Critical pathways of radionuclides to man from agro-ecosystems. Progress report (annual), 1 October 1979-30 September 1980

The studies investigating the environmental behavior of radionuclides released into agricultural systems by a nuclear fuel chemical separations facility have advanced considerably within the past year. Manuscripts reporting uptake of Pu and Cm by agricultural plants have shown that Cm was taken up in greater quantities than Pu. Lime addition to soil depresses uptake of Cm while chelate addition to limed soil increases uptake of Cm. No conclusive effects of soil amendments were observed with regard to Pu uptake. Cesium uptake by agricultural plants differs between species, plant part and year of harvest, with an indication that cesium may be increasingly taken up with the passage of time in some instances. Soil amendments affect 137Cs uptake similarly as that reported for 244Cm. Rice varieties do not differ in their Pu or Cm uptake, nor does uptake by rice in flooded soils differ from those uptake rates reported for dry-land agricultural species. Curium and 239, 240Pu appear to be equally available to rice and more available than 238Pu. Broadleaf crops appear to exhibit Pu concentrations dependent on their shape and form, indicating the importance of physical processes in this field experiment. Because of crop failures caused by drought conditions, there has been little progress on our U-field studies