岩溶动力系统与全球变化研究进展

碳酸盐岩是岩溶发育的物质基础,它记录着地球历史时期的环境变化,是地球最大的碳库,对地球大气和生命演变起到重要作用;现代全球岩溶分布面积2200万km~2,占陆地面积的15%,岩溶动力系统是地球表层系统的重要组成部分,全球25%的人口依赖岩溶地下水资源的供给,岩溶生态系统的脆弱性制约着区域经济社会发展;本文主要针对近30年以来,岩溶学科发展进行综述,包括岩溶动力学概念、内涵与发展,驱动岩溶发育的地质-生态机制,岩溶动力系统与碳循环新进展,岩溶动力系统与水循环新进展,岩溶动力系统与钙循环新进展;岩溶动力系统与全球环境变化研究发展展望(岩溶关键带下的资源环境效应及国际大科学计划的启动)。     

The Preparation and Adsorption Properties of Novel Ternary Composited Diatomaceous Earth

Xianfeng large-scale lignite mining area, symbiotic diatomaceous earth mining area is the second largest diatomaceous earth mining in China with high organic matter content. The Xianfeng diatomaceous earth mining is a difficult development and utilization of low-grade diatomaceous earth, which has not been effective utilized due to low economic value of traditional processes. The objectives of this paper are utilizing high organic matter content diatomite as waste resources and improving the comprehensive utilization ratio of mineral resources in Xianfeng coal mining areas. The high organic content diatomaceous earth was purified by the acid washing and then calcinations under N2 as a protective atmosphere and high temperature of 500 to 800 ℃. The organic matter was carbonized with the formation of amorphous complex of activated carbon and diatomaceous earth. The novel ternary composited diatomaceous earth was prepared by combining carbonation diatomaceous earth and magnetic nanomaterials. The absorption property of ternary composited diatomaceous earth was improved through the organosilane and polyacrylamide modification to meet the needs of practical application. Electron microscopy showed that magnetic precursor calcined under N2 as a protective atmosphere, the surface of the magnetic nanoparticles were coated with amorphous carbon, which improved chemical stability and compatibility with diatomaceous earth. The magnetic nanoparticles and amorphous activated carbon uniformly dispersed in a diatomaceous earth surface and within the pores, to form a stable magnetic nanoparticles - the amorphous active carbon - ternary complexes. The specific surface area and methylene blue adsorption test showed ternary composited diatomaceous earth performing much higher than conventional diatomite products, the novel diatomaceous earth with specific surface area of 55.79 m2/g, methylene blue adsorption capacity of 44.5 m2/g. MgFe2O4 and Co3O4-based superparamagnetic ternary composited diatomaceous earth as an unique adsorbent has great application potential in organic pollutants and heavy metals pollution treatment of water. In addition, the CoFe2O4 based soft magnetic ternary composited diatomaceous earth has potential applications in magnetic plastics, rubber functional filler fields. This study shows that the proposed technology is conducive to a substantial increasing economic value of the Xianfeng diatomaceous earth mining, has a broad industrial application prospects.     

Empirical estimates of the influence of natural and anthropogenic factors on the global surface temperature

The influence of different natural (solar and volcanic activity) and anthropogenic (carbon dioxide concentration in the atmosphere) factors on the growth of the Earth’s global surface temperature (GST) is analyzed on observational evidence by the estimation of Granger causality and a new method proposed for evaluating the long-term effect. The statistically significant influence of all three factors on GST is revealed in the analysis of sequences of data. The contribution of the anthropogenic factor is most important, whereas the influence of solar and volcanic activity is weaker by an order of magnitude.     

Carbon Sequestration and Sediment Accretion in San Francisco Bay Tidal Wetlands

Tidal wetlands play an important role with respect to climate change because of both their sensitivity to sea-level rise and their ability to sequester carbon dioxide from the atmosphere. Policy-based interest in carbon sequestration has increased recently, and wetland restoration projects have potential for carbon credits through soil carbon sequestration. We measured sediment accretion, mineral and organic matter accumulation, and carbon sequestration rates using ¹³⁷Cs and ²¹⁰Pb downcore distributions at six natural tidal wetlands in the San Francisco Bay Estuary. The accretion rates were, in general, 0.2?C0.5?cm?year^?1, indicating that local wetlands are keeping pace with recent rates of sea-level rise. Mineral accumulation rates were higher in salt marshes and at low-marsh stations within individual sites. The average carbon sequestration rate based on ²¹⁰Pb dating was 79?g?C?m^?2?year^?1, with slightly higher rates based on ¹³⁷Cs dating. There was little difference in the sequestration rates among sites or across stations within sites, indicating that a single carbon sequestration rate could be used for crediting tidal wetland restoration projects within the Estuary.     

Air–Water CO<Subscript>2</Subscript> Fluxes and Net Ecosystem Production Changes in a Baja California Coastal Lagoon During the Anomalous North Pacific Warm Condition

The present study examines the temporal variability of air–water CO₂ fluxes (FCO₂) and seawater carbonate chemistry in a Baja California coastal lagoon during an exceptionally warm anomaly that was developed in Northeast Pacific coasts during 2014. This oceanographic condition led to a summer-like season (weak upwelling condition) during the study period, which reached a maximum surface temperature anomaly of 2 °C in September 2014. San Quintín Bay acts as a source of CO₂ to the atmosphere in 2014 (3.3 ± 4.8 mmol C m^?2 day^?1) with the higher positive fluxes mainly observed in summer months (9.0 ± 5.3 mmol C m^?2 day^?1). Net ecosystem production (NEP) switched seasonally between net heterotrophy and net autotrophy during the study period, with an annual average of 2.2 ± 7.1 mmol C m^?2 day^?1, which indicates that San Quintín Bay was a net autotrophic system during the atypical warm oceanographic condition in 2014. This pattern of seasonal variations in the carbon balance at San Quintín Bay appears to be linked to the life cycle of benthic communities, which play an important role in the whole-ecosystem metabolism. Under the limited input from external sources coupled with an increase in seawater temperatures, the recycled benthic carbon and nutrient fluxes play a major role to sustain water-column processes within the bay. Since the upwelling condition may influence the magnitude of the air–water CO₂ fluxes, our results clearly indicated that San Quintín Bay is a net source of carbon to the atmosphere regardless of the adjacent oceanic conditions. Our study sheds light on the carbon dynamics and its metabolic implications in a shallow coastal ecosystem under a regional warm anomaly and contributes potentially relevant information in view of the likely future scenario of global climate change.     

Degassing history and carbon cycle of the Earth: From an impact-induced steam atmosphere to the present atmosphere

The recent theoretical studies on the formation and evolution of the atmosphere and oceans of the Earth are reviewed. Impact degassing during accretion of the Earth would probably generate an impact-induced steam atmosphere on the proto-Earth. At the end of accretion, the steam atmosphere became unstable and condensed to form the proto-ocean with almost the present mass of ocean. The steam atmosphere would have thus evolved to the proto-CO₂ atmosphere during the earliest history of the Earth because CO in the proto-atmosphere may be photochemically converted to CO₂. However, CO₂ in the proto-atmosphere has decreased with time through the global carbon cycle which may have stabilized the terrestrial environment against an increase in the solar luminosity. The continental growth during Hadean and Archean would therefore have a significant influence on the carbon cycle and the surface temperature. It is also suggested that the continental growth is a necessary condition for the terrestrial environment to evolve to the present state. Both the impact degassing and the subsequent continuous degassing are suggested to have played a major role in the formation and evolution of the atmosphere and ocean. In particular, most of N₂ may have been produced by the impact degassing during accretion, and the contribution of the subsequent continuous degassing is at most 10% for N₂. As a consequence, after the CO₂ level decreased to less than 1 bar, the atmosphere may have been at about 1 bar and composed mainly of N₂ for most of the subsequent history of the Earth.     

Surface water changes in the norwegian sea during last deglacial and holocene times

Stable carbon and oxygen isotopes of the polar planktic foraminifera Neogloboquadrina pachyderma sinistral from sediment cores of the Norwegian Sea reveal several anomalous ¹³C and δ¹⁸O depletions in the surface water during the last glacial to interglacial transition and during the later Holocene. The depletions that are observed between the Last Glacial Maximum (LGM) and the end of the main deglacial phase were caused by massive releases of freshwater from thawing icebergs, which consequently resulted in a stratification of the uppermost surface water layer and a non-equilibrium between the water below and the atmosphere. At ~8.5 ka (¹⁴C BP) this strong iceberg melting activity ceased as defined by the cessation of the deposition of ice-rafted detritus. After this time, the dominant polar and subpolar planktic foraminiferal species rapidly increased in numbers. However, this post-deglacial evolution towards a modern-type oceanographic environment was interupted by a hitherto undescribed isotopic event (~7–8 ka) which, on a regional scale, is only identified in eastern Norwegian Sea surface water. This event may be associated with the final pulse of glacier meltwater release from Fennoscandia, which affected the onset of intensified coastal surface water circulation off Norway during a time of regional sea-level rise. All these data indicate that surface water changes are an integral part of deglacial processes in general. Yet, the youngest observed change noted around 3 ka gives evidence that such events with similar effects occur even during the later Holocene when from a climatic point of view relativelystable conditions prevailed.     

南半球对流层气候年代际变化及其与太阳活动的联系

通过南半球对流层温度场谱分析和逐次滤波分析发现，南半球对流层大气温度场半个多世纪以来呈现明显的持续升温趋势，升温幅度由低层到高层逐步增加，其中地面层1 000 hPa年升温率为0.013℃/a，对流层中部500 hPa年升温率为0.019℃/ a，对流层上部300 hPa年升温率为0.036℃/ a；滤除南半球大气温度场的趋势变化，发现南半球大气温度场从地面层直至对流层顶广泛盛行着十分显著的与太阳磁场磁性22年周期变化相一致的变化周期。太阳磁场磁性周期变化趋势略有超前，分析认为，这是南半球对流层大气气候系统对太阳磁场周期性变化的响应。进一步分析还发现，南半球从地面层1 000 hPa到对流层顶，再到平流层中部10 hPa各层次大气温度变化22年周期分量振荡位相基本一致，周期振幅由低层到高层迅速增大，说明太阳磁场变化对对流层高层比低层影响大，对平流层影响更大。其中地面层1 000 hPa温度场的22年变化周期是在滤除趋势变化和11年周期之后才显现出来的，所以太阳磁场磁性周期变化对地面层气候的影响较小并且经常处于被掩盖状态；南半球地面层1 000 hPa温度场滤除趋势变化之后显示出十分显著的与太阳活动11年周期相一致的变化周期，分析认为，这是南半球对流层大气气候系统对太阳活动11周期性变化的响应。对流层上层300 hPa温度场滤除趋势变化和22年周期之后也显示出11年变化周期，而对流层中部500 hPa则无此周期反应，说明太阳活动11年周期对地面层1 000 hPa大气气候影响最明显，对流层中上层影响较弱。     

Seismic efficiency of meteor airbursts

We present the results of numerical simulation for impacts of relatively small asteroids and ice bodies of 30–100 m in size, decelerated in the atmosphere and exploding before they reach the surface, but still producing seismic effects due to the impact wave reaching the surface. The calculated magnitudes fall within the range of 4 to 6, and average seismic efficiency of these events is 2.5 × 10^–5. The results obtained allow the seismic hazard from impacts of cosmic bodies to be estimated.

     

Another Source of Atmospheric Methane

The atmospheric concentration of methane is steadily increasin.Lacking of precise estimates of source and sink strengths for the atmospheric methane severely limits the current understanding of the global methane cycle.Agood budget of atmospheric methane can enhance our understanding of the global carbon cycle and global climate change,The known estimates of the main source and sink strengths are gresented in this paper,In terms of carbon isotopic studies,it is evidenced that the earth‘s primodial methane,which was trapped in the earth during its formation,may be another source of methane,with extensive,earth‘s degassing which is calleld the “breathing“ process of the earth and played an important role in the formation of the promitive atmosphere,large amounts of methane were carried from the deep interior to the surface and then found its way into the atmosphere.     

中国全新世海平面变化周期与世界未来海平面变化规律

从发现海滩岩断代序列模式后,通过多学科综合研究又发现气候变化周期、闽粤海岸升降周期和海平面变化周期等皆为500a 左右。在13000aB.P.前中国气候变暖,海平面为以上升为主的升降期;近6000多年海平面以周期性上下波动为特征;而近3100年寒冷气候以每1000年7个纬度的速度南移,海平面向上波动幅度变小。按气候变化周期,现阶段为变寒期,将抵消一部分“温室效应”,世界未来50—100年的海面可能与今持平或有所下降。按照冰期和间冰期的时间规律,未来6000—7000年的海平面将下降几十米。     

地球密度模型研究进展与热平衡估计

地球科学最新研究成果表明,地表物质运动与核幔边界的大规模能量交换过程密切相关,地球动力系统平均温度的演变具有由高到低的整体趋势。越来越多的证据表明,地球内部处于非绝热状态,正在持续进行的地球冷却过程将对地表环境产生重大影响。人类对地球内部热源的开发尽管可以使地表短时期迅速增强,但也造成地球内部长期加速变冷的严重后果。     

The Paleoceanography during the Time with High δ13C of Phanerozoic marine carbonates

Carbon isotopic composition of marine carbonates is a record for various important geological events in the process of earth development and evolution. The carbonates of Carboniferous, Permian and Triassic, as the transition from Paleozoic to Mesozoic-Cenozoic have very high ¹³C value. Taking this as the main point, and combined with the oxygen, strontium isotopic composition in carbonates, distribution of carbonate basin area through geologic time, the correlation of carbon isotopic composition of marine carbonates to sea level change, organic carbon burial flux, exchange of CO₂ content in atmosphere and ocean, and long cycle evolution of the earth ecosystems were approached. The results are shown as follows: ①The interval of ¹³C >3‰ during Phanerozoic was concentrated in Carboniferous, Permian and the beginning of Triassic, but the beginning of Triassic was characterized by higher frequency and larger fluctuations in ¹³C value during a short time, whereas the Carboniferous-Permian presented a continuously stable high ¹³C value, indicating a larger amount of organic carbon accumulation in this time interval. Relatively high ¹⁸O values during this time was also observed, showing a long time of glaciations and cold climate, which suggest a connection among rapid organic carbon burial, cold climate, as well as pCO₂ and pO₂ states of atmosphere. ②The over consumption of atmosphere CO₂ by green plants during the time with high ¹³C of seawater forced CO₂ being transferred from ocean to atmosphere for the balance, but the decrease in the seawater amount and water column pressure caused by the global cooling could weaken dissolution capacity of CO₂ in seawater and carbon storage of marine carbonates, and also reduce the carbonate sedimentary rate and decrease the carbonate basin area globally from Devonian to Carboniferous and Permian. During the middle-late Permian carbonate was widely replaced by siliceous sediments even though in shallow carbonate platform, which resulted in the decrease of marine invertebrates, suggesting the Permian chert event should be global. ③The Phanerozoic ⁸⁷Sr/⁸⁶Sr trend of seawater showed a sharp fall in Permian and drop to a minimum at the end of the Permian, indicting input of strontium from the submarine hydrothermal systems (mantle flux). Such process should accompany with a supplement of CO₂ from deep earth to atmosphere and ocean system, but the process associated with widespread volcanism and rises of earth’s surface temperature pricked up the mass extinction during the time of end Permian. ④Cold climate and increase of continental icecap volume, the amalgamation of northern Africa and Laurentia continentals were the main reasons responsible for the sea level drop, but the water consumption result from the significantly increased accumulation of organic carbon should also be one of the reasons for the sea level drop on the order of tens of meters. ⑤The mass extinction at the end Permian was an inevitable event in the process of earth system adjustment. It was difficult for marine invertebrates to survive because of the continuously rapid burial of organic carbon, and of the decrease of sea water amount and its dissolution ability to CO₂. At last, at the end of Paleozoic, the supplement of CO₂ to atmosphere and ocean by widely magma activities resulted in a high temperature of earth surface and intensified mass extinction.     

Modelling stalagmite growth and δC as a function of drip interval and temperature

Growth and stable isotope composition of stalagmites are affected by climate changes. To understand the underlying mechanisms, we developed a time dependent multi-box model that describes stalagmite growth and stable isotope fractionation of carbon under disequilibrium conditions. The model takes variations of the drip interval, temperature and the amount of mixing between the impinging drops and the solution on top of the stalagmite into account, which allows to quantify the influence of these parameters. To calculate the variations of δ¹³C, the multi-box model was calibrated by comparison with an existing growth model. The results show that drip interval, temperature and the mixing coefficient do have a significant influence on δ¹³C. However, considering the higher natural variability of the drip interval, this parameter might have the largest influence.     

Major perturbation of ocean chemistry and a 'Strangelove Ocean' after the end-Permian mass extinction

The severe mass extinction of marine and terrestrial organisms at the end of the Permian Period (c. 251 Ma) was accompanied by a rapid (<100 000 years and possibly <10 000 years) negative excursion of c. 3‰ in the δ¹³C of the global surface oceans and atmosphere that persisted for some 500 000 years into the Early Triassic. Simulations with an ocean–atmosphere/carbon-cycle model suggest that the isotope excursion can be explained by collapse of ocean primary productivity, and changes in the delivery and cycling of carbon in the oceans and on land. Model results suggest that severe reduction of marine productivity led to an increase in surface-ocean dissolved inorganic carbon and a rapid, short-term increase in atmospheric pCO₂ (from a Late Permian base of 850 ppm to c. 2500 ppm). Increase in surface ocean alkalinity may have stimulated the widespread microbial and abiotic shallow-water carbonate deposition seen in the earliest Triassic. The model is also consistent with a long-term (>1 Ma) decrease in sedimentary burial of organic carbon in the early Triassic.     

CO<Subscript>2</Subscript> Air–Sea Exchange due to Calcium Carbonate and Organic Matter Storage,and its Implications for the Global Carbon Cycle

Release of CO₂ from surface ocean water owing to precipitation of CaCO₃ and the imbalance between biological production of organic matter and its respiration, and their net removal from surface water to sedimentary storage was studied by means of a quotient θ = (CO₂ flux to the atmosphere)/(CaCO₃ precipitated). θ depends not only on water temperature and atmospheric CO₂ concentration but also on the CaCO₃ and organic carbon masses formed. In CO₂ generation by CaCO₃ precipitation, θ varies from a fraction of 0.44 to 0.79, increasing with decreasing temperature (25 to 5°C), increasing atmospheric CO₂ concentration (195–375 ppmv), and increasing CaCO₃ precipitated mass (up to 45% of the initial DIC concentration in surface water). Primary production and net storage of organic carbon counteracts the CO₂ production by carbonate precipitation and it results in lower CO₂ emissions from the surface layer. When atmospheric CO₂ increases due to the ocean-to-atmosphere flux rather than remaining constant, the amount of CO₂ transferred is a non-linear function of the surface layer thickness because of the back-pressure of the rising atmospheric CO₂. For a surface ocean layer approximated by a 50-m-thick euphotic zone that receives input of inorganic and organic carbon from land, the calculated CO₂ flux to the atmosphere is a function of the CaCO₃ and C_org net storage rates. In general, the carbonate storage rate has been greater than that of organic carbon. The CO₂ flux near the Last Glacial Maximum is 17 to 7×10¹² mol/yr (0.2–0.08 Gt C/yr), reflecting the range of organic carbon storage rates in sediments, and for pre-industrial time it is 38–42×10¹² mol/yr (0.46–0.50 Gt C/yr). Within the imbalanced global carbon cycle, our estimates indicate that prior to anthropogenic emissions of CO₂ to the atmosphere the land organic reservoir was gaining carbon and the surface ocean was losing carbon, calcium, and total alkalinity owing to the CaCO₃ storage and consequent emission of CO₂. These results are in agreement with the conclusions of a number of other investigators. As the CO₂ uptake in mineral weathering is a major flux in the global carbon cycle, the CO₂ weathering pathway that originates in the CO₂ produced by remineralization of soil humus rather than by direct uptake from the atmosphere may reduce the relatively large imbalances of the atmosphere and land organic reservoir at 10²–10⁴-year time scales.     

Rapid Alkalization in Lake Inawashiro, Fukushima, Japan: Implications for Future Changes in the Carbonate System of Terrestrial Waters

The global carbon cycle, one of the important biogeochemical cycles controlling the surface environment of the Earth, has been greatly affected by human activity. Anthropogenic nutrient loading from urban sewage and agricultural runoff has caused eutrophication of aquatic systems. The impact of this eutrophication and consequent photosynthetic activity on CO₂ exchange between freshwater systems and the atmosphere is unclear. In this study, we focused on how nutrient loading to lakes affects their carbonate system. Here, we report results of surveys of lakes in Japan at different stages of eutrophication. Alkalization due to photosynthetic activity and decreases in PCO₂ had occurred in eutrophic lakes (e.g., Lake Kasumigaura), whereas in an acidotrophic lake (Lake Inawashiro) that was impacted by volcanic hot springs, nutrient loading was changing the pH and carbon cycling. When the influence of volcanic activity was stronger in the past in Lake Inawashiro, precipitation of volcanic-derived iron and aluminum had removed nutrients by co-precipitation. During the last three decades, volcanic activity has weakened and the lake water has become alkalized. We inferred that this rapid alkalization did not result just from the reduction in acid inputs but was also strongly affected by increased photosynthetic activity during this period. Human activities affect many lakes in the world. These lakes may play an important part in the global carbon cycle through their influence on CO₂ exchange between freshwater and the atmosphere. Biogeochemical changes and processes in these systems have important implications for future changes in aquatic carbonate systems on land.     

Uptake and recycling of lead by boreal forest plants: Quantitative estimates from a site in northern Sweden

As a consequence of deposition of atmospheric pollution, the lead concentration in the mor layer (the organic horizon) of remote boreal forest soils in Sweden is raised far above natural levels. How the mor will respond to decreased atmospheric pollution is not well known and is dependent on future deposition rates, downward migration losses and upward fluxes in the soil profile. Plants may contribute to the upward flux of lead by ‘pumping’ lead back to the mor surface through root uptake and subsequent litter fall. We use lead concentration and stable isotope (²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb) measurements of forest vegetation to quantify plant uptake rates from the soil and direct from the atmosphere at two sites in northern Sweden; an undisturbed mature forest and a disturbed site with Scots pine (Pinus sylvestris) growing on a recently exposed mineral soil (C-horizon) containing a minimum of atmospherically derived pollution lead. Analyses of forest mosses from a herbarium collection (spanning the last ∼100 yr) and soil matrix samples suggest that the atmospheric lead deposited on plants and soil has an average ²⁰⁶Pb/²⁰⁷Pb ratio of 1.15, while lead derived from local soil minerals has an average ratio of ∼1.47. Since the biomass of trees and field layer shrubs has an average ²⁰⁶Pb/²⁰⁷Pb ratio of ∼1.25, this indicates that 70% ± 10% of the inventory of 1 ± 0.8 mg Pb m⁻² stored in plants in the mature forest originates from pollution. Needles, bark and apical stemwood of the pine growing on the disturbed soil, show lower ²⁰⁶Pb/²⁰⁷Pb ratios (as low as 1.21) than the roots and basal stemwood (having ratios > 1.36), which indicate that plants are able to incorporate lead directly from the atmosphere (∼50% of the total tree uptake). By partitioning the total uptake of lead into uptake from the atmosphere and different soil layers using an isotopic mixing model, we estimate that ∼0.03 ± 0.01, 0.02 ± 0.01 and 0.05 ± 0.01 mg Pb m⁻² yr⁻¹ (mean ± SD), is taken up from the mor layer, the mineral soil and the atmosphere, respectively, by plants in the undisturbed mature forest. These small fluxes, which are at least a magnitude lower than reported downward migration losses, suggest that plant uptake will not strongly prolong the self-cleaning rate of the mor layer.     

全球海平面变化与中国珊瑚礁

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。     

应用高温甲烷吸附实验研究川东北地区五峰组页岩甲烷吸附能力

页岩甲烷吸附能力是决定页岩气井开采方案的重要参数,对评估页岩气藏潜力意义重大。干酪根类型、总有机碳含量、矿物组成、成熟度和孔径等是影响页岩吸附性能的因素,但针对高温高压下过剩吸附现象对页岩甲烷吸附能力影响的研究还需开展进一步的探索。为揭示四川盆地东北地区五峰组页岩甲烷吸附能力,本文通过场发射扫描电镜、低温氮气吸附和高压甲烷吸附实验,研究了高温高压下页岩的甲烷吸附能力,并分析了页岩孔隙结构等对页岩吸附能力的影响。结果表明:①五峰组页岩孔隙结构非均质性强,发育有机孔隙、粒(晶)间孔隙、粒(晶)内孔隙和粒(晶)间溶孔等多种孔隙;②比表面积平均为19.1282m^2/g;孔体积平均为0.0195cm^3/g;孔径平均为5.2226nm;③修正后的饱和吸附气量为2.56m^3/t;④五峰组页岩甲烷吸附性能受控于比表面积、孔体积;有机质含量越大、有机质热演化程度越低,其甲烷吸附性能越强;⑤孔隙结构是影响页岩甲烷吸附能力的重要内因。同时指出低压条件下的实验吸附曲线不适合直接评价页岩甲烷吸附能力。