ABSTRACT

The concentrations of ²¹⁰Pb and ²¹⁰Po in a total of 73 samples of individual rain and snow collected at Fayetteville (36°N, 94°W), Arkansas, were determined radiochemically during the period between October 1982 and January 1984. A clear seasonal pattern of variation of the ²¹⁰Po/²¹⁰Pb ratio in rain was observed: the ratio reaches a maximum during the months of November and December or January and February each year. The ²¹⁰Po/²¹⁰Pb ratio data obtained in our laboratories since 1971 were compared with the results of the studies on seasonal variation of the sulfate concentrations in the stratosphere reported by Sedlacek et al. (1983) and the following general trend was observed: the occurrence of a peak sulfate concentration in the stratosphere caused by a major volcanic eruption is followed by the occurrence of a peak ²¹⁰Po/²¹⁰Pb ratio in rain and snow samples collected several months later. Effect of the atmospheric injections of excess ²¹⁰Po from major eruptions of volcanoes located in Alaska, Aleutian Islands, Kamchatka and Kurile Islands can be seen more clearly at Seattle (47°N, 122°W), Washington, than at Fayetteville (36°N, 94°W), Arkansas.