台湾大鬼湖沉积物元素分布所反映的古环境意义

位于台湾省南部的大鬼湖，由于湖底常缺氧等特殊自然条件，使湖底沉积物免遭干扰，而能完整地记录过去气候的环境的变动．其岩芯中出现的白层，有明显较低的有机质含量和C／P、N／P、S／P及Si／Al比值．与较高的Si／P、Fe／C、Mn／C、Fe／Mn和Mg／Al比值，显示当时气候可能较干冷，集水区植生较差、湖水位较低，而且环境较氧化．相比之下，富含有机质的黑色沉积物，则反映气候较暖湿、湖水面至少升高2m，而且集水区土壤和水体较还原。

Pal eoenvironm ental Records From the Elem ental Distributions in the Sediments of Great Ghost Lake in Taiwan. China

The sediments deposited in the anoxic Great Ghost Lake in southern Taiwan, China were undisturbed due to the lake's unique hydrological and geographic conditions. As a result,past climatic and environmental records were well preserved. The distinctive white laminations appeared in the generally black sediments are characteristic of lower organic-matter content, and lower C/P, N/P, S/P and Si/Al ratios, but higher Si/P, Fe/C, Mn/C, Fe/Mn and Mg/Al ratios.These indicate times of cooler/driver climate, poorer plant growth around the drainage area, lower water-level and more oxidized conditions in the soil and in the water column. On the other hand, the organic-matter-rich black sediments were deposited in a warmer/wetter climate under a more reduced condition. In addition, the variations in the Mg/Al rations seem to reflect at least 12% changes in salinity or water volume, or 2m changes in the water level.