山东塔山黑松树轮稳定碳同位素与气候要素的响应

在山东塔山东坡采集黑松(Pinus thunbergii Parl)树芯样本,建立树轮稳定碳同位素年表,发现在数十年尺度上与工业革命以来大气稳定碳同位素比率降低的事实相吻合,但1976年之后树轮稳定碳同位素比率(δ13C)有逐渐上升的趋势,其原因可能是大气中CO2的积累效应导致了大气与海洋之间CO2交换的不稳定性.通过对样本δ13C序列校正提取高频序列后与气象站气象资料进行相关分析,发现树轮δ13C序列与温度呈正相关,与降水量和日照时数呈负相关,温度和降水以及日照时数对树轮δ13C的影响均存在一定的滞后效应,该地区树木生长的限制性气候因子比较复杂,可能受到多种气候因子的共同影响,在气候重建研究中应当慎重选择.     

贡嘎山木本植物碳同位素沿海拔梯度的变化

对贡嘎山东坡不同海拔的主要木本植物稳定碳同位素的组成进行了测定。结果表明:22种木本植物叶片δ_¹³C值变化范围为-3.236%～-2.521%,平均值(-2.957±0.163)%; 不同海拔间植物叶片δ_¹³C值差异显著,随海拔上升叶片δ_¹³C值呈增加趋势; 同种植物(大叶金顶杜鹃、峨眉冷杉、水青树、箭竹)的δ_¹³C值随海拔的增加也呈相同的变化趋势。不同生活型植物叶片δ_¹³C值之间差异显著,落叶树种显著高于常绿树种。叶片δ_¹³C值与6—9月平均温度呈显著的负相关关系,与6—8月降水量呈显著的正相关关系,温度、降水是影响木本植物叶片δ_¹³C值海拔差异的主要因子。     

树木稳定碳同位素比率的方位差异及其机理初步研究

测定了祁连山一棵千年圆柏不同方位上树木稳定碳同位素比率 (δ13 C值 )和光合作用色素 .结果显示 ,树木中 δ13 C值具有明显的方位差异 :北面的 δ13 C值相对较高 ,西面的 δ13 C值相对较低 .树叶中叶绿素含量、类胡萝卜素含量和类黄酮含量的方位变化趋势与δ13 C值类似 .分析表明 ,后者的方位变化是树木对局部环境的光辐射差异长期适应的结果 ,而树木中δ13 C值的方位差异可归咎于光同时引起光合作用和呼吸作用变化的缘故     

鱼耳石的碳、氧稳定同位素成分研究

鱼耳石是沉淀在真骨鱼类内耳中的结石,矿物成分为碳酸盐类的文石.鱼耳石每日生长一条环带,且其形成过程中在文石矿物和鱼生活周围的水体之间达到(或接近于达到)氧同位素平衡,因而18O/16O的同位素分馏与温度密切相关.鱼耳石中的碳同位素分馏与鱼生活周围的水体不平衡,但可以记录鱼类的性成熟和食物源方面的变化.因此,鱼耳石的氧、碳稳定同位素成分(δ18O和δ13C)真实地记录了鱼类的生态环境和变化,可视为一种天然的环境变化的标记.伴随着微取样技术和同位素质谱仪分析灵敏度的提高,鱼耳石的同位素成分研究近年来在渔业和海洋环境重建方面得到了广泛的应用.     

北京大学未名湖沉积物中公元1747年以来气候变化的氧碳同位素记录

对北京大学未名湖底泥层做了²¹⁰Pb计年法和¹³⁷Cs时标法定年以及氧碳同位素分析。结果表明厚度约50cm的底泥层形成于公元1747—1997年之间,湖泥中碳酸盐的氧碳同位素组成和有机物含量记录了北京地区公元1747年以来的气候变化：1866年以前冬季风盛行,气候比较寒冷干燥;1887年以后夏季风盛行,气候比较温暖湿润,其中1907—1926年是近250年以来气候最为温暖湿润的时期;介于两者之间的1867—1886年是气候急剧转型的时期,也是自然灾害频繁出现的时期。     

碳稳定同位素的分离

简要说明了^13C同位素的用途。详细论述了碳稳定同位素的各种分离方法，并对各种方法进行了分析与展望。     

稳定碳同位素δ13C1在煤层气田勘探中的应用

煤层气分布状态主要受控于两种地质效应：一种是热动力学机制控制下的同位素分馏效应，存在于煤层气生成期；另一种是甲烷δ^13C1解吸一扩散一运移效应，存在于煤层气生成后，源于埋深变浅而造成的泄压条件下。文中以沁水煤层气田为例，探讨了沁水煤层气田煤层气δ^13C1解吸-扩散-运移效应。认为可以利用煤层气δ^13C1特征来评价煤层气保存条件和开采稳定性，指导煤层气田的勘探和开发。     

大洋缺氧事件的碳稳定同位素响应

从碳稳定同位素组成及其分馏机理出发 ,系统探讨了大洋缺氧事件与海相碳酸盐和有机碳稳定同位素分馏之间的关系。缺氧事件期间 ,由于生物大批死亡和快速埋藏 ,其分解消耗海水中大量的溶解氧 ,引起大洋水体缺氧 ,富含 1 2 C的有机质从而得以大量保存 ;相应地大气和海水中富 1 3 C,同期海相碳酸盐岩碳同位素 δ值 (δ1 3C)正偏。在世界各地缺氧事件层内 ,无一例外地碳酸盐岩碳稳定同位素出现了不同程度的正偏 ,Cenomanian- Turonian 界线偏幅达～2‰。海相碳酸盐与有机质碳稳定同位素变化不仅可以提供地质历史中有机碳埋藏量的记录。研究全球碳循环变化 ,还可能追溯有机碳风化和埋藏速率的变化 ,定性地恢复大气 p CO2 变化。     

稳定同位素^13C防伪墨水的研制及检测

将稳定同位素^13C作为一种新型示踪剂加入到打印机墨水中,采用质谱检测方法寻求其最佳浓度。采用含有不同浓度^13C的打印机墨水,用双路进样的质谱方法检测。得到该墨水同位素浓度在大于（1：230）0．4％以上具有稳定的同位素丰度。用稳定同位素^13C作为示踪剂可以开发出大量防伪产品运用到公共安全领域。     

抚仙湖沉积物稳定碳同位素特征及来源分析

通过测定和分析抚仙湖和入湖河流的表层沉积物、流域表层土壤、抚仙湖典型沉水植物、表层湖水中悬浮颗粒物的总有机碳、碳氮比值及稳定碳同位素比值,探讨抚仙湖表层沉积物中有机质来源及特征.实验结果表明:抚仙湖流域表层土壤呈现明显的空间异质性.抚仙湖沉积物中的有机质主要来源于湖泊自身的内源输入,少部分为陆源输入,陆源输入有机质主要...     

Extinction and climate change

Arising from F. He & S. P. Hubbell 473, 368-371 (2011). Statistical relationships between habitat area and the number of species observed (species-area relationships, SARs) are sometimes used to assess extinction risks following habitat destruction or loss of climatic suitability. He and Hubbell argue that the numbers of species confined to-rather than observed in-different areas (endemics-area relationships, EARs) should be used instead of SARs, and that SAR-based extinction estimates in the literature are too high. We suggest that He and Hubbell's SAR estimates are biased, that the empirical data they use are not appropriate to calculate extinction risks, and that their statements about extinction risks from climate change do not take into account non-SAR-based estimates or recent observations. Species have already responded to climate change in a manner consistent with high future extinction risks.     

膜脂与植物抗寒性关系研究进展

对植物的低温反应，抗寒机制以及转基因技术在改良植物抗寒性等方面的研究进展作一综述。     

Effects of climate change on biodiversity

1 Rise of studies on climate change＇s effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America＇s annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].     

Emperor penguins and climate change

Variations in ocean-atmosphere coupling over time in the Southern Ocean have dominant effects on sea-ice extent and ecosystem structure, but the ultimate consequences of such environmental changes for large marine predators cannot be accurately predicted because of the absence of long-term data series on key demographic parameters. Here, we use the longest time series available on demographic parameters of an Antarctic large predator breeding on fast ice and relying on food resources from the Southern Ocean. We show that over the past 50 years, the population of emperor penguins (Aptenodytes forsteri) in Terre Adélie has declined by 50% because of a decrease in adult survival during the late 1970s. At this time there was a prolonged abnormally warm period with reduced sea-ice extent. Mortality rates increased when warm sea-surface temperatures occurred in the foraging area and when annual sea-ice extent was reduced, and were higher for males than for females. In contrast with survival, emperor penguins hatched fewer eggs when winter sea-ice was extended. These results indicate strong and contrasting effects of large-scale oceanographic processes and sea-ice extent on the demography of emperor penguins, and their potential high susceptibility to climate change.     

Impact of urbanization and land-use change on climate

The most important anthropogenic influences on climate are the emission of greenhouse gases and changes in land use, such as urbanization and agriculture. But it has been difficult to separate these two influences because both tend to increase the daily mean surface temperature. The impact of urbanization has been estimated by comparing observations in cities with those in surrounding rural areas, but the results differ significantly depending on whether population data or satellite measurements of night light are used to classify urban and rural areas. Here we use the difference between trends in observed surface temperatures in the continental United States and the corresponding trends in a reconstruction of surface temperatures determined from a reanalysis of global weather over the past 50 years, which is insensitive to surface observations, to estimate the impact of land-use changes on surface warming. Our results suggest that half of the observed decrease in diurnal temperature range is due to urban and other land-use changes. Moreover, our estimate of 0.27 degrees C mean surface warming per century due to land-use changes is at least twice as high as previous estimates based on urbanization alone.     

Land-atmosphere coupling and climate change in Europe

Increasing greenhouse gas concentrations are expected to enhance the interannual variability of summer climate in Europe and other mid-latitude regions, potentially causing more frequent heatwaves. Climate models consistently predict an increase in the variability of summer temperatures in these areas, but the underlying mechanisms responsible for this increase remain uncertain. Here we explore these mechanisms using regional simulations of recent and future climatic conditions with and without land-atmosphere interactions. Our results indicate that the increase in summer temperature variability predicted in central and eastern Europe is mainly due to feedbacks between the land surface and the atmosphere. Furthermore, they suggest that land-atmosphere interactions increase climate variability in this region because climatic regimes in Europe shift northwards in response to increasing greenhouse gas concentrations, creating a new transitional climate zone with strong land-atmosphere coupling in central and eastern Europe. These findings emphasize the importance of soil-moisture-temperature feedbacks (in addition to soil-moisture-precipitation feedbacks) in influencing summer climate variability and the potential migration of climate zones with strong land-atmosphere coupling as a consequence of global warming. This highlights the crucial role of land-atmosphere interactions in future climate change.     

Constraints on radiative forcing and future climate change from observations and climate model ensembles

The assessment of uncertainties in global warming projections is often based on expert judgement, because a number of key variables in climate change are poorly quantified. In particular, the sensitivity of climate to changing greenhouse-gas concentrations in the atmosphere and the radiative forcing effects by aerosols are not well constrained, leading to large uncertainties in global warming simulations. Here we present a Monte Carlo approach to produce probabilistic climate projections, using a climate model of reduced complexity. The uncertainties in the input parameters and in the model itself are taken into account, and past observations of oceanic and atmospheric warming are used to constrain the range of realistic model responses. We obtain a probability density function for the present-day total radiative forcing, giving 1.4 to 2.4 W m-2 for the 5-95 per cent confidence range, narrowing the global-mean indirect aerosol effect to the range of 0 to -1.2 W m-2. Ensemble simulations for two illustrative emission scenarios suggest a 40 per cent probability that global-mean surface temperature increase will exceed the range predicted by the Intergovernmental Panel on Climate Change (IPCC), but only a 5 per cent probability that warming will fall below that range.     

Relationships between tree-ring width index and NDVI of grassland in Delingha

The responses of terrestrial ecosystem to and their impacts on global climate change are key issues in global change research. More studies on vegetationmonitoring and land cover change have been performed by using remote sensing data recently, which bene…