Oana A. Dumitru

Radon survey in caves from Mallorca Island, Spain.

This study reports radon concentration in the most representative caves of Mallorca, identifying those in which the recommended action level is exceeded, thus posing health risks. Two show caves (Campanet and Artà) and three non-touristic caves (Font, Drac, Vallgornera) were investigated. Data were collected at several locations within each cave for three different periods, from March 2013 to March 2014. Except for Vallgornera, where only one monitoring period was possible, and Artà in which low values were recorded throughout the year, a clear seasonal variability, with higher values during the warm seasons and lower during winter time is prominent. Radon concentrations differed markedly from one cave to another, as well as within the same cave, ranging from below detection limit up to 3060 Bq·m(-3). The results of this study have significant practical implications, making it possible to provide some recommendation to cave administrators and other agencies involved in granting access to the investigated caves.

An improved procedure for the determination of 210Po by alpha spectrometry in sediments samples from Danube Delta

The aim of this work is to find the optimal procedure for 210Po leaching from sediment samples. An improved method is described, the optimization consisting in a substantial reduction of leaching time. The method was tested on IAEA standard reference materials and compared with the classical procedure. The repeatability was estimated by analyzing seven duplicates of IAEA 385 Irish Sea sediment. However, the results are satisfactory only when the method is applied for sediments with high organic content. For silicates, a mixture of three acids was used for a complete digestion.

Water isotopic variability in Mallorca: a path to understanding past changes in hydroclimate

This paper reports the first results on δ18O and δ2H analysis of precipitations, cave drip waters, and groundwaters from sites in Mallorca (Balearic Islands, western Mediterranean), a key region for paleoclimate studies. Understanding the isotopic variability and the sources of moisture in modern climate systems is required to develop speleothem isotope-based climate reconstructions. The stable isotopic composition of precipitation was analyzed in samples collected between March 2012 and March 2013. The values are in the range reported by GNIP Palma station. Based on these results, the local meteoric water line δ2H = 7.9 (±0.3) δ18O + 10.8 (±2.5) was derived, with slightly lower slope than GMWL. The results help tracking two main sources of air masses affecting the study sites: rain events with the highest δ18O values (> –5 ‰) originate over the Mediterranean Sea, whereas the more depleted samples ( 50 m) limestone cap (Arta) exhibit more negative values. A well-homogenized aquifer supplied by rainwaters of both origins is clearly indicated by groundwater δ18O values, which show to be within 2.4 ‰ of the unweighted arithmetic mean of –7.4 ‰. Although limited, the isotopic data presented here constitute the baseline for future studies using speleothem δ18O records for western Mediterranean paleoclimate reconstructions.

The activity concentration of 210Po in Romanian commercial cigarettes and the radiation exposure estimation derived from their regular consumption

Due to the relatively high activity concentrations of (210)Po that are found in tobacco, cigarette smoking has been found to be the principal pathway of the intake of this radionuclide. The (210)Po concentrations in the lung tissues may contribute significantly to an increase in the internal radiation dose and in the number of instances of lung cancer observed among smokers. The study of (210)Po in tobacco is required due to its potential for human radiation exposure through ingestion and inhalation. The risk factor caused by (210)Po in Romanian commercial cigarettes is not yet evaluated. Ten of the most frequently smoked brands of cigarettes sold in Romania were investigated in this work for this purpose. The activity concentration of (210)Po was determined by alpha spectrometry using a PIPS detector after chemical leaching and spontaneous deposition of (210)Po on a stainless steel disc from diluted HCl solution. The samples were spiked with (209)Po for chemical recovery calculation. The (210)Po activity concentrations of the measured types of cigarettes ranged from 4.65 to 10.22 mBq sample(-1) and the resulted average concentration of (210)Po isotopes is 8.35±0.80 mBq cigarette(-1) (the errors form a 2σ interval of confidence). When comparing the results of this study with the activity concentration values reported by other countries it was found that the results of this study are in the lower end of the world range. The estimation of this study shows that cigarette smokers, who are smoking one pack (20 cigarettes) per day, are exposed to an effective dose of 75.51 μSv y(-1).