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Uptake of strontium by chamisa (Chrysothamnus nauseosus) shrub plants growing over a former liquid waste disposal site at Los Alamos National Laboratory

Conference ·
OSTI ID:422861
; ;  [1]
  1. Los Alamos National Lab., NM (United States). Environment, Safety, and Health Div.
A major concern of managers of low-level waste burial sites is the translocation of radioactive contaminants by deep-rooted plants to the soil surface. This study investigates the uptake of strontium ({sup 90}Sr), a biologically mobile element, by chamisa (Chrysothamnus nauseosus), a deep-rooted shrub plant, growing over a former liquid waste disposal site (Solid Waste Management Unit [SWMU] 10-003[c]) at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. Surface soil samples (0 to 5 cm depth) were also collected from below (understory) and between (interspace) shrub canopies. Both chamisa plants growing over SWMU 10-003(c) contained significantly higher concentrations of {sup 90}Sr than a control (background) plant -- one plant, in particular, contained 3.35 {times} 10{sup 6}Bq kg{sup {minus}1} ash (9.05 {times} 10{sup 4} pCi g{sup {minus}1} ash) in top-growth material. Similarly, soil surface samples collected underneath (ave. = 4,237 Bq kg{sup {minus}1} dry [114.5 pCi g{sup {minus}1} dry]) and between (ave. = 529 Bq kg{sup {minus}1} dry [14.3 pCi g{sup {minus}1} dry]) plants contained {sup 90}Sr concentrations above upper limit background (30 Bq kg{sup {minus}1} dry [0.82 pCi g{sup {minus}1} dry]) and LANL screening action levels (>163 Bq kg{sup {minus}1} dry [4.4 pCi g{sup {minus}1} dry]); this probably occurred as a result of chamisa plant leaf fall contaminating the soil understory area followed by water and/or winds moving {sup 90}Sr to the soil interspace areas. Although some soil surface migration of {sup 90}Sr from SWMU 10-003(c) has occurred, the level of {sup 90}Sr in sediments collected downstream of SWMU 10-003(c) at the LANL boundary was still within regional upper limit background concentrations.
OSTI ID:
422861
Report Number(s):
CONF-9605266--
Country of Publication:
United States
Language:
English