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1.
Carbon dioxide exchange was studied in the photosynthetic apparatus of Siberian spruce (Picea obovata Ledeb.), Siberian larch (Larix sibirica Ledeb.), and weeping birch (Betula pendula Roth.) in a mature spruce forest. Parameters of CO2 balance in different weather were characterized quantitatively on the basis of daily measurements of CO2 exchange in needles and leaves of woody plants. The percent ratios of the components of carbon balance in needles and leaves of woody plants depending on daily photosynthetic fixation of carbon were determined. In summer, trees consumed 210 kg CO2/ha (57 kg C/ha) in variable weather and 117 kg CO2/ha (32 kg C/ha) in cloudy weather. Species specificity of CO2 consumption was revealed, and the effects of environmental factors on the assimilatory activity of trees were determined.  相似文献   

2.
Studies in three typical forest biotopes of the Valdai Upland were performed to evaluate the stocks and surface area of coarse woody debris from spruce and birch (in linear transects), its colonization by xylotrophic fungi (during reconnaissance surveys), and CO2 emission (by a chamber method). The stock and surface area were minimum in a paludal birch forest (46.4 m3/ha and 960 m2/ha) and maximum in a decay area of spruce forest (256.1 m3/ha and 3761 m2/ha, respectively). The assemblages of wood-decay fungi had a composition typically found in southern taiga forests. The total CO2 flux varied from 145 kg C-CO2/ha per year in the paludal birch forest to 462 kg C-CO2/ha per year in small herb–green moss spruce forest. It is concluded that air temperature is an informative predictor of seasonal C-CO2 flux rate from coarse woody debris.  相似文献   

3.
Carbon dioxide emissions due to fossil fuel consumption are well recognized as a major contributor to climate change. In the debate on dealing with this threat, expectations are high that agriculture based economies of the developing world can help alleviate this problem. But, the contribution of agricultural operations to these emissions is fairly small. It is the clearing of native ecosystems for agricultural use in the tropics that is the largest non-fossil fuel source of CO2 input to the atmosphere. Our calculation show that the use of fossil energy and the concomitant emission of CO2 in the agricultural operational sector - i.e. the use of farm machinery, irrigation, fertilization and chemical pesticides - amounts to merely 3.9% of the commercial energy use in that part of the world. Of this, 70% is associated with the production and use of chemical fertilizers. In the absence of fertilizer use, the developing world would have converted even more land for cultivation, most of which is completely unsuitable for cultivation. Current expectations are that reforestation in these countries can sequester large quantities of carbon in order to mitigate excessive emissions elsewhere. But, any program that aims to set aside land for the purpose of sequestering carbon must do so without threatening food security in the region. The sole option to liberate the necessary land for carbon sequestration would be the intensification of agricultural production on some of the better lands by increased fertilizer inputs. As our calculations show, the sequestration of carbon far outweighs the emissions that are associated with the production of the extra fertilizer needed. Increasing the fertilizer use in the developing world (without China) by 20%, we calculated an overall net benefit in the carbon budget of between 80 and 206 Mt yr?1 dependent on the carbon sequestration rate assumed for the regrowing forest. In those regions, where current fertilizer use is low, the relative benefits are the highest as responding yield increases are highest and thus more land can be set aside without harming food security. In Sub-Saharan Africa a 20% fertilizer increase, which amounts to 0.14 Mt of extra fertilizer, can tie up somewhere between 8 and 19 Mt of CO2 per year (average: 96 t CO2 per 1 t fertilizer). In the Near East and North Africa with a 20%-increased fertilizer use of 0.4 Mt yr-1 between 10 and 24 Mt of CO2 could be sequestered on the land set aside (40 t CO2 per 1 t fertilizer). In South Asia this is 22–61 Mt CO2 yr?1 with an annual additional input of 2.15 Mt fertilizer (19 t CO2 per 1 t fertilizer). In fact, carbon credits may be the only way for some of the farmers in these regions to afford the costly inputs. Additionally, in regions with already relatively high fertilizer inputs such as in South Asia, an efficient use of the extra fertilizer must be warranted. Nevertheless, the net CO2 benefit through implementation of this measure in the developing world is insignificant compared to the worldwide CO2 output by human activity. Thus, reforestation is only one mitigating measure and not the solution to unconstrained fossil fuel CO2 emissions. Carbon emissions should, therefore, first of all be reduced by the avoidance of deforestation in the developing world and moreover by higher energy efficiency and the use of alternative energy sources.  相似文献   

4.
Global atmospheric CO2 concentration has increased since the beginning of reliable monitoring in 1958 at a mean rate of about 0.9 ppm CO2/yr. Now, atmospheric CO2 concentration is at 330 ppm. From about 1860 up to 1974, man's intervention in the global carbon cycle caused a likely increase of 76.6 × 1015 gC, corresponding to 36 ppm CO2 in the atmosphere, if a preindustrial content of 294 ppm CO2 or 625.3 × 1015 g C is adopted to be valid. A further rise of atmospheric CO2 seems to be inevitable and probably will be responsible for a climatic warming in the next several decades; therefore, a global examination of carbon reservoirs and carbon fluxes has been undertaken to determine their storage capacity for excess carbon which orginated mainly from burning fossil fuels and from land clearing. During 1860–1974 about 136 × 1015 g C have ben emitted into the atmosphere by fossil fuel combustion and cement production. At present, the emission rate is about 5 × 1015 g C/yr. The worldwide examination of carbon release, primarily by deforestation and soil cultivation since 1860, is estimated to be about 120 × 1015 g C. The net transfer of carbon to the atmosphere owing to man's interference with the biosphere is now believed to be about 2.4 × 1015 g C/yr. An oceanic uptake of roughly 179 × 1015 g C since 1860 is open to discussion. According to the chemical buffering of sea surface water only about 35.5 × 1015 g C could have been absorbed. It is argued, however, that oceanic circulations might have been more effective in removing atmospheric excess carbon of anthropogenic origin.  相似文献   

5.
Upon arrival on Earth, the reduced carbon pool split into a series of compartments: core, mantle, crust, hydrosphere, atmosphere, biosphere.This distribution pattern is caused by the ability of carbon to adjust structurally to a wide range of pressure and temperature, and to form simple and complex molecules with oxygen, hydrogen and nitrogen. Transformation also involved oxidation of carbon to CO2 which is mediated at depth by minerals, such as magnetite, and by water vapor above critical temperature. Guided by mineral-organic interactions, simple carbon compounds evolved in near surface environments towards physiologically interesting biochemicals. Life, as an autocatalytic system, is considered an outgrowth of such a development.This article discusses environmental parameters that control the CO2 system, past and present. Mantle and crustal evolution is the dynamo recharging the CO2 in sea and air; the present rate of CO2 release from the magma is 0.05 × 1015 g C per year. Due to the enormous buffer capacity of the chemical system ocean, such rates are too small to seriously effect the level of CO2 in our atmosphere. In the light of geological field data and stable isotope work, it is concluded that the CO2 content in the atmosphere has remained fairly uniform since early Precambrian time; CO2 should thus have had little impact on paleoclimate. In contrast, the massive discharge of man-made CO2 into our atmosphere may have serious consequences for climate, environment and society in the years to come.  相似文献   

6.
ABSTRACT

The biogas constituting majorly CH4 and CO2 has been produced by Ca(OH)2 pre-treated wheat straw with pre-digested cow dung. Some of the key thermodynamic parameters like specific heat capacity, density and heating capacity of the biogas produced have also been calculated per day as well as throughout the hydraulic retention time. The governing equations of biogas with appropriate phase and interfacial conditions describing the physics of the biogas have been derived. The control volume approach has been used to predict the total volume (ml) of biogas, CH4 and CO2 throughout the experiment and on the daily basis. The effects of feedstock, temperature and pressure on the production of biogas, CH4 and CO2 in anaerobic digestion have also been studied. The average number of molar fraction and conversion ratio of CH4 and CO2 are correlated with number of carbon atoms available in feedstock. Numerical calculations by using developed model and Modified Gompertz model have shown proficient agreement with the experimental observations.  相似文献   

7.
Past increase of atmospheric CO2 involves significant contributions from both fossil and biospheric sources. The latter are controversial, partly because these CO2 releases may be balanced by accelerated regrowth following clearing of some forests, while others were being converted to agricultural or other nonforest land. A simulation model was used to reconstruct changes since 1860 and project four hypothetical future scenarios of CO2 injection to 2460. Nineteen compartments and their exchanges of carbon were considered. Areal extents of tropical forests, other wooded ecosystems, and nonforests were incorporated into the model. Rapidly and slowly exchanging pools of carbon per unit area were projected by integrating income-loss differential equations numerically. Estimated cumulative releases of CO2 from fossil fuels (plus cement) near 120 Pg of carbon (1 Pg = 1015 g) from 1860 to 1970 were assumed to equal the prompt plus delayed releases due to forest clearing. Limits of exploitable forest area and biomass were evaluated and found to contribute much less future CO2 than usable fossil fuels. Ultimate release from the latter (7500±2500 Pg C) could increase atmospheric CO2 manyfold: doubling the assumed 1860 levels as early as (1) the year 2032 for assumed early fossil-use scenarios and (2) the year 2045 for late fossil-use scenarios. Depending on the poorly known parametes that were programmed to constrain the organic production rates, cumulative storage, and the response of plants and soils to enhanced atmospheric CO2, biospheric storage might reach higher levels for all scenarios than the estimates given here. However, maximizing such storage in real life would require much closer understanding and wiser management of ecosystems than history has shown.  相似文献   

8.
We estimated carbon dioxide (CO2) and methane (CH4) emissions by diffusion, ebullition, and degassing in turbines from a semi-arid hydropower reservoir in northeastern Brazil. Sampling sites were allocated within the littoral and deeper waters of one embayment, the main-stream, and at turbines. Annual carbon emissions were estimated at 2.3?×?105?±?7.45?×?104 t C year?1, or in CO2-equivalents (CO2-eq) at 1.33?×?106?±?4.5?×?105 t CO2-eq year?1. Diffusion across the water surface was the main pathway accounting for 96% of total carbon emissions. Ebullition was limited to littoral areas. A slight accumulation of CO2, but not of CH4, in bottom waters close to the turbines inlet led to degassing emissions about 8?×?103 t C year?1. Emissions in littoral areas were higher than in main-stream and contribute to 40% of the total carbon. Carbon (C) emissions per electricity generated, at 60% of installed capacity, is 0.05 t C-CO2-eq MWh?1. The ratio increases to 0.09 t C-CO2 MWh?1, equating 80% of the emissions from natural gas and 40% of diesel or coal power plants. Retention time and benthic metabolism were identified as main drivers for carbon emissions in littoral areas, while water column mixing and rapid water flow are important factors preventing CH4 accumulation and loss by degassing. Our results indicate that Itaparica Reservoir, located in the semi-arid region of Northeastern Brazil, acts as a source of GHGs. Management measurements are needed to prevent emissions to raise in the future.  相似文献   

9.
Carbon dioxide fluxes from the surface of coarse woody debris (CWD) have been measured in Korean pine forests of the southern Sikhote-Alin mountain range. The seasonal dynamics of oxidative conversion of CWD carbon have been evaluated, and average values of the CO2 emission rate have been determined for CWD fragments of three tree species at different stages of decomposition. The degree of decomposition is an important factor of spatial variation in CO2 emission rate, and temporal variation in this parameter is adequately described by an exponential function of both CWD temperature and air temperature (R2 = 0.65–0.75).  相似文献   

10.
Abstract

In this paper, using the input-output model, the author first calculated the CO2 emissions embodied in exports of China in 2002 and 2007. Then, the author empirically analyzed problems existing in the composition of exported products and analyzed its possible reasons. The research results of this paper are as follows: Since China’s entry into WTO, the CO2 emissions embodied in exports of China have been increasing rapidly; the value of exported products of high-carbon emissions industries accounts for a relatively higher proportion to China’s total exports value because China’s carbon intensive products have a certain competitive advantage. Additionally, this paper has put forward relevant suggestions based on these results.  相似文献   

11.
On account of the background of China’s “new normal” characterized by slower economic growth, this paper analyses the low-carbon economy status quo in the Beijing–Tianjin–Hebei region and empirically investigates the relationship between carbon dioxide (CO2) emissions and its various factors for China’s Beijing–Tianjin–Hebei region using panel data econometric technique. We find evidence of existence of Environmental Kuznets Curve. Results also show that economic scale, industrial structure, and urbanization rate are crucial factors to promote CO2 emissions. However, technological progress, especially the domestic independent research and development, plays a key role in CO2 emissions abatement. Next, we further analyze the correlation between each subregion and various factors according to Grey Relation Analysis. Thereby, our findings provide important implications for policymakers in air pollution control and CO2 emissions reduction for this region.  相似文献   

12.
A chemical pathway combining reverse water gas shift, Fischer‐Tropsch synthesis and hydro‐cracking was considered to re‐synthesise jet fuel from CO2 captured at high purity by oxy‐fuelling of a typical coal‐fired power station (Drax, UK). The oxygen for oxy‐fuelling and hydrogen for the fuel re‐synthesis process are sourced by electrolysis of water. According to material and energy balances , 3.1 MT/year of jet fuel and 1.6 MT/year each of gas oil and naphtha can be produced from the Drax annual emissions of 20 MT of CO2, sufficient to supply 23% of the UK jet fuel requirements. The overall re‐synthesis requires 16.9 GW, to be sourced renewably from (offshore) wind power, and releases 4.4 GW of exothermic energy giving scope for improvements via process integration. The energy re‐synthesis penalty was 82% ideally and 95% on a practical basis. With the cost of offshore wind power predicted to reduce to 2.0 p/kWh by 2020, this ‘re‐syn’ jet fuel would be competitive with conventional jet fuel, especially if carbon taxes apply. The re‐use of CO2 sequestrated from coal power stations to form jet‐fuel would halve the combined CO2 emissions from the coal power and aviation sectors.  相似文献   

13.
Based on the China high resolution emission gridded data (1 km spatial resolution), this article is aimed to create a Chinese city carbon dioxide (CO2) emission data set using consolidated data sources as well as normalized and standardized data processing methods. Standard methods were used to calculate city CO2 emissions, including scope 1 and scope 2. Cities with higher CO2 emissions are mostly in north, northeast, and eastern coastal areas. Cities with lower CO2 emissions are in the western region. Cites with higher CO2 emissions are clustered in the Jing-Jin-Ji Region (such as Beijing, Tianjin, and Tangshan), and the Yangtze River Delta region (such as Shanghai and Suzhou). The city per capita CO2 emission is larger in the north than the south. There are obvious aggregations of cities with high per capita CO2 emission in the north. Four cities among the top 10 per capita emissions (Erdos, Wuhai, Shizuishan, and Yinchuan) cluster in the main coal production areas of northern China. This indicates the significant impact of coal resources endowment on city industry and CO2 emissions. The majority (77%) of cities have annual CO2 emissions below 50 million tons. The mean annual emission, among all cities, is 37 million tons. Emissions from service-based cities, which include the smallest number of cities, are the highest. Industrial cities are the largest category and the emission distribution from these cities is close to the normal distribution. Emissions and degree of dispersion, in the other cities (excluding industrial cities and service-based cities), are in the lowest level. Per capita CO2 emissions in these cities are generally below 20 t/person (89%) with a mean value of 11 t/person. The distribution interval of per capita CO2 emission within industrial cities is the largest among the three city categories. This indicates greater differences among per capita CO2 emissions of industrial cities. The distribution interval of per capita CO2 emission of other cities is the lowest, indicating smaller differences of per capita CO2 emissions among this city category. Three policy suggestions are proposed: first, city CO2 emission inventory data in China should be increased, especially for prefecture level cities. Second, city responsibility for emission reduction, and partitioning the national goal should be established, using a bottom-up approach based on specific CO2 emission levels and potential for emission reductions in each city. Third, comparative and benchmarking research on city CO2 emissions should be conducted, and a Top Runner system of city CO2 emission reduction should be established.  相似文献   

14.
The Welsh Government is committed to reduce greenhouse gas (GHG) emissions from agricultural systems and combat the effects of future climate change. In this study, the ECOSSE model was applied spatially to estimate GHG and soil organic carbon (SOC) fluxes from three major land uses (grass, arable and forest) in Wales. The aims of the simulations were: (1) to estimate the annual net GHG balance for Wales; (2) to investigate the efficiency of the reduced nitrogen (N) fertilizer goal of the sustainable land management scheme (Glastir), through which the Welsh Government offers financial support to farmers and land managers on GHG flux reduction; and (3) to investigate the effects of future climate change on the emissions of GHG and plant net primary production (NPP). Three climate scenarios were studied: baseline (1961–1990) and low and high emission climate scenarios (2015–2050). Results reveal that grassland and cropland are the major nitrous oxide (N2O) emitters and consequently emit more GHG to the atmosphere than forests. The overall average simulated annual net GHG balance for Wales under baseline climate (1961–1990) is equivalent to 0.2 t CO2e ha?1 y?1 which gives an estimate of total annual net flux for Wales of 0.34 Mt CO2e y?1. Reducing N fertilizer by 20 and 40 % could reduce annual net GHG fluxes by 7 and 25 %, respectively. If the current N fertilizer application rate continues, predicted climate change by the year 2050 would not significantly affect GHG emissions or NPP from soils in Wales.  相似文献   

15.
NEWS     
Abstract

Co-integration theory has been employed in this paper and Granger causes are found between urbanization rate and GDP, between capital stock and GDP. Scenario analysis of GDP is performed using the GDP model established in the paper. The energy consumptions in Germany, Japan and other developed countries are analyzed and compared with the energy consumption in China. Environmental friendly scenario of energy demand and CO2 emissions for sustainable China has been formed based on the results of comparison. Under environmental friendly scenario, the primary energy consumption will be 4.31 billion ton coal equivalence (tce) and CO2 emissions will be 1.854 billion t-c in 2050; energy per capital will be 3.06 tce that is 1.8 times of energy consumed in 2005 in China and 51% of consumed energy per capital in Japan in 2003. In 2050, the energy requirement of unit GDP will be 20% lower than that of Germany in 2003, but will be still 37% higher than that in Japan in 2003. It is certain that to fulfill the environmental friendly Scenario of energy demand and CO2 emissions is a difficult task and it needs long term efforts of the whole society, not only in production sectors but also in service and household sectors.  相似文献   

16.
The ecological burden of economic growth is a highly discussed issue. In this article, we focus on the set of European Union (EU) 15 countries in the period 1995–2014. We first decomposed emissions into six effects and afterward the decoupling-effort index was used to calculate the magnitude of impact that each factor has on it, considering the country group. For the group of the EU-15 in the pre-Kyoto period, CO2 changes are only negative in 1998 and 1999 considering the initial view (with respect to the base year of 1995), being positive for all the other years. This positive effect means increased emissions, for which many contributed the positive and significant effects of income per capita and the population effects. The most significant reductions in CO2 changes are verified in the years after the effective Kyoto commitment and observed mainly in the alternative view (year to year changes), for which many contributed the negative and significant effects of carbon intensity of petroleum products, energy intensity and conversion efficiency in the overall period. The effects elasticity decoupling and decoupling effort do not seem to be controlled by the internal drivers of CO2 emissions. Policy makers should bet in policy instruments pointed in the sense of strengthening energy efficiency, in reducing petroleum products consumption and therefore dependency and on the structure of added value generated by the economy.  相似文献   

17.
The dynamics and structure of the phytomass and production of an undisturbed mesotrophic dwarf shrub–sphagnum phytocenosis and one burned by fire have been compared. The net primary production (NPP) of both sites of phytocenoses in the postpyrogenic period is estimated by direct field determination of the productivity parameters, and C emission from the fire is assessed. The obtained data on emission (0.7 kg/m2) differ from the results obtained in the peatlands of western Canada (3.2 kg/m2).  相似文献   

18.
Oxidation of hydrocarbon in asphalt binder leads to the production of carbon dioxide (CO2) during the production of hot mix asphalt. The objective of this laboratory study was to investigate the effects of the asphalt additive Sasobit®, asphalt content and mixing/placement temperature on CO2 emissions from binder with laboratory measurements. The isolated effects of Sasobit on asphalt absorption into the aggregate were also looked at. Temperature was found to be the only statistically significant factor on emissions. This would suggest that warm mix asphalt technology, which employs the use of Sasobit in asphalt mixtures, is a very effective way of lowering the industry's CO2 emission impact, both directly and by the use of less energy for heating. This work predicts that greater than 30% reduction of CO2 emissions is possible with typically used levels of Sasobit.  相似文献   

19.
The Pechelbronn oilfield (Rhine Graben, France), where mining activity ended in the 1960s, has been used for waste disposal for twenty years. Since the wastes are varied, work is underway to identify the discharged materials and their derivatives, as well as to locate and quantify potential discharge sites. Two major goals were assigned to the present work. The first was to identify or refine the location of hidden structures that could facilitate gas emanation up to the surface, by studying soil gas concentrations (mainly 222Rn, CO2, CH4 and helium) and carbon isotope ratios in the CO2 phase. The second was devoted to examining, from a health and safety viewpoint, if the use of the oilfield as a waste disposal site might have led to enhanced or modified gas emanation throughout the area.It appeared that CO2 and 222Rn evolution in the whole area were similar, except near some of the faults and fractures that are known through surface mapping and underground observations. These 222Rn and CO2 anomalies made it possible to highlight more emissive zones that are either related to main faults or to secondary fractures acting as migration pathways. In that sense, the CO2 phase can be used to evaluate 222Rn activities distant from tectonic structures but can lead to erroneous evaluations near to gas migration pathways. Dumping of wastes, as well as oil residues, did not appear to have a strong influence on soil gaseous species and emanation. Similarly, enhanced gas migration due to underground galleries and exploitation wells has not been established. Carbon isotope ratios suggested a balance of biological phenomena, despite the high CO2 contents reached. Other monitored gaseous species (N2, Ar, H2 and alkanes), when detected, always showed amounts close to those found subsurface and/or in atmospheric gases.  相似文献   

20.
Establishing positive and urgent targets for CO2 reduction and emission peak, and promoting energy conservation and energy structure adjustment are among the strategies to address global climate change and CO2 emissions reduction. They are also means to break through the constraints of domestic resources and environment, and internal needs, to achieve sustainable development. Generally speaking, a country's CO2 emission peak appears after achieving urbanization and industrialization. By then, connotative economic growth will appear, GDP will grow slowly, energy consumption elasticity will decrease, and energy consumption growth will slow down – dependent mainly on new and renewable energies. Fossil fuel consumption will not increase further. When CO2 emission reaches its peak, the annual reduction rate of CO2 intensity of GDP is greater than GDP annual growth rate; and the annual reduction rate of CO2 intensity of energy use is greater than the annual growth rate of energy consumption. Therefore, three important approaches to promotion of CO2 emission peak can be concluded: maintaining reasonable control of GDP growth, strengthening energy conservation to significantly reduce the GDP energy intensity, and optimizing the energy mix to reduce the CO2 intensity of energy use. By around 2030, China will basically have completed its rapid development phase of industrialization and urbanization. Connotative economic growth will appear with the acceleration of industrial structure adjustment. The target of GDP energy intensity will still be to maintain an average annual reduction of 3% or higher. The proportion of non-fossil fuels will reach 20–25%, and the aim will be to maintain an average annual growth rate of 6–8%. The total annual energy demand growth of 1.5% will be satisfied by the newly increased supply of non-fossil fuels. The annual decline in CO2 intensity of GDP will reach 4.5% or higher, which is compatible with an average annual GDP growth rate of approximately 4.5% in order to reach CO2 emission peak. This corresponds to the level of China's potential economic growth. Achieving CO2 emission peak will not impose a rigid constraint on economic development, but rather promote economic development and accelerate the transformation of green, low-carbon development. The CO2 emission peak can be controlled with a cap of 11 billion tons, which means that CO2 emission will increase by less than 50% compared with 2010. The per capita emission peak will be controlled at a level of less than 8 tons, which is lower than the 9.5 tons in the EU and Japan and much lower than the 20 tons in the US, future economic and social development faces many uncertainties in achieving the CO2 emission peak discussed above. It depends on current and future strategies and policies, as well as the pace and strength of economic transformation, innovation, and new energy technologies. If the economic transformation pattern fails to meet expectations, the time required to reach CO2 emission peak would be delayed and the peak level would be higher than expected. Therefore, we need to coordinate thoughts and ideas and deploy these in advance; to highlight the strategic position of low-carbon development and its priorities; to enact mid- to long-term energy development strategies; and to establish and improve a system of laws, regulations, and policies as well as an implementation mechanism for green, low-carbon development. Oriented by positive and urgent CO2 reduction and peak targets, the government would form a reversed mechanism to promote economic transformation and embark on the path of green, low-carbon development as soon as possible.  相似文献   

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