Scientists Find Way to Make Ballast Water Safer
A technique that inhibits corrosion in ship ballast tanks also has an added benefit of stopping the spread of foreign organisms via ballast water.
A technique that inhibits corrosion in ship ballast tanks also has an added benefit of stopping the spread of foreign organisms via ballast water. The method removes oxygen from the water by using nitrogen gas, presenting the much sought after "win-win" for economics and the environment. Marine ecologist Mario Tamburri of the Monterey Bay Aquarium Research Institute (MBARI) led the study reported in the January issue of the journal Biological Conservation.
Non-native, or exotic organisms that are introduced into new environments can cause a huge amount of trouble for native species and local economies. Oftentimes, the new species do not have natural enemies so they have a competitive advantage over native plants and animals. They can also bring disease for which local flora and fauna have no natural defense.
Ballast water has been shown to be a big player in the transport of aquatic organisms from one port to another throughout the world and these species introductions are thought to have been involved in 70 percent of native aquatic species extinctions in the last 100 years. Because of these impacts, researchers from all over the world have been developing ways to clear the ballast water of aquatic organisms that may colonize new habitats.
Of the various methods that are used to control ballast water, deoxygenation is seen as the safest for both human health and the environment and it also provides an economic benefit for ship owners.
"Deoxygenation was seen as too expensive for controlling invasive species in ballast water but our study shows that the anticorrosion benefit of this technique is a strong economic incentive for the shipping industry," said Tamburri. "It's a win-win treatment for solving an environmental problem and reducing ship maintenance costs."
The deoxygenation the researchers are speaking of involves bubbling nitrogen gas into ballast water to remove oxygen, thereby preventing oxidation or rust in the tanks. The shipping industry currently uses expensive paints, which must be maintained over the lifetime of the vessel - which is typically around 25 years. It is estimated that nearly $100,000 (US) per year can be saved for each new ship that uses this deoxygenation technique rather than paint to prevent corrosion.
The method works to inhibit rust and also creates a low oxygen environment that invasive species cannot tolerate. In tests conducted by the scientists, larvae from three known nuisance invasive species now found in US waters - an Australian tubeworm, European green crab, and European zebra mussel - did not live after just two or three days in the deoxygenated environment. Major ocean crossings by cargo vessels typically take weeks.
While Tamburri says most invasive species could be controlled by this method, some species that remain dormant as cysts would likely remain unharmed.
"While extremely effective, deoxygenation may not be as comprehensive in removing aquatic organisms as other proposed ballast water treatments but it has the huge advantages of being environmentally benign while also saving ship owners money through rust prevention," said Tamburri. "Until international law mandates total mortality of all ballast water organisms, deoxygenation at very least deserves further consideration as a high priority treatment."
Non-native, or exotic organisms that are introduced into new environments can cause a huge amount of trouble for native species and local economies. Oftentimes, the new species do not have natural enemies so they have a competitive advantage over native plants and animals. They can also bring disease for which local flora and fauna have no natural defense.
Ballast water has been shown to be a big player in the transport of aquatic organisms from one port to another throughout the world and these species introductions are thought to have been involved in 70 percent of native aquatic species extinctions in the last 100 years. Because of these impacts, researchers from all over the world have been developing ways to clear the ballast water of aquatic organisms that may colonize new habitats.
Of the various methods that are used to control ballast water, deoxygenation is seen as the safest for both human health and the environment and it also provides an economic benefit for ship owners.
"Deoxygenation was seen as too expensive for controlling invasive species in ballast water but our study shows that the anticorrosion benefit of this technique is a strong economic incentive for the shipping industry," said Tamburri. "It's a win-win treatment for solving an environmental problem and reducing ship maintenance costs."
The deoxygenation the researchers are speaking of involves bubbling nitrogen gas into ballast water to remove oxygen, thereby preventing oxidation or rust in the tanks. The shipping industry currently uses expensive paints, which must be maintained over the lifetime of the vessel - which is typically around 25 years. It is estimated that nearly $100,000 (US) per year can be saved for each new ship that uses this deoxygenation technique rather than paint to prevent corrosion.
The method works to inhibit rust and also creates a low oxygen environment that invasive species cannot tolerate. In tests conducted by the scientists, larvae from three known nuisance invasive species now found in US waters - an Australian tubeworm, European green crab, and European zebra mussel - did not live after just two or three days in the deoxygenated environment. Major ocean crossings by cargo vessels typically take weeks.
While Tamburri says most invasive species could be controlled by this method, some species that remain dormant as cysts would likely remain unharmed.
"While extremely effective, deoxygenation may not be as comprehensive in removing aquatic organisms as other proposed ballast water treatments but it has the huge advantages of being environmentally benign while also saving ship owners money through rust prevention," said Tamburri. "Until international law mandates total mortality of all ballast water organisms, deoxygenation at very least deserves further consideration as a high priority treatment."
