Variation of Atmospheric Environment as Indicated by Mizuho 700m Core

1)瑞穗高原飘雪和落雪样品采集。-----在近一个月的时间里，从近海岸到内陆600Km的范围内，在瑞穗高原上采集了300多个飘雪和坑雪样本，用于表征瑞穗700m岩心拍摄地点随降雪而沉积的化学成分。在Syowa站进行了全年的大气气溶胶采样，并在3个内陆地点进行了大小分级气溶胶采样。2)瑞穗高原化学成分沉积机理基础研究。-----在近海岸的Syowa站，大气气溶胶中SO_4、甲烷磺酸和Cl/Na比值呈现明显的季节变化，控制了海盐组分向内陆输送通量的变化。漂移雪的化学成分显示，海盐成分到达内陆约300公里，但没有到达瑞穗站。坑雪的年沉降通量和化学成分浓度的年变率均大于0。在此基础上，得出了在内陆地区存在除海盐以外的其他化学成分供应途径的结论。3) Mizuho 700m岩心-----Cl/Na比值显示大气环境变化，岩心上部为正常海盐值，下部为高海盐值，低于500m，对应5000 ~ 9500 YBP。这表明大气环流发生了变化。甲酸浓度在上部呈较高的变化值，随着深度的增加而降低，在300 ~ 600m深度处达到较低的恒定值。这表明，在过去的2000年里，大气中的甲酸浓度显著增加，这似乎是由于森林和化石燃料燃烧的增加。甲烷磺酸和有机金属化合物可以在岩心中富集，但它们的分布复杂，表明它们依赖于复杂的机制。少

1) Collection of drifting and fallen snow samples in Mizuho Plateau. -----More than 300 samples of drifting snow and pit snow were collected over Mizuho Plateau, within nearly a month, and in the area from near sea coast to 600Km inland, for characterization of sedimentation of chemical components accompanied with snow fall at the location where the Mizuho 700m Core was taken. Year-round sampling of atmospheric aerosols at Syowa Station and size-fractionated aerosol sampling at 3 inland locations were also carried out.2) Fundamental studies on sedimentation mechanisms of chemical components on Mizuho Plateau. -----At Syowa Station near sea coast, SO_4, methanesulfonic acid and Cl/Na ratio in atmospheric aerosols showed apparent seasonal variation, which controls that of transportation flux of sea-salt components for inland. Chemical composition of drifting snow revealed that sea-salt components reaches some 300Km inland but not to Mizuho Station. The results on pit snow showed annual s … More edimentation flux and also annual variability of chemical component concentrations. Basing upon these results, in the inland area, the presence of the other supply path of chemical components other than sea-salt was concluded.3) Variation of atmospheric environment as indicated by Mizuho 700m Core-----Cl/Na ratio shows the normal sea-salt value in the upper part of the core and changes to high value at the lower part than 500m which corresponds to 5000-9500 YBP. This suggests the occurrence of change in atmospheric circulation. The formic acid concentration shows high and variable value in the upper part, decreases with depth and reaches to low and constant value in 300-600m depth. This suggests the marked increase in formic acid concentration in the atmosphere within the past 2000 years and it seems due to increased burning of forest and fossil fuels. Methanesulfonic acid and organic metal compounds can be fond in the core but their distributions are complex and suggest that they depend upon complex mechanisms. Less