新疆罗布泊45 ka BP以来沉积物粒度敏感组分记录的区域沙尘活动历史

采用粒级标准偏差法对新疆罗布泊新湖湖心区KY01孔0～8 m沉积物提取了对环境变化敏感的两个粒级组分：3.5～6.2 μm(组分1)、20.7～63.4 μm(组分2)和一个相对不敏感组分：8.9～14.3 μm(组分3)。结合湖泊沉积物粒度一般分布规律、黄土和现代降尘等大气悬浮颗粒物沉降特点,推测3个粒度组分分别指示钻孔所在位置与湖心的相对距离、区域沙尘活动强度和非沙尘活动的粉尘输入强度。根据粒级敏感组分2和AMS14C测年数据重建了该区近4.5万年以来的沙尘活动历史。在过去的4.5万年,罗布泊地区沙尘活动增强主要出现在44.7～44.5、44.2～44.0、41.4～38.8、38.4～37.4、36.4～36.1、34.8～34.5、33.5～32.9、32.5～32.2、31.9～31.5、29.9～29.5、25.6～12.3和8.9～7.8 cal ka BP期间,这些时间段多数对应于以格陵兰NGRIP冰心δ18O记录所代表的北半球气候变化冷阶段或冷事件,说明该区沙尘活动的强弱与全球降温事件所引发的冷干气候密切相关。     

新疆巴里坤湖粒度组分分解及其环境指示意义

选择位于西风影响区的天山东段巴里坤湖湖泊岩芯样品,对沉积物粒度组分进行经验正交函数(EOF)分解,并探讨各分量的环境意义.结果显示,EOF1组分与沉积物粒度小于2μm组分相关系数达0.64以上,并与代表区域有效湿度的碳酸盐氧同位素指标有很好的对应关系,故将EOF1解译为区域有效湿度的替代指标.EOF2组分与粒级为45-...     

新疆巴里坤湖全新世环境记录及区域对比研究

选择位于西风环流显著影响区的巴里坤湖作为研究对象,采用14C测年建立了巴里坤湖沉积剖面约9400cal.aB.P.以来的时间序列。对该湖泊剖面沉积物的矿物X射线衍射、自生碳酸盐稳定同位素、碳酸盐含量和粒度指标的综合分析表明,9400cal.aB.P.以来,巴里坤湖地区的气候环境变化大致经历了冷干（9400～7400cal.aB.P.）-暖湿（7400～5900cal.aB.P.）-暖干（5900～3100cal.aB.P.）-凉湿（3100～1100cal.aB.P.）-冷干（1100～500cal.aB.P.）-暖干（500cal.aB.P.以来）的气候变化过程,该过程基本上同周边区域的气候环境变化记录相一致。在3800cal.aB.P.左右,北疆地区的几个典型湖泊沉积记录序列都指示该时期气候环境发生了较为明显的转折,可能暗示了这一时期亚洲中部干旱区（至少在北疆地区）大气环流状况发生了重大调整。     

济州岛西南泥质区粒度组分变化的古环境应用

利用激光粒度仪对位于东海陆架济州岛西南泥质区的B2孔进行了沉积物粒度分析,根据标准偏差变化检出了B2孔含有4个粒度组分：〉65．6、65．6～10．5、10．5～1．3和〈1．3μm,其中〉65．6μm粗组分含量很低,主要是以底栖有孔虫为主的生源沉积．各组分平均粒径和粒度含量随孔深的变化显示了65．6～10．5μm组分在B2孔含量较高（21％～30％）,变化最明显,是该孔对环境变化最敏感的粒度组分．研究表明该敏感组分的粒度含量和平均粒径变化主要受东亚冬季风的强弱变化制约,其变化恢复的近2ka来东亚冬季风变化和中国东部气候变化序列具有很好的一致性,证明65．6～10．5μm粒度组分可以作为东亚冬季风的替代指标．     

新疆乌伦古湖沉积物粒度特征揭示的环境信息

在放射性同位素210Pb、137Cs定年的基础上,通过对沉积物粒度参数的分析,探讨了近200年来乌伦古湖沉积物粒度敏感组分特征及其环境意义。研究表明,乌伦古湖WL孔沉积物以黏土和细粉砂为主,但在1970 AD前后,粒度参数发生了突变,其中>16 μm组分所占含量迅速升高,在约1830~1842 AD及1910 AD前后这两个时期,沉积物的粒度参数也有较显著的变化。对沉积物粒度频率分布曲线的分析表明,在对应时期内,沉积物的搬运介质或搬运动力发生了变化。基于此,首先通过粒径-标准偏差方法提取了粒度中的敏感组分C2（7~25 μm）,进而通过粒度敏感组分与器测气象数据的相关性分析,明确了组分C2含量的环境指示意义。结果表明,组分C2含量的大小与研究区冬、春季温度和冬季降水量大小有关,反映了积雪融水入湖的强度。在约1830~1842 AD、1910 AD前后,组分C2含量偏高,反映入湖水量较大、湖泊水位较高。而20世纪60年代到70年代,沉积物粒度参数的显著变化与流域人类活动的影响有关。     

南岭东部定南大湖沉积物粒度敏感组分及末次冰消期环境记录

为进一步探究定南大湖湖沼晚冰期以来的水文特征及气候变化,对研究区K02钻孔的粒度特征进行了详细的分析,采用粒级-标准偏差法和主成分分析法对348个沉积样品提取了对环境变化比较敏感的三个粒级组分:0.6~7.1 μm（组分1）,20~44.8 μm（组分2）和89.3~447.7 μm（组分3）。结合湖泊沉积物粒度一般分布规律,并根据敏感组分2和14C测年数据探讨了该区域近16 ka B.P.以来的气候变化。结果表明在过去的16 000年里,大湖地区的水文及气候变化可以分为4个阶段:1）在16.0~11.5 ka B.P.期间,气候总体偏冷干,敏感组分含量增降比较明显,能较好的对应老、中、新仙女木事件和B/A暖期;2）11.5~6.0 ka B.P.期间,大湖地区进入了湿润的全新世适宜期,敏感组分总体含量偏低;3）6.0~3.8 ka B.P.期间,敏感粒度组分含量迅速升高且波动较大,大湖湖沼地区进入一个相对干冷的时期;4）3.8 ka B.P.至今为第四阶段,敏感粒度组分含量总体偏低,考虑到人为干扰因素,暂不做详细讨论。通过对大湖地区水文状况的研究发现,大湖湖沼地区自晚冰期以来气候变化很不稳定。与格陵兰GISP 2冰芯、董哥洞D4石笋及其K02钻孔其他指标的记录对比可以发现,敏感组分2对仙女木、9.5 ka、8.2 ka等冷事件的记录更加明显,也说明了大湖地区的气候变化具有全球性,这种气候变化可能与太阳活动有关。     

新疆柴窝堡湖沉积物中环境敏感粒度组分揭示的环境信息

通过对柴窝堡湖沉积物剖面和流域表层沉积物进行粒度分析,结合沉积剖面年代序列,研究了柴窝堡地区的环境演变与沙尘暴事件。首先通过主成分因子分析,对柴窝堡湖沉积物剖面粒度不同粒级组分含量进行了研究,探讨了湖泊沉积物的物质来源,获得了两个主控因子F1和F2,它们控制了湖泊沉积物近97.7%的粒度变化特征。研究表明,F2代表了以57 μm为众数粒径的次总体,主要来源于地表风沙侵蚀;而F1为以7 μm为众数粒径的次总体,主要受流水作用控制。进而通过粒径-标准偏差法,提取了湖泊沉积物中环境敏感粒度组分,风成组分C2（20~209 μm）反映了区域风沙活动的历史,并揭示了1910-1930年和1980-2000年为百年来的两个沙尘暴相对活动强烈的时期。沉积物中记录的1980年和2000年左右的沙尘事件与器测记录及历史文献记载具有很好的一致性。最后利用均值突变诊断分析,发现柴窝堡湖地区1910年前后存在近百年来最强的沙尘事件,揭示了近百年来该地区一次最强的环境突变事件。      

内蒙古中部达尔罕茂明安联合旗腾格尔诺尔湖泊 沉积物记录的全新世晚期环境演变

通过对内蒙古中部腾格尔诺尔湖泊沉积、粒度组成、孢粉组合等特征的综合分析,重建了该地区全新世晚期1700aBP以来的环境演变过程。结果表明,该地区1700aBP以来的气候环境变化可以分为4个阶段:1700～1170aBP,气候温暖较湿润;1170～840aBP,为温干气候期;840～200aBP,气候转为温暖湿润,间有短期的冷干波动;200aBP以来气候以温干为主,晚期气候有向凉干转变的趋势。     

内蒙古中部达尔罕茂明安联合旗腾格尔诺尔湖泊沉积物记录的全新世晚期环境演变

通过对内蒙古中部腾格尔诺尔湖泊沉积、粒度组成、孢粉组合等特征的综合分析,重建了该地区全新世晚期1700aBP以来的环境演变过程。结果表明,该地区1700aBP以来的气候环境变化可以分为4个阶段:1700～1170aBP,气候温暖较湿润;1170～840aBP,为温干气候期;840～200aBP,气候转为温暖湿润,间有短期的冷干波动;200aBP以来气候以温干为主,晚期气候有向凉干转变的趋势。     

湖泊沉积物中风成和水成组分定量判据的初步研究———以青海湖为例

对青海湖沉积物进行物质来源进行聚类分析, 并对周边风成黄土与现代湖泊表层沉积物进行粒度分析, 在此基础上, 以青海湖周边典型风成黄土作为风成组分端元, 以青海湖表层沉积物作为水成组分端元, 首次利用已知端元的粒度分布特征对青海湖沉积物中典型粒度分布进行拟合, 进而估算了其中风成和水成组分的比例。结果表明, 青海湖沉积物粒度分布特征可分为三大类:1.水成组分占主导; 2.风成组分占主导(风成黄土主导); 3.两者以不同比例混合。希望此方法能成为未来湖泊沉积物中不同组分的定量判据和古环境的解读提供新途径。      

新仙女木事件在罗布泊湖相沉积物中的记录

通过对罗布泊CK-2钻孔湖相沉积物磁化率、粒度、碳酸盐和有机质含量的测定以及地球化学元素的多元统计分析, 探讨了我国西北极端干旱区域的环境对全球气候变化的响应.结果显示各代用指标均一致揭示了发生在12.8~11.6kaBP间非常明显的低温期, 且降温幅度大, 变化迅速.这次冷事件在时间坐标以及发生特点上都与格陵兰冰心记录的末次冰消期中的新仙女木事件相对应, 为新仙女木事件的全球性特征提供了新的证据.这说明在我国新疆的极端干旱区, 其气候与环境的变化也与北半球高纬度地区有着密切的联系; 由主成分分析结果, 揭示了我国西北地区的西风气候区有别于东南季风气候区的水热配置特点, 即冷期湿润, 暖期干旱, 并提出了该事件信号从北大西洋传送到罗布泊地区的潜在机制.      

Contrasting impacts of the 8.2- and 4.2-ka abrupt climatic events on the regional vegetation of the Hulun Lake region in north-eastern China

Studies of the vegetation response to abrupt climatic events may provide valuable insights into assessing the impacts of such events under future global warming scenarios. Here we present a detailed record of regional vegetation change based on high-resolution pollen records for the intervals 9000–7000 and 5000–3000 cal a bp from the Hulun Lake region of north-eastern China. Our aims were to determine the regional expression of the 8.2- and 4.2-ka events in north-eastern China, especially their effects on vegetation composition. The results show that the response of the vegetation of the Hulun Lake region to the climatic cooling of the 8.2-ka event was relatively minor; however, the 4.2-ka event, which resulted in climatic aridification, resulted in pronounced vegetation degradation. We suggest that the specific characteristics of the 8.2- and 4.2-ka events, together with their duration and the regional climatic background on an orbital time scale, were the main factors responsible for the contrasting vegetation responses. The strengthening and northward shift of the Intertropical Convergence Zone (ITCZ) tended to offset the cooling effect of the 8.2-ka event on regional vegetation in the mid–high latitudes of East Asia; in contrast, the decrease in summer insolation in the Northern Hemisphere and the southward shift of the ITCZ may have intensified the drought effect of the 4.2-ka event in East Asia and the associated vegetation degradation. Under future global warming scenarios, both extreme cooling events and extreme drought events may cause a deterioration of the ecological environment; however, the resulting regional vegetation responses may be substantially different.     

沉积特征对低品位钾矿水溶开采的影响——以柴达木盆地马海盐湖北部矿段全新统为例

马海盐湖是柴达木盆地全新世形成的富低品位固体钾盐矿干盐湖,钾盐水溶开采潜力巨大。本文采用岩矿鉴定方法,对含盐系地层的沉积韵律岩性、钾盐矿物与矿层分布特征进行了研究,并分析了地层岩性的分布规律。结果表明,在马海盐湖北部矿区的主要沉积中心,沉积了一套以粘土-粉砂-石盐-粉砂石盐为主的沉积地层,同时在东南部形成了一个次级沉积中心;研究区钾盐矿物主要为杂卤石、光卤石、钾石盐等;沉积韵律分析结果显示,钾盐矿层多分布在Ⅳ₂韵律层顶部和Ⅳ₃-Ⅳ₄韵律层,产出形态在垂向上为层状、透镜状,平面上呈NE-SW向展布且连续性减弱;钾盐矿物和矿层分布与沉积演化关系密切,表明沉积特征对研究区钾盐矿水溶开采具有重要影响,为同类型低品位钾盐矿开采提供了一些参考。     

Magnetic signature of heavy metals pollution of sediments: case study from the East Lake in Wuhan,China

Detailed magnetic measurements and geochemical analyses were performed on 114 sediment samples collected from the East Lake, Wuhan city, China, to establish a possible link between the enhanced concentration of anthropogenic magnetic particles and heavy metals with known sources. Relatively higher magnetic susceptibility values (mass-specific, χ, >150 × 10⁻⁸ m³ kg⁻¹) were observed for samples near the pollution sources: e.g. the Wuhan Iron and Steel Company (WISC), the Qingshan Thermal Power Plant (QTPP), the banks (driveways) of the lake and near the sightseeing route of yachts on the lake. Moreover, χ is positively correlated to the concentration of Pb (correlation coefficient r = 0.682), but negatively or weakly correlated with both Zn and Cu. In contrast, anhysteretic remanent magnetization (ARM) is significantly correlated with these major heavy metals (r = 0.645 for Zn–ARM, 0.699 for Pb–ARM and 0.841 for Cu–ARM, respectively), which indicate that ARM serves a better indicator for the pollution of heavy metals in this lake. Thermomagnetic analysis combined with magnetic hysteresis measurements revealed that magnetites in the pseudo-single-domain/multidomain grain-size regions are dominant. Scanning electron microscopy and energy dispersive X-ray examinations of the magnetic extracts showed that these Fe-rich particles have different morphologies: orange-peel structure, hollow structure with adhered smaller particles, Zr-rich melted-like irregular particles, pear-shaped spherules and spherules with slick surfaces. These features are typical for particles produced by anthropogenic activities. Because of the genetic relationship between the environmental setting of the East Lake and the nearby pollution sources, this study suggests that in situ magnetic surveys are sensitive to evaluate the environmental pollution on the lake bottom.     

Phosphorus in suspended matter and sediments of a hypertrophic lake. A case study: Lake Dianchi,China

From June 2004 to December 2004, Lake Dianchi, which had large scale of cyanobacterial blooms was investigated in order to study P-fractionation in the suspended matter and the sediment. The investigation improves our understanding of phosphorus in Lake Dianchi and the relationship between phosphorus and cyanobacterial blooms. It contributes to the available literature on the behavior of P in hypertrophic lakes. The distribution of P-fractions in Lake Dianchi was not uniform from northwest to south, but was closely related to the trophic status of the whole lake. The concentrations of total phosphorus, labile P (NH₄Cl-P), Organic P (NaOH-NRP) and loss on ignition in suspended matter were positively correlated with the strength of cyanobacterial blooms. Total phosphorus in suspended matter was relatively stable for almost half an year and closely related to Chl. a concentration. The main content of organic phosphorus is in the cyanobacterial blooms. The concentrations of phosphorus bound to metal oxides and carbonates (NaOH-SRP and HCl-P) in sediment were similar to NaOH-SRP and HCl-P in the corresponding suspended matter. The latter two forms of P in suspended matter were not affected by cyanobacterial blooms, indicating that the inorganic phosphorus is derived from the sediment after resuspension from the sediment due to wind and wave action. The contribution of the different P-fractions to TP in sediment and in suspended matter indicates that NH₄Cl-P in the suspended matter is an important buffer for maintaining dissolved phosphorus in water.     

湖泊沉积物不同粒级组分的元素含量特征及其环境指示意义①——以内蒙古黄旗海为例

黄旗海湖泊柱状沉积物的全样、77~20 μm、<20 μm粒级的钛(Ti)、锰(Mn)、锶(Sr)、銣(Rb)、钡(Ba)、锆(Zr)等元素含量分析表明,元素在湖泊沉积物各粒级组分的丰度存在较大差异:Ti、Zr倾向于在粗颗粒中富集,Mn、Sr、Rb倾向于在细颗粒中富集,Ba的富集粒级不明显。Ti、Zr与Mn、Rb的颗粒粒级富集倾向可能是其硅酸盐矿物颗粒碎化过程的结果,而Sr则与湖泊自生碳酸盐有关。元素比值Zrc/（Rbc+Bac）、Zrc/Rbc与Ti、Zr的粒度效应Tic/Tif、Zrc/Zrf指示了沉积物重、轻矿物的相对比率,是流域侵蚀强度与湖泊涨缩的信息指示;Ba、Rb与Sr在细粒级的含量之比Baf/Srf、Rbf/Srf指示了硅酸盐与碳酸盐矿物的相对含量,是流域风化、侵蚀搬运强度与湖泊过程（包括物理/化学/生物）等混合信息指示,没有明确的环境指向性。