- Uppsala University
This section discusses a general sub-model for fixation of radionuclides in catchment areas to be used within the framework of a river model for substances such as radionuclides and metals from continuous and single-pulse fallouts. The model has been critically tested using data from 27 European river sites covering a very wide geographical area and contaminated by radiocesium and radiostrontium from the Chernobyl accident and from the nuclear weapons tests (NWT fallout). This modeling approach gives radionuclide concentrations in water (total, dissolved and particulate phases) at defined sites on a monthly basis. The overall river model is based on processes in the upstream river stretch and in the catchment area. The catchment area is differentiated into inflow (≈ dry land) areas and outflow (≈ wetland) areas. The model has a general structure, which can be used for all radionuclides or substances. It is simple to apply in practice since all driving variables may be readily accessed from maps and standard monitoring programs. The driving variables are: latitude, altitude, catchment area, mean annual precipitation and fallout. Note that for large catchments, this model does not require data on the characteristic soil type or the percentage of outflow areas (wet lands) in the catchment, as in most previous models, since in practice it is very difficult to obtain reliable data on characteristic soil type or percentage of outflow areas, especially in large and topographically complex catchments. Modelled values have been compared to empirical data from rivers sites covering a wide domain (catchment areas from 3000 to 3,000,000 km from 1600 to 280,000 Bq/m The river model with its sub-model for fixation predicts close to the uncertainty factors given2, precipitation from 400 to 1700 mm/yr; fallouts2; altitudes from 0 to 1000 m.a.s.l. and latitudes from 41 to 72 °N). The river model with its sub-model for fixation predicts close to the uncertainty factors given by the empirical data, which have been shown to be about a factor of 1.6 for factor of 2.2 for from the Chernobyl fallout is 2.4, for results from the NWT fallout it is 3 using the new model.137Cs and a90Sr in river water. The obtained characteristic uncertainty factors for 137Cs137Cs from the NWT fallout it is 1.3 and for the 90Sr results from the NWT fallout it is 3 using the new model.
Rivers; Fixation; Model; Catchment; Runoff; Radiocesium; Radiostrontium; Predictive Power
Book title: JAEA-Conf 2010-003 Proceedings of the meeting and computational and experimental studies for modeling of radionuclide migration in complex aquatic ecosystems
Publisher: Japan Atomic Energy Agency
Japan Atomic Energy Agency Conference 2010-003: Meeting on computational and experimental studies for modeling of radionuclide migration in complex aquatic ecosystems
Environmental Sciences related to Agriculture and Land-use
Fish and Aquacultural Science