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1.
大量研究表明，从数小时到十年、百年时间尺度上的天气、气候变化受太阳活动影响显著。近年来，全球云量、北大西洋冬季气旋等气候、气象要素与银河宇宙射线通量变化、太阳能量粒子事件等空间天气事件显著的统计相关被陆续发现。在此基础上，提出太阳活动驱动气候变化空间天气机制，其基本观点是：空间天气事件通过改变云物理特性影响气象、气候，其核心是：太阳活动造成的空间天气事件与云微物理过程的联系，目前空间天气理论分化为离子诱导成核机制和全球大气电路—静电云微物理机制（简称Tinsley机制）。主要回顾和总结了近年来空间天气机制研究的发展，包括观测与理论，取得的成果，并对其未来的发展提出展望。
相似文献
2.
Axelle Bouiges Amir Yassin Maya Ikogou Clément Lelarge Axelle-Rolande Sikoa Stefano Mona Michel Veuille 《Comptes Rendus Geoscience》2013,345(7-8):297-305
Previous genetic studies showing evidence of past demographic changes in African drosophilids suggested that these populations had strongly responded to Quaternary climate changes. We surveyed nine species of Zaprionus, a drosophilid genus mostly present in Africa, in forests located between southern Senegal and Gabon. The mitochondrial COI gene showed contrasted levels of sequence variation across species. Populations of the only cosmopolitan species of the genus, Z. indianus, and of its closely related sibling species, Z. africanus, are highly polymorphic and appear to have undergone a continuous population expansion beginning about 130,000 years ago. Five less variable species probably underwent a population expansion beginning only about 20,000–30,000 years ago. One of them, Z. taronus, was significantly structured between forest blocks. The last two species were nearly monomorphic, probably due to infection by Wolbachia. These results are similar to those obtained in three species from the melanogaster subgroup, and may be typical of the responses of African drosophilid populations to glacial cycles. 相似文献
3.
CHEN Junren WAN Ling Guangzhou Marine Geological Survey MGMR P. O. Box Guangzhou 《《地质学报》英文版》1999,73(2):216-224
Experimental examinations and analyses have been made of the sediments from drill holes in the Zhuhai area, Guangdong Province. The studies show that there occurred four transgressions in this area over the historical times. The first transgression occurred at 7500 a B.P., with the maxium sea level up to about 1 m above the present level. The second transgression occurred at 5750 a B.P., with the sea level possibly 4 m higher than the present. The third and fourth transgressions took place at 4650 a B.P. and 2600 a B.P. respectively, which lasted for a long time with multiple fluctuations. The fifth transgression is in process. It could be predicted that the sea level at Zhuhai would rise by 15-20 cm in the coming 50 years. 相似文献
4.
The Chalbi flat, located 60 km outside the rift to the east, forms a moist, salt-clay encrusted playa which also functions as an inland sink for alluvial fans. Residual lacustrine beds, including freshwater carbonates and travertines, crop out along its higher periphery. Mammalian bones of lacustrine and terrestrial elements, and K/Ar dating of the capping lava suggest a lake or a swamp environment 2–2.5 million years ago. Radiocarbon dating of Melanoides tuberculata and Planorbis and a sediment assemblage composed of clotted micrite, calcareous molds, root marks and stromatolites point to an additional early Holocene Chalbi lake or swamps 11000-9500 yr BP. The data suggest wet environmental conditions outside the rift, which is consistent with the occurrence of a wet period in the early to middle Holocene in intertropical Africa, but out of phase with the climatic conditions in Sinai and Israel and with the high-latitude maximum lake levels and glacier advance. These relations have probably been caused by migration of climatic belts. 相似文献
5.
本文回顾了Aral Sea(咸海)海平面变化的最新认识,以供社会和经济项目决策者使用。我们提出了咸海生态标准的新认识:由于1960年之前当时的人类活动已经引起了湖泊萎缩,咸海在1960年之前是小到中型湖泊,而不是大型湖泊。对咸海认识的改变可能会使许多基于极端情景的昂贵计划变得更加现实。同时,基于地质、考古、历史和水文研究中所获得的多重数据的综合分析,本次结果认为咸海在过去的2万年内经历了多次突然的海侵和海退。然而,除了现代的原因外,引起这些变化的原因的认识仍然不完整,需要进行专门的调查研究。在这篇论文中,我们针对水位变化、气候变化与咸海盆地来自锡尔河和阿姆河供水变化相结合的研究方法进行了讨论。 相似文献
6.
Temporal changes in meltwater abundance, distribution and characteristics (controlling subglacial processes and ice sheet dynamics) can be inferred from subglacial sediment successions. Field evidence for changes in subglacial meltwater characteristics over time is presented from two sites (Doonan, Drummee) near a former late Weichselian (Devensian) ice centre in the north of Ireland. On a macroscale, both sites investigated show subglacial diamicton overlying glacially planated bedrock platforms. In more detail, primary sedimentary structures and facies variability show a complex relationship between depositional processes and meltwater characteristics at the ice/bed interface (IBI). Sedimentary evidence suggests sediment transport and deposition took place by low-viscosity subglacial slurries (mobile sediment–meltwater admixtures), which are part of a continuum between the processes of subglacial sediment deformation and subglacial meltwater flooding. Subtle changes in meltwater abundance and distribution at the IBI controlled slurry rheology, mechanisms of particle support and detailed sediment depositional processes. 相似文献
7.
1957-2006年塔里木河流域气候变化和人类活动对水资源和生态环境的影响 总被引：14，自引：5，他引：9
塔里木河是我国最大的内陆河,历史上是环塔里木盆地九大水系144条河流的总称,目前呈"四源一干"格局.依据1957—2006年近50a气象及水文监测资料,分析了气候变化和人类活动对塔里木河流域水资源的影响.虽然近50a来塔里木河流域山区与平原整体呈现气温升高、降水量增加特征,出山口径流量也呈增加趋势,然而在2000年前塔里木河流域生态环境急剧退化.其成因主要为:1)从20世纪50年代起到近2006年,四条源流入塔里木河水量50a减少了15.4×108m3;2)塔里木河上、中、下游耗水量比例的失调及区域水资源分配发生变化,造成塔里木河下游生态环境恶化;3)实施塔里木河综合治理后,即使进入塔里木河的下游的水量增加,中游段耗水量下降,但是上游耗水迅速增加且数量巨大,还是对塔里木河水资源综合利用、改善的下游生态环境产生负面影响. 相似文献
8.
9.
The Palaeoclimate Variations in the Central Plains Since the Interstade of the Last Glacial Stage 总被引：1，自引：0，他引：1
XIAO Huaguo WU Xihao JIANG Fuchu XUE Bin TIAN Guoqiang LIU Ke Institute of Geomechanics Chinese Academy of Geological Sciences Beijing Lake Sediment Environment Laboratory Chinese Academy of Sciences Nanjing Zhu Xiling 《《地质学报》英文版》1998,72(1):108-113
Through the study of a high-resolution loess record in the Central Plains, the short-term palaeoclimatic variations since the interstade of the last glacial stage have been discussed in this paper. The palaeoclimate in the East Asian monsoon areas shows different variation patterns in summer and winter. A correlation of the palaeomonsoon records of loess with the δ18O records of the ice core and deep sea is made, and some of the causes for their differences are also discussed. 相似文献
10.
洱海沉积物粒度记录与气候干湿变迁 总被引：21，自引：2，他引：19
通过对洱海现代沉积物的精细采样,将放射性核素精确计年与沉积物粒度研究相结合,重建了 6 0 0多年来洱海区域气候的干湿变迁,为恢复百年尺度的气候干湿变化提供了一条新途径。研究结果表明,15世纪是洱海地区最为湿润的一个世纪;洱海区域存在 10 0a、2 0 0a两种时间尺度的气候干湿准周期波动;自 19世纪末以来洱海区域气候整体上向干旱化方向发展,目前正处于干旱期末期,预计气候将由干旱转向湿润。 相似文献
11.
G. Boschian 《International Journal of Earth Sciences》1993,82(2):227-233
The relationships between the land and sea in the northern Adriatic at the Pleistocene—Holocene boundary are examined by considering sea-level curves and archaeological data. Changes in the Mesolithic (Early Holocene) economy of the inhabitants can be interpreted as a result of palaeoecological variations due to glacioecustatic sea-level changes and recent tectonics. This hypothesis is also supported by evidence of older tectonic movements which may have continued until the end of the Pleistocene. 相似文献
12.
Ancient outwash accumulations, deposited in Pleistocene with complicated sedimentary characteristics, are discovered in the midstream valley of Dadu River, Southwestern China. Their sedimentation characteristics are investigated for gaining a deep insight into the dependency of Paleoclimate changes in this area. This is achieved by means of detailed site investigation, sampling and laboratory tests (grain size distribution and Electron Spin Resonance dating tests) for two representative outwash accumulations. Based on the present study, several main conclusions are drown out as follows: 1) The accumulations are composed mainly of coarse soils (coarse fraction is over 50%) and very coarse soils (coarse fraction is about 20%–35%, and very coarse fraction is over 55%); 2) The coarse soils are sub-rounded well-sorted and sub-stratified to well-stratified, while the very coarse soils exhibit sub-rounded to sub-angular and poorly-sorted; 3) The accumulations are postulated to have been intermittently deposited in three time periods. This is evidenced by two layers of weathered/residual clay, purple to brick red in color; and 4) It is inferred that the temperature in the study area increased over three time periods, i.e., 280 ka B.P. to 120 ka B.P., 110 ka B.P. to 80 ka B.P. and 70 ka B.P. to 25 ka B.P., and declined twice at 120 ka B.P. and 77 ka B.P. respectively. 相似文献
13.
近2600年来内蒙古居延海湖泊沉积物的色素含量及环境意义 总被引：10，自引：0，他引：10
通过分析东居延海S1探坑剖面色素含量,结合碳酸盐、介形类化石、腐殖酸、磁化率及化学元素等多环境指标分析结果,探讨该区近 2 6 0 0年来环境气候波动特点。研究区气候变化大致经历几个阶段:温暖湿润(2 6 5 0～ 2 5 6 0aB.P.)→湖泊菱缩,气候偏干暖 (2 5 6 0～ 2 36 0aB.P.)→暖湿气候背景下湖泊的扩张 (2 36 0～2 1 2 0aB.P.)→冷湿向冷干转换,湖泊由大湖开始菱缩 (2 1 2 0～ 1 6 0 0aB.P.)→气候暖湿,湖泊再次扩张,(1 6 0 0～ 6 5 0aB.P.)→湖泊由扩张到菱缩,气候由冷湿向暖干变化 (6 5 0aB.P.-至今 )。同时尝试把色素与其它指标的结合作为指示湖泊古初始生产力的有效性,以及识别沉积记录有关人类活动的可能性。 相似文献
14.
In order to determine time-dependent changes in estuarine pore-water chemistry and flux variations across the sediment-water interface, sediment cores of an intertidal mud flat in the Weser Estuary were taken monthly over a one-year period. Sediment temperature, pH, Eh, Cl–, O2, NO
3
–
, and SO
4
2–
pore-water concentrations were measured and showed variations that relate to the changes of surface temperature and estuarine water composition. Fick's first law was applied to quantify diffusive fluxes from concentration gradients in the diffusive boundary layer and in the pore water. Total nitrate fluxes were calculated from flux chamber experiments. Diffusive oxygen fluxes increased from 5 mmol m–2 d–1 in winter to 18 mmol m–2 d–1 in early summer, while nitrate fluxes into the sediment increased from 3 mmol m–2 d–1 in winter to 60 mmol m–2 d–1 in early summer. Oxygen and nitrate fluxes into the sediment correlated linearly to sediment temperature. Sulfate fluxes increased from 0.5 mmol m–2 d–1 in winter to 10 mmol m–2 d–1 in August and September. Converted into carbon fluxes, the sum of these oxidants ranged from 10 mmol m–2 d–1 in winter to 80 mmol m–2 d–1 in summer. An estimation of the upper limit of the annual nitrate flux into the sediment showed that about 10% of the 250,000 t of nitrate discharged annually by the river may be decomposed within the inner Weser Estuary. 相似文献
15.
《地球科学进展》2012,27(1)
泥炭记录的环境演变是过去全球变化（PAGES）研究的重要领域之一,分析了中国泥炭记录的古气候演化研究的区域范围,当前主要以东北哈尼、青藏高原的红原、神农架大九湖以及华南定南大湖四个位于东部季风区的研究工作最为集中。泥炭沉积高分辨率综合信息揭示了末次冰消期以来中国气候变化的时空特征：冷暖干湿变化既有一致性又表现出区域差异,末次冰消期东北地区、东部山地、华南地区都表现出冷偏湿的气候特点,而青藏高原却为冷偏干或凉偏干;Younger Dr-yas（YD）事件之后,全新世早期和中期青藏高原、东部山地、华南地区气候总体以温湿为主要特征,而东北地区有效降水减少,到全新世晚期,呈现出干旱的变化趋势。并对B～A事件,YD事件,8.2ka以及4.2 ka等重大气候突变事件研究工作进行了综述。最后指出今后应拓展与重建更多区域古气候环境变化序列的对比,加强泥炭沉积及环境指标的基础理论,重视和提高大气沉降泥炭档案以及气候变化背景下泥炭地碳循环机制等研究工作。 相似文献
16.
晚新生代以来天山北缘沉积记录及其稳定同位素变化的环境意义 总被引：1，自引：0，他引：1
晚新生代以来,天山北缘的沉积记录与天山的隆升密切相关。研究表明:始-渐新世安集海河组主要沉积发育水平层理的绿色、灰绿色湖泊相泥岩;晚渐新世沙湾组中上部岩石组合特征为紫红色曲流河相砂岩、粉砂岩和砾岩夹层;早中新世塔西河组下部主要为灰绿色、褐红色砂、泥岩互层,上部主要为土黄色砂岩和粉砂岩夹层;晚中新世-早上新世独山子组为辫状河相灰色砾岩和砂砾岩沉积;晚上新世-早更新世西域组主要为厚层砾岩堆积。土壤碳酸盐中稳定同位素数据表明:安集海河组δ~(13)C平均值为-3.9‰,δ~(18)O平均值为-5.0‰;沙湾组中上部δ~(13)C平均值为-8.1‰,δ~(18)O平均值为-11.0‰;塔西河组δ~(13)C平均值为-5.9‰;δ~(18)O平均值为-7.7‰;独山子组δ~(13)C平均值为-8.5‰,δ~(18)O平均值为-10.3‰;西域组δ~(13)C平均值为-6.0‰,δ~(18)O平均值为-10.4‰。同位素结果和沉积记录共同表明,始-渐新世为湿润温暖气候;晚渐新世为干旱寒冷气候;早中新世早期为半湿润、半温暖气候,晚期为干旱、寒冷气候;晚中新世-早上新世为干旱寒冷气候;晚上新世-下更新世为干旱、半温暖气候。结合古地磁数据和全球气候变化,天山北缘晚新生代以来发生五次主要气候变化事件,即晚渐新世(沙湾组时期中上部)气候转换,约24Ma(沙湾组时期顶部)气候突变,早中新世内部(约24～19Ma)气候转换事件,晚中新世(约7Ma)C_4植被迅速扩张和约3.17Ma以来气候的剧烈震荡。 相似文献
17.
18.
The Las Aguaditas Formation in the Argentine Precordillera of San Juan is the only Ordovician carbonate sequence deposited on a slope. Spiculites, mudstones and calcisiltites represent the autochthonous sediments, characterized by a fine lamination, rare fossils and their dark colour. The pelagic fauna consists of rare radiolarians/calcispheres, trinucleid trilobites, graptolites and conodonts. The latter are typical of an open marine environment and proved a Llanvirn—Llandeilo age for the Las Aguaditas Formation.In the upper part of the succession there are several intercalations of megabreccias. Their thickness decreases from about 20 to 4 m towards the top of the formation, accompanied by an increasing amount of carbonate turbidites. The clasts of the breccias are derived from the slope as well as the platform. Each of the megabreccia horizons represents a system of channels, lobes and interchannel deposits, which together form a slope apron. On top of the lower breccia a small biostrome developed, where bryozoans and crinoids are preserved in an autochthonous position.Sedimentation of the Las Aguaditas Formation started with the drowning of the underlying carbonate platform (San Juan limestones). Near the Arenig-Llanvirn boundary, a rapid ecstatic sea-level rise led to the deposition of graptolitic black shales and mudstones. Upwards, allochthonous carbonates become increasingly abundant. The onset of megabreccia deposition coincides with a major relative sea-level fall, caused by block movements in connection with rifting. The subsequent transition from breccia formation towards turbiditic sedimentation corresponds to an environmental shift from the slope towards the toe of slope and basin and marks a renewed moderate sea-level rise.
Correspondence to: M. Keller 相似文献
19.
孢粉记录揭示的2万年以来若尔盖地区的气候变化 总被引：9，自引：1，他引：9
若尔盖黑河牧场ＤＣ剖面的孢粉记录表明，末次冰期晚阶段若尔盖原高的气候表现为不稳定性，即冷暖变化频繁，其基本变化与全球一致，相对暖的阶段发生在２０－１８ＫａＢＰ，１６－１５ＫａＢＰ和１３－１１．２ＫａＢＰ；相对冷的阶段在１８－１６ＫａＢＰ，１５－１４ＫａＢＰ和１１．２－１０．２ＫａＢＰ。其中末次冰期最盛期发生于１８－１６ＫａＢＰ；１１．２－１０．２ＫａＢＰ的降温可对应于ＹｏｕｎｇｅｒＤｒｙａｓ事件。 相似文献
20.
B.F. Iyun 《GeoJournal》1998,44(2):129-139
The viewpoint that most health problems are environmentally related has always been promoted by medical geography. In recent
times, concern about environmental degradation has been of high priority for many national and international organizations
as ‘we human beings become a threat to our planet’. There is also a need to specifically focus attention on the impact of
so-called development efforts on the health of women and children, in particular those living in highly marginalized regions
which often contribute substantially to the overall development of their countries.
This paper uses the concept of vulnerability as a departure point from which to map the health risks to children in Igbekun
area of Ondo State, the ‘transgressive muddy’ oil-rich coastal area of Nigeria. The paper attempts to highlight the poor quality
of life and health of children in particular, and how it is becoming much more difficult to practice health intervention programmes,
especially oral rehydration therapy (ORT) in the area.
The Igbekun area is an unhealthy and harsh environment, complicated by the devastating effects of oil drilling in recent years.
The siltation and sedimentation of the creeks and lagoons have serious health dimensions as human faeces float in and around
villages because the ‘bush toilets’ can no longer be reached. The on-going environmental crisis has also deprived women of
their traditional means of livelihood; fishing.
There is a relatively high level of ignorance (compared with other women living in the same local government area (LGA) of
causes of the commonest diseases such as diarrhoea, acute respiratory infection (ARI) and measles. A majority of the women
have never heard of family planning, immunization against diseases and interventions such as ORT. Promotive health care services,
especially those that strive to reduce the high mortality of children have passed the mothers by. It is also becoming impracticable
to promote ORT because of the widespread ‘salty and oily’ water supply in the area.
The greatest concern of the women now is that oil drilling activities have further amplified their stressful conditions especially
their health and that of their children. Unfortunately, their plight is not acknowledged by the Nigerian authorities and the
oil companies are least concerned about alleviating the poor health status of the community, in particular the most vulnerable
groups, children under the age of five.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献