ORGANOTIN COMPOUNDS IN MARINE WATER AND SEDIMENTS FROM THE PORT OF ENSENADA, BAJA-CALIFORNIA, MEXICO

During September and October 1995, samples of surface sediments and wa ter were collected to develop an analytical set-up to determine the co ncentrations of the organic compounds known as tributyltins (TBTs), in cluding tributyl-, dibutyl- and monobutyltin. The method was then used to measure the levels of these contaminants in the port of Ensenada, Baja California. The method is based on hydride generation with atomic absorption detection. The concentrations determined were found to be relatively high (33 to 1021 ng g(-1) of Sn in sediments and 66 to 469 ng L-1 in water samples), when compared to those obtained in similar w orks at San Diego Bay in California. USA. Comparisons are also made wi th other geographical locations, These results suggest that the port o f Ensenada is an area that is receiving substantial amounts of these c hemicals and might already be affecting the health of local biota. Two sources of these chemicals were identified: the activities associated with painting and cleaning of both commercial and sport boats, and th e presence, at the time of the sampling, of on old platform near the e ntrance to the: port facilities, The presence of the three compounds s uggests that there is a permanent entry of these pollutants: furthermo re, the presence of decreasing concentrations. starting with the more butylated compounds, suggests a recent introduction. The higher concen trations found in the sediment samples indicates the existence of an e fficient method of removal from the water column to the sediments of t hese compounds. The removal mechanism is associated with the presence of organic matter in the port area, In the sediments, the distribution of TBTs was partially dictated bq the organic content, as a significa nt correlation (alpha = 0.05) between TBT concentration and organic co ntent was found.