Spatiotemporal distribution of organotin compounds in the coastal water of the Bahía Blanca estuary (Argentina).

Several areas within the Bahía Blanca estuary (BBE), with different maritime traffic intensity, were studied in order to confirm the presence and assess the distribution of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in the water column. The organotin compounds (OTCs) were determined in the water samples-taken in summer, autumn, winter, and spring of 2014-by gas chromatography coupled to mass spectrometry after liquid-liquid extraction with hexane. The incidence of TBT throughout the whole sampling period indicated a continuous presence of this compound to the study area. However, in accordance with the butyltin degradation index (BDI), TBT was not recently introduced in the BBE. Furthermore, the average TBT levels exceeded the international guideline established by the Oslo-Paris commission (0.62 ng Sn L-1). As a result, certain biological effects could be expected to occur in sensitive species such as mussels. While DBT were below the detection limit in the 75% of the samples analyzed, MBT was detected in all the samples and no significant differences were found among the concentrations measured in the different seasons (Kruskal-Wallis test, p > 0.05). In addition, no correlations were found among the OTCs levels and the evaluated physiochemical parameters (Spearman coefficient, p > 0.05).