished. They consist of different aerosol sources: crustal-derived elements (Al, Fe, Mn and Co), trace metals of anthropogenic origin (Pb, Cd and Zn) and a third, intermediate, group of trace metals that presented both anthropogenic and natural/crustal influences (Ni and Cu). Reproducible seasonal patterns were observed for crustal and intermediate elements with highest concentrations between May and November, while anthropogenic trace metals did not show a pronounced seasonal cycle. Nevertheless, highest concentrations of anthropogenic trace metals occurred mostly in autumn/winter. Aerosol concentrations of anthropogenic TMs decreased remarkably over the last two decades, while crustal trace metals did not show any evolution. Nickel and copper aerosol concentrations remained constant, as well. Lead concentrations decreased from 1986 (29.34 ng m(-3)) to 2008 (3.33 ng m(-3)), overall by 90%. Cadmium and zinc aerosol concentrations decreased by 66 and 54%, respectively, between 1998 and 2006-08, from 0.27 to 0.09 ng m(-3) and from 23.9 to 10.9 ng m(-3), respectively. These findings demonstrate the response of the atmospheric environment to the implementation of antipollution policies. Possible changes of trace metal emissions sources and local influences are discussed.

Seasonal and decadal variations in lead sources to eastern North Atlantic mussels.

The concentration of Pb and its stable isotope composition were measured in 216 composite samples of 50 blue mussels (Mytilus edulis (M. edulis)) collected quarterly between 1985 and 2005 at three sites along the French Atlantic coast, one in the La Fresnaye Bay and the others in the Loire and Seine River estuaries. Depending on the sites and time periods, Pb concentrations were 5-66 times higher than the natural background value for the North Atlantic. Even for the samples with the lowest Pb concentrations, the isotopic signature of Pb is very different than that of the regional natural Pb, suggesting that most of the bioaccumulated Pb is anthropogenic in origin. Stable Pb isotope ratios measured in the mussels differ markedly from that of Pb emitted in Western Europe as a result of leaded gasoline combustion, which was still a dominant source of contaminant Pb to the atmosphere during most of our study period. The isotope composition of Pb in the mussels was instead more typical of that of the Pb released to the environment by wastewater treatment plants, municipal waste incinerators, and industries such as metal refineries and smelters. Continental runoff, rather than atmospheric deposition, is therefore identified as the leading transport pathway of Pb along the French Atlantic coast. From the strong seasonal variations in (206)Pb/(208)Pb ratios in the mussels from the Seine Estuary site we also conclude that the resuspension of contaminated sediments, triggered by high river runoff events, is a chief factor affecting the bioaccumulation of Pb in M. edulis . The value of this organism as a biomonitor of coastal contamination is thus further demonstrated.

First record of butyltin body burden and imposex status in Hexaplex trunculus (L.) along the Tunisian coast.

We have assessed for the first time the current status of tributyltin (TBT) contamination in Hexaplex trunculus along Tunisian coastal waters. Two sampling campaigns have been performed in July 2004 and July 2007 at seven different sites. The snails were analyzed for imposex status, i.e. Imposex incidence, Relative Penis Length Index (RPLI) and Vas Deferens Sequence Index (VDSI), followed by the quantification of butyltins in their tissues. Imposex was detected in six populations from the 2004 samples and in five populations from the 2007 samples. The imposex incidence ranged from 0 (no imposex) to 100%, the RPLI from 0 to 56.7 and the VDSI from 0 to 4.4. TBT was also detected in six populations in 2004 and five populations in 2007. The concentrations ranged from 1.5 to 73.7 ng Sn g(-1) dw in 2004 samples and from 1.2 to 23.9 ng Sn g(-1) dw in 2007 samples. Temporal comparison of the data indicates some evidence of imposex recovery in most affected populations. Improvements in reduced body concentrations of TBT in both sexes were also seen in most stations. These TBT concentrations were only significantly correlated to imposex indices in samples from 2007 (r > 0.8, n = 7, p < 0.05). The present results will serve as a reference for long-term monitoring of butyltin contamination in the Tunisian coast, where TBT restrictions were not yet implemented.

Changes in the sediment trace metal contamination after the commissioning of a municipal wastewater treatment plant in the Souss estuary (South Morocco).

Monthly samples of sediment were collected from the Souss estuary, to determine the changes which have occurred in the concentrations of ten metals between 2001 when the low estuary was receiving the wastewaters from Agadir city and 2003 after stopping the sewage dumping. The annual contents of Cu, Fe, Zn (in 2001) and those of Cr, Cu, Fe, Mn, Ni, Pb, and Zn (in 2003) showed significant correlations with those of Al, indicating that fluctuations of their concentrations were only due to those of the aluminosilicate fraction of the clayey sediment. After normalization of these metallic concentrations in relation to those of Al, the contents of the different metals showed insignificant correlations between both years, except for Zn which significantly dropped in 2003 and Cu which increased in 2003. The observed metallic fluctuations are more influenced by the natural conditions of the estuary than the anthropogenic ones.

Monitoring of trace metal contamination in the Souss Estuary (South Morocco) using the clams Cerastoderma edule and Scrobicularia plana.

Concentrations of seven metals (Cd, Cu, Cr, Pb, Ni, Zn, Hg) were monitored monthly during 2 years in two bivalves, Cerastoderma edule and Scrobicularia plana collected from the Souss Estuary (South Morocco) before and after the commissioning of a sewage treatment plant in November 2002. According to trace metals, changes in concentrations were observed mainly in S. plana, characterised by a decrease of Cu, Hg and Pb when Cd was clearly increasing. Conversely, no clear changes were observed in C. edule during the same periods. This study suggests the use of S. plana in the monitoring of trace metal contamination of such coastal marine environments.