A soil sampling and analysis program is the most direct means of determining the concentration, inventory, and distribution of radionuclides and radioactivity in the environment within and around nuclear facilities.This report summarizes and evaluates the concentrations of 3H, 13'Cs, 238Pu, 239*240Pu, 241Am, 90Sr, total uranium, and gross alpha, beta, and gamma activity in soils collected from Los Alamos National Laboratory (LANL), perimeter, and regional (background) areas over a 21-year period (1974 through 1994). Also, trends in radionuclide concentrations and radioactivity over time and the total effective dose equivalent (TEDE) were determined for each site. The upper-limit regional background concentration (95 % upperconfidence level) for each radionuclide and level of radioactivity were as follows: 3H (6.34 pCi mL-), Cs (1.13 pCi dry g-'), 238Pu (0.008 pCi dry g-'), 2399240Pu (0.028 pCi dry g-'), 241Am (0.208 pCi dry g-'), 90Sr (0.82 pCi dry g-'), total uranium (4.05 pg dry g-'); and gross alpha (35.24 pCi dry g"), beta (13.62 pCi dry g-'), and gamma (7.33 pCi dry g-l) activity. Based on the average over the years, most LANL and perimeter soils contained three or more radionuclides and/or gross radioactivity that were significantly higher in concentration (p c 0.05) than regional background. The higher concentrations in perimeter soils were attributed to worldwide fallout and to naturally occurring radioactivity in Bandelier tuff soils, whereas the higher concentrations in LANL soils were attributed to worldwide fallout, natural radioactivity, and Laboratory operations. Most radionuclides and radioactivity detected in LANL and perimeter soils, however, showed generally decreasing trends over time; many radionuclides, like 3H and uranium, at most LANL sites exhibited significantly decreasing trends (p c 0.05) over time. The net dose (TEDE minus background) for residents living onsite at LANL or along its perimeter ranged from -0.3 mrem y-' (east of TA-54) to 3.8 mrem y-'(east of TA-53) and from -0.4 mrem y-l (White Rock) to 3.6 mrem y-l (west of LANL on Forest Service land across from TA-WGT site). All net doses were far below the International Commission on Radiological Protection's permissible dose limit of 100 mrem y-l.

Portions of thisSimilarly, most radionuclides in edible crop portions of beans, squash, and corn were detected in significantly higher (p ~0 . 0 1 and 0.05) concentrations than RBG. Most soil-to-plant concentration ratios for radionuclides in edible and nonedible crop tissues from LAC were within the default values given by the Nuclear Regulatory Commission and Environmental Protection Agency. All heavy metals in soils, as well as edible and nonedible crop tissues grown in soils from LAC, were within RBG concentrations. Overall, the total maximum net positive committed effective dose equivalent (CEDE)--the CEDE plus two sigma for each radioisotope minus background and then all positive doses summed--to a hypothetical SO-year resident that ingested 160 kg [352 lb.] of beans, corn, and squash in equal proportions, was 74 mrem y-l. This dose was below the International Commission on Radiological Protection permissible dose limit (PDL) of 100 mrem y-l from all pathways; however, the addition of other internal and external exposure route factors may increase the overall dose over the PDL. Also, the risk of an excess cancer fatality, based on 74 mrem y-', was 3 . 7 x 10'' (37 in a million), which is above the Environmental Protection Agency's (acceptable) guideline of one in a million.

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