pattern aodels,‘provided an'ep imateof ‘exteraalédoseequiveient gts ‘s Exponentially decbining; activity concentrations‘have:been-obsarved ‘in gure: gee face soil for 1370, 129 T, omeOse from1954.‘to;‘ehe:present:On. meg rrr Se patepeersy meyers r es Thue exponential decline in dietary activity vas’estumed and). general equations were derived, ! po de 6 gee J u,/&, ~ 4° (oi Bix o7REy Meh pope. fe 2xiRi eseOreRY i : or a | 4 ) : . o REKLE | (2) my? eye ve bo and “ Xi D = £,\P° By aK, | Kirke =(,4K; de~(A+Kg)c + (1+Kg) e Ba alta (K,*A) (Kh,#0) + q° be ah [Ire where 6 =(,+Ky)t i Je ( 3)