PubMed Health⌕ Search

Biomedical subjects

F Vaca

Publications and source records attributed to F Vaca.

9 recordsLinked to original sources
PubMed2001

Radioactive discharges from an alkaline pulp mill located in the south of Spain.

Artificial and natural radionuclides present in environmental samples (Eucalyptus wood and bark) can be transferred in an alkaline pulp mill and concentrated in the recycling process. Some part of the radionuclides can be released into the environment associated with the discharges from such a factory. An alkaline pulp mill located in the South of Spain was extensively sampled during 1993 and different radionuclides analysed in the collected samples. Thus the concentrations and fluxes of natural (40K, 226Ra, 228Ra and 228Th) and artificial (137Cs and 90Sr) radionuclides associated with the samples collected along the pulp production process are presented. It is shown that radium and thorium radionuclides behave similarly to strontium and calcium and, consequently, concentrate within the Ca-cycle. Furthermore, 40K and 137Cs are concentrated during the Na-cycle. Finally, the results obtained by the authors are compared with the levels found in similar factories, though situated in the North of Europe, by other researchers.

Environmental Monitoring↗
PubMed2001

The presence of some artificial and natural radionuclides in a Eucalyptus forest in the south of Spain.

Long-lived artificial radionuclides (137Cs, 90Sr) were studied in a Eucalyptus plantation located in the south-west of Spain. Radionuclide concentrations were determined in different types of samples corresponding to specific forest components (soil, trees, herbs and litter). Depth profile distributions were obtained in two selected core soils. Two layers were separately measured in three other cores. The concentration factor, defined as the ratio between the mean activity concentration in a component and the mean activity concentration in the soil, was calculated for each component. The biomass of different components was estimated in order to evaluate the total density concentration (Bq/ha) of the artificial radionuclides (137Cs, 90Sr) in the Eucalyptus plantation. The transfer of the radionuclides between the different forest components can be inferred from the results. Additionally, other naturally occurring radionuclides (40K, 226Ra, 228Ra, 228Ac) were determined for comparison. Transport of radionuclides from forest to a nearby pulp mill is also discussed.

Biomass↗
PubMed2001

Factor of merit and minimum detectable activity for 90Sr determinations by gas-flow proportional counting or Cherenkov counting.

The determination of 90Sr in environmental samples can be done by using a gas-flow proportional counter (beta-counting) or a liquid-scintillation spectrometer (Cherenkov counting). In this work, we present the factor of merit (FOM) and the minimum detectable activity (MDA) for both the counters. Quantitative relationships are proposed for FOM and MDA determination.

Journal Article↗