124Sn as a Tracer of tributyltin degradation in seawater

Abstract

This is the first demonstration of the stable isotope 124Sn as a tracer of tributyltin (Bu 3 124Sn) degradation. Gas chromatography-mass spectrometry (GC-MS) was used to determine the labeled parent compound and its degradation products, labeled dibutyltin (Bu 2 124Sn) and (mono)butyltin (Bu 124Sn). This method verified that resident marine microbes degraded Bu 3 124Sn in seawater during 6-day exposures in late summer. Degradation was enhanced by addition of nutrients, and was impeded by total darkness and by laboratory ambient lighting and/or temperature. Increases in Bu 3 124Sn concentration inhibited natural primary production, but in general, led to increased bacterial growth during bottled experiments. We also discovered that some analytical methods can lead to erroneous conclusions about Bu 3 Sn degradation.