Renzo Biondo

A new design of equilibrator to monitor carbon dioxide in highly dynamic and turbid environments

A new design of equilibrator for carbon dioxide monitoring in natural waters is described. It consists in a vertical tube filled with marbles through which water is flowing while equilibrating with a closed air circuit. It offers several advantages compared with classical equilibrators, among which is a fast response time (half-life constant approximately 30 s) and the potential to work in very turbid water. The proposed equilibrator is of particular interest to monitor carbon dioxide in coastal ecosystems, such as estuaries, which are known to be turbid and highly dynamic. Two performance tests and some field results are presented to illustrate the efficiency of the proposed system.

Distribution of heavy metals in the echinoid Paracentrotus lividus from the Mediterranean Posidonia oceanica ecosystem: seasonal and geographical variations

The concentrations of Zn, Pb, Cd, Fe, Cr, Cu, and Ti were measured in specimens of the echinoid Paracentrotus lividus from three Posidonia oceanica meadows in the NW Mediterranean (Marseille, France; Ischia, Italy; Calvi, Corsica). Investigated metals were selectively distributed among the echinoid body compartments (i.e. body wall, Aristotles lantern, digestive wall, and gonads); their concentrations were influenced by season. The present work emphasises the need to consider both body compartment and sampling period as important factors in studies intending to use P. lividus as a biomonitor species. In particular, digestive wall and, secondarily, body wall and gonads are recommended for use in biomonitoring programmes, though with some restrictions for gonads. Concentrations of most metals differed significantly in the echinoid body compartments according to the seagrass meadow considered. However, these differences were generally of low amplitude, except for Fe and Ti (contaminations by these two metals showed significant departures from background concentrations in echinoids from Ischia). Results suggest that the meadows of Calvi and Marseille, although subject to different pollution status (the meadow of Calvi is considered as a reference meadow while the Marseille meadow is exposed to intense domestic and industrial discharges), showed similar patterns of metal contamination.

Distribution of inorganic carbon and related parameters in surface seawater of the English Channel during spring 1994

Abstract The complete CO 2 system, dissolved oxygen, nutrients and chlorophyll concentrations, fluorescence, salinity and temperature of surface seawater have been determined in the English Channel and the Southern Bight of the North Sea during Spring 1994. As already mentioned in a previous study, this area is characterized by important spatial and temporal variations of the considered set of parameters. This paper focuses on the distribution of the homogeneous buffer factor [ β = dln(pCO 2 ) dln(TCO 2 ) ]. It is shown that this parameter is a useful tool for identifying processes that mainly affect the CO 2 distribution, such as primary production or water mass mixing, even in such a complex area.