河北沧州东北部南大港湿地晩全新世环境演变特征  

LATE HOLECENE ENVIRONMENTAL EVOLUTION CHARACTERISTICS OF THE NANDAGANG WETLAND IN NORTHEAST OF CANGZHOU,HEBEI PROVINCE

作　　者：赵永杰 由翰飞[1,2] 张振 杨光 李月丛 ZHAO Yongjie;YOU Hanfei;ZHANG Zhen;YANG Guang;LI Yuecong(College of Geographical Sciences,Hebei Normal University,Shijiazhuang 050024,Hebei;Hebei Key Laboratory of Environmental Change and Ecological Construction,Hebei Normal University,Shijiazhuang 050024,Hebei;College of Huihua,Hebei Normal University,Shijiazhuang 050091,Hebei;College of Earth Sciences,Hebei GEO University,Shijiazhuang 050031,Hebei;No.1 Brigade of Guangdong Geology Bureau,Zhuhai 519000,Guangdong)

机构地区：[1]河北师范大学地理科学学院,河北石家庄050024 [2]河北省环境演变与生态建设重点实验室,河北石家庄050024 [3]河北师范大学汇华学院,河北石家庄050091 [4]河北地质大学地球科学学院,河北石家庄050031 [5]广东省地质局第一地质大队,广东珠海519000

出　　处：《第四纪研究》2024年第3期755-769,共15页Quaternary Sciences

基　　金：国家自然科学基金区域创新发展联合基金项目(批准号:U20A20116);国家自然科学基金项目(批准号:41877433和42377439);中国地质科学院水文地质环境地质研究所联合开放基金项目(批准号:SK202105KF01);河北师范大学汇华学院科学研究项目(批准号:20220401)共同资助。

摘　　要：滨海湿地是全球变化背景下受到严重威胁的生态脆弱带和环境变化敏感区。揭示滨海湿地在长期气候变化和人类活动影响下的演变规律,有助于确定生态系统失衡的阈值,实现对滨海湿地的保护和可持续利用。本研究在8个AMS 14C测年数据基础上,基于孢粉、藻类、粒度、地球化学元素以及氧同位素等代用指标的变化,揭示了河北省沧州市东北部南大港湿地(剖面0~4 m)近4000年以来的环境演变过程及其驱动因素。结果表明:1)南大港湿地在3850~3570 cal.a B.P.期间,端元组分以EM3(海洋沉积)为主,沟鞭藻浓度较高,Cl元素含量和Sr/Ca值为研究段最高,Ti和K元素含量较低,说明沉积环境主要受到海洋影响,为开阔的浅海环境;3570~3450 cal.a B.P.期间,端元组分变为以EM1(河流沉积)为主,沟鞭藻浓度减少,Cl元素含量和Sr/Ca比值降低,Ti和K元素含量增加,陆源沉积物汇集明显,海洋影响减弱,此阶段应为潟湖环境;3450 cal.a B.P.以来,端元组分EM1(河流沉积)减少,EM2(风成或近源沉积)组分增加,沟鞭藻浓度明显减少,表明潟湖消亡,滨海湿地形成。2)南大港湿地岩芯钻孔孢粉组合特征显示3500 cal.a B.P.前后差异显著,3500 cal.a B.P.前孢粉组合以松属和栎属等木本植物为主,区域内木本植物盖度较大;而在3500 cal.a B.P.之后,孢粉组合中木本花粉含量明显减少,近源的草本花粉占据主导,包括藜科和禾本科这些典型的湿地草本植物大量增加,喜干旱环境的蒿属植物增加,指示森林植被占比下降,草地植被占比升高。3)约3500 cal.a B.P.之后木本花粉的减少及草本花粉的增加主要与3500 cal.a B.P.弱季风事件有关,该时期全球太阳辐射量降低,东亚夏季风减弱,气候向冷干化发展,使得渤海湾西部地区植被盖度下降,水土流失加剧,河流输沙能力增强并在海岸处大量沉积,相对海平面下降,南大港湿地形成。Coastal wetland is an ecological fragile zone sensitive to environmental change under the background of global change.Revealing the evolution law of coastal wetlands under the influence of long-term climate change and human activities is helpful to determine the threshold of ecosystem imbalance and realize the protection and sustainable utilization of coastal wetlands.Based on the proxy changes of pollen,algae,grain size,geochemical elements and oxygen isotopes,this study employed 8 AMS 14C dating data and revealed the environmental evolution of the Nandagang wetland in northeast of Cangzhou,Hebei Province during the past 4000 years and its driving factors.The samples were taken from the 400~64 cm depth(3850~0 cal.a B.P.)of the NDG core(38°32'18.6″N,117°27'10.9″E)with a total length of 39 m,which was located in the northeastern part of Cangzhou City on the western side of Bohai Bay.This composite coastal wetland is a land-sea junction zone formed by marine encroachment and fluvial siltation.The lithology consists mainly of clayey silt with minor amounts of clay and sand.The results showed that:(1)During the period of 3850~3570 cal.a B.P.in Nandagang wetland,EM3(Marine deposition)was the main end member,dinoflagellates concentration was high,the contents of Cl and Sr/Ca were the highest in the study section,and the contents of Ti and K were low,indicating that the sedimentary environment was mainly influenced by the ocean and was an open shallow sea environment.During the period from 3570 cal.a B.P.to 3450 cal.a B.P.,the end member became EM1(river deposition),dinoflagellates concentration was decreased,the content of Cl and Sr/Ca was decreased,the content of Ti and K was increased,and the terrigenous sediment obviously ascended,and the Marine influence was weakened.This stage should be a lagoon environment.Since 3450 cal.a B.P.,the end member of EM1(fluvial sediment)decreased,EM2(aeolian or proximate sediment)increased,and the concentration of dinoflagellates decreased significantly,indicating the demise of

关 键 词：晩全新世 南大港湿地 沉积环境 花粉组合 3500 cal.a B.P.弱季风事件 

分 类 号：P534.632[天文地球—第四纪地质学] Q944.571[天文地球—古生物学与地层学] P941.78[天文地球—地质学]