ORGANOTIN COMPOUNDS OCCURRENCE IN SURFACE SEDIMENTS FROM BAHIA BLANCA ESTUARY, ARGENTINA.

DELUCCHI, FEDERICO; TOMBESI, NORMA; FREIJE, R. HUGO; MARCOVECCHIO, JORGE

Buzios, Brasil

Simposio; IV International Symposium on Environmental Geochemistry in Tropical Countries.; 2004

Organotin compounds and particularly tributyltin (TBT) deserve to be mentioned between the most potentially dangerous substances which can be introduced to the Coastal Zone due to human activities. In fact TBT has been recognized as one of the most toxic pollutants, and has been the origin of severe damage on both marine and estuarine biota, even at extremely low concentrations. Those coastal environments which include harbour facilities (not only for large vessels but also for recreation boats) have shown to be particularly exposed to TBT and its degradation products. Along the widespread Argentina´s Atlantic littoral, Bahía Blanca estuary seemed to be an ideal study area to start a systematic programme of assessment on TBT occurrence, distribution and generation of deletereous biological effects. Keeping in mind that surface sediments have demonstrated to be the main sink for these compounds, as well as they have long residence times within this compartment, Bahía Blanca estuarine sediments have been the first target of this study programme. A solid phase microextraction system (SPME) in combination with capillary gas chromatography with mass spectrometry detection (GC-MS) was applied in order to determine the concentrations of these compounds in the analyzed sediments. Tributyltin, tetrabutyltin, dibutyltin and monobutyltin analytical standards were used to identify the determined compounds as well as to certify the analytical quality of the analysis. The corresponding butyltin derivatized hydrides, which have been generated by addition of potassium borohydride, were sampled from the headspace with a polydimetylsiloxane microfiber. Then, the microfiber was removed and introduced within the chromatograph injector, where an adequated temperature allowed the desorption of the corresponding compounds. The obtained results are being discussed not only considering the ability of this analytical method to determine TBT but also considering the corresponding environmental scenario. These results are the starting point of an integrated TBT monitoring program within Argentina´s marine coastal system.