In which environment does molecular diffusion primarily occur?

Molecular diffusion primarily occurs in stagnant zones at the lake bottom because these areas are characterized by minimal movement of water. In stagnant environments, molecules can move freely and spread out from areas of higher concentration to areas of lower concentration due to random thermal motion. This process is efficient in areas where water is still, allowing solutes such as nutrients, gases, and organic compounds to diffuse effectively.

In contrast, flowing rivers and open ocean currents involve significant movement, which generally disrupts the diffusion process by mixing the water and its contents more rapidly. As a result, diffusion plays a less significant role in these dynamic environments compared to stagnant zones. While wetlands can have some stagnant areas that may facilitate diffusion, they often also experience water flow and other physical processes that can limit the extent of molecular diffusion in the overall environment.