The invention relates to an active barrier (1) and a method for its use. The active barrier (1) is used to contain and to collect polluting material floating over bodies of water, such as river, lakes, lagoons, bays or open oceans. More specifically, the active barrier is used in a situation in that pollution is caused by a liquid lighter than the water and immiscible with it, such as oil. The invention comprises a plurality of floating containment modules (3) which are interlinked to form the active barrier (1). When the latter is used in the open ocean it is required to use two supporting units (2), e.g. two vessels, to surround the mass of floating polluting material. Each containment module (3) is provided with collecting tubes (33), into which impeller modules (411) displace in a predetermined direction. The impeller modules (411) may be continuous or spaced apart. The displacement of the impeller modules (411) causes a pumping effect of pollutes water into the collecting tubes (33), and thereby the polluted waters are continuously pumped to traction and treatment assemblages (4) located at the supporting units (2).