The Spiral 2 project at GANIL aims at producing exotic ion beams for Nuclear Physics. The accelerator of the primary beam is a superconducting Linac designed to provide 5 mA deuteron beams at 40 MeV. It will also allow accelerating stable ions of different Q/A values ranging from protons to Q/A=1/6 heavy ions. The accelerator should be commissioned by the end of 2011, first beam in 2012. The first tests aiming to produce exotic beams are planned one year later. The superconducting LINAC consists of 12 low beta (0.07) quarter wave (88 MHz) superconducting (SC) cavities and 24 beta (0.14) SC cavities integrated in their cryomodule. The status of the low beta cryomodules, supplied by the Irfu institute of CEA Saclay, is reported in this paper. The RF full power tests were performed on the qualifying cryomodule at the end of 2008 and the beginning of 2009, and the tests of the first series cavity in vertical cryostat are in course.

The French laboratories CEA/Saclay and IPN Orsay, involved in the SPIRAL2 project, are now preparing the final tests of the two qualifying cryomodules (called respectively A for the beta 0.07 cavities and B for the beta 0.12 cavities) in order to start the series production in 2008. Each cryomodule A and B will be tested at 4.2 K and nominal power (10 kW, CW). This paper presents an update of the cryomodules and cavities developments (first results at room temperature, first assembly...) which have been presented in [1].

During an intense (up to 33 X 106 cells L−1) Alexandrium minutum bloom in the Penzé estuary (France), total NO3, NH4, and PO4 requirements of the bloom were, respectively, 184, 25, and 20 µmol L−1, with peak uptake rates of 43, 6, and 4.8 µmol L−1 d−1. The measured ambient concentrations of NH4 and PO4 were far short of this peak demand, whereas those of NO3 were far in excess, indicating that PO4 supply is important for sustaining the bloom. Comparison of the measured NO3 uptake rates with advective fluxes indicates that a reduction of NO3 concentrations in river waters to <200 µmol L−1 would be necessary to contain the bloom in the Penzé estuary. The role of NO3 was restricted to sustenance of the bloom, whereas warm conditions resulting in a water column stability seem to have triggered the bloom, and a self‐shading, probably coupled with a phosphorus limitation, caused its decline.

In the coastal domain, depending on the importance of hydrodynamics, one can differentiate between several types of systems as follows: (1) a stratified system in regions where the energy dissipated by the tidal currents is weak and a thermal (or haline) stratification becomes established, (2) a homogeneous system in the sectors where the intensity of currents is strong enough to counteract the effect of stratification, and (3) a frontal system, corresponding to a transition between the stratified and well-mixed systems. The functioning pattern in the homogeneous system contrasts with that in zones of weak hydrodynamism (stratified system). The studies carried out in recent years (results obtained mainly in the English Channel) have evidenced this specificity with respect to the nitrogen cycle. When the depth of the well-mixed layers is distinctly greater than that of the euphotic zone (deep homogeneous systems), the production cycle, in terms of nitrogen as well as in terms of carbon, has a broad maximum that extends over the whole summer. The mean light energy available for phytoplankton is low and this limits the growth of the latter throughout the year. On the other hand, nitrogen, the concentrations of which remain high throughout the seasonal cycle, is not a limiting factor for phytoplankton growth. The development of phytoplankton is based mainly on the utilization of regenerated forms of nitrogen, in particular ammonium. The high primary production in the homogeneous system is related to a rapid recycling of ammonium in the water column by the microbial loop and not to a nutrient enrichment with allochthonous inputs. When the well-mixed water column is shallow and light penetration reaches to the bottom in summer (shallow well-mixed systems), the production cycle shows a sharp maximum in spring. The nitrogen stock available in spring for the development of phytoplankton is much smaller than that in the deep well-mixed system. Consequently, in summer nitrate is sometimes near totally exhausted in the shallow well-mixed systems. The decrease in nitrate concentrations is compensated for by the prevalence of high concentrations of ammonium that prevent a marked limitation of nitrogen. Hence, light remains the main factor limiting the development of phytoplankton in this shallow sector of the homogeneous system. The shallow homogeneous system, in spite of a seasonal cycle distinctly different from that in the deep homogeneous system, also shows a primary production mainly of a regenerated nature. Most of the organic matter produced in the entire homogeneous system is decomposed in situ and mineralized; the capacity of this type of system to export organic matter therefore is reduced.

Uptake and regeneration of nitrogen in the Almeria-Oran frontal zone (SW Mediterranean) and adjacent (Atlantic and Mediterranean) systems were studied during the Almofront I cruise (JGOFS-France). The frontal zone was characterized by an upsloping of nitracline from about 50 m in the adjacent systems to 25-30 m within. Along with nitrate, ammonium, chlorophyll a and particulate organic nitrogen also were at higher concentrations in the frontal zone than in the adjacent waters.The nitrate uptake rates were significantly higher in the frontal zone (up to 6.4 nmol l(-1) h(-1)) than in the Atlantic and Mediterranean waters (generally <1 nmol l(-1) h(-1)) indicating a significant increase of new production at the front. This increase was related to the upsloping of the nitracline as shown by the significant correlation (p<0.05) between new production and depth of the nitracline. The new production in the Almeria-Oran was much lower than those recorded in other oceanic and coastal fronts. This could be related to the fact that the nitracline did not rise up to the surface and the high concentrations of nitrate were confined to deeper layers where the ambient light intensity was less. Nitrate uptake in the frontal zone was significantly higher, by 1.7-5.8 times (average 4.2), than the calculated diffusive flux of nitrate, suggesting that vertical advection may be an important source of nitrate. New production rates at the front were also significantly higher (3-9 times, average 5.8) than the PON flux to 100 m depth estimated by sediments traps (Journal of Marine Systems 5, 377-389), suggesting a strong decoupling between surface production and downward flux of POM in the frontal zone.The north-south gradient observed with different parameters indicates the presence of a transfrontal secondary circulation. This distribution also suggests that the primary production in the front is initially nitrate-based, with a diatom-herbivore food chain, whereas regenerated production, associated with an intense recycling of organic matter, later becomes progressively important in time and space. (C) 2001 Elsevier Science Ltd. All rights reserved.

Ammonium regeneration by size-fractionated plankton was measured for 1 year at a coastal station in the shallow well-mixed waters of the western English Channel. Rates of ammonium regeneration in the <200μm fraction varied from 0.6 to 27nmol N l−1 h−1. On the seasonal scale, these rates were relatively low (<7nmol N l−1 h−1) in autumn and winter, increased steadily from March to attain a maximum (27nmol N l−1 h−1) at the end of May and thereafter decreased steadily to the seasonal minimum in December. This pattern is distinctly different from that observed in deep well-mixed waters where the peak ammonium regeneration occurs in summer (Le Corre et al., 1996, Journal of Plankton Research, 18, 355–370). Total ammonium regenerated in a year by the microheterotrophs was 15g N m−2, equivalent to about 60% of the total nitrogen uptake. Microplankton (200–15μm) accounted for about 50% of the regeneration measured between early spring and late summer. Percent contribution of nanoplankton to total ammonium regeneration varied considerably between the seasons, from very high (83–88%) levels in winter to very low (2–13%) levels in summer. Contribution by picoplankton (<1μm) was high (20–45%) in summer but was less than 20% in other seasons. Ammonium regeneration in micro- and nanoplankton fractions was mainly associated with ciliates and in the picoplankton fraction with bacteria. Macrozooplankton dynamics appears to regulate ammonium regeneration by ciliates and bacteria. Low macrozooplankton biomass in spring may favour a high growth of ciliates and an associated high in ammonium regeneration. In summer, the increase in macrozooplankton may exert a grazing pressure on ciliates. This, coupled with the fact that most of the flagellates are autotrophs, would, in turn, lower the grazing pressure on the bacteria, thus favouring their development and increasing the importance of their role in ammonium regeneration. This situation, where the macrozooplankton dynamics apparently regulates ammonium regeneration in nano- and picoplankton fractions, appears to be different from that in deep well-mixed waters. Here, the relative contribution of ciliates and bacteria to ammonium regeneration shows little variation with an increase in macrozooplankton biomass.

Nitrate and ammonium uptake rates were measured in spring and summer in deep and shallow well-mixed waters of the English Channel during different cruises between 1986 and 1994. In the deep waters, nitrate uptake was relatively low during phytoplankton development and ammonium uptake represented more than 70 % of the total uptake irrespective of the season. In the shallow waters, nitrate uptake during spring phytoplankton growth was high and represented about 75 % of the total uptake. Ammonium uptake became substantial towards the end of spring and summer. The high contribution of ammonium to the nitrogenous nutrition of phytoplankton over the whole of the well-mixed waters is related to a high rate of recycling of nitrogen in the water column. Ammonium regeneration by microheterotrophs can satisfy between 62 % and the totality of the phytoplankton nitrogen requirements. The high primary production in deep well-mixed waters is not supported by allochthonous nitrogen supply but by an intense in situ regeneration of nitrogen. The situation is similar in shallow well-mixed waters, except during the spring bloom. (C) Elsevier, Paris.

Une methode electrochimique est proposee pour la determination des traces d'aluminium (III). Elle fait appel a la voltametrie a balayage lineaire apres adsorption d'un complexe aluminium-lumogallion a la surface d'une goutte pendante de mercure. L'influence du pH, de la concentration en ligand, du potentiel et du temps de depot est etudiee. De meme, les interferences, tant organiques que minerales, sont analysees. Le courant de pic varie lineairement en fonction de la concentration en aluminium jusqu'a des teneurs en metal de 1,5.10 -7 mol.L -1 . Le seuil de detection est de 1,5.10 -9 mol.L -1 pour un temps de depot de 60 s.

Uptake rates of ammonium, nitrate, urea and nitrite were measured for 1 year (1988) at a coastal station in the well-mixed waters of the western English Channel. Ammonium was the major form of nitrogen (N) utilized (48%) by phytoplankton, followed by nitrate (32%), urea (13%) and nitrite (7%). Seasonal changes of uptake of ammonium, nitrate and urea showed a broad, intense summer maximum. Nitrite uptake was low throughout the year except for a peak value in June. Uptake rates of ammonium and nitrate were independent of substrate concentrations, whereas those of urea and nitrite were not. The summer maxima of ammonium, nitrate and total N uptake, and the significant relationships of N-uptake index to ambient light, and of chlorophyll-a-specific N uptake to surface-incident light, indicate that light is the major factor controlling N uptake in these waters. This is due to the permanent vertical mixing which reduces the mean light available for N uptake to <15% of the incident light. Mixing also injects regenerated N continuously into the euphotic zone, thus alleviating nitrogen limitation and accounting for the larger proportion of regenerated N uptake in total N uptake.

The determination of the total concentration of a trace element gives only few informations about its toxicity and its bioavailability which depend mainly on the different chemical forms under which it is present. The studies of the chemical speciation is thus particularly important. We propose, in this paper, a selenium speciation model for the studies of natural waters based on Se(IV) voltammetric determination. The separation of the organic and inorganic forms was realized by a rapid ion exchange method and total selenium was determined after a u.v. irradiation.

Seasonal changes in inorganic (NH4+; NO3-; NO2-) and organic (urea) nitrogen uptake were studied with N-15 as a tracer at a shallow station (depth: 22 m) in permanently well-mixed waters of the Western English Channel. Uptake of all the four nutrients was maximum in spring. Nitrate uptake accounted for a third of the total during spring phytoplankton growth, but decrease in summer. This decrease was related to the low ambient nitrate concentrations in early summer and to an inhibition of uptake by high concentrations in late summer. Ammonium was taken up in significant amounts from the beginning of spring (46 % of total uptake), increasing to 59 % in summer. In contrast with nitrate, ammonium concentrations during summer were sufficiently high to saturate uptake and prevent nitrogen limitation. Ammonium supplied about half of the nitrogen required by the phytoplankton in an annual cycle (48 %), followed by nitrate (33 %). Urea and nitrite were taken up at relatively low rates during a major part of the year and satisfied only 15 and 5 % of the total phytoplankton nitrogen requirements. Our results suggest that light controls phytoplankton growth throughout the seasonal cycle.

The reaction between 1,2-dihydroxyanthraquinone-3-sulphonic acid and chlorine dioxide, in phosphate buffer medium, was studied spectrophotometrically and electrochemically. An electroanalytical method is proposed for the determination of traces of ClO2 with a detection limit of 2 μg l−1. The stoichiometry of the reaction, the effects of various operational parameters and the influence of foreign ions are reported.

A method is described for the determination of copper in seawater by adsorptive stripping voltammetry after accumulation of a 1,2-dihydroxyanthraquinone-3-sulfonic acid (DASA) comples. The effects of various operational parameters (pH, ligand concentration, potential, and accumulation time) on the reduction current of the adsorbed chelate are discussed. A linear current concentration relationship was observed up to 5 x 10(-8) M. The detection limit is 0.3 nM.

Seasonal variation of copper, nickel and lead were studied in the Douarnenez Bay and the Iroise Sea during April 1983-February 1984 period. Our results compare favourably with those found in neighbouring coastal areas (1·5 nmol 1-1 <Cu <8·0 nmol l-1; 1·4 nmol l-1 <Ni <6·8 nmol l-1; and 0·07 nmol l-1 <Pb < 2·70 nmol l-1).

Uptake of nitrogenous nutrients (NO3-, NO2-, NH4+ and urea) by phytoplankton was measured over an annual cycle at a coastal station in the well-mixed waters of the western English Channel. Seasonal changes of nitrogen uptake showed a single, but spread-out, maximum in summer. The phytoplankton took up the various forms of nitrogen simultaneously. Ammonium uptake accounted for 48% of the total nitrogen uptake and was quantitatively important from the beginning of spring until early autumn. Nitrate uptake was relatively less important (32% of total nitrogen uptake) though nitrate was the major component of available inorganic nitrogen. Nitrate uptake rates were comparable to those of ammonium in winter and spring, but were much lower than the latter in summer as a result of inhibition by high ambient ammonium concentrations. Urea and nitrite contributed much less (respectively 13 and 7%) to nitrogen nutrition of phytoplankton. Regenerated-production accounts for about 70% of the annual production; this proportion is much higher than in several other coastal ecosystems.

A sensitive procedure for the determination of chromium(VI) is described. A chelate of chromium with an organic ligand is adsorbed on a hanging mercury drop electrode and the reduction current of the accumulated chelate is measured by differential-pulse voltammetry. The effects of various parameters (pH, ligand concentration, potential and collection time) on the response are discussed. Possible interferences by trace metals and organic matter are considered.

Mediterranean nutrient studies differ from one another by their rates of exchange with the Atlantic Ocean and by atmospheric and terrestrial sources, which sometimes vary by six times. During the Medatlante cruises (in 1988 and 1989), increases of phosphate and nitrate concentrations were confirmed in deep western waters and may be related to increasing agricultural, industrial and urban activities around the sea since the 1960s. In a non-steady-state model, this evolution of deep water concentrations constrains uncertainties in the nutrient budgets; we propose a reduced range for atmospheric and terrestrial sources of nutrients. In the Western Basin in the late 1980s the total atmospheric and terrestrial source amounted to 8–10 × 109 mol y−1 of phosphate, and 190–220 × 109 mol y−1 of nitrate; about two-fold greater than estimates based on measurements of atmospheric and terrestrial inputs (the latter is calculated from the Rhône river concentrations over the 1971–1988 period). Consequently, phosphate budgets suggest that some of the riverine particulate input of phosphorus dissolves when entering the sea and constitutes a main source of phosphate, a scenario proposed by Froelich (1988). Likewise, dissolved inorganic nitrogen budgets require biological fixation of molecular nitrogen by plankton species and seagrasses. This process may constitute the main nitrogen source and explain the peculiar molar ratio N/P in the Mediterranean Sea (about 21–23) instead of about 15 in the global ocean.

The behaviour of the complex of copper with 1,10-phenanthroline at a mercury electrode was investigated in acidic chloride media. Adsorption phenomena were observed by both differential-pulse and normal-pulse polarography. These properties were used in developing a sensitive stripping voltammetric procedurefor the determination of traces of copper. The effects of various operational parameters (pH, ligand concentration, potential and accumulation time) on the reduction current of the adsorbed chelate are discussed. Interferences by other trace metals and organic matter were investigated. A linear current-concentration relationship was observed up to about 1.5 × 10−7 M. The detection limit is 1.2 × 10−10 M copper after a 10-min accumulation time with a stirred solution.

The thermotropic phase behavior of an odd- and an even-numbered member of the homologous series of 1,2-di-ω-cyclohexylphosphatidylcholines was studied using Fourier transform infrared spectroscopy. The results obtained indicate that the pronounced discontinuities in the behavior of the odd- and even-numbered homologoues observed by differential scanning calorimetry can be attributed to differences in the organization of their respective gel states. The single phase transition exhibited by the odd-numbered compounds upon heating is shown by infrared spectroscopy to be a direct transition from α condensed, subgel-like phase (Lc phase) to the liquid-crystalline state (Lα phase). In contrast, the multiple transitions exhibited by the even-numbered homologues are shown to be due to the initial conversion of an Lβ-like phase to a more loosely packed gel phase, followed by the acyl chain-melting transition. Moreover, the major changes in the interaction between the acyl chains, and in the organization of the interfacial region of the bilayers formed by the even-numbered homologous, occur at temperatures below that of the chain onset-melting phase transition. The infrared spectroscopic changes observed also suggest that above the chain-melting transition, the odd- and even-numbered homologues form similar liquid-crystalline phases that are more ‘ordered’ than those of normal saturated straight-chain phosphatidylcholines. Most likely this is because the large size and the intrinsic rigidity of the ω-cyclohexyl group reduces the conformational disorder of the liquid-crystalline state by ‘damping’ all acyl chain motions. The formation of a relatively ordered liquid-crystalline state may be the critical property exploited by the thermoacidophylic organisms in which ω-cyclohexyl fatty acids naturally occur.