L.S. Quindós

Conversion factors for external gamma dose derived from natural radionuclides in soils

Field in situ gamma radiation exposure rates and laboratory measured radioactivity contents of 1500 Spanish soils were compared. The main objective was to determine if published theoretically derived conversion factors would yield accurate quantitative activity concentration (Bq kg(-1)) for the data carried out in different surveys developed by our laboratory during the last ten years. The in situ external gamma dose rate results were compared to laboratory gamma analysis of soils samples gathered from each site, considering the concentrations of seven radionuclides: 40K, 214Pb, 214Bi, 212Bi, 212Pb, 208Tl and 228Ac. The coefficient of correlation found between these variables indicate a good relationship. A discussion of the factors contributing to the uncertainties as well as measurement procedure are also given in this paper.

Indoor radon in a Spanish region with different gamma exposure levels.

In the beginning of 1990s within the framework of a national radon survey of more than 1500 points, radon measurements were performed in more than 100 houses located in Galicia region, in the Northwest area of Spain. The houses were randomly selected only bearing in mind general geological aspects of the region. Subsequently, a nationwide project called MARNA dealt with external gamma radiation measurements in order to draw a Spanish natural radiation map. The comparison in Galicia between these estimations and the indoor radon levels previously obtained showed good agreement. With the purpose of getting a confirmation of this relationship and also of creating a radon map of the zone, a new set of measurements were carried out in 2005. A total of 300 external gamma radiation measurements were carried out as well as 300 measurements of 226Ra, 232Th and 40K content in soil. Concerning radon, 300 1-m-depth radon measurements in soil were performed, and indoor radon concentration was determined in a total of 600 dwellings. Radon content in soil gave more accurate indoor radon predictions than external gamma radiation or 226Ra concentration in soil.

7Be concentrations in air, rain water and soil in Cantabria (Spain)

Abstract 7Be concentrations present in air, rain water and soil have been measured in the region of Cantabria (Spain) during the last 4 yr. There was a relationship between rainfall and the deposited areal activity of the nuclide at the study site which was consistent with observed annual global rainfall and fallout.

Influence of low doses of radiation due to 222Rn on proliferation of fibroblasts and MCF-7 human breast cancer cells in vitro

The aim of the present study is to analyze the effects of low doses of radiation due to radon (within the range present in the environment) in the proliferation of normal (fibroblasts) and tumoral (MCF-7 human breast cancer cells) mammalian cells. Both fibroblast and MCF-7 cells were incubated in culture media with different levels of radon (doses of 10-15 000 microGy), or non-radon (control). After incubation the number of cells per plate was measured with a hemocytometer. The dissolution of radon in the culture media decreased the proliferation of MCF-7 cells (not the fibroblasts). Within the range of doses used in this experiment, the lowest as well as the highest doses of radiation had the lowest antiproliferative effects. Intermediate doses strongly decreased the number of final cells with respect to those in the control population.

Study of areas of spain with high indoor radon

Abstract Data for natural radiation from a national survey were used to identify areas in Spain with a high level of natural background radiation. Specific measurements were made in these areas to evaluate indoor radon levels as well as the main sources of this natural gas in houses. Values of indoor radon as high as 800 Bq m −3 were measured and 39% of the houses showed levels over 150 Bq m −3 . For this area, exhalation rates from soil range from 40 Bq m −2 h −1 to 900 Bq m −2 h −2 . Normal values, lower than 10 Bq 1 −1 , for radon dissolved in water were also measured. The results are examined and compared with the values obtained in houses located in other areas of Spain.

Continuous monitoring of radon gas as a tool to understand air dynamics in the cave of Altamira (Cantabria, Spain)

The use of radon as an atmospheric tracer in the Altamira Cave over the past 30years has provided relevant information about gaseous exchanges between the Polychromes Room, the adjoining Chambers inside the cave, and the outside atmosphere. The relatively simple physico-chemical behaviour of radon gas provides a marked advantage over other tracer gases that are usually present in high concentrations in hypogeous environments, such as CO2. Two types of continuous radon measurement were undertaken. The first involves active detectors located in the Hall and Polychromes Room, which provide radon concentration values at 1-hour intervals. In addition, nuclear solid track etched detectors (CR-39) are used in every chamber of the cave over 14-day exposure periods, providing average radon concentrations. In this paper we show some of the specific degassing and recharge events identified by anomalous variations in the concentration of radon gas in the Polychromes Room. In addition, we update knowledge regarding the degree of connection between chambers inside the cave and with the outside atmosphere. We verify that the connection between the Polychromes Room and the rest of the cave has been drastically reduced by the installation of the second closure in 2008. Except for point exchanges with the Crossing zone generated by a negative temperature gradient in that direction, the atmosphere of the Polychromes Room remains stable, or else it exchanges matter with the outside atmosphere through the karst interface. The role of radon as a tracer is demonstrated to be valid both to reflect seasonal cycles of degassing and recharge, and to analyse shorter (daily) period fluctuations.