L. Tositti

Radiation induced decomposition of halogenated organic compounds in water

Decomposition by ionizing radiations of p-chlorophenol and tetrachloroethylene in synthetic water samples at about 2 mg Cl L−1, has been studied on laboratory-scale experiments. Bicarbonate/carbonate and nitrate ions, at two concentration levels (20 and 200 mg HCO3−1 and 1 and 50 mg NO3−L−) were added to synthetic samples in order to evaluate their influence on decomposition yield. At 5 kGy γ dose level, a quantitative degradation of p-chlorophenol is obtained whereas only qualitative consideration can be drawn on tetracholoroethylene. Comparative study with respect to degradation of p-cholophenol solutions (about 2 mg Cl L−1) by γ-rays and electron beam irradiation treatment at 0.5 kGy dose level, are in progress; preliminary results indicate that irradiation with γ-rays seems to be more efficient in terms of removal efficiency respect to electron beams source.

Preliminary investigations on7Be as a tracer in the study of environmental processes

The usefulness of cosmogenic7Be as a tracer in a terrestrial environment has been investigated. Atmospheric fluxes and inventories of the radionuclide in grassland have been determined. Environmental behavior in connection with foliar interception and possibility of subsequent release has been studied.

The use of 210Pb and 137Cs in the study of sediment pollution in the Lagoon of Venice

The activity of 137Cs per unit area in sediments of the central part of the Lagoon of Venice was determined with the aim of identifying boundaries of homogeneous depositional zones. The 210Pb dating technique was used to date vertical profiles of cores from the same area. A comparison of the total amounts of 137Cs and non-supported 210Pb present in each core and the atmospheric input allows us to identify different depositional areas inside the basin and to outline the possible drainage effect of industrial solid wastes used in past reclaiming operations.

Fallout distribution in Padua and Northeast Italy after the chernobyl nuclear reactor accident

Abstract The radioactive cloud from the Chernobyl nuclear reactor accident arrived in northeast Italy on 30 April 1986. Ground-level air activities detected in Padua reached maximum values of 28·6, 19·2, 3·3, 1·7 and 7·5 Bq m −3 for 131 I, 132 Te( 132 I), 137 Cs and 103 Ru, respectively, on 1 May; about 10 days later, the activities had fallen to less than 1% of peak values. Considerations of cloud homogeneity are reported. The distribution of fallout radionuclides in Padua was evaluated on the basis of radioactivity detected on natural surfaces. The average committed dose equivalent to the thyroid for adult people in Padua through 131 I inhalation was estimated at 0·37 mSv. Soil activity was monitored daily in samples collected in Padua during the first weeks of May 1986. Fallout deposition over northeast Italy was measured on 75 surface soil samples collected during June 1986 and long-lived radionuclide distribution maps were derived.

Simultaneous Measurements of Remote Lidar Chlorophyll and Surface CO2 Distributions in the Ross Sea.

A comparison between continuous lidar fluorosensor chlorophyll-a measurements and partial pressure of CO2 (pCO2) in surface water is presented. The data were gathered during the XVI Italian Antarctic expedition in the Western Ross Sea and crossing the Southern Ocean. Anticorrelation between CO2 levels and chlorophyll-a determinations was observed throughout the cruise in the late austral summer 2000/01. The survey revealed the presence of high productivity in polynya regions and close to the ice edges. The lidar data, reported here, are consistent with the results of previous campaigns conducted in the same investigated area. The relationship between pCO2 and chlorophyll-a concentration are discussed in terms of biologically driven phenomena responsible for the pCO2 undersaturation with respect to the atmospheric value during the austral summer.

Stratosphere-troposphere exchanges: case studies recorded at Mt. Cimone during VOTALP project

Abstract In order to point out and study transports of ozone rich air masses in the lower troposphere from the stratosphere/upper troposphere, continuous measurements of several parameters have been undertaken at Mt. Cimone during the European Community VOTALP project (Vertical Ozone Transport in the Alps). Several high values of surface ozone concentration due to vertical stratospheric-tropospheric exchanges have been recorded in the four mountain peak stations involved in this project (Jungfraujoch, Sonnblick, Zugspitze and Mt. Cimone) in 1996–1997. This paper presents and analyses data concerning the Mt. Cimone ground-based station, which is the highest peak of the Italian Northern Apennines and the most representative WMO-GAW site in Italy. Episodes of vertical exchange in the lower stratosphere, as tropopause folding, or in the upper troposphere, as down draft transport, have been registered at Mt. Cimone since March 1996 and subsequently studied. In fact, the comparison between the behaviours of different background trace gases at a mountain baseline station, the weather situations and the backward trajectory analyses can bring to light these events and be very useful for a better knowledge of transport phenomena. Correlation between high level of ozone concentration, chemical and meteorological parameters and three-dimensional backward trajectories relative to two particular events are herein presented.

Trace elements distribution in Antarctic sediments by neutron activation analysis

In the present investigation iron and trace elements were determined by instrumental neutron activation analysis in a number of sea bottom sediment samples, collected in the Ross Sea and close to the Italian Station at Terra Nova Bay in Antarctica. Full listing of results is presented and discussed as well as the evaluation of precision and accuracy. In order to find correlations and similarities among the sediment samples, the analytical data were submitted to statistical treatment. In addition rare earth element patterns were obtained. Typical trends were observed with no evident Eu negative anomaly and a depletion of heavy rare earth elements.

Self-absorption correction for low energy gamma rays: Application to 210Pb determination in marine sediments

A series of nondestructive, low energy gamma-ray spectrometric measurements by means of intrinsic Ge detectors was carried out for the activity determinations of several naturally occurring radionuclides in marine sediments. The system was calibrated for efficiency using a radioactive sample obtained by combining standard radioactive solutions with a suitable matrix. This procedure is strictly only correct for the analysis of samples of similar composition with the same mass absorption coefficients at the investigated energies. Nevertheless, the efficiency calibration can be extended to different matrix samples if the variation in self-absorption is accurately taken into account. A method for calculating the self-absorption correction at any energy of interest is proposed and verified for the determination of 210Pb activity at an energy of 46.5 keV. The direct gamma method and the conventional, accurate, but tedious, alpha technique via 210Po, which can be alternatively applied to the determination of 210Pb, agreed mostly within 8%.

Italian Antarctic Research Program: Environmental radioactivity survey around the Italian base (1987–1991) Terra Nova Bay — Ross sea region

Investigations have been carried out by the Italian Antarctic Research Program to determine the natural and artificial radioactivity levels of both the marine and terrestrial environments. Also, natural and anthropogenic fluxes of aerosol particles onto the Antarctic surface have been examined.

Distribution of 226Ra in the Ross Sea—Antarctica

Abstract An improved procedure for the determination of 222Rn and 226Ra in seawater developed for easier on-board operations is presented. Data on the radioactive disequilibrium between the mentioned radionuclides as directly determined in the field can be greatly helpful in the study of the gas-exchange processes at the air-sea interface, especially as far as the Antarctic Ocean is concerned. The method employed has been preliminarly tested in laboratory on a set of seawater samples collected in the Ross Sea and 226Ra data collected are discussed and compared to literature data.