Update on the status of the contamination by organotin compounds in sediment of Nuevo Gulf, Argentina. Insights from field and experimental studies.

Organotin compounds are persistent pollutants and are considered chemicals of high environmental concern. In the present study, the distribution and degradation of tributyltin were evaluated in field sediments and through an ex situ experiment. For this, sediment samples from two locations were analysed: Luis Piedrabuena Harbour, with higher maritime traffic, and Cerro Avanzado, which receives less impact from anthropogenic activities. The results indicated that pollution levels at Luis Piedrabuena Harbour have decreased compared with studies performed 9 years ago for the same area. On the contrary, traces of organotin compounds have been found for the first time at Cerro Avanzado. Moreover, the butyltin degradation index indicated that organotin compounds undergo an advanced degradation process in the collected samples at both sites. Ex situ experiments revealed a limited capacity of sediments to retain tributyltin, and suggested an active role of bioturbation activity in the degradation of these compounds. In addition, visualisation using chemometric techniques (principal components analysis) allowed a simpler analysis of two sediment characteristics: the degree of contamination and the degradation levels of organotin compounds. • Update on contamination of two sites with different anthropogenic pressure. • At Luis Piedrabuena Harbour, MBT and DBT were predominantly detected, indicating an advanced degradation process of TBT. • For the first time, traces concentrations of both TBT and its degradation products were recorded at Cerro Avanzado. [ABSTRACT FROM AUTHOR]