Sulfur dioxide emissions and sulfur deposition from international shipping in Asian waters

Emissions of sulfur dioxide from international shipping in Asian waters have been estimated using information on typical shipping parameters and quantities of goods shipped to and from the major ports. Emissions are estimated to be 236,000 t SO2 per year in 1988. This represents 11.7% of emissions in Southeast Asia and 0.7% of total continental Asian emissions. Emissions from vessels in transit between ports are estimated to be 226,000 t SO2 per year, and emissions from port activities are estimated to be 10,200 t SO2 per year. Deposition of this sulfur was calculated using the ATMOS model of atmospheric transport and deposition. Shipping emissions were found to be the dominant source of sulfur deposition in large areas of the Indian Ocean, the western Pacific Ocean, and the South China Sea. Land areas most heavily affected are those bordering the Strait of Malacca, where portions of Sumatra, peninsular Malaysia, and Singapore have contributions from shipping in excess of 10% of total sulfur deposition. Observational data in Malaysia are consistent with these findings. It is suggested that emissions from shipping may be contributing to ecological damage in areas surrounding the Strait of Malacca.