Energy and CO2 balance of maize and grass as energy crops for anaerobic digestion

Energy crops can be used to feed anaerobic digesters and produce renewable energy. However, sustainability of this option requires that it contributes to a net production of renewable energy and a net reduction of fossil CO2 emission. In this paper, the net balance of CO2 emission and renewable energy production is assessed for maize and grass energy crops produced in several agricultural systems relevant for Southern Belgium and surrounding areas. The calculated net energy yields are 8-25 (maize) and 7.4-15.5 (grass) MWh of renewable CH4 per MWh of fossil energy invested, depending on the agricultural option considered. After conversion to electricity, the specific CO2 emissions range from 31 to 104 kg(CO2)MWhelectricity(-1), depending on the case considered. This corresponds to a significant reduction in CO2 emissions compared to the current reference gas-steam turbine technology which produces 456 kg(CO2)MWhelectricity(-1).     

Changes in annual CO2 fluxes estimated from inventory data in South Korea

Using a slightly modified IPCC method, we examined changes in annual fluxes of CO2 and contributions of energy consumption, limestone use, waste combustion, land-use change, and forest growth to the fluxes in South Korea from 1990to 1997. Our method required less data and resulted in a larger estimate of CO2released by industrial processes, comparing with the original IPCC guideline. However, net CO2 emission is not substantially different from the estimates of IPCC and modified methods. Net CO2 emission is intimately related to GDP as Koreaneconomy has heavily relied on energy consumption and industrial activities, which are major sources of CO2. Total efflux of CO2 was estimated to be 63.6 Tg C/ain 1990 and amounted to 112.9 Tg C/a in 1997. Land-use change contributed to annual budget of CO2 in a relatively small portion. Carbon dioxide was sequesteredby forest biomass at the rate of 6.5 Tg C/a in 1990 and 8.5 Tg C/a in 1997. Although CO2 storage in the forests increased, the sink effect was overwhelmed by extensive energy consumption, suggesting that energy-saving strategies will be more effective in reducing CO2 emission in Korea than any other practices. It is presumed that plant uptake of CO2 is underestimated as carbon contained in plant detritus and belowground living biomass were not fully considered. Furthermore, the soil organic carbon stored in forest decomposes in various ways in rugged mountains depending on their conditions, such as slope, aspect and elevation, which could have an effect on decomposition rate and carbon stores in soils. Thus, carbon sequestration of forests deserves further attention.     

A human development framework for CO2 reductions

Although developing countries are called to participate in CO(2) emission reduction efforts to avoid dangerous climate change, the implications of proposed reduction schemes in human development standards of developing countries remain a matter of debate. We show the existence of a positive and time-dependent correlation between the Human Development Index (HDI) and per capita CO(2) emissions from fossil fuel combustion. Employing this empirical relation, extrapolating the HDI, and using three population scenarios, the cumulative CO(2) emissions necessary for developing countries to achieve particular HDI thresholds are assessed following a Development As Usual approach (DAU). If current demographic and development trends are maintained, we estimate that by 2050 around 85% of the world's population will live in countries with high HDI (above 0.8). In particular, 300 Gt of cumulative CO(2) emissions between 2000 and 2050 are estimated to be necessary for the development of 104 developing countries in the year 2000. This value represents between 20 % to 30 % of previously calculated CO(2) budgets limiting global warming to 2 °C. These constraints and results are incorporated into a CO(2) reduction framework involving four domains of climate action for individual countries. The framework reserves a fair emission path for developing countries to proceed with their development by indexing country-dependent reduction rates proportional to the HDI in order to preserve the 2 °C target after a particular development threshold is reached. For example, in each time step of five years, countries with an HDI of 0.85 would need to reduce their per capita emissions by approx. 17% and countries with an HDI of 0.9 by 33 %. Under this approach, global cumulative emissions by 2050 are estimated to range from 850 up to 1100 Gt of CO(2). These values are within the uncertainty range of emissions to limit global temperatures to 2 °C.     

Stomatal density and stomatal index as indicators of paleoatmospheric CO(2) concentration

A growing number of studies use the plant species-specific inverse relationship between atmospheric CO(2) concentration and stomatal density (SD) or stomatal index (SI) as a proxy for paleo-CO(2) levels. A total of 285 previously published SD and 145 SI responses to variable CO(2) concentrations from a pool of 176 C(3) plant species are analyzed here to test the reliability of this method. The percentage of responses inversely responding to CO(2) rises from 40 and 36% (for SD and SI, respectively) in experimental studies to 88 and 94% (for SD and SI, respectively) in fossil studies. The inconsistent experimental responses verify previous concerns involving this method, however the high percentage of fossil responses showing an inverse relationship clearly validates the method when applied over time scales of similar length. Furthermore, for all groups of observations, a positive relationship between CO(2) and SD/SI is found in only 相似文献   

Assessment of CO 2 Emission Reduction Strategies for the Japanese Petrochemical Industry

Abstract: This article analyzes the possibilities for reducing carbon dioxide (CO₂) emissions in the life cycle of Japanese petrochemicals, focusing primarily on the nonenergy use of fossil fuels. For this purpose a linear programming model called CHEAP (CHemical industry Environmental strategy Analysis Program) has been developed. The results show a moderate autonomous growth of emissions by 5% in the period 2000 to 2020, if it is assumed that no new technology is introduced and demand (measured in physical units) increases 1% per year, on average. However, if it is assumed that ongoing technology development succeeds, emissions in 2020 may decrease by 5% from 2000 levels (a decrease of 10% compared to the case that assumes no new technology). This is a significant contribution to emission reduction. According to this model, a further emission reduction by 10% in 2020 is possible but costly as it requires emission reduction incentives of up to 10,000 yen per ton CO₂ (approximately 100 US/ton). The use of biomass feed-stocks, waste recycling, energy recovery from waste and gas-based co-generation are the main strategies for achieving this emission reduction.     

Diverting residual biomass to energy use: Quantifying the global warming potential of biogenic CO2 (GWPbCO2)

To calculate the global warming potential of biogenic carbon dioxide emissions (GWP_bCO2) associated with diverting residual biomass to bioenergy use, the decay of annual biogenic carbon pulses into the atmosphere over 100 years was compared between biomass use for energy and its business-as-usual decomposition in agricultural, forestry, or landfill sites. Bioenergy use increased atmospheric CO₂ load in all cases, resulting in a ¹⁰⁰GWP_bCO2 (units of g CO₂e/g biomass CO₂ released) of 0.003 for the fast-decomposing agricultural residues to 0.029 for the slow, 0.084–0.625 for forest residues, and 0.368–0.975 for landfill lignocellulosic biomass. In comparison, carbon emissions from fossil fuels have a ¹⁰⁰GWP of 1.0 g (CO₂e/g fossil CO₂). The fast decomposition rate and the corresponding low ¹⁰⁰GWP_bCO2 values of agricultural residues make them a more climate-friendly feedstock for bioenergy production relative to forest residues and landfill lignocellulosic biomass. This study shows that CO₂ released from the combustion of bioenergy or biofuels made from residual biomass has a greenhouse gas footprint that should be considered in assessing climate impacts.     

黄淮海平原河北省范围内农田土壤二氧化碳和氧化亚氮排放量的估算

以黄淮海平原河北省范围内的农田土壤为研究对象,通过与田间实际观测数据进行比较发现,DNDC模型能够较好地反映农田土壤温室气体CO2和N2O的排放通量,可以用来模拟估算农田土壤CO2和N2O的排放通量.根据模型估算,2003年河北省111个县市农业土壤CO2排放量约3.758×106tC,各县市总的N2O排放量40.345×106kgN.全省释放的CO2和N2O中有40%左右来自冬小麦/夏玉米地.因此,减少该地区农业土壤CO2和N2O排放量的措施,应集中用于排放量高的县市和这些地区的冬小麦/夏玉米地,进行大范围的普遍减排可能收效甚微,并且没有必要.     

Biofixation of CO2 from synthetic combustion gas using cultivated microalgae in three-stage serial tubular photobioreactors

Coal is the most abundant of the fossil fuels, with reserves estimated at 102 billions of tons. The feasibility of using coal as a fuel depends upon reducing emissions of gas when it is burnt, such as carbon dioxide (CO2), sulfur oxides (SO(x)), and nitrogen oxides (NO(x)). The removal of CO2 with microalgae may be one of the most efficient ways of reducing this gas, without the need for radical changes in the world's energy supply and production methods. Spirulina sp. LEB-18 and Scenedesmus obliquus LEB-22 were cultivated in serial tubular photobioreactors, with the aim of measuring the potential of CO2 biofixation and the resistance of the microalgae to SO2 and NO. Spirulina sp. and S. obliquus had CO2 biofixation scores of 0.27 and 0.22 g L(-1) d(-1), respectively. Both microalgae were resistant to SO2 and NO, and grew during the 15 d they were cultivated, which proves that using microalgae is an efficient method of biofixation of CO2 emitted when fossil fuels are burnt.     

Full assessment of Sida (Sida hermaphrodita) biomass as a solid fuel

Due to an increased awareness of climate change and limited fossil resources, the demand for alternative energy carriers such as biomass has risen significantly during the past years. This development is supported by the idea of a transition to a bio‐based economy reducing fossil‐based carbon dioxide emissions. Based on this trend, biomass for energy is expected to be used in the EU mainly for heating until the end of the decade. The perennial herbaceous mallow plant Sida hermaphrodita (L.) Rusby (‘Sida’) has high potential as an alternative biomass plant for energy purposes. Different density cultivation scenarios of Sida accounting for 1, 2, or 4 plants per m² resulted in a total biomass yield of 21, 28, and 34 tons dry matter/ha, respectively, over a 3‐year period under agricultural conditions while the overall investment costs almost doubled from 2 to 4 plants per m². Subsequently, Sida biomass was used as SI) chips, SII) pellets, and SIII) briquettes for combustion studies at pilot plant scale. Pellets outcompeted chips and briquettes by showing low CO emission of 40 mg/Nm³, good burnout, and low slagging behavior, however, with elevated NO_x and SO₂ levels. In contrast, combustion of chips and briquettes displayed high CO emissions of >1,300 mg/Nm³, while SO₂ values were below 100 mg/Nm³. Contents of HCl in the flue gas ranged between 32 and 52 mg/Nm³ for all Sida fuels tested. High contents of alkaline earth metals such as CaO resulted in high ash melting points of up to 1,450°C. Life cycle assessment results showed the lowest ecological impact for Sida pellets taking all production parameters and environmental categories into consideration, showing further advantages of Sida over other alternative biomasses. Overall, the results indicate the improved applicability of pelletized Sida biomass as a renewable biogenic energy carrier for combustion.     

CO2 reduction potentials by utilizing waste plastics in steel works

Background, aim, and scope  Feedstock recycling has received attention as an effective method to recycle waste plastics. However, estimating the reduction potential by life cycle assessment using coke oven and blast furnace in steel works has been a challenging task due to the complex structure of energy flow in steel works. Municipal waste plastics consist of several plastic resins. Previous studies have generally disregarded the composition of waste plastics, which varies significantly depending on the geographical area. If the reduction potentials by using each plastic resin in steel works can be quantified, the potential of municipal waste plastics (mixtures of plastic resins) can be estimated by summing up the potential of each resin multiplied by the composition of each resin in municipal waste plastics. Therefore, the goal of this study is to investigate the reduction potentials of CO₂ emissions by using individual plastic resins (polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET)) and those for municipal waste plastics in the coke oven and blast furnace. Materials and methods  A model was developed to clarify the energy flow in steel works. In order to estimate the changes in energy and material balance in coke ovens when waste plastics are charged, the equations to calculate the coke product yield, gas product yield, and oil product yields of each plastic resin were derived from previous studies. The Rist model was adopted to quantify the changes in the inputs and outputs when plastics were fed into a blast furnace. Then, a matrix calculation method was used to calculate the change in energy balance before and after plastics are fed into a coke oven. Results  It was confirmed that product yields of municipal waste plastics (mixtures of plastic resins) could be estimated by summing up the product yield of each plastic resin multiplied by the composition of each resin in municipal waste plastics. In both cases of coke oven and blast furnace feedstock recycling, the reduction potential of CO₂ emissions varies significantly depending on the plastic resins. For example, in the case of coke oven chemical feedstock recycling, the reduction potential of PS and PP is larger than that of PE. On the other hand, in the case of blast furnace feedstock recycling, PE has the largest CO₂ emissions reduction potential, whereas the CO₂ emission reduction potential of PP is smaller than those of PE and PS. In both cases, PET has negative CO₂ emission reduction potentials, i.e., there is an increase of CO₂ emissions. In addition, the reduction potentials of CO₂ emissions are slightly different in each city. Discussions  The differences in the reduction potentials of CO₂ emissions by coke oven chemical feedstock recycling of each plastic resin is attributable to the differences in calorific values and coke product yields of each plastic resin. On the other hand, the difference in the CO₂ emission reduction potential for each plastic resin in blast furnace feedstock recycling is attributable to the difference in calorific values and the carbon and hydrogen content of each plastic resin, which leads to a difference in the coke substitution effect by each plastic resin. In both cases, the difference in those of municipal waste plastics is mostly attributable to the amount of impurities (e.g., ash, water) in the municipal waste plastics. Conclusions  It was found that the reduction potential of CO₂ emissions by coke oven and blast furnace feedstock recycling of municipal waste plastics (mixtures of plastic resins) could be estimated by summing up the potential of each resin multiplied by the composition of each resin in municipal waste plastics. It was also clarified that feedstock recycling of waste plastic in steel works is effective for avoiding the increase in CO₂ emissions by incinerating waste plastics, such as those from household mixtures of different resins. Recommendations and perspectives  With the results obtained in this study, reduction potentials of CO₂ emissions can be calculated for any waste plastics because differences in composition are taken into account.     

Lifecycle climate impact and primary energy use of electric and biofuel cargo trucks

Heavy trucks contribute significantly to climate change, and in 2020 were responsible for 7% of total Swedish GHG emissions and 5% of total global CO₂ emissions. Here we study the full lifecycle of cargo trucks powered by different energy pathways, comparing their biomass feedstock use, primary energy use, net biogenic and fossil CO₂ emission and cumulative radiative forcing. We analyse battery electric trucks with bioelectricity from stand-alone or combined heat and power (CHP) plants, and pathways where bioelectricity is integrated with wind and solar electricity. We analyse trucks operated on fossil diesel fuel and on dimethyl ether (DME). All energy pathways are analysed with and without carbon capture and storage (CCS). Bioelectricity and DME are produced from forest harvest residues. Forest biomass is a limited resource, so in a scenario analysis we allocate a fixed amount of biomass to power Swedish truck transport. Battery lifespan and chemistry, the technology level of energy supply, and the biomass source and transport distance are all varied to understand how sensitive the results are to these parameters. We find that pathways using electricity to power battery electric trucks have much lower climate impacts and primary energy use, compared to diesel- and DME-based pathways. The pathways using bioelectricity with CCS result in negative emissions leading to global cooling of the earth. The pathways using diesel and DME have significant and very similar climate impact, even with CCS. The robust results show that truck electrification and increased renewable electricity production is a much better strategy to reduce the climate impact of cargo transport than the adoption of DME trucks, and much more primary energy efficient. This climate impact analysis includes all fossil and net biogenic CO₂ emissions as well as the timing of these emissions. Considering only fossil emissions is incomplete and could be misleading.     

Biotransformations of carboxylated aromatic compounds by the acetogen Clostridium thermoaceticum: generation of growth-supportive CO2 equivalents under CO2-limited conditions.

Clostridium thermoaceticum ATCC 39073 converted vanillate to catechol. Although carboxylated aromatic compounds which did not contain methoxyl groups were not by themselves growth supportive, protocatechuate and p-hydroxybenzoate (nonmethoxylated aromatic compounds) were converted to catechol and phenol, respectively, during carbon monoxide-dependent growth. Syringate is not subject to decarboxylation by C. thermoaceticum (Z. Wu, S. L. Daniel, and H. L. Drake, J. Bacteriol. 170:5705-5708, 1988), and sustained growth at the expense of syringate-derived methoxyl groups was dependent on supplemental CO2. In contrast, vanillate was growth supportive in the absence of supplemental CO2, and 14CO2 was the major 14C-labeled product during [carboxyl-14C]vanillate-dependent growth. Furthermore, the decarboxylation of protocatechuate and p-hydroxybenzoate supported methanol- and 1,2,3-trimethoxybenzene-dependent growth (CO2 is required for growth at the expense of these substrates) when supplemental CO2 was depleted from the growth medium, and the decarboxylation of protocatechuate was concomitant with improved cell yields of methanol cultures. These findings demonstrate that (i) C. thermoaceticum is competent in the decarboxylation of certain aromatic compounds and (ii) under certain conditions, decarboxylation may be integrated to the flow of carbon and energy during acetogenesis.     

Biogenic vs. geologic carbon emissions and forest biomass energy production

In the current debate over the CO₂ emissions implications of switching from fossil fuel energy sources to include a substantial amount of woody biomass energy, many scientists and policy makers hold the view that emissions from the two sources should not be equated. Their rationale is that the combustion or decay of woody biomass is simply part of the global cycle of biogenic carbon and does not increase the amount of carbon in circulation. This view is frequently presented as justification to implement policies that encourage the substitution of fossil fuel energy sources with biomass. We present the opinion that this is an inappropriate conceptual basis to assess the atmospheric greenhouse gas (GHG) accounting of woody biomass energy generation. While there are many other environmental, social, and economic reasons to move to woody biomass energy, we argue that the inferred benefits of biogenic emissions over fossil fuel emissions should be reconsidered.     

Organic acid production from CO2/H2 and CO/H2 by mixed-culture anaerobes

The gases CO, CO₂, and H₂ were used as substrates in anaerobic fermentations producing organic acids. Various mixed bacterial sources were used, including sewage sludge digester effluent, rabbit feces, and soil. Nonsterile microorganism selection was carried out using CO₂/H₂ and CO/H₂ as the primary carbon and energy sources. Cultures were grown in specially designed, high-pressure (to 70 psig) flasks. Methanogenic bacteria were eliminated from the cultures. Liquid products of the fermentations were acetic through caproic acids, with the even-numbered acids predominating. Carbon balances showed conclusively that acetic acid was formed from carbon contained in the CO or CO₂ feed gas. Measurements made included rates of acid product formation, cell density, and degree of gas utilization. Limited characterization of the microorganisms was also performed. Production of organic acids by mixed culture inocula from CO₂/H₂ or CO/H₂ had not been reported previously. Application of this work is to the production of organic chemicals from synthesis gas (SNG), produced by the gasification of fossil fuels (peat, lignite, and various ranks of coals), biomass (agricultural and forest residues, and various biomass crops grown expressly for energy recovery), and municipal solid waste.     

Assessing factors underlying variation of CO2 emissions in boreal lakes vs. reservoirs

Reservoirs and lakes were compared to test the hypothesis that they are similar with respect to factors driving the variation in CO(2) emissions to the atmosphere. Understanding this variation is necessary for the assessment of the contribution of these freshwater ecosystems to the global carbon cycle. This study, in contrast to previous ones, included analyses of the relationships between CO(2) emissions and microbial communities. Pooled data (lakes and reservoirs) showed that variations in CO(2) emissions were strongly related to variations in temperature, dissolved organic matter (DOM) quality, and bacterial production (BP). Results also showed that lakes were characterized by higher water temperature, lower DOM quality, larger size of Daphnia, and enriched δ(13) C zooplankton compared to reservoirs. Moreover, interactions within plankton communities and relationships between CO(2) emissions and zooplankton δ(13) C signatures differed in lakes vs. reservoirs, indicating among-system type differences in food web structure and carbon cycling. As a result of these ecosystem-type characteristics, CO(2) emission variation was mainly explained by temperature and BP in lakes, and by DOM quality and the ratio of phytoplankton biomass to microheterotroph biomass in reservoirs. These results showed that differences in temperature and DOM quality between lakes and reservoirs translate into differences in microbial interactions and ultimately in the importance of factors driving CO(2) emissions to the atmosphere. They indicated that considering microbial communities and environmental variables such as temperature and DOM quality can help improve our understanding of the variation in CO(2) emissions from freshwater ecosystems.     

The issues of energy and carbon cycle: new perspectives for assessing the environmental impact of animal waste utilization

This paper focuses on the benefits of an efficient use of animal waste from the standpoint of curbing the rise of anthropogenic carbon dioxide (CO(2)) in the atmosphere. An effective use of animal waste resources might provide a partial, but still important, contribution in reducing net CO(2) emissions. In particular: the fulfillment of nutrient requirements of crop plants growing in non-limiting conditions and thus sequestering CO(2) at their potential level; the chance of diminishing the use of fossil energy, and related CO(2) emissions, required for manufacturing industrial fertilizers; the possibility of enhancing carbon sequestration in agricultural soils by the application of farmyard manure. The future success of agriculture in providing these ecosystem services can only be achieved with a changed social awareness of the links between sustainable land use and global environmental change.     

CO2, economic growth,and energy consumption in China's provinces: Investigating the spatiotemporal and econometric characteristics of China's CO2 emissions

This study addresses the spatiotemporal variations at play in China's CO₂ emissions, based on an estimation of emission levels in the period 1995–2012 and an provincial analysis of the relationship of CO₂ emissions to economic growth and energy consumption. Using a series of econometric models and data on the combustion of fossil fuels and cement manufacturing, the study first estimated CO₂ emission levels during the study period, exploring their spatiotemporal pattern. The results indicate that both China's total and its per capita CO₂ emissions have increased significantly over the study period, with both measures evidencing a similar evolution (albeit one that is characterized by noticeable regional discrepancies at the provincial level and which displays properties of convergence). From a geographical perspective, we found both total and per capita CO₂ emissionsto be higher in China's eastern region than in the country's central and western regions. Panel data analysis was subsequently undertaken in order to quantify the dynamic casual relationship between economic growth, energy consumption, and CO₂ emissions. The empirical results indicated that the variables were in fact cointegrated and exhibited a long-run positive relationship. The results of further Granger causality tests indicated the existence of a bidirectional positive causality between economic growth and energy consumption, as well as between energy consumption and CO₂ emissions, and a unidirectional positive causality running from economic growth to CO₂ emissions. The findings of this study suggest that China is, in the long run, dependent on carbon energy consumption for its rapid economic growth, a dependency which is the cause of considerable increases in CO₂ emissions. China should therefore make greater efforts to develop low-carbon technologies and renewable energy, and improve energy efficiency in order to reduce emissions and achieve green economic growth.     

12CO2 emission from different metabolic pathways measured in illuminated and darkened C3 and C4 leaves at low,atmospheric and elevated CO2 concentration

The detection of 12CO2 emission from leaves in air containing 13CO2 allows simple and fast determination of the CO2 emitted by different sources, which are separated on the basis of their labelling velocity. This technique was exploited to investigate the controversial effect of CO2 concentration on mitochondrial respiration. The 12CO2 emission was measured in illuminated and darkened leaves of one C4 plant and three C3 plants maintained at low (30-50 ppm), atmospheric (350-400 ppm) and elevated (700-800 ppm) CO2 concentration. In C3 leaves, the 12CO2 emission in the light (Rd) was low at ambient CO2 and was further quenched in elevated CO2, when it was often only 20-30% of the 12CO2 emission in the dark, interpreted as the mitochondrial respiration in the dark (Rn). Rn was also reduced in elevated CO2. At low CO2, Rd was often 70-80% of Rn, and a burst of 12CO2 was observed on darkening leaves of Mentha sativa and Phragmites australis after exposure for 4 min to 13CO2 in the light. The burst was partially removed at low oxygen and was never observed in C4 leaves, suggesting that it may be caused by incomplete labelling of the photorespiratory pool at low CO2. This pool may be low in sclerophyllous leaves, as in Quercus ilex where no burst was observed. Rd was inversely associated with photosynthesis, suggesting that the Rd/Rn ratio reflects the refixation of respiratory CO2 by photosynthesizing leaves rather than the inhibition of mitochondrial respiration in the light, and that CO2 produced by mitochondrial respiration in the light is mostly emitted at low CO2, and mostly refixed at elevated CO2. In the leaves of the C4 species Zea mays, the 12CO2 emission in the light also remained low at low CO2, suggesting efficient CO2 refixation associated with sustained photosynthesis in non-photorespiratory conditions. However, Rn was inhibited in CO2-free air, and the velocity of 12CO2 emission after darkening was inversely associated with the CO2 concentration. The emission may be modulated by the presence of post-illumination CO2 uptake deriving from temporary imbalance between C3 and C4 metabolism. These experiments suggest that this uptake lasts longer at low CO2 and that the imbalance is persistent once it has been generated by exposure to low CO2.     

开放式空气CO2增高对稻田CH4和N2O排放的影响

在FACE(free aircarbondioxideenrichment)平台上 ,采用静态暗箱 气相色谱法观测研究了大气CO2 浓度增加对稻田CH4和N2 O排放的影响 .结果表明 ,在 15 0和 2 5 0kgN·hm-2 两种氮肥水平下大气CO2 浓度增加 2 0 0 μmol·mol-1均明显促进水稻生长 ,水稻生物量积累 .大气CO2 浓度增加对 15 0和 2 5 0kgN·hm-2 两种氮肥水平下稻田CH4排放均无显著影响 ,并简要分析了与现有文献报道结果不一致的原因 .大气CO2 浓度增加也未导致 15 0和 2 5 0kgN·hm-2 两种氮肥水平下稻田N2 O排放的明显变化 ,与大多数研究结果一致 .     

我国典型城市化石能源消费CO2排放及其影响因素比较研究

城市是化石能源消费和CO₂排放的主要区域。分析典型城市化石能源消费CO₂排放特征,明确不同城市CO₂排放动态及主要影响因素的差异,是开展城市减排行动的重要科学依据。采用IPCC推荐方法及中国的排放参数核算11个典型城市2006—2015年间化石能源消费产生的CO₂排放量。根据各城市经济发展和CO₂排放特征将之分为四类:经济高度发达城市(北京、上海、广州)、高碳排放城市(重庆、乌鲁木齐、唐山)、低排放低增长城市(哈尔滨、呼和浩特和大庆)和低排放高增长城市(贵阳、合肥),并运用对数平均迪氏指数法(Logarithmic Mean Divisia Index,即LMDI分解法)对比分析了四类城市CO₂排放量的影响因素。结果表明:(1)研究期内大部分城市CO₂排放总量有所增加,仅北京和广州呈下降趋势,工业部门CO₂排放在城市排放总量及其变化中占据主导地位;四类城市的人均CO₂排放量表现出与排放总量相...