The History Of Asian Summer Monsoon In Holocene Recorded By Diatom From Wusulangzi Lake In Aershan

Asian summer monsoon profoundly affect the ecological environment and the economic development in the largest population and the most economically developed areas of China.Therefore,research on Asian summer monsoon chang history has the very vital significant.In recent years,the academia has carried out a number of studies about the Holocene Asian summer monsoon,and put forward Asian summer monsoon mainly have three kinds of changes during the holocene:(1)Asian summer monsoon intensity gradually increased since the holocene to 9.0 Ka B.P.,In 9.0-7.0Ka B.P.,it is strongest,since 7.0 Ka B.P.it begin to decay;(2)Asian summer monsoon intensity gradually increased since the holocene to 7.8 Ka B.P.,and is strongest between 7.8 Ka B.P.to 5.3 Ka B.P.,and then gradually weakened since 5.3Ka B.P.;(3)Asian summer monsoon intensity enhancement since the early holocene continuous to 4 Ka B.P.,and then begin to decay.This article intend to study from the perspective of the diatom,using the diatom assemblage,as well as the ratio values change of planktonic diatom and benthic diatom(P/B),to research the holocene Asian summer monsoon change history.The study area,Wusulangzi Lake,is located in Aershan City in Xingan League,the Nei Monggol Autonomous Region.Diatom in the drilling core of Wusulangzi lake was carried out the processing work,appraisal work,statistical work and analysis work,and establish the relationship between diatom-water-the summer wind,then have the following research results and conclusions.1?37 genes and 186 species are recognized(including varieties and undefined species).The major planktonic species include: Aulacoseira ambigua,Aulacoseira granulata,Fragilaria berolinensis,Stephanodiscus hantzschii and so on.The major benthic species include: Fragilaria oldenburgiana,Punctastriata pinnata(ellipse),Staurosira construens f.venter,Staurosirella pinnata and so on.According to the percentage of major taxa diatom,we divides into two diatom zone???,the zone?is subdivided into three subzone ?-A??-B??-C.2?The Wusulangzi lake has experienced the change history that include the period of high water level?the high water level toward to the gradually decreased water level?the low water level and the higher water level in small increments in turn baseing on the diatom P/B value curve and diatom assemblage.3?According to the relationship between diatom-water-the summer wind,we consider the summer monsoon at Wusulangzi lake has experienced the change history what include the period of summer monsoon intensity gradually strengthened,strong summer monsoon period,the period of summer monsoon intensity gradually weakened,weak summer monsoon period and summer monsoon intensity increases period in turn.4?The change history during the holocene of the Asian summer monsoon base on the diatom in Wusulangzi lake and stalagmite in Dongge Cave,respectively,although there are some differences in some period,have the same trend on the general?...