龙感湖钻孔揭示的末次盛冰期以来的环境演化

通过龙感湖滩地钻孔24．4m深度以内的沉积物岩性、生物和物理指标分析，在^14C年代测定的基础上，对龙感湖末次盛冰期以来的环境演化进行了恢复，15．0kaBP前和10．0－6．3kaBP，龙感湖区发育河流沉积，以低生物量和高磁化率为特征；约15．0－10．0kaBP期间的晚冰期，龙感湖首次成湖，湖泊中生物量明显提高；现代龙感湖雏形始于约6．3kaBP后，至3．7kaBP后发展为稳定的湖泊环境，此外，花粉结果显示，龙感湖湿地相干被大致形成于3．3kaBP后，然后，龙感湖的成因和演化，及其与长江关系的研究，还必须重视对沉各物物源的追踪。

Environmental Changes Revealed by Lacustrine Sediment from Longgan Lake since Last Glacial Maximum

Longgan Lake is located in the lower reaches of the Yangtze River. Based on the sediment pigments, total organic carbon, pollen, grains and susceptibilities, combining with 14 C dating, the environmental evolutions were reconstructed since the Last Glacial Maximum. Before 15.0kaBP and during 10.0-6.3kaBP,the Longgan Lake was characterized by river deposition with lower productivity and higher susceptibility. During 15.0-10.0kaBP,Longgan Lake was formed initiated, as documented by obvious increase of organic production. The rudiment of the lake started from 6.3 kaBP, followed by the stable lake condition after 3.7kaBP. The wetland vegetation was extablished around the lake area after 3 3kaBP. It is necessary, however, to track the changes of sediment source, in order to study the mechanism of lake formation and evolution in Longgan lake,as well as the relationship between the lake and Yangtze River.