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1.
Values of the oxygen isotope ratios (delta(18)O) in tree-ring cellulose closely reflect the delta(18)O values in atmospheric precipitation and hence mean annual temperature. The change in delta(18)O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of delta(18)O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2 degrees +/- 0.5 degrees C per 1000 meters calculated from cellulose delta(18)O values agrees with the accepted mean annual lapse rate of 5 degrees C per 1000 meters for this region. Cellulose delta(18)O values and delta(18)O values of carbon dioxide equilibrated with leaf water differ by a fixed 16 per mil. 相似文献
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Pore fluids from the upper 60 meters of sediment 3000 meters below the surface of the tropical Atlantic indicate that the oxygen isotopic composition (delta18O) of seawater at this site during the last glacial maximum was 0.8 ± 0.1 per mil higher than it is today. Combined with the delta18O change in benthic foraminifera from this region, the elevated ratio indicates that the temperature of deep water in the tropical Atlantic Ocean was 4°C colder during the last glacial maximum. Extrapolation from this site to a global average suggests that the ice volume contribution to the change in delta18O of foraminifera is 1.0 per mil, which partially reconciles the foraminiferal oxygen isotope record of tropical sea surface temperatures with estimates from Barbados corals and terrestrial climate proxies. 相似文献
4.
张掖大气降水的δ~（18）O特征及水汽来源 总被引：1，自引：1，他引：1
利用全球同位素监测网（GNIP）张掖站的大气降水环境同位素数据,分析了张掖大气降水中δ18O的变化规律,通过分析其与气温和降水之间的关系,发现δ18O月加权平均值表现出很好的温度效应,且其与降水成正相关关系,这与张掖干旱半干旱气候有关。对张掖大气降水线的研究发现,当地大气降水线（LMWL）比全球降水线（GMWL）及中国降水线的斜率和截距都低。冬秋季降水线的斜率低于春夏季,原因是局地蒸发的水汽在春夏季占有较大的比重,并且受海洋性水汽影响较大。利用降水同位素资料结合后向轨迹法（Backwards Trajectory）对张掖水汽来源进行推断,结果表明,张掖全年以西风带大陆性水汽为主,春夏季还会受到海洋性水汽的影响,同时由于较高的温度,春夏季受局地蒸发性水汽的影响相当明显。 相似文献
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Timing, duration, and transitions of the last interglacial Asian monsoon 总被引：16，自引：0，他引：16
Yuan D Cheng H Edwards RL Dykoski CA Kelly MJ Zhang M Qing J Lin Y Wang Y Wu J Dorale JA An Z Cai Y 《Science (New York, N.Y.)》2004,304(5670):575-578
Thorium-230 ages and oxygen isotope ratios of stalagmites from Dongge Cave, China, characterize the Asian Monsoon and low-latitude precipitation over the past 160,000 years. Numerous abrupt changes in 18O/16O values result from changes in tropical and subtropical precipitation driven by insolation and millennial-scale circulation shifts. The Last Interglacial Monsoon lasted 9.7 +/- 1.1 thousand years, beginning with an abrupt (less than 200 years) drop in 18O/16O values 129.3 +/- 0.9 thousand years ago and ending with an abrupt (less than 300 years) rise in 18O/16O values 119.6 +/- 0.6 thousand years ago. The start coincides with insolation rise and measures of full interglacial conditions, indicating that insolation triggered the final rise to full interglacial conditions. 相似文献
6.
Shackleton NJ 《Science (New York, N.Y.)》2000,289(5486):1897-1902
The deep-sea sediment oxygen isotopic composition (delta(18)O) record is dominated by a 100,000-year cyclicity that is universally interpreted as the main ice-age rhythm. Here, the ice volume component of this delta(18)O signal was extracted by using the record of delta(18)O in atmospheric oxygen trapped in Antarctic ice at Vostok, precisely orbitally tuned. The benthic marine delta(18)O record is heavily contaminated by the effect of deep-water temperature variability, but by using the Vostok record, the delta(18)O signals of ice volume, deep-water temperature, and additional processes affecting air delta(18)O (that is, a varying Dole effect) were separated. At the 100,000-year period, atmospheric carbon dioxide, Vostok air temperature, and deep-water temperature are in phase with orbital eccentricity, whereas ice volume lags these three variables. Hence, the 100,000-year cycle does not arise from ice sheet dynamics; instead, it is probably the response of the global carbon cycle that generates the eccentricity signal by causing changes in atmospheric carbon dioxide concentration. 相似文献
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Large, abrupt shifts in the (l8)O/(16)O ratio found in Greenland ice must reflect real features of the climate system variability. These isotopic shifts can be viewed as a result of air temperature fluctuations, but determination of the cause of the changes-the most crucial issue for future climate concerns-requires a detailed understanding of the controls on isotopes in precipitation. Results from general circulation model experiments suggest that the sources of Greenland precipitation varied with different climate states, allowing dynamic atmospheric mechanisms for influencing the ice core isotope shifts. 相似文献
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Oxygen isotope zoning in garnet 总被引：1，自引：0，他引：1
Oxygen isotope zoning was examined within garnet with the use of the stable isotope laser probe. Four metamorphic garnets from the regional metamorphic terrane in Vermont and the skarn deposit at Carr Fork, Utah, were examined and were found to be concentrically zoned in delta(18)O values. The largest variations in delta(18)O values were observed in the regional metamorphic garnets, where delta(18)O values change by 3 per mil from core to rim. These oxygen isotope zoning profiles reflect the changes in the delta(18)O values of the rocks during garnet growth, which are caused by infiltration of fluids and by dehydration reactions during metamorphism. 相似文献
9.
Friedman I Lipman PW Obradovich JD Gleason JD Christiansen RL 《Science (New York, N.Y.)》1974,184(4141):1069-1072
Oxygen isotope analyses of sanidine phenocrysts from rhyolitic sequences in Nevada, Colorado, and the Yellowstone Plateau volcanic field show that delta(18)O decreased in these magmas as a function of time. This decrease in delta(18)O may have been caused by isotopic exchange between the magma and groundwater low in (18)O. For the Yellowstone Plateau rhyolites, 7000 cubic kilometers of magma could decrease in delta(18)O by 2 per mil in 600,000 years by reacting with water equivalent to 3 millimeters of precipitation per year, which is only 0.3 percent of the present annual precipitation in this region. The possibility of reaction between large magmatic bodies and meteoric water at liquidus temperatures has major implications in the possible differentiation history of the magma and in the generation of ore deposits. 相似文献
10.
The Eocene greenhouse climate state has been linked to a more vigorous hydrologic cycle at mid- and high latitudes; similar information on precipitation levels at low latitudes is, however, limited. Oxygen isotopic fluxes track moisture fluxes and, thus, the δ(18)O values of ocean surface waters can provide insight into hydrologic cycle changes. The offset between tropical δ(18)O values from sampled Eocene sirenian tooth enamel and modern surface waters is greater than the expected 1.0 per mil increase due to increased continental ice volume. This increased offset could result from suppression of surface-water δ(18)O values by a tropical, annual moisture balance substantially wetter than that of today. Results from an atmospheric general circulation model support this interpretation and suggest that Eocene low latitudes were extremely wet. 相似文献
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利用滨州市1971~2000年降水、气温、湿度等资料,解析滨州市(鲁北地区)干旱化趋势。结果表明,滨州市降水量每10年减少26mm。升温达0.03℃/a,夏秋季温度升高,其中20世纪90年代比70年代高出0.5℃以上,特别是冬季竟高出了1.4℃。这与全国乃至全球变暖趋势一致。通过对滨州1971~2000年观测资料中有关数据的计算,滨州市近30年气候变化已呈现出年降水量总体上持续降低、气温总体上持续升高,且当地水热平衡已明显呈现出新的关系和规律的状况。滨州市年湿润指数呈明显下降趋势,气候干旱化。湿润指数平均10年减少0.057,主要原因是降水量逐年减少,气温逐年上升。受其影响,蒸散量平均每10年增加26.85 mm。滨州市这种干旱化趋势与副高综合指数、副高面积和强度指数的年代际变化与极涡中心平均纬度和平均经度的年代际变化有直接关系。 相似文献
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Friedman I O'neil JR Adami LH Gleason JD Hardcastle K 《Science (New York, N.Y.)》1970,167(3918):538-540
The water content of the breccia is 150 to 455 ppm, with a deltaD from-580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a deltaD of -830 to -970 per mil. The CO(2) is 290 to 418 ppm with delta (13)C = + 2.3 to + 5.1 per mil and delta(18)O = 14.2 to 19.1 per mil. Non-CO(2) carbon is 22 to 100 ppm, delta(13)C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H(2)O (D = 80 ppm) and 188 ppm total carbon(delta(13)C = -17.6 per mil). The (18)O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100 degrees to 1300 degrees C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite. 相似文献
13.
Strontium isotopic composition of estuarine sediments as paleosalinity-paleoclimate indicator 总被引：1，自引：0，他引：1
The strontium isotopic composition of biogenic precipitates that occur in estuarine sediments can be used as proxy indicator of paleosalinity and for assessing precipitation and river discharge rates over thousands of years. In the San Francisco Bay estuary, river water with low (87)Sr/(86)Sr ratio (average, 0.7065) and low Sr concentration (0.13 parts per million) mixes with seawater with a higher (87)Sr/(86)Sr ratio (0.7092) and Sr concentration (7.9 parts per million). The predicted mixing relation between salinity and Sr isotopic composition is confirmed by measurements of modern estuarine surface waters. A paleosalinity record obtained from foraminifera for the ancestral San Francisco Bay during oxygen isotope substage 5e of the last interglacial reflects a global rise and fall of sea level, and short time-scale variations related to fluctuations in discharge rates of the Sacramento and San Joaquin rivers. 相似文献
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水汽稳定同位素组成（v）可以为水循环研究提供大量有价值的信息。近年来,稳定同位素红外光谱技术（isotope ratio infrared spectroscopy, IRIS）的发展为获得高时间分辨率的水汽稳定同位素原位测量数据提供了可能。在水汽稳定同位素组成研究取得了巨大进展的同时,适时对v及其在生态系统水循环应用的研究进展进行综述,可以为后续研究提供借鉴和参考。从5个方面对水汽稳定同位素组成的研究进行了详述,分别是:①水汽稳定同位素分析仪的在线校正;②v的变化规律;③氘过量的变化特征;④蒸散发组分的区分;⑤叶片水18O富集的估算。目前水汽稳定同位素的观测站点十分稀少,尽快建立全球的水汽稳定同位素观测网络并进行长时间的连续观测,将大大促进生态系统水循环和生态过程解析及其模拟方面的研究。同时,将稳定同位素在线观测数据和通量观测以及遥感模型结合起来,可以更好地揭示区域乃至全球水循环模式和机理机制。表1参81 相似文献
15.
Idso SB 《Science (New York, N.Y.)》1980,207(4438):1462-1463
The mean global increase in thermal radiation received at the surface of the earth as a consequence of a doubling of the atmospheric carbon dioxide content is calculated to be 2.28 watts per square meter. Multiplying this forcing function by the atmosphere's surface air temperature response function, which has recently been determined by three independent experimental analyses to have a mean global value of 0.113 K per watt per square meter, yields a value of 相似文献
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The ocean is an important global source of nitrous oxide (N(2)O), a greenhouse gas that contributes to stratospheric ozone destruction. Bacterial nitrification and denitrification are thought to be the primary sources of marine N(2)O, but the isotopic signatures of N(2)O produced by these processes are not consistent with the marine contribution to the global N(2)O budget. Based on enrichment cultures, we report that archaeal ammonia oxidation also produces N(2)O. Natural-abundance stable isotope measurements indicate that the produced N(2)O had bulk δ(15)N and δ(18)O values higher than observed for ammonia-oxidizing bacteria but similar to the δ(15)N and δ(18)O values attributed to the oceanic N(2)O source to the atmosphere. Our results suggest that ammonia-oxidizing archaea may be largely responsible for the oceanic N(2)O source. 相似文献
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应用梧州地区5个站点1954～2011年逐月降水和平均气温资料,采用趋势分析、小波分析法,分析了近58年梧州地区降水和气温的变化趋势、变化周期性等气候特征。结果表明,近58年梧州地区年降水量、冬季降水量总体呈增加趋势,年降水量存在25年左右、10年左右的震荡周期,季降水量存在一个10年左右的振荡周期最为明显;年平均气温存在一个9～11年的振荡周期;近58年梧州全年、夏季、秋季、冬季平均气温总的趋势均表现为升高趋势,但升高的幅度不同,梧州全年平均气温上升幅度为0.152℃/10a,气候变暖表现明显;梧州58年来出现夏季严重多雨事件8次,严重少雨事件7次;出现秋季严重多雨事件3次,严重少雨事件2次。 相似文献
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[目的]研究我国西北干旱区春季降水与全球海温的相关特征。[方法]利用1979～2008年GPCP全球逐月降水资料和NOAAERSST海温资料,采用相关分析和合成分析等方法,分析了西北干旱区30年来降水特征及其与全球海温的相关分布特征。[结果]1979～2008年西北干旱区春季降水量均呈波动增加;15°S～22°N、45°～105°E范围的印度洋海温对西北干旱区春季的降水具有持续性影响,可以作为一个预报西北干旱区春季降水的稳定因子。印度洋、孟加拉湾、阿拉伯海地区的海温偏高时,春季西北干旱区的降水有可能偏多;同时前期夏、秋、冬季赤道东太平洋附近的海温若偏高,对于次年西北干旱区春季降水很有利;阿拉伯海、中印度洋以及西太平洋地区的海温场是影响西北干旱区春季降水的关键因素。[结论]该研究为干旱区降水的预测预报提供理论依据。 相似文献
19.
Prell WL 《Science (New York, N.Y.)》1984,226(4675):692-694
Oxygen isotope data for a Pliocene interval from 3.6 to 2.8 million years ago show a mean increase (0.5 per mil) of benthic delta(18)O at about 3.2 million years ago, whereas planktic delta(18)O does not increase. This lack of covariance indicates that the event at 3.2 million years did not result in a permanent increase in the ice budget of either the Northern or the Southern Hemisphere. 相似文献
20.
基于18O稳定同位素对银川平原北部4种灌木夏季水分利用特征研究 总被引：1，自引：0，他引：1
为了分析银川平原北部4种灌木对不同水源的利用特征,测定了20年生多枝柽柳(Tama-rix ramosissima)、3年生多枝柽柳、3年生宁夏枸杞(Lycium barbarum)和3年生四翅滨藜(Atri-plex canescens)木质部水及不同潜在水源稳定氧同位素组成(δ18 O),应用同位素线性混合模型估算了不同灌木对不同水源的利用率。结果表明:不同深度土壤水δ18 O值存在较大差异,并呈规律性变化。表层(0～5cm)土壤水δ18 O值较井水δ18 O值偏正,说明其受蒸发影响较大。120～140cm土层δ18 O值最正,说明该土层同位素分馏作用最大。140～200cm土壤水受蒸发影响最小,土壤水δ18 O与井水最为接近。3年生多枝柽柳、3年生宁夏枸杞、3年生四翅滨藜的木质部水δ18 O值分别为-8.62‰、-8.64‰和-9.23‰,均比20年生多枝柽柳木质部水δ18 O(-9.40‰)偏正。用Iso-Source软件计算的结果显示20年生多枝柽柳和3年生四翅滨藜对地下水和表层土壤水(0～5cm)的利用程度较高,分别利用11.6%和9.3%的地下水,18.2%和14.6%的表层水。3年生多枝柽柳和3年生宁夏枸杞对40～120cm土层水分利用程度较高,分别为93.8%和92.3%。 相似文献