Ballast Tank of Ocean-Going Ship

The empty interior of an ocean-going ship's ballast tank. Such tanks are filled with water to balance a ship's loads. Unless the water is treated before it is emptied into foreign waters, it can introduce foreign organisms into the water that may become established and compete with native species, causing untold ecological and economic damage. USGS scientists are taking up the challenge of dosing, mixing and testing cost-effective treatments in such large tanks that will kill the organisms but render the water safe for discharge.