Identification of Chernobyl Fall-Out as a New Reference Level in Northern Hemisphere Glaciers

Among the various artificial radioactive markers (mainly from atmospheric nuclear tests), the contamination from the Chernobyl accident has been found at five sampling sites on Northern Hemisphere glaciers. Total beta-activity measurements reveal a very high radio-active level. However, due to the short time of its occurrence, the temporal resolution of this event in the snow layers can be generally quite low and positive results require careful sampling. The size of the signal also depends on the trajectory of the contaminant cloud, the amount of precipitation, and the surface conditions during deposition.