Soil and sediment sample analysis for the sequential determination of natural and anthropogenic radionuclides.

A new sequential method for the determination of both natural (U, Th) and anthropogenic (Sr, Cs, Pu, Am) radionuclides has been developed for application to soil and sediment samples. The procedure was optimised using a reference sediment (IAEA-368) and reference soils (IAEA-375 and IAEA-326). Reference materials were first digested using acids (leaching), 'total' acids on hot plate, and acids in microwave in order to compare the different digestion technique. Then, the separation and purification were made by anion exchange resin and selective extraction chromatography: transuranic (TRU) and strontium (SR) resins. Natural and anthropogenic alpha radionuclides were separated by uranium and tetravalent actinide (UTEVA) resin, considering different acid elution medium. Finally, alpha and gamma semiconductor spectrometer and liquid scintillation spectrometer were used to measure radionuclide activities. The results obtained for strontium-90, cesium-137, thorium-232, uranium-238, plutonium-239+240 and americium-241 isotopes by the proposed method for the reference materials provided excellent agreement with the recommended values and good chemical recoveries. Plutonium isotopes in alpha spectrometry planchet deposits could be also analysed by ICPMS.

Evaluation of 137Cs fallout from the Chernobyl accident in a forest soil and its impact on Alpine Lake sediments, Mercantour Massif, S.E. France.

The Boréon area in the Mercantour Massif, S.E. France, was contaminated by radionuclides after the Chernobyl accident in the first days of May 1986. Sediments from a small mountain lake in this area were collected, as well as forest soils in its vicinity, in order to obtain 137Cs and 210Pb profiles. Calculated from the 210Pb inventory in a soil of a horizontal area, the flux is high in the area (0.06 Bqcm(-2)y(-1)) probably because of the great frequency of rain and uranium ores outcropping in the massif. The comparison of the 137Cs soil inventories and the unsupported 210Pb suggests that the 137Cs fallout due to the Chernobyl accident in the study site (Boréon) was at least 3.5 Bqcm(-2), more probably the double. The recent lake sediments still undergo a rather strong contamination by 137Cs and the sediment profiles show that the residence time of 137Cs in the catchment area is long. The study area is frequented by many inhabitants of the city of Nice and other cities at the Mediterranean coast during week-end and during summer and winter holidays. Thus the 137Cs external exposure impact was evaluated at 2 mSvy(-1) for 2002 in the most contaminated point.

Transuranic and fission product contamination in lake sediments from an alpine wetland, Boréon (France).

Transuranics and fission products have been measured in lake sediment samples, collected in an alpine wetland, to determine their vertical distribution and calculate inventories. The radionuclides considered are 90Sr, 137Cs, 238Pu, 239/240Pu and 241Am. From the results, a better knowledge of radionuclide accumulation mode and behaviour was obtained. In addition, the origins of the individual pollutants could be deduced from activity ratios. Analyses were made on different sediment cores. The sampling sites were chosen to enable future determination of the mass balances of the radiopollutants. As the selected study area is in a recreational area used by urban populations, a rough estimate was made of the mean external dose from 137Cs for comparison with the French regulation.

[Hip prosthesis: idea, indications, development]. / Le artroprotesi dell'anca. L'idea, le indicazioni, l'evoluzione.

The authors describe the evolution and the successive stages that were necessary until the present total substitution of the hip joint could be worked out. The earliest attempts were made in 1923, but only in 1953, professor Marino Zuco, of Rome University Orthopedic Department started to carry out operations of arthroplasty, after 3 years of experimental research. In 1960, Charnley introduced the use of cement (methyl methacrylate), thus initiating the practice of total hip substitution. This surgery is indicated in a variety of joint pathologies of which osteoarthritis is the most frequent one. The implant of a cemented or non cemented prosthesis is conditioned both by the patient's age and by bone structure. Differences between the two types of prostheses are illustrated as well as the causes of failure or subsequent pathology and their diagnosis.

[Surgical treatment of gonarthrosis]. / Trattamento chirurgico della gonartrosi.

Gonarthosis, a frequent complaint in women over 50, brings about changes in the knee which alter its macro and micro structure and are responsible for alteration of the anatomical axis of the lower limb. The most frequent consequence is knock-knee leading to overloading of the medial compartment and reduction of the internal interosseous space. Whereas in the initial forms symptomatic therapy is the treatment of choice, in severe and advanced cases with complete articular blockage arthroprosthesis is the alternative and in cases with minor limitations of joint movement the best results are obtained by osteotomy intended to restore the correct axis. In order to evaluate which of the surgical techniques available is the most appropriate, the authors analyzed 40 cases of tibial osteotomy performed between 1974 and 1984. On the basis of the results obtained, cupuliform osteotomy above the tuberosity appears to lead to the highest success rate.