Paola Cellini Legittimo

1980–1990: Ten years of geochemical investigation at Phlegrean Fields (Italy)

Abstract A systematic geochemical investigation on the thermal manifestations of the volcanic area of Phlegrean Fields started in 1980, with the aim of obtaining useful information about the changes possibly occurring at the same time of vertical ground movements, termed as “bradyseismic”, which frequently interested this area. The attention was initially given to the fumaroles and the boiling pools of Solfatara and Pisciarelli, then subsequently extended to thermal springs, dug wells, and crater lakes. Analytical data pertaining to a period preceding the last crisis of 1982–1984 were then available, as well as other data collected during the previous crisis of 1970; a comprehensive picture of the variations observed before, during and after the acceleration of vertical movement has been drawn. According to the results obtained, the intrusion of a magmatic body as the trigger of the observed ground deformation is considered unrealistic. The whole area appears now in a quiet stage, and no further perturbation is expected without previous significant tectonic activity; chemical precursors appear suitable for an early detection of changes occurring at depth, to forecast possible consequences to be expected in the surface environment.

Relations between chemical species distribution and the fluctuating activity of Vulcano (Italy)

Abstract Five years of systematic observation of the fumaroles of Vulcano have allowed us to detect some compositional trends coincident with a fluctuation in temperature. A gradual decrease of CO2, H2S+SO2, HF is observed with the lowering of temperature, while HCl slightly increases. These physical-chemical characters of the system are not readily explained as simply produced by different stages in magma degassing, and the previous hypothesis of the significant influence of a brackish aquifer on the fumaroles still appears a reliable working model. R-mode factor analysis allowed to distinguish the differentiated role of chemical species for which different genetic processes can be derived. The ratios HF HCl and SO 2 H 2 S are taken as indicators of the changing activity of the system, and also the available data for Usu (Japan) and Mount St. Helens (USA) are considered.

Mercury Pollution in the Surface Environment of a Volcanic Area

Abstract The mercury content has been determined in samples of fumarolic gases, phreatic waters, soil and vegetation collected at Vulcano, Aeolian Islands, Italy. Volcanic activity is demonstrated as a source of natural mercury pollution whose extent has been evaluated here by studying the contribution of different components of the surface environment. The possible influences for living organisms are examined.

The Ecological Significance of the Coexistence of Sulphur Dioxide and Hydrogen Sulphide in Volcanic Fumaroles

Abstract The relative concentrations of hydrogen sulphide and sulphur dioxide in volcanic gases cannot be explained simply by the temperatures and pressures, and appear as the result of the influence of different natural factors. SO2 is directly related to magma degassing, while H2S can be produced by the reaction of acidic solutions on dispersed sulphide minerals. As long as these inputs to the surface environment are of moderate extent, then readjustment of redox conditions to an equilibrium situation will occur; a permanent disequilibrium will result in increased contributions of any component. A wide spectrum of trace elements is normally associated with the presence of sulphur compounds in volcanic areas; their importance can be estimated for any system on the basis of the quantitative relationship between the oxidized and the reduced sulphur species. Extensive polluting effects can be produced by a continuous flow from a deep magmatic source, while minor consequences are associated with a re-circula...

A study of the ruthenium-2,2′,2″-terpyridine system

Abstract The chemical and electrochemical behaviour of the ruthenium(II) and ruthenium(III) complexes with 2,2′,2″-terpyridine has been studied. Spectrophotometric measurements proved the existence of a protonated ruthenium(II) complex with p K a =2.9. Potentiometric and voltammetric studies showed a difference in the behaviour of the ruthenium(II) complex against chemical and electrochemical oxidation. Potentiometric data showed also that the ruthenium(III) complex may be reduced rapidly and spontaneously.

Cu, Pb and Zn determination in rainwater by differential pulse anodic stripping voltammetry

The parameters affecting the determination of some heavy metals in rainwater of Florence and its suburbs are investigated The maximum sensitivity for zinc determination by DPASV is obtained for a pulse amplitude of +50 mV.Samples of rainwater, collected in the center of Florence, show a metal concentration which is higher than samples collected in the suburb for the same meteorological event. Other sampling along the Tyrrenean seashore revealed a higher metal concentration in relation to the section of the coast that receives the polluted waters of the Arno river.In samples acidified to pH = 2, Cu and Zn are partially released in a very slow process.

Iodine trichloride in glacial acetic acid as an oxidizing titrant

Abstract A systematic study of the redox reactions of iodine trichloride with various inorganic ions in glacial acetic acid medium is described. Sodium sulphite, arsenic trichloride, antimony trichloride, iron(II) perchlorate and mecury(I) perchlorate were examined. Potentiometric and amperometric methods were used to follow the reduction of iodine trichloride, which yields different products according to the type of reductant.

Heavy Metals in Epiphytic Mosses: An Experience in Florence

Abstract The epiphytic moss Hypnum cupressiforme has been used for passive monitoring of airborne heavy metals pollution by vehicular traffic in the urban area of Florence. Lead, cadmium, zinc and copper were determined by differential pulse anodic stripping voltammetry (DPASV). in the summer of 1993 about 30 samples were collected from the trunks of holm oak at the same height (1 metre) from the soil. Lead contents fall within the range of 0.02–1.08 μ moles g−1 (dry weight) and for this metal, the emission source may be attributed mainly to vehicular traffic in poorly industrialized urban areas. Some evaluations have been carried out about the employment of Zn/Pb molar ratio for characterizing airborne pollution in urban areas.

Observations on the reaction between nitric acid and brucine

Abstract The reaction between nitric acid and brucine has been investigated by spectrophotometric and potentiometric methods With cerium(IV) and dichromate the oxidation of brucine corresponds to two electrons per mole and the spectrum taken during oxidation is similar to that observed in the reaction with nitric acid. By studying the reaction of brucine with nitrous acid, and the effect of chloride ions, an interpretation of the oxidation reaction can be suggested and chemicals that interfere in practice can be indicated.

Complexing Capacity of Thermal Waters of Montecatini Terme (Italy)

Abstract Two typical waters from thermal springs of Montecatini Terme-used as therapeutical beverages-exhibit a small complexing capacity towards Cu2+. By differential pulse anodic stripping voltammetry the following values were found: 0.46 μmol 1−1 and 0.10 μmol 1−1, respectively for Regina and Rinfresco waters. Owing to the presence of a small amount of complexed copper in the original samples, the complexing capacity has to be regarded as residual capacity. In bottled waters from the same springs no complexing capacity was detected. Values of formation constants for copper complexes are given. No residual complexing capacity for Cu2+ was displayed for Tamerici and Tettuccio thermal waters.