Sea foam

Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignins, and lipids) derived from sources such as the offshore breakdown of algal blooms. These compounds can act as surfactants or foaming agents. As the seawater is churned by breaking waves in the surf zone adjacent to the shore, the surfactants under these turbulent conditions trap air, forming persistent bubbles that stick to each other through surface tension. Sea foam is a global phenomenon, and it varies depending on location and the potential influence of the surrounding marine, freshwater, and/or terrestrial environments. Due to its low density and persistence, foam can be blown by strong on-shore winds from the beach face inland. Human activities, such as production, transport or spillage of petroleum products or detergents, can also contribute to the formation of sea foam. Sea foam is formed under conditions that are similar to the formation of sea spray. One of the main distinctions from sea spray formation is the presence of higher concentrations of dissolved organic matter from macrophytes and phytoplankton. The dissolved organic matter in the surface water, which can be derived from the natural environment or human-made sources, provides stability to the resulting sea foam. The physical processes that contribute to sea foam formation are breaking surface waves, bubble entrainment, a process of bubbles being incorporated or captured within a liquid such as sea water and whitecap formation. Breaking of surface waves injects air from the atmosphere into the water column, leading to bubble creation. These bubbles get transported around the top few meters of the surface ocean due to their buoyancy. The smallest bubbles entrained in the water column dissolve entirely, leading to higher ratios of dissolved gases in the surface ocean. The bubbles that do not dissolve eventually make it back to the surface.