Over the past several decades, there has been a steady increase in the size and number of ships involved in international shipping. In addition to cargo, these ships transport large quantities – often thousands of tons – of water as ballast to maintain proper buoyancy and stability. As cargo is unloaded in port, water is drawn into the ship’s ballast tanks, or to load cargo, ballast water is discharged from the ship. The ballast water can contain millions of unseen aquatic organisms – both animal and plant species – that are transported from one ecosystem to another via the ballast tanks. When released into a new environment, these aquatic organisms often become invasive and extremely harmful to their new environment, resulting in infrastructure damage, toxic algal blooms and the collapse of native coastal fisheries.
One of the most devastating invasive aquatic species – the Zebra Mussel – was first discovered in the Great Lakes near Windsor, Canada in 1988. It was transported in the ballast of a ship arriving from the Black Sea. The effort to stop the spread of this invasive aquatic organism now costs Canada and the United States hundreds of millions of dollars annually. Although the Great Lakes became the initial focal point of this problem, there are now thousands of similar examples around the world.
To mitigate the growing risk of invasive aquatic species, pending international regulations will soon require globally-trading ships to install ballast water treatment systems (BWTS) to eliminate the problem of ballast water-transported organisms from one ecosystem to another. Specifically, the International Maritime Organization (IMO) adopted the Ballast Water Management Convention requiring mandatory installation and use of BWTS starting in 2012. This Convention is currently in the process of being ratified by the IMO Member Nations, many of which are also developing national regulations to enforce this pending new international regulation. For more information, visit the IMO Ballast Water Management website and our Ballast Water Regulation page.
The inside of a ship’s ballast tank is a highly corrosive environment, causing steel to rust when not properly protected. Water, particularly salt water, acts as a catalyst to cause steel to rust, causing a major maintenance cost problem for the ship and significantly reducing the useful life of the vessel:
If oxygen can be eliminated from the equation above, then the problem of ballast tank corrosion, or deteriorated ballast tank coatings, can be eliminated.