On the elemental composition of the Mediterranean euhalophyte Salicornia patula Duval-Jouve (Chenopodiaceae) from saline habitats in Spain (Huelva,Toledo and Zamora)

Environmental Science and Pollution Research - A complete survey is presented on the inorganic composition of the euhalophyte annual succulent species Salicornia patula (Chenopodiaceae), including...     

The spatial statistics formalism applied to mapping electromagnetic radiation in urban areas

Determining the electromagnetic radiation levels in urban areas is a complicated task. Various approaches have been taken, including numerical simulations using different models of propagation, sampling campaigns to measure field values with which to validate theoretical models, and the formalism of spatial statistics. In the work, we present here that this latter technique was used to construct maps of electric field and its associated uncertainty from experimental data. For this purpose, a field meter and a broadband probe sensitive in the 100-kHz–3-GHz frequency range were used to take 1,020 measurements around buildings and along the perimeter of the area. The distance between sampling points was 5 m. The results were stored in a geographic information system to facilitate data handling and analysis, in particular, the application of the formalism of spatial statistical to the analysis of the distribution of the field levels over the study area. The spatial structure was analyzed using the variographic technique, with the field levels at non-sampled points being interpolated by kriging. The results indicated that, in the urban area analyzed in the present work, the linear density of sampling points could be reduced to a distance which coincides with the length of the blocks of buildings without the statistical parameters varying significantly and with the field level maps being reproduced qualitatively and quantitatively.     

Radon in indoor air of primary schools: determinant factors,their variability and effective dose

Radon is a radioactive gas, abundant in granitic areas, such as in the city of Porto at the north-east of Portugal. This gas is a recognized carcinogenic agent, being appointed by the World Health Organization as the leading cause of lung cancer after smoking. The aim of this preliminary survey was to determine indoor radon concentrations in public primary schools, to analyse the main factors influencing their indoor concentration levels and to estimate the effective dose in students and teachers in primary schools. Radon concentrations were measured in 45 classrooms from 13 public primary schools located in Porto, using CR-39 passive radon detectors for about 2-month period. In all schools, radon concentrations ranged from 56 to 889 Bq/m³ (mean = 197 Bq/m³). The results showed that the limit of 100 Bq/m³ established by WHO IAQ guidelines was exceeded in 92 % of the measurements, as well as 8 % of the measurements exceeded the limit of 400 Bq/m³ established by the national legislation. Moreover, the mean annual effective dose was calculated as 1.25 mSv/y (ranging between 0.58 and 3.07 mSv/y), which is below the action level (3–10 mSv). The considerable variability of radon concentration observed between and within floors indicates a need to monitor concentrations in several rooms for each floor. A single radon detector for each room can be used, provided that the measurement error is considerably lower than variability of radon concentration between rooms. The results of the present survey will provide useful baseline data for adopting safety measures and dealing effectively with radiation emergencies. In particular, radon remediation techniques should be used in buildings located in the highest radon risk areas of Portugal. The results obtained in the current study concerning radon levels and their variations will be useful to optimize the design of future research surveys.     

Seasonal variations in radionuclide transfer in a Mediterranean grazing-land ecosystem.

We made quarterly determinations of the transfer coefficients and effective transfer coefficients for the radionuclides 137Cs, 90Sr, 40K, 226Ra, 228Ra and 228Th over a full annual cycle, in a Mediterranean grazing-land ecosystem. The input and output fluxes of the radionuclides between the different compartments of this ecosystem were quantified for the following processes: root uptake; variation in root and aerial biomass; pasture production; translocation; leaf fall; efflux due to grazing action; resuspension and subsequent aerial deposition of radionuclides. We observed there to be a marked seasonal variation for this type of ecosystem in both the transfer coefficients and the radionuclide fluxes, which impedes the soil-plant transfer being characterized on the basis of values that are constant with time.