The subject of the project is organotin compounds as pollutants in the marine environment, in particular tributyltin (TBT), which is used as a biocide in antifouling paints and is considered one of the most harmful compounds ever introduced into the marine environment. Despite bans, it is still present in the environment, particularly in sediments. Based on current knowledge, it is not possible to estimate how long it will be a problem or how to solve it. On the other hand, methyltin (MeT) compounds are not only of anthropogenic origin, but can also be formed naturally by methylation of inorganic tin. Although this alters the biological activity and mobility of tin, the effectiveness of methylation and behavior of MeT compounds are not yet known.The aim of this interdisciplinary project is to explain the behavior, transformation, and persistence of BuT and MeT compounds in the marine environment using an innovative and comprehensive approach. The project will integrate in situ research and advanced analytical techniques, as well as biological-molecular and sedimentological analyzes to explain the processes that these compounds undergo in the environment and the factors that influence these processes. The project will explain the persistence of TBT in polluted sediments and determine its possible role in the pollution of the water column. The project also aims to identify the microbial community that plays an active role in the degradation of TBT in sediments. The knowledge gained will make an important contribution to further research aimed at defining biotechnological processes for the bioremediation of polluted sediments. A further aim is to determine the efficiency of tin methylation and the fate and transfer of MeT compounds in the marine environment.In addition to answering current scientific questions, the proposed project will also contribute to the development of action strategies within the framework of programs for the protection of the marine environment.