内蒙古岱海湖泊沉积记录的小冰期气候环境

通过对岱海深水区沉积柱样有机碳同位素,总有机碳、碳酸盐含量、频率磁化率等环境代用指标的分析,结合剖面的岩性特征和＾２１０Ｐｂ定年,初步探讨了岱海小冰期以来气候环境演化过程,结果表明：在小冰期初期７４０－５４０ａＢＰ,以冷湿气候为主;在５４０－４８０ａＢＰ为寒冷干旱气候,可能为小冰期盛期;４８０－３７０ａＢＰ,气候转温和,以凉偏湿气候为主;３７０－２２０ａＢＰ,凉偏干气候为主;２２０－１３０ａＢＰ,     

近200年来黑河下游天鹅湖湖泊沉积记录的环境变迁

根据2002-2004年洞庭湖水质监测数据,参照GB3838-2002中Ⅲ类水质标准,选用内梅罗水污染指数法和黄浦江污染指数对洞庭湖水质现状进行评价,结果表明:(1)洞庭湖水体的主要污染指标是总磷,总氮和粪大肠菌群;(2)黄浦江污染指数平均值为0．27,所以洞庭湖12个断面水质无黑臭现象发生;(3)枯水期西洞庭湖和南洞庭湖水质污染最严重,平水期西洞庭湖水质污染最严重,洞庭湖丰水期的污染程度小于平水期;(4)洞庭湖的大部分水体的水质主要处于轻度污染的状态,局部水体的水质在枯水期达到重污染的状态．     

青海湖近900年来气候环境演化的湖泊沉积记录

通过对青海湖沉积物碳酸盐含量、磁化率、TOC等多环境指标的分析,探讨了青海湖地区近900年来的气候环境演变。结果表明青海湖地区近900年来气候变化属于暖干－冷湿的气候演替类型,经历了5次冷湿期和5次暖干期,中世纪暖期、小冰期以及20世纪以来的升温在该沉积岩芯有清晰的记录。沉积物的磁化率和沉积速率的变化忠实地记录了本世纪以来人类活动的影响。     

内蒙古东乌珠穆沁旗乌拉盖高毕湖泊沉积记录的5万年来环境演变

中国北方季风边缘区的湖泊对环境的反应很敏感,乌拉盖高毕是位于内蒙古高原东北部的一个已干涸的内陆封闭湖泊.研究剖面总厚度为405 cm,根据取得的9个AMS¹⁴C及光释光测年数据,建立了51.9 ka BP以来的年代序列.结合岩性的变化、粒度组分分析、粒度参数(标准偏差、偏度、峰度等)及Rb/Sr比值特征进行了详细的分析,恢复了乌拉盖高毕湖泊沉积记录的5万年来的环境演化过程.将0~405 cm的剖面划分为4个较大的气候阶段:51.9-44.1 ka BP(405~343 cm),气候为干冷期,各环境指标显示为滨湖沉积,湖泊水位较低;44.1-28.5 ka BP(343~130 cm),气候为温湿期,湖泊逐渐扩张,湖泊水位升高;28.5-11.38 ka BP(130~35 cm),气候转冷,湖面萎缩,并在盛冰期出现砂楔,该阶段后期湖泊干涸;11.38 ka BP至今(35~0 cm),气温回升.     

历史时期希门错湖泊沉积色素记录的古环境变化

湖泊沉积物中色素的含量,种类以及相应的参数是研究湖泊初始生产力和湖泊环境的有效手段之一。本文根据青藏高原东部希门错短柱岩芯ＸＭ９２０１沉积物的色素指标的综合判别,讨论了该地区过去２０００多年来的古环境变化过程和特点,对比分析我国东西部气候记载及冰芯研究,探讨了各气候事故表现形式的异同点。     

青藏高原苟鲁错近几十年环境变化的湖泊沉积记录

通过对青藏高原苟鲁错湖泊沉积物碳酸盐含量,粒度、C值的综合分析,得出湖泊流域气候近几十年来气候呈干暖化趋势。另外,通过苟鲁错附近五道梁和沱沱河气象站统计资料和湖泊沉积特性的对比分析,说明通过碳酸盐、粒度、C值等综合指标对重建苟鲁错流域古气候是可行的,这为苟鲁错流域古气候重建提供了参考和依据。     

近1800年来云南洱海流域气候变化与人类活动的湖泊沉积记录

对云南洱海湖泊岩芯沉积物进行了多环境指标（年代学、色素、硅藻、有机碳稳定同位素、磁化率、化学元素）的分析,建立了近１８００年来云南洱海流域气候与环境变化的序列,气候演化具有暖干、冷湿交替的组合呈些特征气候阶段如中世纪温暖期、小冰期气候特征在洱海源泊沉积记录中均有反映,洱海湖泊上沉积记录的气候暖干－冷湿交替变化规律,反映了西南委风影响下的气候演化特征,湖泊沉积记录中包含丰富的人类以的信息,磁化率,元     

龙感湖地区近3000年来的气候环境变迁

本文通过分析龙感湖沉积物中的色素、孢粉、硅藻研究结果,探讨该区近３０００年来环境气候波动特点,结果表明：３２００－２４００ａＢＰ,色素含量较高,与温度条件较好有关。该带孢粉浓度也最高,阔叶乔木绎种花粉丰富,湿生及水生植物经常出现。总体上为相对暖湿阶段,其中仍有凉湿波动。２４００－１６００ａＢＰ,具体分为两个阶段,前期约２４００－２０００ａＢＰ,ＣＤ、ＴＤ、Ｍｙｘ含量明显较低,水生、湿生草本减少,气     

若尔盖盆地兴措湖沉积记录揭示的近代气候与环境

依据湖泊沉积记录进行古气候环境要素定量的是过去全球变化研究的重要内容,本文通过若尔盖盆地兴措湖近代湖泊沉积特征、沉积物总有机碳及其同位素指标分析,并与器测气象资料进行比较,对兴措湖泊近代湖泊沉积物中有机碳及其同位素指标所代表的气候环境信息进行了定量研究,在此基础上,建立了兴措湖沉积物总有机碳及其同位素记录与对应的降水和气温间的函数关系,为定量恢复该区长尺度历史时期古气候环境特征提供了基础。     

近1200 a来黄河下游梁山泊沉积记录的环境变迁

利用梁山泊670 cm柱状岩芯沉积物,基于精确的AMS-~(14)C年代测定,通过高分辨率的粒度、磁化率、总有机碳、C/N比值等环境代用指标的综合分析,并结合历史文献记载,初步揭示了1200 a来黄河下游地区平原湖泊沉积特征及环境演化历史.结果表明,梁山泊环境演化大致分为5个阶段:790-940 AD期间,为低湖面的沼泽沉积环境,气候冷干;940-1215 AD期间,屡次受到黄河决溢洪水影响,湖盆扩张,湖泊水位上升,为梁山泊极盛期,气候暖湿;1215-1310 AD期间,黄河夺淮入黄海,湖区淤积严重,湖泊萎缩减小;1310-1470 AD期间,再次受到黄河决溢洪水影响,水位上升,面积扩张,但逊于极盛期;1470 AD至现代,黄河河道进一步南移,远离梁山泊,湖盆淤积抬高,梁山泊最终消失,直到1855AD,黄河第6次大改道北移,湖泊再次受到黄河洪水影响,由于前期受到泥沙淤积抬高,该地区仅作为黄河泥沙承载区.在气候变化大背景下,黄河改道决溢是梁山泊演化的主因.     

洱海地区一万多年以来气候环境演化的湖泊沉积记录

根据对洱海北部10．8m深水区ES孔沉积物高分辨率的孢粉、粒度、碳屑、藻类分析,结合AMS^14C测年数据,划分了11个阶段,恢复了一万多年以来云南洱海地区气候环境演化序列．全球性的降温事件在该地区都有明显的反映,包括9900aBP(Younger Dryas)、8500aBP、7100aBP、5100aBP左右的四次冷事件,6800—5500aBP为全新世水热配置最佳期,距今2400年开始该地区出现较为明显的人类活动．     

黄河下游南四湖地区黄河河道变迁的湖泊沉积响应

黄河下游地区湖泊演化多与黄河河道变迁密切相关,进行高分辨率的湖泊沉积环境的研究,可揭示历史时期黄河下游的河道变迁,本文以南四湖ＤＳ孔为例,探讨河道变迁的湖泊沉响应。     

近50年来洞庭湖区的内湖变化

洞庭湖区除洞庭湖外,在圩垸内尚分布着为数众多的内湖,近50年来,由于人类活动的强烈作用,内湖与洞庭湖一样呈现出急剧萎缩的态势,1km2以上内湖的数量由20世纪50年代的255个减少到目前的122个,湖泊面积也由1534.4km2缩小至644.2km2,其衰亡的速度甚至超过了洞庭湖.分析洞庭湖区内湖急剧萎缩的原因,其主要表现为前期是围湖造田,后期为湖泊鱼塘化.     

2600年以来台湾大鬼湖中的金属通量

Sediment cores were collected from the remote subalpine Great Ghost Lake in southern Taiwan. Because the lake is anoxic the sediments are well preserved, distinctive past variations can be dated accurately. The vertical distributions of total and acid-leached metal concentrations for aluminum, arsenic, cadmium, cerium, chromium, cesium, copper, iron, magnesium, manganese, nickel, lead, rubidium, strontium, vanadium and zinc are measured and the fluxes determined. The dates of higher fluxes in the past 2600 years seem to correlate with dry spells. Further, trace metal fluxes show a large increase but Pb-206/Pb-207 ratios show a large decrease since 1950, suggesting a significant anthropogenic input.     

沔阳地区一万多年来孢粉记录的环境演变

依据Ｍ１孔孢粉组合特征及＾１４Ｃ年龄数据,结合孢粉数理统计分析,重建了江汉平原沔阳地区一万多年来的古季风气候变迁序列。研究结果表明,该区气候经历了六个阶段的变化。６．７－４．４ｋａＢＰ间。为水热配置最佳时期。夏季降水显著增多;３．９－１２．７ｋａＢＰ,气温有所下降,但有效湿度很高,为古云楚泽扩张时期,其湿度的增加既受锋面降水带的影响,同时恙长江南移,河床迅速抬高有关。约６ｋａＢＰ后,人类活动在本区     

龙感湖钻孔揭示的末次盛冰期以来的环境演化

通过龙感湖滩地钻孔24．4m深度以内的沉积物岩性、生物和物理指标分析,在^14C年代测定的基础上,对龙感湖末次盛冰期以来的环境演化进行了恢复,15．0kaBP前和10．0－6．3kaBP,龙感湖区发育河流沉积,以低生物量和高磁化率为特征;约15．0－10．0kaBP期间的晚冰期,龙感湖首次成湖,湖泊中生物量明显提高;现代龙感湖雏形始于约6．3kaBP后,至3．7kaBP后发展为稳定的湖泊环境,此外,花粉结果显示,龙感湖湿地相干被大致形成于3．3kaBP后,然后,龙感湖的成因和演化,及其与长江关系的研究,还必须重视对沉各物物源的追踪。     

Environmental changes reflected by the lake sediments of the South Hongshan Lake, Northwest Tibet

The 1.07-m long lake core with 1 cm interval cutting, which was obtained by drilling in the South Hongshan Lake of Northwest Tibet, was dated by the 210Pb and 137Cs methods, and a 150-year consecutive lake sedimentary sequence (1840─1997) with 1.4 year resolution was obtained. Some environmental proxies, such as the total organic carbon (TOC), total nitrogen (TN), ratio of TOC to TN (TOC/TN), trace chemistry elements (TCE), CaCO3, grain size, richness of ostracoda etc. showed that they are of well coincidence. These results implied that the environmental background varied from the cold-wet period in the late 19th century, to the warm-wet period from the end of the 19th century to the 1920s and to the warm-dry period since the 1920s. There were sub-variations since the 1920s: the cold-dry/warm-wet fluctuation from 1922 to 1960, the intensively warm-dry period since 1960 with a short cold-wet period in the mid-1970s to the end of the 1980s. The humid period from the mid-1970s to the end of the 1970s and the dry period beginning from the early 1980s were well documented by climatic data of the nearby weather station records while the grain size was well correlated to the annual precipitation. Compared with the records from Guliya ice core in the same area, the TOC proxy in the lake core indicating warm/cold conditions well corresponded to the ( 18O records representing temperature variations in the ice core. However, the proxies with dry/wet significance in the lake core were different from the variations of snow accumulation reflected by the ice core. It can be concluded that the chosen environmental proxies have clear environmental significance and the lake sediments can reflect climatic and environmental changes at high-resolution.     

太湖14000年来古环境演化的湖泊记录

Two sediment cores, one 396 cm long from west Taihu Lake, another 246 cm long from east Taihu Lake, are interpreted from the analysis of their magnetic susceptibility, total organic carbon, total nitrogen, total pigments, organic carbon isotope, hydrogen index, saturated hydrocarbons, ¹⁴C dating and surficial sediment conditions. The west Taihu Lake core is the longest one studied in this lake so far, and has provided us the most complete environmental and climatic information for this lake. The results from the west Taihu lake core indicate that Taihu Lake has undergone the following stages:from ca.14 300 to 13 300 aB.P. Taihu Lake was in low lake-level, and there existed exposed features from the proxies reflecting arid paleoclimate. From ca.13 300 to 12 400 aB.P. an arid transitional stages occurred with a slightly warmer and wetter climate. From ca. 12 400 to 10 900 aB.P. a period of large climatic fluctuation occurred and from 10900-10 000 aB.P. a warm period developed with deep water and strongly reducing sediments. During ca.10 000-7 200aB.P., a cool transitional period alternating with a warm climate occurred. It was warm and wet during 7 200-5 700aB.P.; some proxies changed violently in 5 050aB.P., reflecting obvious changes in material source and a probable interruption of sedimentation. The east Taihu Lake history from ca. 6 550 to 6 450 aBP, the climate was cold and dry, and gradually turned warm and wet in ca. 6 450-6 050 aBP. It was warm and wet in ca. 6 050-5 800 aBP and had a cold tendency in 5 800-ca. 5 000 aBP. An abrupt change occurred at ca. 5 000 aBP, and the lake sediment in the uppmost part was disturbed by wave action indicating shallow water conditions.     

近30年来太湖流域湖泊岸线形态动态变化

湖泊的岸线特征是表征湖泊形态特征的一项重要内容．本文应用分形理论中的计盒维数,基于岸线长度与面积 关系的分形维数及岸线发育系数,对太湖流域主要湖泊的湖泊岸线变化进行了研究．结果表明,分形维数可以更好的对 湖泊岸线进行量化描述,太湖流域主要湖泊的岸线具有自相似性;近30年来,太湖流域湖泊的岸线曲折度降低,岸线长度 减少,岸线结构趋于单调．     

洪湖人类活动的沉积物记录

对洪湖150cm长的沉积物样芯进行了TOC、TN、TP、Ca、硫化物测试和AMS定年,在此基础上对洪湖地区人类活动的湖泊沉积响应进行了讨论.TOC和TN的含量呈现相似的变化规律,它们在样芯顶部和底部都出现显著峰值,而中部变化平坦,表示1500年来洪湖环境变演的三个显著不同的阶段;TP从过去到现在总体呈上升的趋势,但上升的幅度不大,这与磷在沉积物中复杂的循环机制有关;Ca的剖面变化显示为底部含量高上部低,其变化情况较复杂;硫化物在顶部15cm的含量比背景值略高,可能指示了上个世纪人类对铁矿和矿物燃料开采强度的增大.