古气候替代性指标的研究现状及应用

古气候变化以不同的形式记录下来,通过提取替代性指标可以恢复其演化过程,这种气候变化的过程和驱动机制的研究是预测未来气候变化的基础。不同气候载体的替代性指标不同,基于不同指标对气候变化的响应机理,按气候信息载体的类型、指标适用范围、实验测定的可行性、气候解释的惟一性以及目前研究的完善程度,将气候载体的替代性指标划分为3个等级;此外,对两极地区、青藏高原地区、暖池区、季风区等气候敏感区的气候载体的选择提出建议,并在替代性指标划分基础上,从单一气候要素解释的角度出发构建了气候信息载体的替代性指标体系;分级替代性指标及气候载体替代性指标体系可以为今后古气候研究提供良好的依据。同时,选取气候信息载体的典型性指标进行对比,总结了载体记录气候变化信息的灵敏度、载体响应气候变化的分辨率以及影响载体记录气候信息变化的因素。     

山东半岛近岸海区全新世泥质沉积体研究现状

20世纪80年代以来,山东半岛近岸海区全新世泥质沉积体引起了地学界的关注,很多学者对其进行过研究并发表了众多相关论文。综合前人的研究成果认为,山东半岛全新世泥质沉积体受到黄海暖流和黄海沿岸流的共同作用,呈现出中间厚、向海向陆减薄的楔形,并沿山东半岛发育,其物质来源主要是黄河注入所带来的沉积物;在形成机制上,受到海平面上升、潮流和黄河入海口的迁移等多种因素的控制,成因复杂;在形成时间上,现今的研究成果普遍认为该泥楔形成于全新世冰后期海平面上升时期。对目前研究中仍存在的问题进行讨论,提出了山东泥楔的未来研究方向,指出应该建立多种水动力耦合作用下的泥沙输运与沉积模式,着重从海洋沉积动力学角度进行新的研究。     

Sediment records of environmental changes in the south end of the Zhejiang-Fujian coastal mud area during the past 100 years

Previous studies carried out in the East China Sea （ECS） mud area focused on long-term environmental changes in sedimentary records during the Holoeene, especially during the mid-Holocene high-stand water levels period. These results indicate that sensitive grain size groups can be used as a sedimentary proxy to reconstruct the evolution of the East Asian Winter Monsoon （EAWM）. The studies have been carried out mainly in the northern and middle portions of the Zhejiang-Fujian coastal mud, however, similar research in the southern portion and the comparison between sedimentary proxy and modern measured data of EAWM are lacking. In this paper, we focused on a sedimentary record of the past 100 years with an enhanced resolution of 1.8 years. Investigations of the southern end of the Zhejiang-Fujian coastal mud area were conducted on the basis of 21~Pb chronology, grain-size analysis and chemical element analysis. The correspondence between the mean grain size （Mz） of sediment sensitive grain size and the measured EAWM was confirmed for the first time. We found that during the recent 100 years, the variation of the mean grain size of the sensitive population in the southern portion of the Zhejiang-Fujian mud was mainly controlled by the EAWM intensity changes; and not directly related to changes in the sediment discharge from Datong station of the Changjiang River （DTSD）. Finally, recent changes in the content of heavy metals in study area reflect the impact of human activities on the environment.     

Source Evolution and Its Relationship to Climate Change Since the Middle–Late Pleistocene in Laizhou Bay,China

Through the geochemical analysis of two hundred-meters cores KD4 and ZK3 from Laizhou Bay,in this study,we determined the distribution law and controlling factors of the geochemical elements.We analyzed 24 elements with respect to their R factors and major principal components,which were combined with the source discrimination functions DFCr/Th and DFCa/Al to obtain the sediment source index and its variation with depth for this area.A comparison of the changes in climate indicators suggests a clear correlation between the source and climate changes.The results show that the Yellow River and surrounding short-term rivers are the main sediment sources in this area.The PC3 of the KD4 core and PC2 of the ZK3 core(e.g.,CaO,MnO,SiO2)exhibit significant variations and reflect the relative contributions of Yellow River sources.The deposition process can be divided into six stages:in Phase I(MIS 5c–MIS 5a),the Yellow River formed,and the composition of the Yellow River had a greater influence on the sedimentary composition of the study area.In Phase II(MIS 5a–MIS 3),the sediment sources of the Yellow River and the short-term streams in this area were wavering,with the sediments derived from short-term rivers playing a more important role.In Phase III(MIS 3),with a sharp drop in temperature,the study area was in the process of retreat,and the sediment source changed from the Yellow River to short-term rivers,after which the Yellow River source material remained the main sediment source for the region.A similar process occurred three more times in Phase IV(MIS 3–MIS 2),Phase V(MIS 2–MIS 1),and Phase VI(MIS 1).With changes in climate,especially during alternating sea-land phases,the sediment source varied in marine-terrestrial-marine phases,and the changes are observed as Yellow River source-surrounding provenance-Yellow River source.However,this process of change is not synchronized with the sea-land strata alternation.     

埕岛海域海底冲淤的初步数值研究

从沉积动力学的角度,在分析实测和历史资料的基础上,首先总结出埕岛海域的海底冲淤变化规律,尔后通过潮流场的模拟,数值求解输沙方程,以研究埕岛海域的海底冲淤.初步探讨运用数值模拟手段来研究海底冲淤变化.     

利用TM合成图像研究滨海平原城市东营市的时空扩展

利用遥感 (RS)与地理信息系统 (GIS)一体化技术 ,对黄河三角洲上的新兴城市——东营市的城市时空扩展进行动态监测。并在地物光谱研究的基础上 ,提出了适合于近海平原地区的遥感波段组合 (TM- R5 G3B1)和本区内最易于识别城镇、居民地的波段组合 TM- R5 G7B4 (7月 )、TM-R3G4 B2 (10月 )和 TM- R5 G2 B4 (5月 )。结果表明 ,东营市自 1983年建市以来 ,迅速向东发展 ,由一块城区扩展为东城、西城并立。国家的政策和规划、石油工业的发展是东营城区迅速扩展的驱动力。     

三维多组分泥沙数值模型在胶州湾的应用

基于环境流体动力学模型(Environmental Fluid Dynamics Computer Code EFDC)水动力和泥沙模块,把底床泥沙分为1个黏性组分和4个非黏性组分,建立起一个多组分泥沙三维胶州湾数学模型。模型很好地反演了胶州湾三维水动力场和悬沙浓度场。结果表明,在潮流作用下,胶州湾水体中悬沙浓度较小,以黏性组分(<0.063 mm)为主。悬浮起来的黏性组分泥沙随着潮流的涨落,在湾内外作长距离往复运动。可悬浮的非黏性泥沙(0.063~0.25 mm)基本上集中在湾外水体底层,表现为局部悬移,就近落淤。胶州湾总体上冲淤变化幅度较小。内湾以冲刷为主,局部淤积;外湾基本上呈淤积状态;湾外冲淤形式较为复杂。     

山东半岛沿岸流强度与悬浮体时空变化特征

基于2014—2018年NOAA/AVHRR遥感数据,在山东半岛海域选取6条剖面,结合海表温度和表层悬浮体的时空变化特征,详细研究了山东半岛沿岸流的年周期变化规律与移动路径。研究结果表明,山东半岛沿岸流年周期变化可分为4个阶段：成长期（10—12月）时开始形成于黄河口附近,沿莱州湾南部向东运移;强盛期（次年1—3月）时山东半岛沿岸流完全成型,扩散带最宽,鼎盛时期北部可以至38°N附近,东部可以至123°E附近,在35°～36°N附近分成NE—SW向的2个分支,主干部分最远可到达胶州湾东部海域,余流沿岸向西南方向转折;衰退期（4—6月）时沿岸流强度减弱,只在山东半岛北部和东部小范围内有微弱的显示;消亡期（7—9月）时基本消失。山东半岛沿岸流在冬季时对悬浮体扩散具有强烈的驱动作用,使其在黄河口南侧与山东半岛北岸-成山头东部海域分别形成呈“弧形”和“条带状”分布的2个高浓度区域。     

南海南部北康盆地中新世碳酸盐台地地震响应及分布特征

以大量高精度2D地震资料分析为基础,对北康盆地碳酸盐台地地震反射特征、演化期次及分布特征开展了系统研究。北康盆地碳酸盐台地自早中新世开始发育,中中新世广泛分布,而从晚中新世开始衰退淹没。中新世碳酸盐台地多为孤立台地,台地边缘常发育断层,台地顶部在地震剖面上多呈现为两条平行和亚平行强反射轴,内部呈杂乱和亚平行空白及弱反射轴,底部则多为一条光滑的平行和亚平行弱反射轴。北康盆地中新世碳酸盐台地发育可以划分为3个期次,第1期台地发育范围大且厚度较薄;第2期台地范围缩小,受到断层控制明显;第3期台地范围进一步缩小直至被淹没。北康盆地中新世碳酸盐台地主要为北东向和北西向,这与周边盆地和现今碳酸盐台地走向一致,其平面分布受到构造隆起和断裂的控制。     

Relocation of the Yellow River as revealed by sedimentary isotopic and elemental signals in the East China Sea

The Yellow River (YR) supplies a large amount of nutrients and fresh water to the northern Chinese marginal seas, and greatly influences the ecosystem and current patterns. The relocation of the YR outlet from the southern Yellow Sea (YS) to the Bohai Sea in 1855 was demonstrated using northern East China Sea (ECS) sediment characteristics. Both isotopic (δ¹³C, δ¹⁵N) signals and C/N ratios in the organic matter (OM) indicate that prior to 1750, the predominant source of OM to the sediments was terrestrial. The terrestrial influences continuously weakened until 1855, when the YR estuary moved; after 1855, the OM was characterized by oceanic sources. Major elements (Al, Ti, Fe, Mn) and trace elements (Ni, Cr, Cu, Pb) had a much closer association with Malan loess prior to 1855, as >90% of the YR sediment was loess-derived. These results reveal that the relocation of the YR induced significant changes in the current patterns of the northern China Seas in the last 250 years; however, more studies are needed to further examine these linkages.