Journal of Environmental Radioactivity (v.88, #2)
Editorial board (CO2).
Dr. Henning Dahlgaard 1950–2005 by Sven P. Nielsen (107-108).
234U and 230Th determination by FIA-ICP-MS and application to uranium-series disequilibrium in marine samples by Maria Luiza D.P. Godoy; José Marcus Godoy; Renato Kowsmann; Guaciara M. dos Santos; Rosana Petinatti da Cruz (109-117).
A 234U and 230Th determination method based on an extraction chromatographic separation on a flow injection system coupled to a quadruple ICP-MS was developed. Two-milliliter UTEVA (Eichrom Co.) cartridges were applied as separation tool and 236U and 229Th as spikes. Loading and washing steps were carried out in 3 M HNO3 solution and 0.05 M ammonium oxalate applied to elute both uranium and thorium. The method was applied initially to the IAEA-327 soil reference sample and NIST SRM 4357 ocean sediment reference material, with the obtained 234U and 230Th concentrations in agreement with the reference levels. Samples from a deep-sea sediment core (2450 m water depth) were analyzed and based on 230Th/234U dating, a mean sedimentation rate of 3.3 cm ky−1 was calculated. Samples from two sediment layers were also dated by 14C-AMS and the observed ages agree with the 230Th/234U results.
Keywords: Inductively coupled plasma mass spectrometry; Accelerator mass spectrometry; 230Th/234U dating; 14C dating; Deep-sea sediment; Bacia de Campos;
Assessment of radiation exposure in the uranium mining and milling area of Mailuu Suu, Kyrgyzstan by H. Vandenhove; L. Sweeck; D. Mallants; H. Vanmarcke; A. Aitkulov; O. Sadyrov; M. Savosin; B. Tolongutov; M. Mirzachev; J.J. Clerc; H. Quarch; A. Aitaliev (118-139).
The area of the town of Mailuu Suu, Kyrgyzstan, is polluted by radionuclides and heavy metals from tailing dumps and heaps resulting from the historic exploitation of uranium mines. In the frame of a European Commission-TACIS funded project, radiological assessment was performed for critical group members living in the city of Mailuu Suu, located downstream the tailings, or in the village of Kara Agach, partially located on a uranium mine waste dump. The actual external exposure is around 1.2 mSv a−1 at both locations and exposure from radon is around 3 mSv a−1 at Mailuu Suu and around 10 mSv a−1 at Kara Agach. Ingestion dose was negligible for a critical group member living at Mailuu Suu. At Kara Agach, however, under the hypothesis that all food and fodder is cultivated locally, exposure from ingestion is much higher (∼10–30 mSv a−1). In case of an accidental scenario [(part of) Tailing 3 content thrust to river], estimated additional maximum doses result in 45 and 77 mSv for an adult and a child, respectively.
Keywords: Mailuu Suu; Kyrgyzstan; Uranium mining and milling; Radiation exposure; Assessment;
Radioecological characterization of a uranium mining site located in a semi-arid region in Brazil by Horst M. Fernandes; F. Fernando Lamego Simoes Filho; Valeska Perez; Mariza Ramalho Franklin; Luiz Alberto Gomiero (140-157).
The work presents the radioecological characterization of the new Brazilian uranium mining and milling site located in a semi-arid region of the country. The process characterization demonstrated that in heap leach plants most of the 226Ra remains in the leached ore. Despite the potential higher availability of radium isotopes in the soils of the studied region the lack of precipitation in that area reduces the leaching/mobilization of the radionuclides. High 226Ra and 228Ra concentrations were found in manioc while 210Pb was significant in pasture. It was suggested that a range from 10−3 to 10−1 may conveniently encompass most of the transfer factors (TF) values for soil/plant systems (i.e. involving different cultures, different soils and natural radionuclides). Impacts due to aerial transportation of aerosols and radon generated in the mining were proved to be minimal and restricted to an area not greater than 15 km2. Finally, uranium complexation by carbonates was shown to be the main mechanism responding for the elevated radionuclide concentration in groundwater.
Keywords: Uranium mining; Semi-arid region; Natural radionuclides;
Natural radioactivity and radon exhalation in building materials used in Italian dwellings by Serena Righi; Luigi Bruzzi (158-170).
Forty-two samples of building materials commonly used in Italian dwellings were surveyed for natural radioactivity. External (gamma), as defined and used by the European Commission, and internal (alpha) hazard indexes were calculated and radon specific exhalation rate and emanation fraction were measured. The accumulation method, by using the E-PERM electret ion chambers, was employed to determine specific exhalation rates of 222Rn. Several of the materials had hazard indexes that exceeded the European Commission limit values. However, it was evident that limit values for internal hazard indexes set based on Rn emanation should take into account the properties and use of the materials. For example, Rn emanation from basalt and glazed tiles was substantially lower than the Rn emanation from other materials with similar hazard indexes. Clearly there is need for improved guidelines and regulations in this area.
Keywords: Building materials; Indoor exposure; Naturally occurring radioactive materials; Radon exhalation; Emanation fraction; Hazard indexes;
Vertical migration of 134Cs bearing soil particles in arid soils: implications for plutonium redistribution by R.D. Whicker; S.A. Ibrahim (171-188).
Vertical migration of plutonium in soils at the Waste Isolation Pilot Plant (WIPP) and the Rocky Flats Environmental Technology Site (RFETS) was evaluated based on observed 134Cs migration in soil column experiments. After applying 134Cs-labeled soil particles to the surfaces of large, undisturbed soil cores collected from each site, resulting soil columns were subjected to experimental cycles of irrigation plus drying (treatment columns) or to cycles of irrigation only (control columns). Mean losses of 134Cs inventory from soil surfaces were 3.1 ± 0.6% cycle−1 and 0.7 ± 0.6% cycle−1 respectively for RFETS treatment and control columns. WIPP columns had mean respective losses of 1.3 ± 1.2% cycle−1 and 0.5 ± 0.2% cycle−1. Bulk transport of labeled soil particles through soil cracks was an important process in RFETS soils, accounting for 64–86% of total 134Cs migration. Colloidal transport processes governed migration in WIPP soils.
Keywords: Soil; Contaminant transport; Vertical migration; 134Cs; Plutonium;
Evaluation of indoor radon measurements in Hungary by Krisztián Hámori; Eszter Tóth; Lénárd Pál; George Köteles; András Losonci; Mihály Minda (189-198).
The RAD Laboratory measured annual means of radon activity concentrations in 15 277 first-floor rooms of dwellings and in 325 rooms on upper floors in Hungary (1994–2004). The original purpose of the survey was to find radon-prone area in Hungary. The maximum measured value was 5800 Bq m−3, while the minimum was 10 Bq m−3. Due to geological diversity and different structures of buildings, the data set of first-floor rooms did not follow the lognormal distribution. Therefore, strata were chosen so that the measured data fitted the lognormal distribution. The numbers of dwellings above a given radon level were determined in each stratum. The national distribution was then taken as the sum of the individual distributions of all strata. This distribution was not lognormal. The parameters of the best fitting lognormal distribution were GM = 58 Bq m−3, GSD = 2.2. The weighted averages of strata values GM = 62 Bq m−3, GSD = 2.1 were obtained corresponding to 92% of Hungarian dwellings.
Keywords: Indoor radon; Lognormal distribution; Stratification; GM; GSD;
Atmospheric deposition of 137Cs between 1994 and 2002 at Cienfuegos, Cuba by C.M. Alonso-Hernández; H. Cartas-Águila; M. Díaz-Asencio; A. Muñoz-Caravaca; J. Martín-Pérez; R. Sibello-Hernández (199-204).
Levels of 137Cs in total atmospheric deposition have been measured in the Cienfuegos region (Cuba) between 1994 and 2002. Samples were collected every three months, evaporated to dryness to obtain residual samples, and measured by gamma spectrometry. The 137Cs mean concentration in total deposition was 0.24 Bq m−2 and data ranged between <0.05 and 0.62 Bq m−2. Precipitation rates and raintime have proved to be the most important factors controlling the concentration and depositional flux of 137Cs in the atmosphere over Cienfuegos, showing a high correlation coefficient (R = 0.93).
Keywords: 137Cs; Atmospheric deposition; Cienfuegos; Cuba;