Fallout 137Cs in soils and sediments of some Texas watershed ecosystems

The distribution of 137Cs in the soils and sediments of 13 watershed ecosystems located in seven physiographic regions of Texas was determined. The average areal concentration of 137Cs in the watershed soils ranged from 40 to 94 nCi/m2 with an average of 60 nCi/m2. The average areal concentration of 137Cs in the reservoir sediments ranged from 135 to 1026 nCi/m2 with an average of 511 nCi/m2. The build-up of 137Cs in the reservoir sediments when compared with the watershed soils on an area basis ranged from 3.1 to 19.4 with an average build-up of 8.6, indicating that 137Cs is moving in the watersheds and that the reservoir sediments are acting as 137Cs ''traps or sinks''. Applying stepwise multiple regression to the data showed that only four to six watershed characteristics were needed to explain 90% of the observed variation in the distribution of 137Cs in the soils and sediments