Radon (222Rn) and thoron (220Rn) are radioactive gases emanating from geological materials. Inhalation of these gases is closely related to an increase in the probability of lung cancer if the levels are high. The majority of studies focus on radon, and the thoron is normally ignored because of its short half-life (55.6 s). However, thoron decay products can also cause a significant increase in dose. In buildings with high radon levels, the main mechanism for entry of radon is pressure-driven flow of soil gas through cracks in the floor. Both radon and thoron can also be released from building materials to the indoor atmosphere. In this work, we study the radon and thoron exhalation and emanation properties of an extended variety of common building materials manufactured in the Iberian Peninsula (Portugal and Spain) but exported and used in all countries of the world. Radon and thoron emission from samples collected in the closed chamber was measured by an active method that uses a continuous radon/thoron monitor. The correlations between exhalation rates of these gases and their parent nuclide exhalation (radium/thorium) concentrations were examined. Finally, indoor radon and thoron and the annual effective dose were calculated from radon/thoron concentrations in the closed chamber. Zircon is the material with the highest concentration values of 226Ra and 232Th and the exhalation and emanation rates. Also in the case of zircon and some granites, the annual effective dose was higher than the annual exposure limit for the general public of 1 mSv y−1, recommended by the European regulations.
Vineyard management can influence the growth and yield components in the vineyards and therefore on the grape and wine quality. In this work, a chemical study was conducted (2014-2015) to examine the effect of fertigation on chemical composition of Albariño. A control (Rain-fed) and fertigation (60% and 100%) treatments were apply at same irrigation depth, where fertigation 100% is complete nutrient requirements to Albariño trellis system in this location (Rias Baixas AOC, NW Spain). Results showed that non-volatile compounds of Albariño musts were not affected by fertigation treatments. However, the effect of fertigation treatments on the volatile composition was observed. Terpenes and C13-norisoprenids were the most affected families of volatile compounds by fertigation treatments, where 60% fertigation exhibited the highest concentration, improving the wine aroma quality. Application of principal component analysis (PCA) showed a good separation of Albariño grape according to fertigation treatments and vintages.
23 January 2013 in The Journal of Physical Chemistry B
In this work, we explore the protection with Nafion of commercial sputtered-bismuth screen-printed electrodes (BiSPSPEs), to improve its ability for on-site determination of Cd(II) and Pb(II) ions in ambient water samples. The modified screen-printed platform was coupled with a miniaturized cell, in combination with a battery-operated stirring system and a portable potentiostat operated by a laptop for decentralized electrochemical measurements using Square-Wave Anodic Stripping Voltammetry (SWASV). We also describe a detailed electrode surface characterization by microscopy and surface analysis techniques, before and after the modification with Nafion, to get insight about modification effect on signal size and stability. Optimization of the chemical composition of the medium including the optimization of pH, and instrumental parameters, resulted in a method with detection limits in the low ng/mL range (3.62 and 3.83 ng·mL−1 for Cd and Pb respectively). Our results show an improvement of the sensitivity and stability for Nafion-protected BiSPSPEs in pH = 4.4 medium, and similar or lower detection limits than comparable methods on commercial BiSPSPEs. The values obtained for Pb(II) and Cd(II) in natural water samples agreed well with those obtained by the much more costly Inductively Coupled Plasma Mass Spectrometry, ICP-MS, technique as a reference method (recoveries from 75% to 111%).