气候变化在今后1000年中是不可逆的

NOAA的Amanda Scott等最近的研究表明,即使CO2排放减少,它对全球温度变化的影响在今后很长时期仍然会非常显著,而且这种变化是不可逆的。影响包括全球海平面升高和某些地区降水减少。变化的后果可能会表现为供水紧张、火灾频繁、沙漠扩大以及农业歉收。研究人员指出,目前海洋通过吸收热量使全球变暖减缓,最终会将这些热量释放回大气,导致更为显著的全球性增温,格陵兰和南极的冰原融化引起海平面上升。     

Modeling Methane Emissions from Paddy Rice Fields under Elevated Atmospheric Carbon Dioxide Conditions

Methane(CH4 ) emissions from paddy rice fields substantially contribute to the dramatic increase of this greenhouse gas in the atmosphere.Due to great concern about climate change,it is necessary to predict the effects of the dramatic increase in atmospheric carbon dioxide(CO2 ) on CH4 emissions from paddy rice fields.CH4MOD 1.0 is the most widely validated model for simulating CH4 emissions from paddy rice fields exposed to ambient CO2(hereinafter referred to as aCO2 ).We upgraded the model to CH4MOD 2.0 b...     

Impacts of Future NOx and CO Emissions on Regional Chemistry and Climate over Eastern China

A coupled chemical/dynamical model (SOCOL-SOlar Climate Ozone Links) is applied to study the impacts of future enhanced CO and NOx emissions over eastern China on regional chemistry and climate. The result shows that the increase of CO and NOx emissions has significant effects on regional chemistry, including NOx, CO, O₃, and OH concentrations. During winter, the CO concentration is uniformly increased in the northern hemisphere by about 10 ppbv. During summer, the increase of CO has a regional distribution. The change in O₃, concentrations near eastern China has both strong seasonal and spatial variations. During winter, the surface O₃, concentrations decrease by about 2 ppbv, while during summer they increase by about 2 ppbv in eastern China. The changes of CO, NOx, and O₃, induce important impacts on OH concentrations. The changes in chemistry, especially O₃, induce important effects on regional climate. The analysis suggests that during winter, the surface temperature decreases and air pressure increases in central-eastern China. The changes of temperature and pressure produce decreases in vertical velocity. We should mention that the model resolution is coarse, and the calculated concentrations are generally underestimated when they are compared to measured results. However, because this model is a coupled dynamical/chemical model, it can provide some useful insights regarding the climate impacts due to changes in air pollutant emissions.     

CO2 Flux Estimation by Different Regression Methods from an Alpine Meadow on the Qinghai-Tibetan Plateau

CO2 efflux was estimated using different regression methods in static chamber observation from an alpine meadow on the Qinghai-Tibetan Plateau. The CO2 efflux showed a seasonal pattern, with the maximun flux occurring in the middle of July. The temperature sensitivity of CO2 efflux (Q10> was 3.9, which was at the high end of the range of global values. CO2 emissions calculated by linear and nonlinear regression were significantly different (p<0.05). Compared with the linear regression, CO2 emissions calculated by exponential regression and quadratic regression were 12.7% and 11.2% larger, respectively. However, there were no significant differences in temperature sensitivity values estimated by the three methods. In the entire growing season, the CO2 efflux estimated by linear regression may be underestimated by up to 25% compared to the real CO2 efflux. Consequently, great caution should be taken when using published flux data obtained by linear regression of static chamber observations to estimate the regional CO2 flux in alpine meadows on the Qinghai-Tibetan Plateau.     

大气CO215 μm吸收带对温度依赖关系的研究

利用最新版本的大气分子吸收光谱资料HITRAN 2004,以CO215 μm吸收带为例,通过精确的逐线积分模式,详细讨论了温度对谱线半宽度、线强以及吸收系数的影响。结果发现：吸收系数对温度的依赖关系主要受线强对温度依赖关系的影响,受半宽度对温度依赖关系的影响较小;在吸收带的中心区域,温度对线强和吸收系数的影响较弱,而在带翼影响较强。     

全球变化的生态系统适应性

全球变化的适应性研究已经成为全球变化研究的重点,亦是制定全球变化适应对策的关键。基于全球变化的定义,从生态系统对全球变化适应的4个方面：①对大气CO2浓度变化的适应性;②对气候变化的适应性;③对CO2浓度与气候变化协同作用的适应性;④对人为干扰的适应性,综述了当前的研究成果,进而提出了未来关于全球变化的生态系统适应性研究需要重视的方面,尤其是关于生态系统对全球变化响应的阈值研究应引起高度重视。     

莺歌海盆地乐东区片钠铝石特征及其对浅层CO2充注的指示

作为天然CO₂的示踪矿物,片钠铝石的形成与CO₂充注密切相关.莺歌海盆地乐东区乐东X构造莺歌海组-黄流组CO₂气藏内发育含片钠铝石砂岩,在开展的岩石学和地球化学研究基础上,确定了研究区片钠铝石的产状和纵向分布特征,分析了形成片钠铝石的“碳来源”和气水条件,进而探讨了与片钠铝石具有成因联系的CO₂的成因.乐东X构造含片钠铝石砂岩为细—极细粒长石石英砂岩和岩屑石英砂岩,片钠铝石主要以充填孔隙及交代颗粒的形式产出,是成岩共生序列中形成较晚的自生矿物之一.在纵向上,片钠铝石仅集中发育于高含CO₂气层的底部以及其下的水层中,这一分布特征以地质实例的形式证实了片钠铝石的形成需要水的参与.研究区浅层CO₂充注后形成的碳酸盐矿物为片钠铝石和铁白云石.片钠铝石的碳氧同位素特征表明形成片钠铝石的“碳”与LDX构造气层中CO₂具有相同的碳来源,以无机幔源成因CO₂为主.红河断裂以及莺歌海盆地中央坳陷内一系列底辟构造及伴生的垂向裂隙可能为CO₂的运移通道.      

CO2驱微观可视化技术在超低渗储层中的应用可行性研究:以鄂尔多斯盆地为例

CO₂驱油是提高特低渗、超低渗油藏驱油效率的重要途径,但目前由于匮乏CO₂驱油微观可视化实验技术,制约了CO₂驱油微观机理研究及驱油效果评价。本研究提出特低、超低渗油藏高温高压下CO₂驱油微观可视化实验技术,为该类油藏CO₂驱油机理研究提供良好的研究手段。以鄂尔多斯盆地超低渗储层为例,利用首次研制成功的高温、高压、防暴真实砂岩模型,成功进行了CO₂驱油微观可视化实验研究,首次镜下观察不同相态CO₂在超低渗储层复杂孔喉中驱替原油的动态现象,重新认识超低渗油藏注CO₂驱油时不同孔喉结构中CO₂赋存状态和渗流规律。结果表明,储层微观孔喉结构,尤其是孔喉大小分布的均匀程度,对CO₂驱油效率的重要影响超出预期,直接决定着CO₂能否进入储层以及其后的渗流路径。CO₂驱油微观可视化实验技术可有效进行CO₂驱油微观机理研究及驱油效果评价研究,并为后期进行油藏矿场试验提供指导意见。     

白云凹陷第三系储层中铁白云石的成因机理及与CO2活动的关系

白云凹陷第三系储层中发育大量的铁白云石,受研究区热流背景的影响,铁白云石主要见于高地温梯度地区埋深1000～3000m、地层温度60～130℃的浅—中部地层中及CO_2热流体活动区域。铁白云石的δ~(13)C值(-2.83‰～-1.83‰)具有无机成因的特征,与研究区气藏中幔源岩浆成因CO_2的δ~(13)C值较为一致,铁白云石的δ~(18)O值(-9.45‰～-5.37‰)和~(87)Sr/~(86)Sr值(0.7101～0.7161)也反映了其沉淀受到深部热流体活动的影响。以两口典型CO_2气井为例,储层中流体包裹体均一温度及蒙脱石向伊利石的演化特征证明储层经历了热流体侵入;CO_2热流体活动区域不仅是铁白云石集中分布地带,并出现片钠铝石+铁白云石+菱铁矿等示踪CO_2运移、聚集的自生矿物组合。地层中铁白云石、高岭石含量与气藏中CO_2的含量呈正相关关系,绿泥石含量与CO_2、铁白云石含量呈反消长关系。高地温梯度地区丰富的CO_2热流体活动是该地区储层中铁白云石沉淀与含量高的重要原因,无机岩浆成因CO_2是铁白云石沉淀的主要碳源,CO_2热流体充注造成绿泥石等黏土矿物异常转化,为铁白云石沉淀提供了所需的Fe~(2+)、Mg~(2+)离子。     

水库水体二氧化碳分压研究进展

天然水体中存在同化二氧化碳(CO2)的光合作用,也存在释放CO2的微生物呼吸过程。地球表层水体与大气之间的CO2交换构成全球碳循环的一个重要环节。水-气之间CO2交换的方向和通量主要受大气圈和水体表层CO2分压(pCO2)的制约。水体pCO2值可以通过对近水面气体成分变化过程的现场仪器检测或者根据测定的水体化学参数运用经验公式计算求得。迄今对陆地水体,尤其河流筑坝形成的"蓄水河流"(下称水库)水体CO2动态研究中,由于水域及其近表层大气成分的时空多变,一般采用水化学参数计算方法求得水体的pCO2值。全球约70.97%的水库表层水体pCO2高于大气pCO2。全球尺度上水库表层水体pCO2自热带向寒温带逐渐递减;单个水库水体的pCO2一般呈现"出库>入库>库中"、pCO2随深度而增加的变化规律。水库表层水体pCO2的时间变化一般表现为"冬季>夏季、消融期>冰冻期、黑夜>白天"。水库水体的pCO2是其水化学平衡的结果,受水温、水体pH、水生生物活动以及外来水体的混合等多种因素影响,变化较为复杂。为精确量化水库水-气界面CO2交换通量,水文学、湖沼学、生态学和地球化学等领域的学者有必要合作,共同努力进行水库流域尺度的实地观测,完善水体溶解无机碳计算模型,深入探讨水库水体碳动力学机制,为全球碳循环研究和气候变化预测提供可靠的基础数据。