Spatial patterns in PCBs, pesticides, mercury and cadmium in the common sole in the NW Mediterranean Sea, and a novel use of contaminants as biomarkers

We assessed spatial patterns in 37 PCB congeners, eight pesticides, and the heavy metals mercury and cadmium in the flatfish Solea solea at four sites in the Gulf of Lions (NW Mediterranean). Overall contaminant concentrations generally exceeded those reported for S. solea elsewhere, but fell into the range of other Gulf fishes, testifying of a relatively high contaminant load of this area. Spatial patterns in all three contaminant classes were highly significant, but differed among classes. PCB congener and chlorination class profiles also differed among sites. The observed patterns would be consistent with (1) PCB point-sources in the Eastern Gulf (Marseille, Rhone River) versus dominance of atmospheric input in the West, (2) pesticide input by the Rhone and from agricultural fields in the West, and (3) mercury point-sources near Marseille. The unique, site-specific contaminant profiles prove to be a powerful tool to differentiate between S. solea populations from different sites.     

Reactivity of transparent exopolymeric particles: A key parameter of trace metal cycling in the lagoon of Nouméa, New Caledonia

Seawater samples were collected in the lagoon of Nouméa (New Caledonia) along two transects from coastal bays to the oligotrophic barrier reef. Dissolved (<0.2 μm) and sub-micrometer (0.2–0.8 μm) concentrations of chromium, nickel and zinc were measured. Concentrations in the 0.2–0.8 μm size range were correlated with transparent exopolymeric particles (TEP) turnover rates, suggesting that a TEP pool rapidly cycling in the system is more reactive toward metals. The role of TEP reactivity in the transfer efficiency of metals from dissolved to particulate phases was estimated through variations of the metal partitioning coefficient K between sub-micrometer TEP and solution, as a function of the water mass residence time. The log K (6.0–8.0) increased from high to low residence time, suggesting that TEP reactivity increases when water masses renew rapidly. This suggests that hydrodynamics control TEP reactivity toward metals. The characteristics (adsorption vs. complexation) of TEP-metal association are discussed.     

Development of a fish-based index to assess the ecological quality of transitional waters: The case of French estuaries

The Water Framework Directive requires the assessment of the ecological status of transitional waters considering the fish component. An original methodology, based on a pressure-impact approach, was established to develop a multimetric fish-based index to characterize the ecological quality of French estuaries. An index of contamination, based on the chemical pollution affecting aquatic systems, was used as a proxy of anthropogenic pressure. The fish metric selection was based on their response to disturbances tested via statistical models (generalized linear models) taking into account sampling strategy and estuarine features. Four metrics, for which discriminating responses to level of pressure were demonstrated, were retained to constitute the estuarine multimetric fish index. This new tool appeared particularly relevant to detect the contamination effects on fish communities in estuaries. It could help managers to take decisions in order to maintain or reach the good status required by the Water Framework Directive for 2015.     

Controls on upper Campanian–Maastrichtian chalk deposition in the eastern Danish Basin

Detailed facies analysis of a 350 m long core of upper Campanian–Maastrichtian chalk at Stevns Peninsula, eastern Denmark, shows that four mudstone and wackestone chalk facies account for close to 95% of the succession, and that bioturbated mudstone chalk alone accounts for nearly 55% of the sediment. Sedimentation took place in deep water, below the photic zone and storm‐wave base, and is characterized by decimetre to metre‐scale variations in facies and trace fossil assemblages indicating repeated shifts in depositional environment. Integration of facies with published data on sea‐surface temperature and accumulation rates suggests that sea‐surface temperature is the most important parameter in controlling stratification of the water column and thereby, indirectly, the observed variations in depositional facies. However, bioturbated mudstone chalk occurs in all stratigraphic levels independent of accumulation rates and sea temperatures and is interpreted to represent a very broad set of deep water environmental conditions with an ample supply of calcareous nannofossil debris and intense bioturbation. Longer term shifts in deposition are best expressed by distribution of clay, flint and bioturbated micro‐wackestone, bioturbated wackestone and laminated mudstone chalk facies, whereas the trace fossil assemblages appear less useful. The data set indicates overall shallowing over time with two distinctive events of clay influx to the basin during the late Campanian–earliest Maastrichtian and late Maastrichtian.     

Filament Recognition and Image Cleaning on Meudon Hα Spectroheliograms

This paper presents the techniques developed for the automated detection of filaments on Meudon H spectroheliograms, and, by extension, on any full-disk H Sun observations. Some cleaning processes are first applied to the images to correct them from defects characteristic of the instrument. Indeed, these defects may lead to spurious detections. From the cleaned images, filament areas are then segmented using a region growing method which efficiently returns the full extent of these dark areas. The filaments are finally described by means of their pruned skeleton. This representation allows one to compare the automatically segmented filaments with those manually recorded for Meudon Synoptic Maps. The very good agreement observed on a representative set of images confirms that this method can effectively be used in the frame of the EGSO (European Grid of Solar Observations) project in order to produce a reliable catalog dedicated to solar features.     

EPR microplates, a model for the Oman Ophiolite

Structural mapping in the Southern half of the Oman ophiolite has revealed a palaeoridge organization with similarities to an EPR microplate, forming in superfast spreading conditions. A NW-trending propagator was rapidly opening in a lithosphere no more than 1 Myr older and itself created in a NE-SW ridge system. The NW-trending propagator, underlined by small mantle diapirs, was active or dying when detached as part of a future ophiolite. Local thrusting of the future ophiolite was also initiated very early, between 1 and 5 Myr after ridge accretion; it was accompanied by a 40° rotation within this time lapse. Such an activity supports the comparison of the Oman palaeoridge system with an oceanic microplate, and provides evidence to suggest the existence of thrusts at active microplates.     

IO and Its Plasma Torus

A brief review of our courrent understanding of the interaction between the innermost Galilean satellite,Io,and Jupiter's magnetosphere is presented.Particular consideration is given to the neutral clouds and lo plasma torus which have been monitored by ground-based and Earth-orbiting observations for the past 25 years.Detailed investigation of observed phenomena in the neutral clouds has revealed several processes which have a direct bearing on the nature of the interaction and suggest that a revision of the existing concept is necessary.Similarly.observed variability in the torus indicates the presence of complex plasma processes which at present remain unexplained.Areas where further research is necessary are outlined.     

Determination of mercury in seawater at sub-nanogram per liter levels

Using a refined two-stage gold amalgamation preconcentration technique in conjunction with cold vapor atomic absorption (CVAA) detection, mercury in various Pacific Northwest coastal waters has been determined. Through the use of extremely clean reagents and special handling techniques, the blank has been reduced and reproducibility greatly improved for both “easily reducible mercury” and “total mercury”.Samples of unfiltered water, taken at the surface, as well as at 10 m, 100 m, and 175 m have all yielded “easily reducible mercury” at between 0.1 and 0.5 ng l^?1, and “total mercury” between 0.2 and 1.0 ng l^?1. Variability within replicate field samples is less than 10%, although variations of greater than 100% may be seen over a period of hours in Sequim Bay.