Cesium-Labeled Phlogopite as a Tracer for in Situ Studies of Sediment Burial, Reworking, and Resuspension Rates

Abstract

Abstract Phlogopite is a mica mined commercially in eastern Canada. Its major exchangeable cation, K+, can be removed with sodium tetraphenylboron. When the K-depleted phase is soaked in CsCl (aq), it binds Cs+, forming a new crystalline phase, CsPhlog, that contains up to 10 weight-% Cs. The new phase binds Cs+ strongly (KD > 106), making CsPhlog stable enough to be useful as a tracer for clay particles. We investigated the direct determination of Cs in lacustrine sediments using neutron activation analysis, X-ray fluorescence spectrometry, and radio frequency (r. f.) glow-discharge mass spectrometry. Glow discharge mass spectrometry proved insufficiently sensitive due to isobaric interferences, but the other two methods were usable at tracer levels. Activation analysis was used for routine determinations because of its superior sensitivity. Starting with CsPhlog containing a few percent Cs by weight, the observed sensitivity translated to a measurable dispersal factor of at least 104. We used CsPhlog de...