What is a non-example of concentration gradient

Hello,

concentration gradient is the process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles. The areas are typically separated by a membrane.

correct me if i'm wrong!

But since concentration gradient is the process of particles, then Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they settle as individual particles and do not flocculate