Preliminary study of Be-10/Be-7 in rainwater from Xi'an by Accelerator Mass Spectrometry

Abstract

The Be-10/Be-7 ratio is a sensitive tracer for the study of atmospheric transport, particularly with regard to stratosphere-troposphere exchange. Measurements with high accuracy and efficiency are crucial to Be-7 and Be-10 tracer studies. This article describes sample preparation procedures and analytical benchmarks for Be-7 and Be-10 measurements at the Xi'an Accelerator Mass Spectrometry (Xi'an-AMS) laboratory for the study of rainwater samples. We describe a sample preparation procedure to fabricate beryllium oxide (BeO) AMS targets that includes co-precipitation, anion exchange column separation and purification. We then provide details for the AMS measurement of Be-7 and Be-10 following the sequence BeO--> Be2+-> Be4+ in the Xi'an- AMS. The Be-10/Be-7 ratio of rainwater collected in Xi'an is shown to be about 1.3 at the time of rainfall. The virtue of the method described here is that both Be-7 and Be-10 are measured in the same sample, and it is suitable for routine analysis of large numbers of rainwater samples by AMS