Marine Micro- and Nanoplastic

Globally, a cumulated amount of more than 11 billion tons of plastics have been produced so far – 481 million tons of which were produced in 2022 alone. Some of this material ultimately ends up in the environment, e.g. due to littering, waste mismanagement or insufficient wastewater treatment. Beside large plastic debris, which has been observed in the oceans since more than 50 years, there is another, less visible side to plastics pollution: Micro- and nanoplastics are plastic particles of less than 1 mm or even 0.001 mm in size, respectively. Some of these particles were already manufactured in this final form, e.g. as ingredients of cosmetic products. Others result from the fragmentation of larger plastic items during use or directly within the environment, e.g. promoted by sunlight and wave action. Microplastics have been found to be ubiquitous in the environment. They were even detected in remote habitats with minimal human influence, e.g. deep sea sediments.

Recent years saw intensified research efforts focusing on the emissions, transport and fate of plastic particles in the environment and on their possible impacts on organisms, ecosystems and humans. Still, many open questions remain. For instance, rivers are a major pathway for plastic debris to enter the marine environment. Yet, according to different studies, estimates for the annual riverine input of plastics to the oceans still vary largely between 0.055 and 12.7 million tons per year. Other knowledge gaps still exist with regard to the interplay between plastic particles and natural biogeochemical cycles in the oceans.

Within the group of Prof. Dr. Anja Engel at GEOMAR, we are continuously working to answer some of these questions, usually in collaboration with other partner institutions.

As part of the FACTS project (2020–2023), we investigated the vertical transport of microplastics in the ocean. For instance, different water depths were sampled using sediment traps and a Marine Snow Catcher. Moreover, the interactions of microplastics with natural marine particles were studied in lab experiments. Settling organic particles and aggregates constitute an integral part of the marine carbon cycle, since they transport fixed CO₂ into the deep ocean.

The project LabPlas (2021–2025) aims at a better understanding of the sources, transport and environmental implications of plastic pollutions from the rivers to the sea. Within LABPLAS, we participated in different field sampling campaigns, e.g. examining German rivers as potential sources of marine microplastics.

The PlastTrack project (2023–2026) is a Danish-German collaboration and funded by the Interreg program. It focuses on characterizing the distribution plastic debris in the Western Baltic Sea. In particular, it aims on the development of new methods to sample and analyze not only environmental microplastics, but also nanoplastics – which poses additional challenges.