Andra-Rada Iurian

Indicators of the Fukushima radioactive release in NW Romania.

As a result of the Fukushima nuclear release, (131)I was found in different environmental media (rainwater, sheep and cow milk, herbage, sheep meat and thyroid tissue) in north-west Romania. On April 4, 2011 a maximum value of 1.40 ± 0.21 Bq/L in (131)I activity was found in rainwater obtained from the Arad region. The obtained value corresponded with the maximum of (131)I concentration in air, as measured by Toma et al. (2011) for the Piteşti area. One day later, sheep milk from the Cluj area was found to contain a maximum activity of 9.22 ± 0.95 Bq/L. A value of 0.85 ± 0.07 μSv was calculated as the total monthly effective dose received by the population as a result of the ingestion of sheep milk and sheep meat contaminated with (131)I. Only rainwater samples contained (134)Cs and (137)Cs at levels close to minimum detectable activity. Since the determined values could be influenced by Chernobyl (137)Cs, the (137)Cs concentrations are subject to uncertainty. The radioiodine transfer coefficients (Fm) and the concentration ratio (CR) from herbage to sheep milk, as well as sheep meat, from the Cluj-Apahida area are also presented.

Comparative assessment of erosion and deposition rates on cultivated land in the Transylvanian Plain of Romania using 137Cs and 210Pbex

Soil erosion and sedimentation are natural landscape forming processes. However, they can be accelerated by human activities and therefore increase negative impacts on agricultural production as well as disturbing watershed management. Romania currently faces major environmental challenges and pressure on soil and water resources due to unsustainable farming practices and inappropriate tillage practices. The present work represents the first attempt to test the combined use of radionuclide approaches (i.e. (137)Cs and (210)Pb(ex)) to quantify soil erosion changes in cultivated Transylvanian fields (Romania) at different temporal scales. Fourteen soil cores were collected along two transects in a cultivated field and two reference sites were selected to establish the mean reference inventories for both (137)Cs and (210)Pb(ex). A value of 5460 ± 880 Bq m(-2) (n = 10; CV = 16%) was determined for the (137)Cs mean reference inventory for both sites, given as areal activity ± standard deviation, at 2σ confidence interval. As regarding (210)Pb(ex) reference inventory, its value (9640 Bq m(-2)) is only given by the areal activity of one soil core from the second site. The high erosion rates obtained with the (210)Pb(ex) approach are an effect of the up and down ploughing practices which took place at the time of the local agricultural cooperative starting in the late 1950s. The middle-term redistribution rates provided by the (137)Cs technique highlighted preponderant deposition processes in the field investigated, reflecting the changes in the cultivation system with ploughing across the slope at the beginning of 1990s.

Modelling Deposition and Erosion rates with RadioNuclides (MODERN) - Part 1: A new conversion model to derive soil redistribution rates from inventories of fallout radionuclides

The measurement of fallout radionuclides (FRN) has become one of the most commonly used tools to quantify sediment erosion or depositional processes. The conversion of FRN inventories into soil erosion and deposition rates is done with a variety of models, which suitability is dependent on the selected FRN, soil cultivation (ploughed or unploughed) and movement (erosion or deposition). The authors propose a new conversion model, which can be easily and comprehensively used for different FRN, land uses and soil redistribution processes. The new model MODERN (Modelling Deposition and Erosion rates with RadioNuclides) considers the precise depth distribution of any FRN at the reference site, and allows adapting it for any specific site conditions. MODERN adaptability and performance in converting different FRN inventories is discussed for a theoretical case as well as for two already published case studies i.e. a 137Cs study in an alpine and unploughed area in the Aosta valley (Italy) and a 210Pbex study on a ploughed area located in the Transylvanian Plain (Romania). The tests highlight a highly significant correspondence (i.e. correlation factor of 0.91) between the results of MODERN and the published results of other models currently used by the FRN scientific community (i.e. the Profile Distribution Model and the Mass Balance Model). The development and the cost free accessibility of MODERN (see modern.umweltgeo.unibas.ch) will ensure the promotion of wider application of FRNs for tracing soil erosion and sedimentation.

Mobility and Bioavailability of Radionuclides in Soils

It is crucial to understand the behaviour of radionuclides in the environment, their potential mobility and bioavailability related to their long-term persistence and their radiological hazard and potential impact on human health. Such key information is used to support decision-making. The environmental behaviour of radionuclides depends on ecosystem characteristics. A given soil’s capacity to immobilise radionuclides has proved to be the main factor responsible for their resulting activity concentrations in plants. The mobility and bioavailability of radionuclides in soils is complex, depending on clay-sized soil fraction, clay mineralogy, organic matter, cation exchange capacity, pH and quantities of competing cations. Moreover, various plant species have different behaviours regarding radionuclide absorption from soils.