Comparison and Analysis of CO_2 Emissions Data for China

This paper reviews the CO2emissions data for China provided by various international organizations and databases(namely IEA,BP,EDGAR/PBL/JRC,CDIAC,EIA and CAIT)and compares them with China’s official data and estimation.The difference among these data is due to different scopes,methods and underlying data,and particularly the difference in fossil fuel consumption.Compared with data from other databases,IEA and CAIT data have the best comparability with China’s official data.The paper recommends that China enhance its coal statistics,raise the frequency of official data publication and improve the inventory completeness.

Decoupling economic growth from CO_2 emissions: A decomposition analysis of China's household energy consumption

This paper analyzes Chinese household CO_2 emissions in 1994-2012 based on the Logarithmic Mean Divisia Index(LMDI) structure decomposition model, and discusses the relationship between household CO_2 emissions and economic growth based on a decoupling indicator.The results show that in 1994-2012, household CO_2 emissions grew in general and displayed an accelerated growth trend during the early 21 st century. Economic growth leading to an increase in energy consumption is the main driving factor of CO_2 emission growth(an increase of 1.078 Gt CO_2) with cumulative contribution rate of 55.92%, while the decline in energy intensity is the main cause of CO_2 emission growth inhibition(0.723 Gt CO_2 emission reduction) with cumulative contribution rate of 38.27%. Meanwhile, household CO_2 emissions are in a weak state of decoupling in general. The change in CO_2 emissions caused by population and economic growth shows a weak decoupling and expansive decoupling state, respectively. The CO_2 emission change caused by energy intensity is in a state of strong decoupling, and the change caused by energy consumption structure ?uctuates between a weak and a strong decoupling state.

Effects of moisture and carbonate additions on CO_2 emission from calcareous soil during closed–jar incubation

Calcareous soil contains organic and inorganic carbon(C) pools,which both contribute to CO2 emission during closed-jar incubation. The mineralization of organic C and dissolution of inorganic C are both related to soil moisture,but the exact effect of water content on CO2 emission from calcareous soil is unclear. The objective of this experiment was to determine the effect of soil water content(air-dried,30%,70%,and 100% water-holding capacity(WHC)),carbonate type(CaCO3 or MgCO3),and carbonate amount(0.0,1.0%,and 2.0%) on CO2 emission from calcareous soil during closed-jar incubation. Soil CO2 emission increased significantly as the water content increased to 70% WHC,regardless of whether or not the soil was amended with carbonates. Soil CO2 emission remained the same or increased slowly as the soil water content increased from 70% WHC to 100% WHC. When the water content was ≤30% WHC,soil CO2 emission from soil amended with 1.0% inorganic C was greater than that from unamended soil. When the soil water content was 70% or 100% WHC,CO2 emission from CaCO3 amended soil was greater than that from the control. Furthermore,CO2 emission from soil amended with 2.0% CaCO3 was greater than that from soil amended with 1.0% CaCO3. Soil CO2 emission was higher in the MgCO3 amended soil than from the unamended soil. Soil CO2 emission decreased as the MgCO3 content increased. Cumulative CO2 emission was 3-6 times higher from MgCO3 amended soil than from CaCO3 amended soil. There was significant interaction effect between soil moisture and carbonates on CO2 emission. Soil moisture plays an important role in CO2 emission from calcareous soil because it affects both biotic and abiotic processes during the closed-jar incubation.

Analysis of CO_2 emissions peak:China's objective and strategy

Establishing positive and urgent targets for CO_2 reduction and emission peak,and promoting energy conservation and energy structure adjustment are among the strategies to address global climate change and CO_2 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 CO_2 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 CO_2 emission reaches its peak,the annual reduction rate of CO_2 intensity of GDP is greater than GDP annual growth rate;and the annual reduction rate of CO_2 intensity of energy use is greater than the annual growth rate of energy consumption.Therefore,three important approaches to promotion of CO_2 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 CO_2 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 CO_2 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 CO_2 emission peak.This corresponds to the level of China's potential economic growth.Achieving CO_2 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 CO_2 emission peak can be controlled with a cap of 11 billion tons,which means that CO_2 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 CO_2 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 CO_2emission 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 CO_2 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.

SOIL CO_2 EMISSIONS ON THE GLACIER SHRINKING AREA IN HAILUOGOU GLACIER

From the middle of 19 century, mountain glacier recession occurs widely and Hailuogou glacier does so on a great scale. There is a primary vegetation succession series on the shrinking glacial area. The enhancement of greenhouse gases result in the climate warming. Glacier recession is a response to the global climate warming. Determination on soil respiration plays an important role in the research on the global carbon cycling, which is one key problem for the global climate change studies. The observed values differ in different sites or with different measuring methods or by distinct observers, which add up one indefinite factor to the study on the global carbon balance. There exist different base courses at one same climatic district on the glacier shrinking area in Hailuogou, Gongga Mountain.Comparing the characteristic of different soil CO 2 emissions through the synchronous observation by the analyze ways of on\|the\|spot infrared CO 2(CI\|301) and chromatographic mainframe(HP5890A),and with the achievements of the study on the glacial recession area and vegetation succession, we established a series of soil CO 2 emission flux that can be a reference to emend the determination of soil CO 2 emission on different regions of the globe and that can be a useful parameter for modeling the global carbon cycling . Vegetation succession in the more than 2000m long glacial recession area is serially divided into 6 phases :①exposed shrinking area phase,②herbs phase,③shrubs phase,④deciduous and broad\|leaved mixed forest phase⑤coniferous and broad\|leaved mixed forest phase,⑥coniferous forest phase. Based on the two\|year’s measurement, the series of the mean intensity of soil respiration was arranged: 0, 1 960, 1 136, 2 080, 3 688 and 4 706μmol CO\-2/(m\+2·s); the series of the flux of soil CO\-2 emission was arranged: 0, 74 510, 43 185, 79 071, 140 200 and 178 890kg CO\-2/(hm\+2·d), respectively.Among the effect factors of soil respiration, temperature is the main one. All kinds of temperature influence soil respiration during the 6 succession phases.. The 2nd phase is influenced by atmospheric temperature, the 3rd and 4th phase by near\|surface temperature, the 5th and 6th phases by 5～10cm soil temperature.

Life-cycle CO_2 Emissions and Their Driving Factors in Construction Sector in China

As the construction sector is a major energy consumer and thus a significant contributor of CO_2 emissions in China,it is important to consider carbon reduction in this industry.This study analyzed six life-cycle stages and calculated the life-cycle CO_2 emissions of the construction sector in 30 Chinese provincial jurisdictions to understand the disparity among them.Results show that building materials production was the key stage for carbon reduction in the construction sector,followed by the building operation stage.External variables,e.g.,economic growth,industrial structure,urbanization,price fluctuation,and marketization,were significantly correlated with the emission intensity of the construction sector.Specifically,economic growth exhibited an inverted U-shaped relation with CO_2 emissions per capita and per area during the period examined.Secondary industry and land urbanization were negatively correlated with CO_2 emission intensity indicators from the construction sector,whereas tertiary industry and urbanization were positively correlated.Price indices and marketization had negative effects on CO_2 emission intensity.The policy implications of our findings are that cleaner technologies should be encouraged for cement providers,and green purchasing rules for the construction sector should also be established.Pricing tools(e.g.,resource taxes)could help to adjust the demand for raw materials and energy.

Impact of demographic dynamics on CO_2 emissions in Sichuan,China

Global climate change is one of the major environmental issues faced by humans.Existing evidence indicates that the anthropogenic push for a rise in the atmospheric concentration of greenhouse gases(GHGs)(particularly CO_2)has been a primary cause for global warming.Aside from economic and teclinological factors,demographic dynamics(including human consumption in a broad demographic sense)has been a major driver for CO_2 emissions.In this paper,we performed both nonlinear regression analysis(based on the STIRPAT model)and gray correlation degree analysis(based on gray system theory)on the impact of demographic dynamics on CO_2 emissions.Our results reveal that CO_2 emissions are positively correlated with population size and GDP per capita and negatively correlated with energy intensity.We also show that gray correlation degree with CO_2 emissions for five variables(i.e.,household consumption,urbanization rate,household size,population aging rate,population size)varies substantially:household consumption>urbanization rate>household size>population aging rate>population size,with household consumption being the highest,and population size the lowest.To mitigate the impact of demographic dynamics on CO_2 emissions,it is of vital significance to nurture people's awareness of sustainable consumption and to adhere to current population control policies.

Energy efficiency in a water supply system:Energy consumption and CO_2 emission

This paper presents important fundamentals associated with water and energy efficiency and highlights the importance of using renewable energy sources. A model of multi-criteria optimization for energy efficiency based on water and environmental management policies, including the preservation of water resources and the control of water pressure and energy consumption through a hybrid energy solution, was developed and applied to a water supply system. The methodology developed includes three solutions： （1） the use of a water turbine in pipe systems where pressures are higher than necessary and pressure-reducing valves are installed, （2） the optimization of pumping operation according to the electricity tariff and water demand, and （3） the use of other renewable energy sources, including a wind turbine, to supply energy to the pumping station, with the remaining energy being sold to the national electric grid. The use of an integrated solution （water and energy-） proves to be a valuable input for creating benefits from available hydro energy in the water supply system in order to produce clean power, and the use of a wind source allows for the reduction of energy consumption in pumping stations, as well as of the CO2 emission to the atmosphere.

Analysis of CO_2 emission and mitigation methods in integrated iron and steel works

CO2 emission of the steel industry takes up a great proportion of the total emission of the world. It is necessary to reduce the CO2 intensity of steel products in order to save energy,protect the environment and keep a sustainable development in the steel industry. Based on the research of steel products＇ life cycle inventory, those who conducted this research have focused on the analysis of CO2 emission factors and measures. Adopting the life cycle inventory model of a certain steelmaking site,together with the Tornado Chart, the researchers have identified significant factors, provided some explanation, and suggested some possible measures to reduce CO2 emission. The results have shown that the most important factors are the CO2 intensity of blast furnace gas （BFG）, hot metal ratio of basic oxygen furnace （BOF） and the material utilization efficiency. Accordingly,some measures such as removing CO2 in BFG,decreasing the hot metal proportion in BOF, and improve material utilization efficiency in each process ,may be taken to decrease CO2 emission.

Changing trends and determinating factors of trade-embodied CO_2 emissions in China

Embodied carbon in trade has attracted the attention of researchers, developers, and industry leaders worldwide, as it has become a considerable source of trade conflict. Because China is the world's leading carbon-emitting country, it is important to study the change trends of embodied CO_2 in Chinese trade to identify key influencing factors. This paper investigates the trade embodied CO_2 in China, with special focus on the production process and materials of each industrial sector from 1990 to 2013. This study was conducted by using an input-output model, which analyzes the specific causes of periodic waves. Our findings suggest that the machine manufacturing sector produced the largest share of emissions, whereas the metal and non-metal sector has the highest emission intensity. Moreover, the total emission quantities in trade increased from 612 to 3331 million tons in 1990 to 2013, a period characterized by decentralized trends in emissions exported to trade partners. We also employed the log-mean Divisia index(LMDI) model to decompose the carbon emissions changes into export structure, export scale, energy structure, and energy intensity, and estimate the influence of these factors at a number of time points. We found that energy intensity curbs emissions increase, and that export scale expansion is the strongest driving force.

International trade,pollution industry transfer and CO_2 emissions in Chinese industries

Will developed countries turn China into a haven for "dirty" industries through international trade by specializing in producing and exporting "clean" products and importing pollution-intensive products from China? How does international trade affect Chinese industries' CO2 emissions? This paper presents an empirical test of these hypotheses using statistical techniques such as the environmental input-output model and net exports as a proportion of consumption(NETXC) based on the trade data of 20 industries in China,and G7 and OECD developed countries.In this study,we draw three conclusions:(1) The proportion of domestically produced CO2 emissions in CO2 emissions embodied in products exported from China has been declining;(2) Industries migrated or displaced from developed countries into China include both "dirty" and "clean" industries;(3) International trade can help industries reduce CO2 emissions in aggregate and per unit of output.China has not become a haven for developed countries' "dirty" industries as a result of international trade.

Mitigating Carbon Emissions:A Comprehensive Analysis of Transitioning to Hydrogen-Powered Plants in Japan’s Energy Landscape Post-Fukushima

One of the impacts of the Fukushima disaster was the shutdown of all nuclear power plants in Japan,reaching zero production in 2015.In response,the country started importing more fossil energy including coal,oil,and natural gas to fill the energy gap.However,this led to a significant increase in carbon emissions,hindering the efforts to reduce its carbon footprint.In the current situation,Japan is actively working to balance its energy requirements with environmental considerations,including the utilization of hydrogen fuel.Therefore,this paper aims to explore the feasibility and implications of using hydrogen power plants as a means to reduce emissions,and this analysis will be conducted using the energy modeling of the MARKAL-TIMES Japan framework.The hydrogen scenario(HS)is assumed with the extensive integration of hydrogen into the power generation sector,supported by a hydrogen import scheme.Additionally,this scenario will be compared with the Business as Usual(BAU)scenario.The results showed that the generation capacities of the BAU and HS scenarios have significantly different primary energy supplies.The BAU scenario is highly dependent on fossil fuels,while the HS scenario integrates hydrogen contribution along with an increase in renewable energy,reaching a peak contribution of 2,160 PJ in 2050.In the HS scenario,the target of reducing CO_(2) emissions by 80%is achieved through significant hydrogen penetration.By 2050,the total CO_(2) emissions are estimated to be 939 million tons for the BAU scenario and 261 million tons for the Hydrogen scenario.In addition,the contribution of hydrogen to electricity generation is expected to be 153 TWh,smaller than PV and wind power.

Co_(3)O_(4)as an efficient passive NO_(x) adsorber for emission control during cold-start of diesel engines

The Co_(3)O_(4)nanoparticles,dominated by a catalytically active(110)lattice plane,were synthesized as a low-temperature NO_(x) adsorbent to control the cold start emissions from vehicles.These nanoparticles boast a substantial quantity of active chemisorbed oxygen and lattice oxygen,which exhibited a NO_(x) uptake capacity commensurate with Pd/SSZ-13 at 100℃.The primary NO_(x) release temperature falls within a temperature range of 200-350℃,making it perfectly suitable for diesel engines.The characterization results demonstrate that chemisorbed oxygen facilitate nitro/nitrites intermediates formation,contributing to the NO_(x) storage at 100℃,while the nitrites begin to decompose within the 150-200℃range.Fortunately,lattice oxygen likely becomes involved in the activation of nitrites into more stable nitrate within this particular temperature range.The concurrent processes of nitrites decomposition and its conversion to nitrates results in a minimal NO_(x) release between the temperatures of 150-200℃.The nitrate formed via lattice oxygen mainly induces the NO_(x) to be released as NO_(2) within a temperature range of 200-350℃,which is advantageous in enhancing the NO_(x) activity of downstream NH_(3)-SCR catalysts,by boosting the fast SCR reaction pathway.Thanks to its low cost,considerable NO_(x) absorption capacity,and optimal release temperature,Co_(3)O_(4)demonstrates potential as an effective material for passive NO_(x) adsorber applications.

Regulatory potential of soil available carbon,nitrogen,and functional genes on N_(2)O emissions in two upland plantation systems

Dynamic nitrification and denitrification processes are affected by changes in soil redox conditions,and they play a vital role in regulating soil N_(2)O emissions in rice-based cultivation.It is imperative to understand the influences of different upland crop planting systems on soil N_(2)O emissions.In this study,we focused on two representative rotation systems in Central China:rapeseed–rice(RR)and wheat–rice(WR).We examined the biotic and abiotic processes underlying the impacts of these upland plantings on soil N_(2)O emissions.The results revealed that during the rapeseed-cultivated seasons in the RR rotation system,the average N_(2)O emissions were 1.24±0.20 and 0.81±0.11 kg N ha^(–1)for the first and second seasons,respectively.These values were comparable to the N_(2)O emissions observed during the first and second wheat-cultivated seasons in the WR rotation system(0.98±0.25 and 0.70±0.04 kg N ha^(–1),respectively).This suggests that upland cultivation has minimal impacts on soil N_(2)O emissions in the two rotation systems.Strong positive correlations were found between N_(2)O fluxes and soil ammonium(NH_(4)^(+)),nitrate(NO_(3)^(–)),microbial biomass nitrogen(MBN),and the ratio of soil dissolved organic carbon(DOC)to NO_(3)^(–)in both RR and WR rotation systems.Moreover,the presence of the AOA-amoA and nirK genes were positively associated with soil N_(2)O fluxes in the RR and WR systems,respectively.This implies that these genes may have different potential roles in facilitating microbial N_(2)O production in various upland plantation models.By using a structural equation model,we found that soil moisture,mineral N,MBN,and the AOA-amoA gene accounted for over 50%of the effects on N_(2)O emissions in the RR rotation system.In the WR rotation system,soil moisture,mineral N,MBN,and the AOA-amoA and nirK genes had a combined impact of over 70%on N_(2)O emissions.These findings demonstrate the interactive effects of functional genes and soil factors,including soil physical characteristics,available carbon and nitrogen,and their ratio,on soil N_(2)O emissions during upland cultivation seasons under rice-upland rotations.

A combination of straw incorporation and polymer-coated urea offsets soil ammonia and nitrous oxide emissions in winter wheat fields

The combined effects of straw incorporation(SI)and polymer-coated urea(PCU)application on soil ammonia(NH_(3))and nitrous oxide(N_(2)O)emissions from agricultural fields have not been comprehensively evaluated in Northwest China.We conducted a two-year field experiment to assess the effects of combining SI with either uncoated urea(U)or PCU on soil NH_(3)emissions,N_(2)O emissions,winter wheat yields,yield-scaled NH_(3)(/NH_(3)),and yield-scaled N_(2)O(/N_(2)O).Five treatments were investigated,no nitrogen(N)fertilizer(N_(0)),U application at 150 kg N ha-1 with and without SI(SI+U and S_(0)+U),and PCU application at 150 kg N ha^(-1) with and without SI(SI+PCU and S_(0)+PCU).The results showed that the NH_(3);emissions increased by 20.98-34.35%following Sl compared to straw removal,mainly due to increases in soil ammonium(NH_(4)^(+)-N)content and water-flled pore space(WFPS).SI resulted in higher N_(2)O emissions than under the So scenario by 13.31-49.23%due to increases in soil inorganic N(SIN)contents,WFPS,and soil microbial biomass.In contrast,the PCU application reduced the SIN contents compared to the U application,reducing the NH_(3)and N_(2)O emissions by 45.99-58.07 and 18.08-53.04%,respectively.Moreover,no significant positive effects of the SI or PCU applications on the winter wheat yield were observed.The lowest /NH_(3) and /N_(2)O values were observed under the S_(0)+PCU and SI+PCU treatments.Our results suggest that single PCU applications and their combination with straw are the optimal agricultural strategies for mitigating gaseous N emissions and maintaining optimal winter wheat yields in Northwest China.

Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

Multi-scale integrated assessment of urban energy use and CO_2 emissions

Accurate and detailed accounting of energy-induced carbon dioxide （CO_2） emis- sions is crucial to the evaluation of pressures on natural resources and the environment, as well as to the assignment of responsibility for emission reductions. However, previous emission inventories were usually productionor consumption-based accounting, and few studies have comprehensively documented the linkages among socio-economic activities and external transaction in urban areas. Therefore, we address this gap in proposing an analytical framework and accounting system with three dimensions of boundaries to comprehensively assess urban energy use and related CO_2 emissions. The analytical framework depicted the input, transformation, transfer and discharge process of the carbon-based （fossil） energy flows through the complex urban ecosystems, and defined the accounting scopes and boundaries on the strength of ＇carbon footprint＇ and ＇urban metabolism＇. The accounting system highlighted the assessment for the transfer and discharge of socio-economic subsystems with different spatial boundaries. Three kinds methods applied to Beijing City explic- itly exhibited the accounting characteristics. Our research firstly suggests that urban carbon-based energy metabolism can be used to analyze the process and structure of urban energy consumption and CO_2 emissions. Secondly, three kinds of accounting methods use different benchmarks to estimate urban energy use and CO_2 emissions with their distinct strength and weakness. Thirdly, the empirical analysis in Beijing City demonstrate that the three kinds of methods are complementary and give different insights to discuss urban energy-induced CO_2 emissions reduction. We deduce a conclusion that carbon reductions responsibility can be assigned in the light of production, consumption and shared responsibility based principles. Overall, from perspective of the industrial and energy restructuring and the residential lifestyle changes, our results shed new light on the analysis on the evolutionary mechanism and pattern of urban energy-induced CO_2 emissions with the combination of three kinds of methods. And the spatial structure adjustment and technical progress provides further elements for consideration about the scenarios of change in urban energy use and CO_2 emissions.

Experimental study on soil CO_2 emission in the alpine grassland ecosystem on Tibetan Plateau

The Tibetan Plateau, the Roof of the World, is the highest plateau with a mean elevation of 4000 m. It is characterized by high levels of solar radiation, low air temperature and low air pressure compared to other regions around the world. The alpine grassland, a typical ecosystem in the Tibetan Plateau, is distributed across regions over the elevation of 4500 m. Few studies for carbon flux in alpine grassland on the Tibetan Plateau were conducted due to rigorous natural conditions. A study of soil respiration under alpine grassland ecosystem on the Tibetan Plateau from October 1999 to October 2001 was conducted at Pangkog County, Tibetan Plateau (31.23°N, 90.01°E, elevation 4800 m). The measurements were taken using a static closed chamber technique, usually every two weeks during the summer and at other times at monthly intervals. The obvious diurnal variation of CO2 emissions from soil with higher emission during daytime and lower emission during nighttime was discovered. Diurnal CO2 flux fluctuated from minimum at 05:00 to maximum at 14:00 in local time. Seasonal CO2 fluxes increased in summer and decreased in winter, representing a great variation of seasonal soil respiration. The mean soil CO2 fluxes in the alpine grassland ecosystem were 21.39 mgCO2 · m-2 · h-1, with an average annual amount of soil respiration of 187.46 gCO2 · m-2 · a-1. Net ecosystem productivity is also estimated, which indicated that the alpine grassland ecosystem is a carbon sink.

A Brief Overview of Low CO_2 Emission Technologies forIron and Steel Making

The global steel production has been growing for the last 50 years, from 200 Mt in 1950s to 1 240 Mt in 2006. Iron and steel making industry is one of the most energy-intensive industries, with an annual energy consumption of about 24 EJ, 5% of the world＇s total energy consumption. The steel industry accounts for 3%-4% of totat world greenhouse gas emissions. Enhancing energy efficiency and employing energy saving/recovering technologies such as coke dry quechning （CDQ） and top pressure recovery turbine （TRT） can be short-term approaches to the steel industry to reduce greenhouse gas emission. The long-term approaches to achieving a significant reduction in CO2 emissions from the steel industry would be through developing and applying CO2 breakthrough technologies for iron and steel making, and：through increasing use of renewable energy for iron and steel making. Thus, an overview of new CO2 breakthrough technologies for iron and steel making was made.

An estimation of energy consumption and CO_2 emissions in tourism sector of China

In 2009, nearly 900 million international tourist arrivals were counted worldwide. A global activity of this scale can be assumed to have a substantial impact on the environment. In this contribution, five major aspects such as the change of LUCC and the use of energy and its associated impacts had been recognized. Recently, the impact of tourism on environment and climate attracts the attention of international organizations and societies in pace with rapid development of tourism industry. Energy consumption and CO2 emissions in tourism sector are becoming a hot spot of international tourism research in recent five years. The use of energy for tourism can be divided according to transport-related purposes （travel to, from and at the destination） and destination-related purposes excluding transports （accommodation, food, tourist activities, etc.）. In addition, the transports, accommodation and foods are related to many other industries which are dependent on energy. Thus, the estimations of energy consumption and CO2 emissions in tourism sector have become a worldwide concern. Tourism in China grows rapidly, and the number of domestic tourists was 1902 million in 2009. Energy use and its impact on the environment increase synchronously with China’s tourism. It is necessary to examine the relationship between energy use and CO2 emissions. In this article, a preliminary attempt was applied to estimate the energy consumption and CO2 emissions from China’s tourism sector in 2008. Bottom-up approach, literature research and mathematical statistics technology were also adopted. According to the calculations, Chinese tourism-related may have consumed approximately 428.30 PJ of energy in 2008, or about 0.51% of the total energy consumptions in China. It is estimated that CO2 emissions from tourism sector amounted to 51.34 Mt, accounting for 0.86% of the total in China. The results show that tourism is a low-carbon industry and also a pillar industry coping with global climate change, energy-saving and CO2 emission reduction. Based on this, the authors suggested that tourism should become an important field in low-carbon economic development.