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1.
本文以政府间气候变化专业委员会（IPCC）于2001年专门报告中关于21世纪内全球气候变化的温度和海平面变化的预估为前提。简要介绍了中国珊瑚礁的定位、类型和分布,对其进行了成熟度分类,评估了全球海平面变化对中国珊瑚礁的影响。据预测,21世纪我国各海域海平面上升以南海最大,为32 ~ 98cm,其平均上升速率为0.32 ~ 0.98cm/a。从海平面上升速率与珊瑚礁生长速率的理论对比分析,中国珊瑚礁基本上能与前者同步生长,即使海平面以预估高值上升,也不会威胁其生存。从中国珊瑚礁成熟度较高、其生长趋势以侧向生长为主的现实状况出发,未来全球海平面上升能为其创造向上生长的有利条件。从古地理学“将古论今”观点出发,自全新世6000aBP以来曾存在过的高海平面和较高表层海水温度的历史,也可以佐证,21世纪的全球海平面上升不会对中国珊瑚礁的存在和发育造成威胁。现存的珊瑚礁岛应对于全球海平面上升,可以做到“水涨岛高”,它们能够屹立于上升了的未来海平面之上;但对于岛上的人工建筑物则会被浸、被淹,或被淘蚀和破坏,因此必须根据海平面上升的幅度和速率,采取相应的防御措施。 相似文献
2.
综述了第四纪湖相介形虫化石种属组合在环境重建研究中取得的进展和存在问题,讨论了今后发展的趋势.湖泊沉积物介形类种属组合正逐渐成为古环境重建研究的常规微体生物学指标,过去几十年来国际国内研究取得重要进展,种属组合与环境参数的定量化研究成为主要趋势.化石壳体样品处理、埋藏条件评价等是提取种属组合指标的重要影响因素,需要规范化.现生种的个体与群落生态信息定量观测、调查研究是利用现代类比法(MAT)定量重建古环境的基础,也是我国介形类化石组合与环境重建中应该加强的方面. 相似文献
3.
Keiichi Sasaki Akio Omura Kazuo Murakami Natsume Sagawa Toru Nakamori 《Quaternary International》2004,120(1):51
Coral reef terraces are one of the best recorders of relative sea-level changes during the last glacial cycle. Thus far, knowledge of relative sea-level record based on coral reefs during the marine Oxygen Isotope Stage (OIS) 3 has been limited to studies of the Huon Peninsula, Papua New Guinea. High-precision a α-spectrometric 230Th/234U dating demonstrated an offlapping sequence of five coral reef complexes, ages of which are 66, 64, 62, 55 and 52 ka, in the northern part of Kikai Island, central Ryukyus of Japan. Interstadial reefs, characterized by deepening-upward sequences of coral assemblages, recorded three hemicycles from transgression to highstand at 52, 62, and 66 ka, during which these reefs were drowned. These highstands in the relative sea-level record can be correlated with the eustatic record reconstructed from the Huon reef terraces and with the interstadials 14, 18, and 19 of the GISP 2 oxygen isotope record. This consistency confirms the Huon sea-level record of OIS 3 and implies that the eustatic sea level responded to the millennial-scale climate changes even during the glacial period of OIS 4. 相似文献
4.
Raised Coral Terraces at Malakula, Vanuatu, Southwest Pacific, Indicate High Sea Level During Marine Isotope Stage 3 总被引：2，自引：0，他引：2
The occurrence of a series of raised coral reefs from the uplifted island of Malakula (Vanuatu, SW Pacific) provide an opportunity to examine sea-level fluctuations over at least the past 120,000 years. Thirteen fossil coral samples from Malakula were analyzed by the thermal ionization mass spectrometry (TIMS) U/Th dating technique, yielding information on sea levels during late marine isotope stage 3 and early stage 4. Our findings are in good agreement with sea-level estimates from raised coral terraces in Papua New Guinea and the recent sea-level reconstruction from the deep-sea sedimentary δ18O records. In particular, our coral data appear to confirm that sea levels at about 45,000–50,000 yr B.P. were only 30 to 60 m below the present level. Combined with other evidence of sea-level change, our data provide a strong case for much higher sea levels and therefore markedly reduced continental ice volume at 47,000 to 49,000 years ago. 相似文献
5.
基于磁性矿物的性质变化能敏感记录现在和地质历史时期的气候环境变化信息,环境磁学方法能鉴别环境演化过程中磁性物质在大气圈、水圈和岩石圈中运移、沉积和转化的过程,系统介绍了沉积物中磁性矿物的特征和鉴别方法以及主要的环境磁学参数和意义,着重回顾了环境磁学在以黄土、湖泊和海洋沉积物为载体的古气候环境研究中的应用及其取得的重要进展,指出了环境磁学在古气候环境研究过程中要加强多磁学参数综合应用,促进地质记录和磁学指标之间的定量研究,有利于理解不同沉积物的磁性矿物特征和环境变化过程的相关关系。同时强调沉积物还原成岩作用过程的环境磁学研究是目前以至今后发展的一个重要方向。 相似文献
6.
珊瑚礁是发育于热带海洋环境中由生物作用和地质作用共同形成的地质体,具有独特的新构造运动意义。南海西北部珊瑚礁记录所反映的新构造运动主要有火山活动、地壳升降运动和地震活动等。珊瑚礁区第四纪火山活跃,到现代已停止活动,部分火山构成珊瑚礁的基座,个别出露海面为火山岛;地壳升降运动差异较大,雷州半岛西南部珊瑚礁呈上升趋势,上升率为0.02~0.05mm/a;西沙群岛等岛礁地壳运动则呈下降趋势,下降率为-0.07~-0.10mm/a,岛礁中的造礁石珊瑚生长率、礁顶和灰沙岛的堆积率均相当于或大于地壳下降率与现代海平面上升率的总和;南海西北部珊瑚礁区内地震活动较强,尤其是1994年12月31日和1995年1月10日在雷州半岛西南部海域发生了6.1级和6.2 级地震,这两次地震对该区珊瑚礁的发育有较大的影响。 相似文献
7.
古温度定量重建的良好代用指标———湖泊沉积摇蚊化石记录研究进展 总被引：4，自引：0，他引：4
（双翅目）摇蚊科昆虫对环境因子的变化相当敏感，其水生幼虫的头囊能保存于湖相沉积物中，在国际古湖泊和古环境研究中常被用作一种环境替代指标。因为不同种属的摇蚊对环境因子的最适值和耐受范围有较大差异，所以利用湖相沉积物中的摇蚊化石组合面貌的变化可达到古环境的定量重建。在欧洲和北美进行的许多研究已证实摇蚊是古温度的有效指示器，重建夏季温度相对准确可靠，比其它气候变化代用指标有优势，很可能成为国际上古气温重建所使用的首要生物代用指标。截止目前，该领域研究在国内尚未开展，我国湖泊众多，利用摇蚊研究古温度记录潜力巨大。 相似文献
8.
通过对山西芮城桃花涧剖面孢粉分析,结合沉积物的粒度特征和沉积物AMS 14C测年数据,探讨了中全新世晚期该区的古文化年代及古环境变化,为恢复其古环境面貌提供了可靠的定量数据。分析结果表明,该遗址文化层的年代为庙底沟文化时期。根据孢粉组合特征,可将剖面划分为3个孢粉带：5 250~5 000 aBP期间气候温和湿润,呈现出稀树草原的植被面貌;5 000~4 800 aBP期间气候温凉偏干,呈现出荒漠草原的植被景观;4 800 aBP之后气候温凉湿润,呈现出稀树草原的植被面貌;气候变化与邻区同期相吻合。 相似文献
9.
Research Progress in Responses of Modern Terrestrial Plant Carbon Isotope Composition to Climate Change 总被引：1，自引：0，他引：1
Global climate change has been one of the most concerned environmental problems in the world since the 1980s. Since stable carbon composition (13C) in plant tissues can record abundant information on climate changes, it has been widely used as an important climate proxy in global change studies and becomes a powerful tool for obtaining paleoclimate information, understanding paleoenvironment reconstruction and modern climate change, and predicting future climate trends. However, a lot of potential uncertainties have always involved in the reconstruction of paleoclimate and paleoenvironment by carbon isotope of the past period sediment or fossils. Among them, the most dominant uncertainty is due to our poor understanding of the relations between carbon isotope ratios of plants and climatic factors and the climatic and environmental significance indicated by modern plant 13C. This may limit the application of plant 13C in the study of climatic and environmental changes. Based on the Summary of plant 13C fractionation and carbon isotope distribution of different photosynthetic plants, the effects of environmental factors, e.g., temperature, precipitation, atmospheric CO2 concentration, and altitude on terrestrial plant 13C and their relationships were reviewed in this paper, and the response mechanism of plant 13C to climate changes were also analyzed. Furthermore, the current existing problems and the future prospects in carbon isotope study were discussed. It is pointed out that strengthening some studies such as the response of C4 plants 13C to climate environmental parameters, the transformation relation of different scale plant 13C, intersection and permeation of related disciplines, and various proxies and scientific method, will undoubtedly make us have a more accurate understanding of the climate history and eventually broaden the development of the field during the process of global change study by plant carbon isotope techniques. 相似文献
10.
Studies on the coral reefs of the South China Sea (SCS) was the theme of the 6th Session of the 3rd Conference on Earth System Science (CESS) in Shanghai, 2014. This session discussed the most recent study developments on the SCS coral reefs, including coral reefs’ responses to global changes, coral reefs’ records on past climatic variations, and the activities about constructions and oil gas explorations in the coral reefs areas of the SCS. Disturbed by intensive anthropogenic activities and global climate warming, coral reefs in the SCS have declined dramatically, reflecting the up to 80% decrease of living coral cover and many areas having less than 20% of living coral cover. Geochemical data of SCS coral skeletons clearly show that since the Industry Revolution, the pollution situation of the SCS have dramatically increased and the seawater pH values have been continuously lowering, i.e. oceanic acidification. All these environmental phenomenon are further stressing the healthy development of the coral reef ecosystem in the SCS. Meanwhile, the poor coral reef ecosystems in the SCS are facing more anthropogenic disturbances such as coastal developments and engineering constructions. Obviously, the SCS coral reefs will be faced with more environmental challenges in the coming future. We therefore suggest that the policy makers should realize the extreme importance and the fragile of the coral reef ecosystems, and scientifically and with great cautions design construction project when in coral reef areas. We initiated the concept of “green engineering” for future developments in coral reef areas. Coral reefs are widely spreading in the whole SCS, and most of them developed since Miocene. Variations in coral reef structures provide good future oil-gas exploration. Because the SCS coral reefs have a long-developing history and a wide spatial distribution, they provide great potential in recording past environmental changes. 相似文献
11.
Rhodolites occurring over wide areas of the tropical Pacific (Solomons, Loyalties, Vanuatu and Australes) are dated in many places by diagnostic larger foraminifera as of Middle Miocene age. They are preceded in Early Miocene and succeeded in Late Miocene by hermatypic coral deposits. The processes linking this facies change with time to paleo-oceanographic events documented in deep-sea sediments are identified as sea-level rise drowning the reefs, a slight drop of winter surface water temperature and an increase of the fertility of surface waters inhibiting compensatory growth of hermatypic corals until sea-level fall restored the earlier, original conditions of deposition. 相似文献
12.
T. C. Brachert C. Betzler J. C. Braga J. M. Martin 《International Journal of Earth Sciences》1996,85(2):327-337
In order to evaluate the geological record of climatic change in neritic carbonates, we studied Late Miocene rock outcrops
in southern Spain. Six episodes of reef growth are documented (Burdigalian to Messinian) in Neogene basins of the Betic Cordillera,
which were located close to the margin of the global reef belt. The reefs are characterized by various zooxanthellate corals
which decrease in diversity with time, andHalimeda; the youngest reefs of the latest Messinian are characterized by the dominance of the genusPorites. Late Miocene coral reefs and reef-rimmed platforms alternate over time with non-reefal carbonate ramps characterized by
skeletal calcirudites or with gypsum such as that formed during the Messinian salinity crisis. The calcirudites lack reef
corals, calcified green algae and extensive marine cement, but exhibit skeletal components described from both modern and
fossil nontropical carbonates. These include bryozoans, mollusks, foraminifers, echinoderms and minor balanids, as well as
coralline algae of a bryomol association. The presence of some larger foraminifers indicates high temperatures, close to the
lower temperature threshold of the reef assemblage. Sea level lowstands and highstands are documented by wedges of bryomol
carbonate and chlorozoan patch reefs or prograding platforms. Thus, temperate climate depositional modes correspond to relatively
low sea levels, and warm-water modes to high sea levels. The Neogene infill of the Agua Amarga and Sorbas basins documents
two of these cycles. Other climate/sea-level cycles (including Messinian gypsum in the cool water depositional mode) are well
established in adjacent Neogene basins in southern Spain. This type of composite sequence seems to occur only along the margin
of the global reef belt and indicates an oscillatory latitudinal movement of the margin, which is associated with global climatic
change. The analysis of turnover in neritic depositional carbonate systems may therefore be considered a sensitive tool for
reconstructing climatic change from the fossil record. However, warm-water modes and temperate-water modes of carbonate sedimentation
and diagenesis differ significantly. For this reason the interpretation of composite system sequences by sequence stratigraphy
requires an extended concept. The particular type of mixed bryomolchlorozoan depositional sequence also bears some potential
for drowning, because sea level rise may be faster than the net production rate of temperate carbonate systems. 相似文献
13.
Jürgen Titschack Daniel Baum Ricardo De Pol‐Holz Matthias López Correa Nina Forster Sascha Flögel Dierk Hebbeln André Freiwald 《Sedimentology》2015,62(7):1873-1898
Cold‐water coral ecosystems present common carbonate factories along the Atlantic continental margins, where they can form large reef structures. There is increasing knowledge on their ecology, molecular genetics, environmental controls and threats available. However, information on their carbo‐nate production and accumulation is still very limited, even though this information is essential for their evaluation as carbonate sinks. The aim of this study is to provide high‐resolution reef aggradation and carbonate accumulation rates for Norwegian cold‐water coral reefs from various settings (sunds, inner shelf and shelf margin). Furthermore, it introduces a new approach for the evaluation of the cold‐water coral preservation within cold‐water coral deposits by computed tomography analysis. This approach allows the differentiation of various kinds of cold‐water coral deposits by their macrofossil clast size and orientation signature. The obtained results suggest that preservation of cold‐water coral frameworks in living position is favoured by high reef aggradation rates, while preservation of coral rubble prevails by moderate aggradation rates. A high degree of macrofossil fragmentation indicates condensed intervals or unconformities. The observed aggradation rates with up to 1500 cm kyr?1 exhibit the highest rates from cold‐water coral reefs so far. Reef aggradation within the studied cores was restricted to the Early and Late Holocene. Available datings of Norwegian cold‐water corals support this age pattern for other fjords while, on the shelf, cold‐water coral ages are reported additionally from the early Middle Holocene. The obtained mean carbonate accumulation rates of up to 103 g cm?2 kyr?1 exceed previous estimates of cold‐water coral reefs by a factor of two to three and by almost one order of magnitude to adjacent sedimentary environments (shelf, slope and deep sea). Only fjord basins locally exhibit carbonate accumulation rates in the range of the cold‐water coral reefs. Furthermore, cold‐water coral reef carbonate accumulation rates are in the range of tropical reef carbonate accumulation rates. These results clearly suggest the importance of cold‐water coral reefs as local, maybe regional to global, carbonate sinks. 相似文献
14.
Mineralogical, petrological and geochemical analyses of corals and associated skeletal limestones taken from three transects across the Late Quaternary raised coral reefs of the Huon Peninsula, Papua New Guinea, show that tectonic uplift can be related to the degree of subaerial diagenesis of the reefs. Where the uplift rate is high, Pleistocene corals frequently retain their aragonite mineralogy, even though the annual rainfall is relatively high. In contrast, similar age corals from low‐uplift areas are consistently altered neomorphically to calcite. The transformation of reef skeletal limestones shows a similar, but less pronounced, trend to the corals. Chemical analysis shows that the neomorphic calcite crystals of coral skeletons from the low‐uplift areas have relatively higher Sr and Mg concentrations, compared with those in high‐uplift areas. This may indicate that neomorphism of corals in the low‐uplift terraces takes place at a relatively higher rate and an earlier stage than that in the high‐uplift areas. The pattern of diagenesis of the Huon reefs can be explained by the effects of tectonic uplift on the regional hydrological regime. First, lower uplift rates allow a raised reef or any part of it to remain in the meteoric phreatic zone for a relatively long time. Second, river gorge slopes from low‐uplift regions have lower gradients and reef terraces in these areas have more extensive raised lagoon depressions than in high‐uplift areas. Thus, there is less runoff and consequently more extensive vadose percolation in the former areas. Third, the resulting low‐relief topography in low‐uplift areas prompts formation of soils on the terraces, and further increases the ability of interaction between coral reefs and formation water. 相似文献
15.
Corals are animals living in shallow seas (where they may form coral reefs) or in the deep sea. Because they fossilize well, these stones inform us in detail about the geological past; not only about the history of the Earth as a whole (rotation, tectonics, sea-level changes), but also about past local environmental conditions in the sea. Joint research of marine biology and marine geology can therefore solve many questions about our changing world, and can be used to discover what factors cause deterioration of living coral reefs. 相似文献
16.
陆生植物氮同位素组成与气候环境变化研究进展 总被引：3，自引：0，他引：3
近年来,由于植物氮同位素组成(δ15N)记载了气候环境变化的信息,因而被广泛应用于全球变化研究中,成为古气候环境再造和了解现代气候环境变化信息的有力工具。然而,人们对气候环境引起的δ15N变化及其指示的气候环境意义并不完全清楚,这就有可能限制植物δ15N在古气候环境变化等领域研究中的应用。在概述植物氮同位素分馏和植物不同氮源的氮同位素分布的基础上,分析了温度、降水、大气CO2浓度和海拔高度等气候环境因子对陆生植物δ15N的影响以及它们的关系。指出了目前研究中存在的问题及其研究前景,认为在全球变化研究中利用植物氮同位素技术不仅可以重建古气候环境(如重建大气CO2浓度变化),揭示历史时期温度、降水的变化,而且还可以在一定的时间和空间上综合反映生态系统氮循环的特征。 相似文献
17.
热带生物海岸对全球变化的响应 总被引：2，自引：0，他引：2
以热带生物海岸现代过程研究成果为基础,结合国内外相关资料,分析我国红树林海岸和珊瑚礁海岸对全球变暖、海平面上升、大气CO2浓度升高和海洋酸化的响应.其中,全球变暖和大气CO2浓度升高总体上有利于红树林生长发育,海平面上升对红树林和珊瑚礁的影响取决于红树林潮滩淤积速率和珊瑚礁礁坪堆积速率与海平面上升速率之间的对比关系.海平面加速上升将威胁部分红树林、珊瑚礁及其后的海岸堤防.全球变暖海表异常高温导致珊瑚白化、海洋酸化导致珊瑚和珊瑚藻钙化率降低将成为21世纪珊瑚礁的重大威胁.全球变化的不确定性和生态系统响应机制仍然有待进一步研究.主要是人类不合理开发活动导致目前红树林和珊瑚礁的广泛严重破坏,加强海岸带综合管理和生态环境保护,加强生态系统恢复重建,是有效适应本世纪全球变化影响的重要措施. 相似文献
18.
Climate change impacts on U.S. Coastal and Marine Ecosystems 总被引：1，自引：0，他引：1
Donald Scavia John C. Field Donald F. Boesch Robert W. Buddemeier Virginia Burkett Daniel R. Cayan Michael Fogarty Mark A. Harwell Robert W. Howarth Curt Mason Denise J. Reed Thomas C. Royer Asbury H. Sallenger James G. Titus 《Estuaries and Coasts》2002,25(2):149-164
Increases in concentrations of greenhouse gases projected for the 21st century are expected to lead to increased mean global air and ocean temperatures. The National Assessment of Potential Consequences of Climate Variability and Change (NAST 2001) was based on a series of regional and sector assessments. This paper is a summary of the coastal and marine resources sector review of potential impacts on shorelines, estuaries, coastal wetlands, coral reefs, and ocean margin ecosystems. The assessment considered the impacts of several key drivers of climate change: sea level change; alterations in precipitation patterns and subsequent delivery of freshwater, nutrients, and sediment; increased ocean temperature; alterations in circulation patterns; changes in frequency and intensity of coastal storms; and increased levels of atmospheric CO2. Increasing rates of sea-level rise and intensity and frequency of coastal storms and hurricanes over the next decades will increase threats to shorelines, wetlands, and coastal development. Estuarine productivity will change in response to alteration in the timing and amount of freshwater, nutrients, and sediment delivery. Higher water temperatures and changes in freshwater delivery will alter estuarine stratification, residence time, and eutrophication. Increased ocean temperatures are expected to increase coral bleaching and higher CO2 levels may reduce coral calcification, making it more difficult for corals to recover from other disturbances, and inhibiting poleward shifts. Ocean warming is expected to cause poleward shifts in the ranges of many other organisms, including commercial species, and these shifts may have secondary effects on their predators and prey. Although these potential impacts of climate change and variability will vary from system to system, it is important to recognize that they will be superimposed upon, and in many cases intensify, other ecosystem stresses (pollution, harvesting, habitat destruction, invasive species, land and resource use, extreme natural events), which may lead to more significant consequences. 相似文献
19.
五千年来南海海平面变化的研究 总被引：13，自引：0，他引：13
大型块状滨珊瑚的生长上限充其量只能达到大潮低潮面,礁坪面成为古高海面的极好标志。多数学者认为,５０００ａＢ．Ｐ．以来南海周边曾有３—６ｍ的高海面。但南海曾否有古高海面有着两种截然相反的意见。作者对南沙群岛、西沙群岛、海南岛、雷州半岛和台湾恒春半岛珊瑚礁的考察,实测礁顶面的高程,钻取岩芯样品做(１４)Ｃ测年,并收集大量古高海面礁的资料,进一步证实了南海同它的周边情况一样,确实出现过至少比现今高２—３ｍ的高海面。 相似文献
20.
选用华北平原地区长时间序列的HS1钻孔, 在对其沉积物主、微量元素含量、相关程度及地球化学指标分析的基础上对区内古环境变化、古气候演化进行了讨论。结果表明, 自上新世晚期(3.50 Ma)以来HS1钻孔所在区域经历了温暖湿润—温和偏湿—寒冷略干—寒冷干旱—温和偏干—温凉潮湿—温和偏干—温暖潮湿8个气候演化阶段, 整体趋势由湿润变为干旱, 这与孔内孢粉、碳-氧同位素和粒度记录具有同趋性。区域对比结果显示, 重建长时间尺度内的气候变化, 地球化学可作为孢粉的更优等效指标, 短时间序列内的气候变化则以高分辨率的孢粉记录最优。区内整体处于陆缘弱氧化的沉积环境, 且第四纪时期化学风化程度相较古土壤层发育的上新世晚期更弱。HS1钻孔不同地质时期冲洪积物的元素地球化学组成的差异性, 主要取决于其母质来源和搬运距离; 具体表现为一方面与受地形地貌影响、一级构造调节转换带及次级构造单元控制的古水流有关, 另一方面与受气候变化影响的沉积环境、水动力条件、化学风化和成土作用等有关。 相似文献