The radiocarbon (14C) specific activity was measured in vegetation and atmosphere in Ramnicu Valcea, Romania. On the sampling location operates a nuclear installation, namely “Experimental Pilot for Separation of Tritium and Deuterium” (PESTD), a semi-industrial installation designed for the detritiation of heavy water moderator of CANDU reactors and a 315 MW coal-fired thermoelectric power plant. Because one of the important releases of PESTD is gaseous radioactive effluent, the baseline of radiocarbon was a must for the environmental program. On the other hand, due to the Suess effect, a relative decrease of the radiocarbon-specific activity on a local scale is expected as a result of the dilution of the carbon isotopic mixture by fossil carbon. All the measurements were done by liquid scintillation counting and direct absorption method. It can be observed that the specific activity of 14C was similar for both types of samples investigated. The variations encountered are generally within the limit of uncertainty associated with the 14C. The average radiocarbon-specific activity recorded has the following values: 0.226 ± 0.016 Bq/gC for the vegetation and 0.228 ± 0.016 Bq/gC for the atmosphere. The results have a clear decreasing trend, but due to local influence caused by the continuous production of fossil CO2, cannot be observed 14C seasonal variations. A strong correlation between radiocarbon activity in air and vegetation was highlighted.

The CO2 absorption and liquid scintillation counting (LSC) are methods used in radioactivity monitoring programs of nuclear facilities for 14C measurements due to high number of samples and relatively high expected level of 14C concentration. The paper describes the chemical sample preparation applied to a quality control material (IAEA-C3 Cellulose), in order to evaluate the reproducibility of CO2 absorption method for this type of material. Consequently, in the experiments we used two home-made scintillation cocktails, containing two amines, 2-methoxyethylamine (MEA) and 3-methoxypropyl amine (MPA), which detained CO2 as carbamates. Due to the fact that the material used in the dedicated experiments is cellulose (contained in all vegetable materials), the method can be considered as appropriate for 14C determination from biological and vegetable materials.

In this paper, we investigate a procedure for radiocarbon determination in forest soil and slurry from lake sediments. The total carbon in these samples can be both inorganic and organic. Inorganic carbon can be analyzed in a straightforward manner using the direct absorption method by sample acidification and CO2 capture. For organic carbon, we investigate a hybrid method using the wet-oxidation of organic carbon followed by direct absorption. To evaluate the wet-oxidation processes with potassium dichromate (K2Cr2O7) and potassium permanganate (KMnO4), we performed several experiments using different quantities of soil and sediments in order to establish the quantity of CO2 for each type of sample. The 2 methods offer comparable results for 14C-specific activity (about 0.234 ± 0.024 Bq/g C), values that are expected for these kinds of samples. We also investigated the possibility of isotopic fractionation occurring during CO2 production from raw material by measuring δ13C levels from samples and obtained CO2.

The Lower Danube Basin covers the Romanian-Bulgarian sub-basin downstream from Cazane Gorge and the sub-basins of the Siret and Prut rivers. To extensively survey the Romanian nuclear power plant impact on the Danube water, tritium and radiocarbon baseline values are required. Therefore, the reported study tried to establish these values based on a 2-yr sampling campaign covering 975 km of the Danube from Cazane Gorge to Tulcea. The tributaries Cerna, Jiu, Olt, and Arges were also included in this study. During the sampling campaigns, tritium concentration of different sampling locations showed values between 7 ± 2.1 and 33.5 ± 2.3 TU. Measured 14C activity for the same locations ranged between 88.45 ± 1.46 and 112.36 ± 1.56 pMC. Lower values were recorded for tributaries: between 8.3 ± 2.1 and 12.2 ± 2.2 TU for tritium and between 67.3 ± 1.29 and 86.04 ± 1.42 pMC for 14C. Despite the nuclear activity in the observed areas, tritium and 14C activities presented slightly higher values for specific locations without any influence on Danube River water.

We investigated a simple, reliable radiocarbon measurement procedure for water samples using the direct absorption method for sample preparation, followed by low-level liquid scintillation spectrometry. This process has involved quantitative evaluation of the conversion steps in order to estimate the appropriate working parameters. The 14C activity of dissolved inorganic carbon (DIC) for several types of water (ranging from seawater to groundwater) has been measured, paying attention to the preparation requirements of each type of water. The main advantage of this method is the simplified sample preparation, allowing measurement of a great number of samples in less time. This method was designed for routine analysis of water samples, and it is proposed particularly for use in 14C monitoring programs of CANDU-type reactors.