CONCENTRATION DISTRIBUTION OF SOIL PARTICLES AND POLLUTANTS IN THE MARINE ATMOSPHERE AND THEIR TRANSPORT TO THE OCEAN

In order to investigate the concentration distribution of soil particles and pollutants in the marine atmosphere and their transport to the ocean, atmospheric concentrations of Al, Si, Fe, S and Cl were measured in the Pacific Ocean, the Indian Ocean and the Antarctic Ocean. The marine aerosol samples, collected on board the research ship SHIRASE, were analyzed by X-ray fluorescence analysis. The samples were taken every day by a low volume air sampler at the flow rate of 30l/min, during the cruises of SHIRASE from Tokyo to Fremantle in November and from Fremantle to Syowa Station in December 1988. As a result, the average concentrations of the soil derived elements were 11.9ng/m^3 for Al, 50.6ng/m^3 for Si and 12.5ng/m^3 for Fe over the western Pacific Ocean between Tokyo and Fremantle. These values are as low as 1/100 of atmospheric concentration over land except Antarctica. Especially, over the Indian Ocean and the Antarctic Ocean between Fremantle and Syowa Station, concentrations were very low, 6.5ng/m^3 for Al, 13.4ng/m^3 for Si and 3.5ng/m^3 for Fe on an average. It is considered that these values are the background concentrations of soil derived elements in the marine atmosphere. The main sources of S and Cl in the marine atmosphere are sea salt. Therefore, a strong correlation between concentrations of S and Cl was observed over the Indian Ocean and the Antarctic Ocean. However, over the western Pacific Ocean between Tokyo and Fremantle, a correlation between concentrations of S and Cl was not observed. The concentration of S was highly correlated with that of soil derived elements. The western Pacific Ocean was not far from land including the Asian Continent and Southeast Asia. It is considered that S originated from oil burning in Asia with soil particles. Thus, the marine atmosphere over the western Pacific Ocean is influenced by anthropogenic sources on land