洛川黄土微米级至纳米级物质颗粒度分布规律

PARTICLE SIZE DISTRIBUTION OF MICROMETER-NANOMETER LOESS MATERIAL IN LUOCHUAN SECTION, CHINA

以洛川黄土剖面为对象，应用碎形模式和分形理论进行颗粒分布特征研究，获得了Ｓ层位古土壤微米级至纳米级粒子数、单位表面积、质量、表面积、粒子数积分量等与粒径关系的一组关系曲线。Ｓ０、Ｌ１ＬＬ１、Ｌ１ＬＬ２、Ｓ１、Ｌ２等层位全岩样品比表面积研究结果表明：各层位全岩样品颗粒比表面积由小到大的递变次序与样品层位所反映的气候由冷至暖的递变次序恰好一致。呈现了一种新的可能的古气候、古环境变化的替代性指标。Ｓ１层位古土壤面分维数为２．３８；Ｌ２层位黄土面分维数为２．３２。亚微米级至纳米级颗粒具有明显巨大比表面积，在现代环境自净研究中可能有着重要的应用前景。

Fractal theory has been used to study the characteristics of loess particle size distribution in the Luochuan section. A series of curves for the μm-nm range particles of paleosol S1 have been obtained. They include the number density, and specific surface area of particles, and their cumulation distribution as a function of particle radius. The specific surface area of bulk samples tends to increase gradually as the stratigraphic change in the order of L1LL1→L2→L1LL2→S0→S1, which indicates climatic change from dry-cold to wet-warm. This could be a kind of new proxy for palaeoclimatic and palaeoenvironmental change. The surface fractal dimension Ds are 2.38 for the S1 palaeosol and 2.32 for the L2 loess. The μm-nm range particles have very huge specific surface area and may be expected to have important application in studying modern environmental self-purification.