Study of pollution in the El Jadida-Safi Atlantic coastal zone (Morocco) by using PIXE and SSNTD methods

In this work PIXE experiments were performed for measuring heavy and light elements (ranging from aluminium to lead) concentrations inside various polluted and unpolluted soils as well as liquid samples collected from different phosphate factory sewers in the El Jadida-Safi Atlantic coastal region (Morocco). In addition, uranium (238U) and thorium (232Th) contents were evaluated in the same samples studied by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The influence of the phosphate industry wastes on the concentrations of both radioactive and non-radioactive elements of the samples studied was investigated

Dating of a quaternary limestone cave by combining the SSNTD technique with paleodose measurements: application to the stalagmite and stalactite growth

Abstract Uranium ( 238 U) and thorium ( 232 Th) contents were evaluated in di erent stalagmite and stalactite samples belonging to a quaternary limestone cave by using a method based on determining mean critical angles of etching of the CR-39 and LR-115 II solid-state nuclear track detectors (SSNTDs). Annual absorbed -, ÿ-and -dose rates were determined in the stalagmite and stalactite materials. The stalagmite and stalactite samples were dated by exploiting data obtained for the total annual absorbed dose rates and measuring the corresponding paleodoses. Results obtained were compared with those obtained by classic thermoluminescence and U=Th disequilibrium methods. The studied speleothem began from about 121 kyr and continued to about 69 kyr, coinciding almost with the last interglaciation corresponding to the fourth and ÿfth isotope stages. The formation rates of the stalagmite and stalactite samples were found equal to 0.88 and 0:94 cm kyr −1 , respectively

Case Study of Bacterial Decontamination of an Aromatic and Medicinal Plant: Decontamination of Thymus Satureioides by Gamma Radiation at Low Doses and Impact on Hygienic and Physicochemical Quality

The purpose of our study is to verify the usefulness of gamma irradiation treatment at low doses (0.25, 0.5 and 1 kGy) combined to vacuum packaging on commercial teas of Thymus satureioides deliberately contaminated with Escherichia coli. The efficiency and the influence of the process on contamination level and the shelf life of the product were studied. The phenolic composition and concentration were identified in the unirradiated and irradiated thyme. The total phenolic content (TPC) was assayed by the Folin-Ciocalteu method, the individual phenolic compounds were determined by high liquid chromatography (HPLC) and the essential oil was characterized by gas chromatography coupled to mass spectroscopy (GC-MS). The plant was observed by scanning electrons microscopy and the radioactivity effect was analyzed. The results show a complete decontamination of thyme depending to the dose and the storage time. Privileged hygienic quality was found in the irradiated thyme with the highest concentrations of polyphenols. The process showed the conservation of thyme quality without any alteration of its characteristics or radioactivity effect

The presence and dosimetry of radon and thoron in a historical, underground metalliferous mine

A combination of long term passive, and short term active radon-222, radon-220 and respective progeny measurements were conducted in both traverse and longitudinal axes of a historical metalliferous underground mine in North Queensland, Australia. While the passive monitor results provided average radon and thoron air concentrations over periods of 70–90 days, active measurements over a four day period provided significantly more detail into the dynamics of radon and progeny concentrations in the naturally ventilated mine environment. Passive monitor concentrations for radon and thoron ranged between 60 and 390 Bq m−3 (mean: 140 ± 55 Bq m−3) and 140 and 2600 Bq m−3 (mean: 1070 ± 510 Bq m−3) respectively, with passive thoron progeny monitors providing a mean concentration of 9 ± 5 Bq m−3EEC. Active measurement mean concentrations for radon, thoron, radon progeny and thoron progeny in the centre of the mine drive were 130 ± 90 Bq m−3, 300 ± 100 Bq m−3, 20 ± 20 Bq m−3EEC and 10 ± 10 Bq m−3EEC respectively.It was identified that thoron passive detector placement is critical in establishing reliable monitoring data, and is the reason for the discrepancy between the active and passive thoron results in this study. Site specific progeny measurements are required for the accurate estimation of dose to persons entering the mine. Based on short term active measurements and passive thoron progeny monitor results, the dose contribution from thoron and progeny in the mine was observed to contribute up to 80% of the total radon/thoron inhalation dose, and therefore should not be underestimated in monitoring programs under similar conditions