BE-7, BE-10, AND CL-36 IN PRECIPITATION

We have measured the cosmogenic radionuclides Be-7, Be-10, and Cl-36 i n mid-latitude precipitation collected in West Lafayette, IN. In the p eriod April 18, 1992 to August 31, 1993, 350 samples were collected. A series of samples was collected through each precipitation event with 3 mm resolution. The Be-7/Cl-36 and Be-10/Cl-36 ratios vary by as muc h as a factor of 60 with a mean Be-10/Cl-36 ratio of 9.1. Be-7, Be-10, and Cl-36 concentrations through a single event are correlated and ty pically decrease from high values at the beginning of an event to lowe r values at the end. Mean concentrations of Be-7, Be-10, and Cl-36 are 1.4 x 10(7), 1.8 x 10(7), and 0.2 x 10(7) atoms/l.