We characterized the physical transport of soil, and therefore contaminants attached to the soil, onto vegetative surfaces due to rainsplash. Soil accumulation by tomato plants (Lycopersicon esculentum) was investigated as a function of soil particle size, rainstorm characteristics, foliage height, surface area and canopy cover of the plants. No soil particles greater than 105 micron in diameter were detected on the plants. Most of the soil was splashed no higher than 40 cm above the ground surface. Linear relationships were observed for concentrations of less than 53 micron soil on vegetation and certain rainfall characteristics. Data from this study, as well as ancillary calculations, provide evidence that a significant fraction of surficial contamination of foliage may be attributed to the rainsplash mechanism.
During periods of weapons testing at the Nevada Test Site (NTS) between 1951 and 1958, the Environmental Measurements Laboratory (EML) monitored daily fallout at about 100 sites in the U.S. using gummed-film collectors. These gummed-film data represent the only comprehensive set of actual measurements of fallout during this period for areas outside the immediate vicinity of the NTS. The measured beta activities originally reported by EML have been reviewed and reevaluated. This reevaluation corrected a number of errors in the original data set and allowed fairly accurate estimates to be made of specific radionuclide depositions from individual NTS shots. Estimates of the geographical and temporal variations in cumulative 137Cs and 131I depositions from all NTS shots through 1957 are presented, as well as estimates of the relative impact of particular shots and test series. The revised gummed-film estimates of total NTS fallout depositions are compared with estimates based on contemporary and historical soil sample analyses. These reevaluated gummed-film fallout deposition estimates are being extensively utilized in a number of ongoing programs to reconstruct the radiation exposure of the U.S. population from Nevada weapons testing.
Determining the consumption of milk contaminated with 131I, resulting from atmospheric nuclear weapons tests conducted at the Nevada Test Site, by the United States population during the 1950s constitutes one part of the methodology used by the National Cancer Institute to assess radiation exposures to Americans. In order to make these estimates for locations throughout the United States, it is necessary to determine the pasture intake by cows and the distribution of the milk produced for human consumption at times when the weapons were tested. Since the milk industry has undergone many changes during the past 35 y, historical records and information must be used. The methodology developed to estimate the intake of contaminated pasture by dairy cows, milk production, and milk distribution on a county basis for the continental U.S. during the 1950s is described in detail. The relevant data on milk consumption by humans are also discussed.
This paper summarizes the results of a study on the distribution of Hg, 137CS, 238Pu, and 239,240Pu in channel sediments and adjacent bank soils in an intermittent stream used for treated liquid effluent disposal since 1963.
Concentrations of the three radionuclides and Hg in stream bank soils were comparable to adjacent channel sediments demonstrating that the stream bank serves as a deposition site for chemicals released to the channel. This finding has important implications on the long‐term behavior of effluent contaminants since other studies at Los Alamos have shown that the vegetated stream banks retard downstream movement of chemicals bound to soils and provide a pathway for transport of these materials to biota.
Concentrations of the radionuclides and mercury were more uniformly distributed with distance and depth in the channel sediments than in the bank soils. The action of periodic surface water in the channel partially explains those differences. Statistical analysis of the data revealed that 50 to 85% of the variability in contaminant concentrations in bank and channel locations was due to variation with distance while depth contributed relatively little to variability.
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