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Radionuclide Transport above a Near‐Surface Water Table: III. Soil Migration and Crop Uptake of Three Gamma‐Emitting Radionuclides, 1990 to 1993
Author(s) -
Wadey P.,
Shaw G.,
Bell J.N.B.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.3041341x
Subject(s) - radionuclide , lysimeter , crop , soil water , environmental science , water table , soil horizon , hydrology (agriculture) , chemistry , soil science , groundwater , agronomy , geology , physics , geotechnical engineering , quantum mechanics , biology
This paper summarizes the vertical distributions of 22 Na, 137 Cs, and 60 Co above controlled water tables in deep and shallow lysimeters during a four‐year experiment. The activity concentration profiles were all determined at the time of harvest of a winter wheat ( Triticum aestivum L. cv. Pastiche) crop. Activity concentrations in different crop tissues were determined and crop uptake expressed as both an inventory ratio (IR) and a transfer factor (TF w ), weighted to account for root and radionuclide distributions within the soil profile. Experimental variates were subjected to analysis of variance to determine the single and combined effects of the soil depth and the year of the experiment on the results obtained. Each radionuclide showed significant variations in activity concentration with soil depth, but the significance of these variations from year to year was dependent on radionuclide. A distinction in the behavior of weakly sorbed ( 22 Na) and more highly sorbed ( 137 Cs and 60 Co) radionuclides was observed. The former exhibited significant variations in its distribution in the soil profile from year‐to‐year whereas the latter did not. Relatively high TF w values for 22 Na were maintained throughout the experiment, whereas for 137 Cs and 60 Co, the highest TF w values were recorded in 1990 followed by a significant decline in 1991, with TF w remaining low in 1992 and 1993. The TF w values were, in general, significantly higher for deep lysimeters than for shallow lysimeters. This is thought to provide evidence of enhanced radionuclide absorption by the relatively small fraction of roots in the vicinity of the deeper water table.