Kienzler and Polig (1975) and Polig (1975a, b) have reported on the use of alpha autoradiography in biological studies. Film determinations of natural alpha activity have been used in uranium exploration (Gingerich, 1975) and geochronology (Fisher, 1977). Bhatt and Singh (1974) have suggested film use for ; lutonium contamination measurements, Center and Ruddy (1976) have applied the method to characterization of alpha-radioactive aerosols, and Levy et aZ. (1977) have used it to study the history of uptake of Pu by a coral in Bikini lagoon. Alpha autoradiography has many advantages: it is nondestructive; it yields information about the spatial distribution of activity within a sample; and for many applications, it is faster, simpler, and less expensive than conventional radioanalytical techniques. Its failure to achieve wider application has probably resulted from the fact that, until recently, commercial detectors and standard methods were not available, requiring investigators to develop their own films and validate technique on a step-by-step basis. However, Eastman Kodak now markets two alpha-sensitive cellulose nitrate films (CA 80-15, 100 um thick, and LR-115, with a sensitive layer thickness ranging from 6 to 13 um depending on type and batch), and a substantial literature on their use and characteristics has developed (for example, Costa-Ribeiro and Labdo, 1975; Qaqish and Besant, 1976; Spurn¥ and Turek, 1976; Levy et al., 1977; Eastman Kodak, no date). The purpose of the study reported on here was to investigate the utility of Kodak LR-115, Type II for rapid quantitative or semiquantitative activity measurements and studies of activity distribution in biogeochemical samples and environments contaminated with plutonium. MATERIALS AND METHODS Most of the work reported here was done with batch I.76.1 of Kodak LR-115, Type II film. This film has a dark red cellulose nitrate layer 13 um thick deposited on a plastic backing. The recommended development procedure (Eastman Kodak, no date) is to etch in 2.5 N NaOH solution at 60° C. for 90 minutes. Under these conditions, damage tracks resulting from alpha particles with energies less than 4 MeV are expected to etch completely through the cellulose nitrate layer, leaving holes on the order of a few um to a few tens of um which may readily be observed, counted, and measured with transmitted light. Activity sources and samples used included commercial 241am standard planchets, Pu-electroplated planchets which had been accurately counted by alpha spectrometry at Lawrence Livermore Laboratory, and soils, sediments, and other samples from the Pu/Am-contaminated environments of Enewetak and Bikini atolls. 594