137Cs) were measured in the soils of a small catchment in the Central Pyrenees, Spain. The
study was carried out in a mountainous area that was representative of the Tertiary Flysch
landscapes in the Southern Pyrenees. Bulk soil cores (n= 77) were collected at the
intersections of a 200× 200-m grid established in the Arnás River Catchment. Mean
radioisotope activities (Bq kg− 1) were 40 (238U), 27 (226Ra), 35 (232Th), 74 (210Pb), 48 …