Laura Tositti

Tracking of Airborne Radionuclides from the Damaged Fukushima Dai-Ichi Nuclear Reactors by European Networks

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous (131)I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous (131)I and the large underestimation of the total (131)I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous (131)I fraction to total (131)I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the (134)Cs to (137)Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total (131)I inventory that has passed over Europe during this period was <1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe.

A 6‐year analysis of stratospheric intrusions and their influence on ozone at Mt. Cimone (2165 m above sea level)

were analyzed. Moreover, three-dimensional backward trajectories calculated by the FLEXTRA model and potential vorticity values along these trajectories were used. In order to identify SI and evaluate their contribution to the tropospheric ozone at Mt. Cimone, a statistical methodology was developed. This methodology consists of different selection criteria based on observed and modeled stratospheric tracers as well as on tropopause height values recorded by radio soundings. On average, SI effects affected Mt. Cimone for about 36 days/year. The obtained 6-year SI climatology showed a clear seasonal cycle with a winter maximum and a spring-summer minimum. The seasonal cycle was also characterized by an interannual variation. In particular, during winter (autumn), SI frequency could be related to the intensity of the positive (negative) NAO phase. In order to separate direct SI from indirect SI, a restrictive selection criterion was set. This criterion, named Direct Intrusion Criterion (DIC), requested that all the analyzed tracers were characterized by stratospheric values. Direct SI affected Mt. Cimone for about 6 days/year, with frequency peaks in winter and early summer. At Mt. Cimone, SI contribution to background ozone concentrations was largest in winter. On average, an ozone increase of 8% (3%) with respect to the monthly running mean was found during direct (indirect) SI. Finally, the typical variations of stratospheric tracers during SI events were analyzed. The analysis of in situ atmospheric pressure values suggested that direct SI were connected with intense fronts affecting the region, while indirect SI were possibly connected with subsiding structures related with anticyclonic areas.

Anthropogenic carbon distribution in the Ross Sea, Antarctica

Abstract The Ross Sea is an area of dense water formation within the Southern Ocean, hence it potentially plays an important role for anthropogenic CO2 sequestration. In order to estimate the penetration of anthropogenic carbon in the Ross Sea from total inorganic carbon (TCO2) measurements carried out in 2002–03 Antarctic Italian Expedition, we applied two independent models. Anthropogenic carbon was present throughout the water column. The highest concentrations were associated with the recently ventilated shelf waters, namely High Salinity Shelf Water (HSSW) and Ice Shelf Water (ISW), due to their recent contact with the atmosphere. The lowest concentrations were observed for Circumpolar Deep Water (CDW), due to its relatively older ventilation age. This water mass intrudes onto the shelf in some parts of the Ross Sea and hence is observed in the sampled section, where it is recognizable for its low O2 and high TCO2 concentrations. The overflow of the dense High Salinity Shelf Water out of the continental slope was observed in the area off Cape Adare. Since this recently formed shelf water contributes to the formation of the Antarctic Bottom Water (AABW), this process represents a pathway for anthropogenic carbon export down to the deep ocean.

Comparison of radioactivity data measured in PM10 aerosol samples at two elevated stations in northern Italy during the Fukushima event

The follow-up of Fukushima radioactive plume resulting from the 11th March 2011 devastating tsunami is discussed for two Italian stations in the northern Apennines: Mt. Cimone (Modena) and Montecuccolino (Bologna). Radioactivity data collected at both stations are described, including comparison between local natural background of airborne particulate and artificial radioactivity referable to the arrival of the radioactive plume and its persistence and evolution. Analysis of back-trajectories was used to confirm the arrival of artificial radionuclides following atmospheric transport and processing. The Fukushima plume was first detected on 3rd April 2011 when high volume sampling revealed the presence of the artificial radionuclides (131)I, (137)Cs and (134)Cs. The highest activity concentrations of these nuclides were detected on 5th April 2011 at the Montecuccolino site. Fukushima radioactivity data at the two stations were usually comparable, suggesting a good vertical mixing of the plume; discrepancies were occasional and attributed to different occurrence of wet removal, typically characterized by a scattered spatial pattern. To understand the relevance to the local population of the extra dose due to the Fukushima plume, atmospheric activities of the related artificial nuclides were compared to those of the main natural radionuclides in ambient particulate, and found to be lower by over one order of magnitude. Radiation doses referable to Fukushima, maximized for a whole year occurrence at the highest activity level observed at our stations in the weeks affected by the Japanese plume, were estimated at 1.1 μSv/year.

Calibration with MCNP of NaI detector for the determination of natural radioactivity levels in the field

In view of assessing natural radioactivity with on-site quantitative gamma spectrometry, efficiency calibration of NaI(Tl) detectors is investigated. A calibration based on Monte Carlo simulation of detector response is proposed, to render reliable quantitative analysis practicable in field campaigns. The method is developed with reference to contact geometry, in which measurements are taken placing the NaI(Tl) probe directly against the solid source to be analyzed. The Monte Carlo code used for the simulations was MCNP. Experimental verification of the calibration goodness is obtained by comparison with appropriate standards, as reported. On-site measurements yield a quick quantitative assessment of natural radioactivity levels present ((40)K, (238)U and (232)Th). On-site gamma spectrometry can prove particularly useful insofar as it provides information on materials from which samples cannot be taken.

Temporal variability and environmental availability of inorganic constituents in an Antarctic marine sediment core from a polynya area in the Ross Sea

Marine sediments are sinks and repositories of matter recirculated in the environment by a number of different processes. They behave as environmental archives, providing a key to the understanding of the processes occurring in a given region in the course of time. In this work, we characterized the inorganic composition of a surface sediment core collected in the polynya of Terra Nova Bay (TNB) in the Ross Sea, an area of major environmental interest as it hosts a number of crucial processes connecting atmospheric transport with the Southern Ocean system. The total concentrations of major, minor, and trace elements were determined. The results were treated with chemometric techniques. In order to investigate the environmental mobility of several elements, the modified Bureau of Community Reference (BCR) three-step sequential extraction procedure was applied and the partitioning of eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) into different fractions was determined. The knowledge of the metal distribution across this Antarctic sediment core allowed us to assess long-term climatic changes and possible natural background values in this specific environment. Furthermore, the results showed a separation between higher and lower sections of the core that suggests a stronger fingerprint from biogenic and geological processes, respectively.

Marine Sediments and Snow from Ross Sea Region (Antarctica) Dating by 210Pb Method

Abstract 210Pb is widely used to determine accumulation rates in order to obtain a time scale in environmental samples. The most accurate method uses the determination of 210Pb via its grand-daughter 210Po by alpha spectrometry. Unfortunately this method requires a complex wet-chemistry procedure to achieve the separation of 210Po from its matrix. In this work a simplified procedure for the chemical separation of 210Po is proposed and applied to three marine sediment cores and a 10 m snow core collected in Antarctica. The calculated sedimentation rates for marine sediments range from 0.053 to 0.071 cm y−1. The mean annual accumulation rate for the snow is 16.6 cm y−1 w.e. A comparison with literature data in the same region is given.

The Relationship Between Health Effects and Airborne Particulate Constituents

This chapter reviews in detail chemical composition, formation processes and reactivity of airborne particulate matter. The relationship between sources and PM is treated both mechanistically and in terms of methodological strategies adopted assess the link between emissions, atmospheric processes and health hazard. The most accredited biochemical pathways leading to adverse health effects are also described.

Investigation of Atmospheric Reactive Gases at Mt. Cimone

The Mediterranean basin represents a global hot spot for climate change, air quality, and anthropogenic contributions to these issues. In this region, a relevant role is played by reactive gases (RGs), i.e., O3, CO, SO2, NOx, and VOCs. At the “O. Vittori” observatory at Mt. Cimone, a number of RGs are observed since more than 20 years. These observations are carried out within the framework of international program (e.g., WMO/GAW, ACTRIS) representing a valuable resource of information for quantifying the variability of these atmospheric key compounds and for investigating the influence of specific atmospheric processes to this variability (e.g., polluted air mass transport, open fire emissions, mineral dust outbreaks, stratospheric intrusion events). These observations were used to experimental applications like near-real-time data delivery services or model verification and satellite data ground-truthing.

Non-CO 2 Greenhouse Gases

In the past decades, accurate and precise atmospheric measurements of radiatively active gases have been crucial in revealing the rapid and unceasing growth of their global concentrations that has been long recognized as the main driver of climate change. Even if carbon dioxide is the major anthropogenic contributor to radiative forcing, other gases such as methane, nitrous oxide, and halogenated gases are extremely relevant in climate issues because of their very high global warming potential. Continuous measurement programs of these gases are carried out at CMN in the frame of important international programs. This chapter reports an overview of the scientific results obtained based on 15 years of atmospheric measurements. These results have been achieved combining atmospheric data with different modeling approaches, with the aim of understanding the budget of these radiatively active gases and providing emission estimates at the regional scale. Such estimates constitute an important support to improve bottom-up emission data that each country is required to submit every year in the frame of the most important international global protocols aimed at combatting climate change.