Nowadays, most ecosystems in addition to transfer of biologic samples, carry chemical compounds including oil compounds considering the importance of biodiversity of the region & prevention of invasion organisms, which may impart ecosystem balance, analysis of the appropriate probable solutions to preserve ecosystem balance is highly required. Transfer of water ballast and the increasing rate of oil extraction operations in the region, will intensify the need for such study.
In the course of this project, samples were taken from 6 Russian commercial ships, in order to analyse oil pollution (15-18 December 2002) in Bandar Anzali. By using different solvent Nhexane & dichlorometane recovery tests oil based hydrocarbons from non-oil based hydrocarbons were separated. Using GC equipment, it was found that, these samples contained high amount of PAH's, SHC's and related alkilhomiloges.
Eicosane, Tetracosahexane, Hexadecatrien, Methylpalmitate, Dodecane, Methylstearate compounds were also identified using GC-MS equipment. Using FT-IR method, the amounts of oil concenteration were determined. The result of wich shows the minimum concenteation of 22 ppm and maximum of 155 ppm.
Finally, the average of oil hidrocarbons, which was discharged into the estuarine ecosystem of Anzali per ballasted ship, at the same period in a year of 2002, considered being around 66.2 kg. In other hand, noting that total number of ships harboured at Anzali jetties in the same period, the amount of oil hidrocarbons discharge into the aquatic environment was estimated 27.9 tons.
Based on International Marine Organization, Draft MEPC-48/2(2002) ballast water is water with its suspended solids taken on board a ship to control trim, list, draught stability or stresses of a ship.
Ballast water is taken on via pump and the sea chest located at the side or on the bottom of the ship.
From other advantages of ballast water can be pointed to: controlling ship balance, increasing propeller efficiency by submerging in water, and maximizing rudder efficiency.
In order to control ship stability, balance, and solidarity the tanks are filled with water when the ship is unloaded and apparently are discharged during loading (1).
More than ninety percent of commercial cargos are transported via ships and it is estimated about 3-5 milliard ton ballast water is transferring via 85000 ships every day globally. Ballast water has been suggested as a major vector for introduction of the marine species and chemical compounds. Based on ship size and its object every ship may carry some litter up to 130000 tonnages ballast water. The volume of ships' ballast water is depending on design, size, and stability of a ship (1).
The other hazardous factors added to the ballast water concern and its volume is the number of arrived ships to harbors and also ecosystem similarity of departure harbor and arrival port (2).
International Marine Organization (IMO) and member nations in 1973 adopted a convention named MARPOL in order to solve ballast water pollution. MARPOL Convention is on marine pollutions by ships and includes certain regulations for navigation.