What does it mean to adsorb in environmental science?

In environmental science, the term "adsorb" refers specifically to the process where molecules from a liquid or gas adhere to the surface of a solid object without penetrating its structure. This is a surface phenomenon where the attracted substances create a layer on the solid's surface. This process is crucial in various environmental applications, such as water purification and pollutant removal, where certain contaminants adhere to materials like activated carbon. The binding that occurs is often due to physical forces, such as van der Waals forces or chemical interactions, which are essential for understanding how contaminants can be removed from aquatic systems.

Other options describe different processes: distributing evenly throughout a liquid refers to diffusion rather than adsorption; breaking down a substance into its components describes decomposition or chemical reactions; and causing an object to float is related to buoyancy, which does not pertain to the interaction of solids and liquids in the context of adsorption.