Since the introduction of steel-hulled vessels around 135 years ago, water has been used as ballast to stabilize vessels at sea. Ballast water is pumped in to maintain safe operating conditions throughout a voyage. This practice reduces stress on the hull, provides transverse stability, improves propulsion and maneuverability, and compensates for weight changes in various cargo load levels and due to fuel and water consumption.
While ballast water is essential for safe and efficient modern shipping operations, it may pose serious ecological, economic and health problems due to the multitude of marine species carried in ships’ ballast water. These include bacteria, microbes, small invertebrates, eggs, cysts and larvae of various species. The transferred species may survive to establish a reproductive population in the host environment, becoming invasive, out-competing native species and multiplying into pest proportions.
Scientists first recognized the signs of an alien species introduction after a mass occurrence of the Asian phytoplankton algae Odontella in the North Sea in 1903. In the late 1980’s, Canada and Australia were amongst countries experiencing particular problems with invasive species, and they brought their concerns to the attention of IMO’s Marine Environment Protection Committee (MEPC)
The problem of invasive species in ships’ ballast water is largely due to the expanded trade and traffic volume over the last few decades and, since the volumes of seaborne trade continue to increase, the problem may not yet have reached its peak. The effects in many areas of the world have been devastating. Quantitative data show that the rate of bio-invasions is continuing to increase at an alarming rate and new areas are being invaded all the time.
The spread of invasive species is now recognized as one of the greatest threats to the ecological and the economic wellbeing of the planet. These species are causing enormous damage to biodiversity and the valuable natural riches of the earth upon which we depend. Direct and indirect health effects are becoming increasingly serious and the damage to the environment is often irreversible.
In order to control the spread of invasive aquatic species through ship’s ballast water, IMO through international co-operation adopted the International Convention for the Control and Management of Ship’s Ballast Water and Sediments (BWMC) in 2004.
The Convention will require all ships to implement a ballast water management plan, carry a ballast water record book, carry out ballast water management procedures to a given standard, and hold a valid International Ballast Water Management Certificate.
During the Convention development process, considerable efforts were made to formulate appropriate standards for ballast water management. They are the ballast water exchange (BWE) standard and the ballast water performance standard. Ships performing ballast water exchange shall do so with an efficiency of 95 per cent volumetric exchange of ballast water and ships using a ballast water management system (BWMS) shall meet a performance standard based on agreed numbers of organisms per unit of volume.
The Convention will enter into force after ratification by 30 States, representing 35 per cent of world merchant shipping tonnage.
In the interim period, whilst the Convention is yet to enter into force, ships are carrying out BWE in the open sea (> 200nm from nearest land and water depth > 200m) to meet Port State Control requirements.
Till date, 49 contracting States with 34.82% of the world’s gross tonnage have ratified the Convention, so we are very close to meeting the entry into force criteria. It is expected that the criteria would be met soon and the Convention would enter into force probably before the end of 2016.
It would be one of the most expensive Conventions to implement as retrofit of a Ballast Water Treatment System would cost US $ 1 to 5 million per ship depending on size, capacity and layout.
Presently, there is still a dilemma with regard to approvals as only MEPC approved systems would be acceptable and further for trading in US waters, US Coast Guard approval would also be required. A few companies have installed retrofit systems on some of their ships, for early compliance. Majority would comply close to the due date for a ship which would be the next renewal date of the individual ship’s pollution prevention certificate. This would effectively space out compliance over the next five years.
Although in the prevailing very low freight market situation it is going to be difficult for the shipping industry to implement BWMC due to high cost, but to protect the marine environment it would need to be done.
0 comments:
Post a Comment