Iurian Andra-Rada, Mabit Lionel, Cosma Constantin
Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fantânele, 400294 Cluj-Napoca, Romania.
Soil and Water Management and Crop Nutrition Laboratory, Joint FAO/IAEA Programme Nuclear Techniques in Food and Agriculture, Department of Nuclear Sciences and Applications, Austria.
J Environ Radioact. 2014 Oct;136:112-20. doi: 10.1016/j.jenvrad.2014.05.013. Epub 2014 Jun 14.
This study presents an alternative method to empirically establish the effective diffusion coefficient and the convective velocity of (137)Cs in undisturbed soils. This approach offers the possibility to improve the parameterisation and the accuracy of the (137)Cs Diffusion and Migration Model (DMM) used to assess soil erosion magnitudes. The impact of the different input parameters of this radiometric model on the derived-soil redistribution rates has been determined for a Romanian pastureland located in the northwest extremity of the Transylvanian Plain. By fitting the convection-diffusion equation to the available experimental data, the diffusion coefficient and convection velocity of (137)Cs in soil could be determined; 72% of the (137)Cs soil content could be attributed to the (137)Cs fallout originating from Chernobyl. The medium-term net erosion rate obtained with the calculated input parameters reached -6.6 t ha(-1) yr(-1). The model highlights great sensitivity to parameter estimations and the calculated erosion rates for undisturbed landscapes can be highly impacted if the input parameters are not accurately determined from the experimental data set. Upper and lower bounds should be established based on the determined uncertainty budget for the reliable estimates of the derived redistribution rates.
本研究提出了一种实证确定¹³⁷Cs在原状土壤中的有效扩散系数和对流速度的替代方法。这种方法为改进用于评估土壤侵蚀程度的¹³⁷Cs扩散与迁移模型（DMM）的参数化及准确性提供了可能性。对于位于特兰西瓦尼亚平原西北端的罗马尼亚牧场，已确定了该辐射模型的不同输入参数对推导的土壤再分配速率的影响。通过将对流扩散方程拟合到可用的实验数据，可以确定¹³⁷Cs在土壤中的扩散系数和对流速度；72%的¹³⁷Cs土壤含量可归因于源自切尔诺贝利的¹³⁷Cs沉降。用计算得到的输入参数得出的中期净侵蚀速率达到-6.6 t·ha⁻¹·yr⁻¹。该模型突出显示了对参数估计的高度敏感性，并且如果未根据实验数据集准确确定输入参数，那么计算得到的原状景观侵蚀速率可能会受到很大影响。应根据确定的不确定性预算来确定上下限，以便可靠地估计推导的再分配速率。
