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1.
Plant root growth is generally stimulated under elevated CO2. This will bring more carbon to the below-ground through root death and exudate. This potential increase in below-ground carbon sink may lead to changes in long-term soil sequestration and relationship between host plants and symbions. On the other hand, changes in litter components due to the changes in plant chemical composition may also affect soil processes, such as litter decomposition, soil organic matter sequestration and hetero-nutritional bacteria activities. These issues are discussed. 相似文献
2.
Based on the long-term monitoring data on CO2 concentration, variation trend and characteristics of CO2 background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO2 background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991–2000. The average annual CO2 growth increment is 1.59 μL/L, and the average annual CO2 growth rate is 0.44%. Distinct seasonal variations of CO2 background concentration are observed, and the averaged amplitude of CO2 seasonal variations is 10.35 μL/L. Regional variation characteristics of CO2 background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well. 相似文献
3.
Measuring the response of terrestrial ecosystems to elevated CO2 concentrations is very important for understanding the effects of global change. In this study, OTC (open top chambers) were used to simulate elevated CO2 concentrations in the Songnen Grassland. As well, phytoliths in Leymus chinensis were extracted to study the relationships between phytoliths and CO2 concentration. The results show the rondel is abundant in Leymus chinensis, while the trapeziform polylobate is rare. When phytolith production is increased, the rondel phytoliths grow bigger and the proportions of the different phytolith types changes under high CO2 con-centration. These types include elongate hollow, acicular hair cell, square and laminate and are only observed in samples grown under high CO2 concentrations. All this evidence demonstrates that phytoliths in Leymus chinensis are sensitive to CO2 concentration, and indicate that phytolith analysis may have potential use in the study of global change, identifying different ecotypes of Leymus chinensis and for the reconstruction of paleoatmospheric CO2 concentrations. 相似文献
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5.
The areal extent of cold freshwater wetlands on the Qinghai-Tibet Plateau (QTP) is estimated at 0.133 × 106 km2, suggesting a significant methane potential. Methane fluxes from wet alpine meadows, peatlands,Hippuris vulgaris mires and secondary marshes were 43.18, 12.96, −0.28 and 45.90 mg · m−2 · d−1, respectively based on the transect flux studies at the Huashixia Permafrost Station (HPS) from July to August 1996. Average CH4 fluxes in the thaw season were extrapolated at 5.68 g · m−2 according to the areal percentage of wetland areas in the Huashixia region. The CH4 fluxes at four fixed sites, representative of similar ecosystems, ranged from −19.384–347.15 mg · m−2 · d−1, and the average CH4 fluxes varied from 6.54 to 71.97 mg · m−2 · d−1 at each site during the observation period from April to September 1997. The CH4 emissions at each site during the entire thaw season was estimated from 1.21 to 10.65 g · m−2, displaying strong spatial variations. Seasonal variations of CH4 fluxes also were observed at four sites: CH4 outbursts occurred upon the spring thaw in May and June, CH4 fluxes increased afterwards with rising soil temperatures. Episodic fluxes were observed in summer, which influenced the average CH4 fluxes considerably. Annual CH4 emissions from cold wetlands on the QTP were estimated at about 0.7–0.9 Tg based on the distribution of wetlands, representative CH4 fluxes, and number of thaw days. The centers of CH4 releasing were located in the sources of the Yangtze and Yellow rivers, and Zoigê Peatlands. 相似文献
6.
页岩为CO2盐水层地质封存常见盖层岩石类型,强化盖层封堵能力有利于提高CO2地质埋存量和安全性。为探究随CO2混注纳米SiO2(SNPs)强化盖层封堵能力的有效性和可行性,对CO2地质封存页岩盖层样品开展原地条件下的超临界CO2酸蚀反应试验,基础组为页岩样品-地层水、对照组为页岩样品-地层水+超临界CO2、优化组为页岩样品-地层水+SNPs+超临界CO2,并采用核磁共振测试、场发射扫描电镜可视化观测、X射线衍射测试和岩石力学试验,探究CO2酸蚀反应前后的页岩孔隙结构、表面形貌、矿物成分及力学性质特征。结果表明：优化组的大孔孔隙分量及孔隙度和渗透率增大幅度低于对照组;与对照组相比,优化组黏土矿物与碳酸盐岩矿物相对含量损失少,表明随CO2混注SNPs可使岩样内部酸蚀作用减弱;SNPs在岩石端面吸附聚集或进入岩心孔喉,可使优化组页岩样品力学性能损伤程度降低;随CO2... 相似文献
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采用3种有机络合剂(葡萄糖、柠檬酸、酒石酸),通过溶胶-凝胶燃烧法制备钙钛矿结构的LaCoO3催化剂,并用X射线衍射(XRD)、扫描电子显微镜(SEM)、激光粒度分析仪、低温N2吸脱附等温线(BET)、程序升温还原(H2-TPR)以及程序升温脱附(O2-TPD)表征催化剂的结构,考察了3种络合剂合成的样品对甲烷催化燃烧反应的催化活性.结果表明,在600℃焙烧下,以葡萄糖为络合剂合成的LaCoO3催化剂呈现单一的钙钛矿结构,且颗粒粒度最小、分散度最高,具有较高的催化活性;以酒石酸为络合剂合成的催化剂以LaCoO3物相为主,并伴有La2O3和Co3O4物相,催化活性也较好;以柠檬酸为络合剂合成的样品以LaCoO3物相为主,伴有少量的La2O3和Co3O4物相,分散度最差,催化活性最低. 相似文献
8.
环境中化石燃料的大量使用导致CO2浓度不断增加,这是全球变暖的主要原因。为了解决这一问题,开发一种高效廉价的吸附材料至关重要。以甘蔗渣为碳源,尿素为N源,通过碳化和K2CO3活化制备出N掺杂多孔碳。多孔碳的物理化学性质用N2解吸等温线、傅里叶红外光谱、元素分析、扫描电子显微镜观察和X射线衍射等方法进行表征。结果表明：该材料具有高度发达的孔隙、较高的N含量和较高的石墨化程度。当尿素与甘蔗渣混合比是2、碳化温度是800℃、K2CO3浸渍比是3时,多孔碳的比表面积高达2 486.67 m2·g-1,同时CO2吸附量高达250.73 mg·g-1。由此可见以廉价的甘蔗渣制备N掺杂的多孔碳用于吸附CO2具有广阔的应用前景。 相似文献
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采用内蒙古纳岭沟砂岩铀矿床的地下水样,根据其具体成分制备模拟地下水,研究了CO2+O2地浸采铀浸出剂对砂岩铀矿床地下水pH、Eh和HCO－3质量浓度的调控作用。研究结果表明:1)随着CO2注入量增加,地下水的pH迅速降低、Eh小幅度升高、HCO－3质量浓度小幅度降低;随着O2注入量增加,地下水的Eh大幅度升高、pH小幅度升高、HCO－3质量浓度保持稳定;随着NH4HCO3加入量增加,地下水的pH小幅度升高、Eh小幅度降低、HCO－3质量浓度显著升高;CO2、O2、NH4HCO3各自单独作用,对地下水pH、Eh、HCO－3质量浓度的调控结果不符合浸铀的实际要求。2)当CO2的分压为0.08 MPa、O2的分压为0.7 MPa、NH4HCO3的质量浓度为1 040 mg/L时,地下水的pH被调控至6.25,Eh被调控至251 mV,HCO－3的质量浓度被调控至1 027 mg/L左右,符合浸铀的实际要求。 相似文献
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将CO_2注入地下油藏用于驱替原油是减少温室气体的排放及提高原油采收率的一种有效方法。CO_2注入地层后会与地层流体和岩石发生反应,其中岩石组成中的碳酸盐矿物极易与CO_2和水发生反应导致储层岩石物性发生改变。论文以方解石为代表样品,采用X射线衍射仪(XRD),电诱导双等离子体原子排放光谱测定仪(ICP-AES),扫描电镜(SEM)及在5 MPa压力下填砂模型的试验方法进行评价,分别考察了方解石的矿物学性质、CO_2-水-方解石反应前后方解石的表面物性、反应前后溶液的离子浓度变化及方解石填砂模型与CO_2、水反应后渗透率的变化。实验结果表明,与CO_2和水反应后,方解石出现溶蚀现象;反应压力增加,方解石溶蚀现象增加,反应后溶液中Ca~(2+)、HCO_3~-浓度增加;反应温度增加,方解石溶蚀现象增加,反应后溶液中Ca~(2+)、HCO_3~-浓度先增加,后降低;与CO_2和水反应后的方解石/石英砂填砂模型水测渗透率增加。 相似文献
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H2S-rich gas in carbonate reservoirs is usually attributed to thermochemical sulfate reduction （TSR）. In this paper, thermal simulation experiments on the reaction system of CH4-MgSO4-H2O were carried out using autoclave at 425℃--525℃. The threshold temperature for initiating TSR is much lower than our previous studies （550℃）. Properties of the reaction products were analyzed by microcoulometry, gas-chromatography （GC）, Fourier transform-infrared spectrometry （FT-IR） and X-ray diffraction （XRD） methods. Thermodynamics and reaction kinetics of TSR processes were investigated on the basis of the experimental data. The results show that thermochemical reduction of magnesium sulfate with methane can proceed spontaneously to produce magnesium oxide, hydrogen sulfur, and carbon dioxide as the main products, and high temperature is thermodynamically favorable to the reaction. Ac- cording to the reaction model, the calculated activation energy of TSR is 101.894 kJ/mol, which is lower than that by most previous studies. Mg^2＋ may have played a role of catalytic action in the process of TSR. The elementary steps of TSR and reaction mechanism were discussed tentatively. The study can provide important information on the explanation of geochemical depth limit for natural gas and on the generation of high H2S gas in deep carbonates reservoirs. 相似文献
12.
Studies were carried out on the early phase of fluid inclusions which occur in residual olivines in harzburgite from the Yushigou ophiolitic mantle peridotite, the North Qilian Mountains. Components of these inclusions, analyzed by micro laser Raman spectroscopy, are dominantly CH, (70%–95%) with minor H2, N2, H2S, CO2,C2H4, C2H6, and C3H6 but there are no H2O,CO and SO2. The highly CH4-rich fluid was probably derived from an ancient deep mantle. This discovery plays an important role in all-round understanding of the fluid property of the upper mantle, especially the ancient oceanic upper mantle. 相似文献
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利用三维激光粒子动态分析仪(LDV/APV系统)测量距离同轴流动燃烧装置Cup Burner出口不同位置的细水雾雾场特性(雾滴速度、雾滴粒径),利用Cup Burner系统地研究了细水雾抑制小尺度CH4/空气顺流非预混火焰,考察细水雾的粒径和雾滴质量分数对CH4/空气顺流非预混火焰结构的影响. 研究结果表明粒径为10～100 μm的细水雾能有效地抑制CH4/空气顺流非预混火焰,随着细水雾粒径减小或空气流中雾滴质量分数的增加,细水雾抑制熄灭CH4/空气顺流非预混火焰的能力增强. 细水雾抑制熄灭CH4/空气顺流非预混火焰的机理主要是气相吸热冷却和稀释氧气,在CH4/空气顺流非预混火焰的根部,气相吸热冷却起主导作用,而在火焰的上部稀释氧气起主导作用. 相似文献
14.
利用故障树分析法,结合油田CO_2驱和埋存示范区泄漏及环境监测结果,对油藏埋存CO_2发生泄漏的途径和泄漏机制进行分析,并对CO_2驱和埋存示范区进行环境监测。结果表明:对圈闭性很好的油藏,井的密封性失效(包括套管和井口设施损坏)、固井不完善及水泥环腐蚀是造成CO_2泄漏的主要原因;整体上,埋存于地下的CO_2没有发生大规模的泄漏,但在近井土壤中CO_2含量有增加的趋势,越靠近井口土壤中CO_2含量越大,表明CO_2通过井内套管柱或不完整水泥环发生了微量泄漏。故障树分析结果对CO_2埋存区的泄漏监测和预防具有指导意义。 相似文献
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Conclusions The initial slope of A/ light curve became steep under high CO2 (700 μmol · mol-1) compared with that under low CO2 (350 μmol · mol-1) for the C3 species growing in very high CO2(>2 200 μmol · mol-1) for a long period. The light compensation points remained unchanged, but the light saturation points were found increased. The ϕm,app and Amax of the C3 species increased respectively by 79 % and 80 %, while those of C4 species decreased by 10% and 14%, respectively. The shape of A/light curve of C4 species did not change. Such results indicated that C3 species increased the capacity of photosynthesis, while C4 did not change, otherwise it decreased a little. This work only compared the changes of capacity in photosynthesis of some species under different CO2 levels in Biosphere 2. We need further investigation on the effects of high CO2 on the same species outside Biosphere 2, in order to fully undertand the effects and mechanism of response of plants to the elevated CO2. 相似文献
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针对壬基酚聚氧乙烯醚系列非离子表面活性剂,利用高温高压可视化泡沫仪,在不同温度、压力和矿化度条件下对CO2泡沫性能进行测试,分析(聚氧乙烯基)EO聚合度、矿化度、压力和温度对CO2泡沫性能的影响。同时通过驱替试验对CO2泡沫作为驱油剂的封堵和流度控制能力进行测试,并与高温高压泡沫仪的试验结果进行对比,分析泡沫仪测试的泡沫综合性能指数与泡沫在驱替试验中的阻力系数的相关性。结果表明:随着EO聚合度的增大,表面活性剂的亲水性增加,所产生CO2泡沫的性能及稳定性提高;泡沫液矿化度增大、压力增大和温度升高都会导致CO2泡沫性能下降。驱替试验结果揭示了表面活性剂分子结构对CO2泡沫的影响,对CO2泡沫用非离子表面活性剂的设计和性能提高具有指导意义。 相似文献
17.
A lot of liquid-gas and liquid-gas-solid inclusions were found in Pharkant jadeitites, northwestern Myanmar and their characteristics, geological setting and porphyroclastic jadeites with inclusions in them were described in detail. The results analyzed by Raman spectrometer showed that the component of liquid-gas phase and solid phase (daughter minerals) in fluid inclusions is H2O + CH4 and jadeite separately. The results indicated that Pharkant jadeitites were crystallized from H2O + CH4 bearing jadeitic melt which may originate from mantle. The P-T conditions in which the jadeitites were crystallized were speculated to be T ＞650℃, P ＞1.5 GPa. 相似文献
18.
CO2作为全球温室气体,正在危害人类赖以生存的环境,而工业上现正在大力发展有机胺溶液用于脱除烟气中的CO2,并已得到了广泛的应用和极好的发展趋势.由于三乙烯四胺（TETA）溶液具有稳定性好、吸收效率高等优势,再对比传统胺试剂试验的浓度,试验选取0.2~0.8 mol/L体积浓度范围的TETA作为吸收剂吸收模拟烟气中的CO2.当温度在25~40℃时,其温度对CO2吸收速率的影响不明显;当溶剂体积浓度在0.2~0.8 mol/L和CO2体积分数在10%~18%时,溶剂体积浓度和CO2体积分数对CO2吸收速率的影响明显. 相似文献
19.
以硝酸铈为前驱物,以尿素为助剂,采用一种简单的模板法合成了介孔氮掺杂CeO2材料.利用X射线衍射仪(XRD)、吸附-脱附仪(BET)、透射电子显微镜(TEM)和傅里叶变换红外光谱(FT-IR)等设备对合成材料进行表征.多种测试结果证明:试验得到的纳米材料具有均一的介孔结构和较高的比表面积(124.8 m2·g-1)并掺杂了氮元素.同时,测定了介孔CeO2材料对于CO2的吸附性能,并研究了氮掺杂对CeO2材料的CO2吸附性能的影响.结果表明:相比未掺杂氮的介孔CeO2,氮掺杂的介孔CeO2具有更好的CO2吸附性能和循环吸附脱附性能. 相似文献
20.
采用溶胶-凝胶法制备（CoFe2O4）x/（SiO2）1-x纳米复合材料. 利用X射线衍射（XRD）和振动样品磁强计（VSM）研究样品结构、 晶粒尺寸及磁性. 结果表明, 随SiO2含量增加, 样品的晶粒尺寸减小, 比饱和磁化强度和矫顽力降低. 相似文献