Methanesulfonic Acid and Non-Sea-Salt Sulfate over Both Hemispheric Oceans

[摘要] The collection of aerosol particles using an Andersen high-volume air sampler was carried out during the austral summer, between 15 November 1986 and 13 March 1987, on board the icebreaker Shirase over the Indian and Antarctic oceans. Data sampling was also made during the cruise of the Hakuho Maru from 3 June to 1 August 1986, over the northern Pacific Ocean. The collected samples were analyzed by ion-chromatography to examine the mass concentrations of methanesulfonic acid (CH3SO3H or MSA) and non-sea-salt sulfate (nss-SO2-4) within the aerosols. Methanesulfonate (CH3SO-3 ), anion component of MSA, was detected in the fine aerosol particles less than 1.1μm in diameter. In general, the CH3SO-3 concentrations increased with decreasing air temperature, whilenss-SO2-4 concentrations showed an opposite tendency. The highest concentrations of CH3SO-3 and nss-SO2-4 were found to be 0.067μgm-3 and 0.77μgm-3, respectively, near 40°S where wind speeds were relatively strong. The results demonstrate first that, at higher latitudes, low air temperatures accelerate MSA production while the lower concentration of oxidants, such as H2O2 and OH, retards nss-SO2-4 production from MSA and SO2. Second, strong wind contributes to the increase of the flux of dimethylsulfide ((CH3)2S or DMS) from the ocean to the atmosphere.

[学科分类] 大气科学