现代尘暴和非尘暴天气大气花粉特征及其环境意义--以北京地区为例

通过2001²003年取得的尘暴和非尘暴天气大气花粉的对比研究,发现两类天气条件下大气花粉组合虽都以北京地区木本植物花粉为主,但尘暴天气样品中草本植物花粉数量有较多增加。根据尘暴活动和北京地区物候分析,推测这些草本植物花粉来自尘暴源区和路径区的表土沉积。基于上述认识,进一步对风成黄土古土壤层的花粉进行探讨,认为古土壤中草本植物花粉和木本植物花粉是同期沉积的,其木本植物花粉数量比较少可能是尘暴降尘导致草本植物花粉数增多所致。通过现代尘暴、非尘暴天气大气花粉特征的研究,对正确认识过去风成黄土和古土壤层中以草本植物花粉为主的孢粉组合特征提出了新的思路。

Air pollen assemblage characteristics derived from duststorms and non-duststorms and its significance

Pollen assemblage characteristics which have been used to reconstruct paleoenvironment are taken as an important agent based on modern climate conditions for plants growth.It is particularly so in the loess research.Nevertheless,there are still some problems in deducing paleoclimate by the pollen assemblage discovered in paleosols,which were supposed to have developed under relatively warm and wet climate conditions,thus containing more pollens of trees than of herbs,but it is reverse actually.The best way to probe into such a question period is to observe the process of pedogenesis which was presumed to happen in the interglacial period with the similar climate conditions of today.What happened on the soil surface today might be the same as that in the interglacial period.Therefore this research takes air pollen samples in Beijing under different weather conditions of duststorms and non-duststorms in spring to discuss the pollen assemblage characteristics.The results show that both samples derived from duststorms and non-duststorms contain pollens of trees and herbs,in the majority of trees,representing modern sedimentary environment.Samples of duststorms contain more herbs pollens than samples of non-duststorms,which is argued by the authors to be transported from the source and pathway of storms.Further on,based on the analyses of the amount of dustfall annually,this paper concludes that more pollens of herbs have been transported and deposited under duststorm weather conditions than pollens of trees under non-duststorm weather conditions,which possibly is partial reason for the presence of pollens assemblage in paleosols.Though limit to the samples number this paper's view needs more proof,a new thoughtway on pollen research of eolian sediments still has been put forward.