What happens to nanomaterials after their usage for environmental remediation?

The nanomaterials will remain within the environment. What happens there in the long term cannot easily be answered with current methods. A major obstacle is the high natural background of the respective material in the environment. This makes it hard to distinguish between natural occurring and specifically introduced nanomaterials used for remediation purposes (e.g. iron). In any case, the nanomaterials will undergo transport and transformation processes (see basics article: transport & transformation, in preparation). However, most nanomaterials do not travel very far in the environment as they have a strong tendency to bind to other particles, e.g. soil particles.