The use of a compressed air barrier in the water is manifold. In addition to preventing the spread of flotsam or oil, it can also be used as Turbidity Barrier or control a jellyfish plague. This film was animated to demonstrate how it works. In this case, it protects the intake of an industrial seawater desalination plant.
How a compressed air barrier works
Hoses prepared with special nozzle openings are laid on the sea bed and anchored there. The compressed air generated by compressors is directed into the hose system. The escaping air initially creates a vertical flow that pulls up everything in the body of water. The flow splits in two horizontal directions at the water surface and holds back, which floats on the water. Ships or boats, however, can pass the compressed air lock unhindered. Wikipedia
Skimming off the floating substances
An additional global flow, such as in a river or ocean current, ensures the automatic removal of the floating substances. If this is not the case, the compressed air barrier function is obtained, in which the floating substances are skimmed off.