Uptake by plants of radionuclides from FUSRAP waste materials

Abstract

Ed CO r-1 © m CO M O > O en tai co ABSTRACTRadionuclides from FUSRAP wastes potentially may be taken up by plants during remedial action activities and permanent near-surface burial of contaminated materials. In order to better understand the propensity of radionuclides to accumulate in plant tissue, soil and plant factors influencing the uptake and accumulation of radionuclides by plants are reviewed. In addition, data describing the uptake of the principal radionuclides present in FUSRAP wastes (uranium-238, thorium-230, radium-226, lead-210, and polonium-210) are summarized. All five radionuclides can accumulate in plant root tissue to some extent, and there is potential for the translocation and accumulation of these radionuclides in plant shoot tissue. Of these five radionuclides, radium-226 appears to have the greatest potential for translocation and accumulation in plant shoot tissue.

Remedial Investigation Report on Bear Creek Valley Operable Unit 2 (Rust Spoil Area, Spoil Area 1, and SY-200 Yard) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Volume 1, Main text

“…Information describing uptake and accumulation of radionuclides by plants is based mostly on short-term, relatively high-exposure laboratory experiments (Knight 1983) that may not be applicalde to long-term, low-level exposure conditions, such as those at BCV OU 2. While an herb, Tradescantia, exposed to 6 mR/d experienced an increased mutation rate (Mericle and Mericle 1965), the lowest levels of long-term ionizing radiation at which nongenetic effects on higher plants were observed was -2 rad/d (Woodwell 1962).…”

Baseline risk assessment for exposure to contaminants at the St. Louis Site, St. Louis, Missouri

“…For radionuclides, surface soil concentrations were estimated from the data for the 0-to 0.3-m (0-to 1-f1) layer; for chemicals, surface soil concentrations were estimated as described in Section 3.3.1.1. Only the surface soil layer was used because the erosion rate of the soil is low enough to preclude the deeper layers from contributing to inhalation exposure (Knight 1983). However, for the construction worker scenarios at SLDS and the ditches, radionuclide concentrations were estimated from data for the 0-to 2.4-m (0-to 8-ft) layer.…”

“…The interaction of plants with radionuclides can occur by foliar absorption of radionuciides deposited on leaf and stem surfaces or by uptake from the plant root zone in the soil. Information describing uptake and accumulation ofradionuclides by plants is based mostly on short-term, relatively high-exposure laboratory experiments (Knight 1983) that may not be applicable to long-term, low-level exposure conditions such as those at the St. Louis Site. Of the radionuclides present in site wastes, radium-226 appears to have the highest potential for uptake and accumulation by plants because it serves as an enalog for calcium, an essential plant nutrient (Knight 1983).…”

“…Information describing uptake and accumulation ofradionuclides by plants is based mostly on short-term, relatively high-exposure laboratory experiments (Knight 1983) that may not be applicable to long-term, low-level exposure conditions such as those at the St. Louis Site. Of the radionuclides present in site wastes, radium-226 appears to have the highest potential for uptake and accumulation by plants because it serves as an enalog for calcium, an essential plant nutrient (Knight 1983). Lead-210 that is taken up by the plant roots will remain in the roots, with little translocation to aboveground plant parts (Knight 1983).…”

“…Of the radionuclides present in site wastes, radium-226 appears to have the highest potential for uptake and accumulation by plants because it serves as an enalog for calcium, an essential plant nutrient (Knight 1983). Lead-210 that is taken up by the plant roots will remain in the roots, with little translocation to aboveground plant parts (Knight 1983).…”