Nanoparticles are between 1 and 100 nanometres (billionth of metre) in size and due to their unique properties are being added to more and more consumer products, such as clothing and sunscreens. During their production and use nanoparticles are released in the aquatic environment, especially in coastal systems where they accumulate.
Coasts are important ecosystems for human populations: they produce oxygen that we breathe, they provide food for fishes and shells, they are used as recreational areas… Coastal sediments host a large diversity of microorganisms that support several of these services, especially oxygen production, carbon trapping and recycling of nutrients that would otherwise pollute the water.
This project aims to investigate the impact of nanoparticles on coastal microorganisms, the consequences of these impacts for the functioning of coastal systems, and therefore for human populations.
We chose two types of nanoparticles: titanium oxide nanoparticles, that are the most produced nanoparticles, and one of the main components of sunscreens; and silver nanoparticles, which are the nanoparticles used in the wider range of products, such as clothing, medical material, food packaging, household appliances…
Our aims were to determine:
- how nanoparticles influence coastal microorganisms in near-natural conditions;
- how nanoparticles influence oxygen, carbon and nutrient cycles in coastal zones;
- whether these effects are dependent on the type of nanoparticle considered and of the season.
We found that at current concentrations, these nanoparticles have limited impact on microorganisms and coastal ecosystem functions. However at higher concentrations, titanium oxide nanoparticles have the potential to limit the growth of microorganisms and alter their ability to produce oxygen and recycle nutrients. This toxicity appears after contact with the nanoparticles for several weeks, and is different between seasons.
