Estimating ‘rhizosphere priming effect’: Comparison of the indirect <Emphasis Type="Italic">y</Emphasis>-intercept regression approach and direct bare plot Approach

Determined the contribution of root derived CO₂ efflux to total CO₂ efflux (including root and non-root derived CO₂ efflux) is import to grope the mechanism of CO₂ efflux, however, becaused of ‘rhizoshere priming effect’ (RPE), it is difficult to achieve in practice. In this study, we attempted to estimate the RPE via comparing basal soil respiration (R_b) achieved by two different methods namely, y-intercept regression and direct bare plot approach in an arid cotton field, central Asia. On the basis of the y-intercept of linear regressions between below-ground respiration (BGR) and root biomass, R_b was indirectly calculated. Comparing with the first approach, the second approach involved direct measurements of soil respiration from bare plots. R_b estimated by y-intercept method contained the component of RPE whereas direct bare plot did not. We found that RPE showed a phenological trend with highest value in flowering stage at 0.145 g CO₂ m^–2 h^–1 and lowest at budding stage (0.007 g CO₂ m^–2 s^–1), even after the data had been corrected for the influence of soil temperature. We concluded that RPE needed to be considered when R_b was estimated by y-intercept approach.     

Economic Analysis of CO2 Emission Trends in China

Climate change is one of hot spots all around the world. China, the second biggest CO₂ emitter, is facing increasingly severe pressure to reduce CO₂ emission. The article first describes Kaya Identity and its policy implications. Second, it uses the modified Kaya Identity and makes decomposition without residues on CO₂ emission during the period 1971-2005. Taking into account the changes of macroeconomic background, it conducts a detailed analysis in terms of CO₂ emission trend from 4^th Five Year Plan through 10^th Five Year Plan. The decomposition results indicate that economic development and increase in population are major driving forces, and that improvement in energy efficiency contributes to the reduction of CO₂ emission, and that decarbonization in primary energy structure is also an important strategic choice. Finally, the article stresses that in CO₂ order to realize the binding target of 20% reduction in GDP energy intensity during the 11^th Five Year Plan, China should speed up the readjustment of the industrial structure and energetically develop the energy-efficient technologies and clean fuel technology, which will effectively promote the country to reduce CO₂ emission and contribute to the mitigation of climate change.     

Causality relationship between CO2 emissions,GDP and energy intensity in Tunisia

This article analyzes the causality between the economic growth, the energy and the environment, measured by CO₂ emissions. Our empirical study is based on a series of annual data from 1980 to 2010 in Tunisia. Our study was conducted using the Granger causality test and variance decomposition. The empirical results confirm the presence of a positive effect between the energy consumption and the economic growth measured by gross domestic product (GDP). Thus, there is a unidirectional relationship between GDP and CO₂ emissions in the short term. This analysis shows, as is common to relatively fast-growing economies in Tunisia, that the biggest contributor to the rise is CO₂ emissions. Hence, in congruence with the result of variance decomposition, the GDP affects CO₂ emissions in the short and medium term at an almost constant level (10 %). The non-renewable energy intensity in Tunisian economy is responsible for a modest reduction in CO₂ emissions, which suggests the implementation of conservation policies aimed at energy efficiency and the orientation toward renewable energy.     

Soil Respiration and Carbon Storage of an Acrisol Under Forest and different Cultivations in rio de Janeiro State, Brazil

Soil respiration rates of a clay-loam textured Acrisol under different uses (Atlantic forest, manioc, horticulture and pasture) from Rio de Janeiro State were measured. The relationship between carbon dioxide (CO₂) emissions and soil physico-chemical properties were investigated. Rates of CO₂ emission of two sites (Atlantic forest and horticulture) were also evaluated in different seasons in 1997 and 1998. In the forest site, monthly means of measured respiration rates showed good correlation with soil temperature in the range 19.6–24.1°C (r² = 0.89). In the horticulture site, no change was observed with soil moisture alone, in the range 3.0–13.2 wt%. In the horticulture soil, even when the surface soil was very dry, respiration rates increased in the hot, wetter summer but remained higher than the mean flux from forest soil. The CO₂ emission flux of the Acrisol under different use showed good correlation with soil temperature (r² = 0.72) and moisture (r² = 0.61).     

Carbon fluxes from coarse woody debris in southern taiga forests of the Valdai Upland

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.     

The global carbon cycle and possible disturbances due to man's interventions

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.     

Dynamic Changes,Regional Differences,and Influencing Factors of CO2 Emission Performance in China

Abstract

This paper proposes to use DEA models with undesirable outputs to construct the Malmquist index that can be use to investigate the dynamic changes of CO₂ emission performance. With the index, the authors have measured the CO₂ emission performance of 28 provinces and autonomous regions in China from 1996 to 2007; with the convergence theory and panel data regression model, the authors analyze the regional differences and the influencing factors. It is found that the performance of CO₂ emissions in China has been continuously improved mainly due to the technological progress, and the average improvement rate is 3.25%, with a cumulative improvement rate of 40.86%. In addition, the CO₂ emission performance varies across four regions. As a whole, the performance score of eastern China is the highest. The northeastern and central China has relatively lower performance scores, and the western China is relatively backward. The regional differences are decreasing, and the performance of CO₂ emissions is convergent. The influence of some factors on the performance of CO₂ emissions is significant, such as the level of economic development, the level of industrial structure, energy intensity, and ownership structure. The influence of some factors, such as opening-up to the outside world, on the performance of CO₂ emissions is not significant.     

Greenhouse gases emissions from a closed old landfill cultivated with biomass crops

Closed landfills need after-closure rehabilitation. The chosen option should ensure greenhouse gases release, from the landfill, is not promoted once settled. The objective of this study was to estimate and confront, during different seasons, CH₄, CO₂ and N₂O emissions under three vegetation covers in a closed landfill in Buenos Aires, Argentina. CH₄ (methane), CO₂ (carbon dioxide) and N₂O (nitrous oxide) emissions from landfill’s technosol under spontaneous vegetation (control), Pennisetum purpureum and Miscanthus giganteus (biomass crops), were quantified with non-steady-state non-flow-through chambers, in July 2014 and from February to July 2015. A linear regression analysis was performed to relate the variables “flux of a gas” and “concentration of that gas” from the 3 treatments and 6 dates, separating the 5 sampling times. A high correlation between concentrations and fluxes of CO₂ and N₂O was found, but no correlation was established for CH₄. Mean emissions (2014–2015) varied from: ?2.3 to 639.41 mgCH₄ m^?2 day^?1, 3884 to 46,365 mgCO₂ m^?2 day^?1 and 0.40 to 14.59 mgN₂O m^?2 day^?1. Vegetation covers had no significant effect on CH₄ and N₂O concentration in time, but they had on CO₂ concentration. Season of the year had a significant effect on concentration of the three gases. This is the first study on CH₄, CO₂ and N₂O emissions from a landfill closed 27 years ago covered with biomass crops.     

Analysis of CO2 emissions peak: China’s objective and strategy

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.     

A subsystem input–output decomposition analysis of CO<Subscript>2</Subscript> emissions in the service sectors: a case study of Beijing,China

The carbon emissions in service sectors have attracted increasing attention around the world. However, few studies have examined the driving forces for CO₂ emissions from service sectors in developing countries. With the process of accelerating industrialization, China’s service sectors are facing growing pressure to pursue energy savings and emission reductions, especially in several developed regions. In this paper, in order to better understand how CO₂ emissions in Beijing’s service sectors have evolved, we utilized a subsystem input–output decomposition analysis to study the pattern and driving factors of consumption-based emissions in Beijing’s service sectors. The results showed that the transportation sector and the Scientific Studies Technical Services sector caused the most CO₂ emissions in Beijing’s service sectors. The emission intensity effect potentially reduced CO₂ emissions by 10,833 Mt, primarily due to the decreased energy intensity of non-service sectors. Effects of demand and technology were mainly responsible for the increased CO₂ emissions in Beijing’s service sectors. Such influence was mainly related to the external component of service sectors, indicating a strong pull effect exerted by service sectors on non-service sectors. Thus, decarbonizing the supply chain of service sectors and improving the energy intensity are necessary to alleviate CO₂ emissions in Beijing.     

A laboratory study on CO2 emission from asphalt binder and its reduction with the use of warm mix asphalt

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.     

The history of CO2

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.     

On the Nexus of SO<Subscript>2</Subscript> and CO<Subscript>2</Subscript> emissions in China: the ancillary benefits of CO<Subscript>2</Subscript> emission reductions

This paper examines the issue of ancillary benefits by linking sulfur dioxide (SO₂) emission to CO₂ emission using a panel of 29 Chinese provinces over the period 1995–2007. In the presence of non-stationarity and cointegrating properties of these two data series, this paper applies the panel cointegration techniques to examine both the long-run and short-run elasticities of SO₂ with respect to CO₂. The major findings are that: (1) there exhibits a stable long-run equilibrium relationship between the SO₂ and CO₂ emission with the long-run elasticity being 2.15; (2) there exists a short-run relationship between these two emissions with the short-run elasticity being 0.04. In addition, following an exogenous shock that causes a deviation from the long-run equilibrium, it would take approximately 15 years for SO₂ emission to revert toward the long-run equilibrium path with an average annual convergence rate of 6.5%; (3) the derived ancillary benefits that is generated from one metric ton of CO₂ emission reduction, are 11.77 Yuan (approximately US1.7) in the short run and 196.16 Yuan (US 1.7) in the short run and 196.16 Yuan (US 30) in the long run. These findings are not only crucial from the econometric modeling perspective, but also have important policy implications.     

Carbon dioxide emissions from cities in China based on high resolution emission gridded data

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.     

The Rate of Carbon Dioxide Emission into the Atmosphere from a Southern Karelian Mesooligotrophic Bog

Carbon dioxide exchange in the intact and reclaimed sites of a woodless mesooligotrophic dwarf shrub–cotton grass–sphagnum bog was studied in field experiments. The average values of gross respiration in the ecosystem over the warm period (including respiration of plant cover, CO₂emission from peat, and CO₂flow from the litter) were 3.17 and 6.11 g CO₂/m²per day in the natural and drained sites, respectively.     

Evaluation of carbon stock variation in Northern Italian soils over the last 70 years

Carbon (C) sequestration in soils is gaining increasing acceptance as a means of reducing net carbon dioxide (CO₂) emissions to the atmosphere. Numerous studies on the global carbon budget suggest that terrestrial ecosystems in the mid-latitudes of the Northern Hemisphere act as a large carbon sink of atmospheric CO₂. However, most of the soils of North America, Australia, New Zealand, South Africa and Eastern Europe lost a great part of their organic carbon pool on conversion from natural to agricultural ecosystems during the explosion of pioneer agriculture, and in Western Europe the adoption of modern agriculture after the Second World War led to a drastic reduction in soil organic carbon content. The depletion of organic matter is often indicated as one of the main effects on soil, and the storage of organic carbon in the soil is a means of improve the quality of soils and mitigating the effects of greenhouse gas emission. The soil organic carbon in an area of Northern Italy over the last 70 years has been assessed In this study. The variation of top soil organic carbon (SOC) ranged from −60.3 to +6.7%; the average reduction of SOC, caused by agriculture intensification, was 39.3%. This process was not uniform, but related to trends in land use and agriculture change. For the area studied (1,394 km²) there was an estimated release of 5 Tg CO₂-C to the atmosphere from the upper 30 cm of soil in the period 1935–1990.     

Proposing of new building scheme and composite towards global warming mitigation for Malaysia

The building sector has been regarded as a potential sector where there is large capacity to reduce the climate change effect. This study has proposed solutions to mitigate environmental impacts and achieve low CO₂ emission from residential sector. Therefore, full life cycle assessment (LCA) has been run to assess the CO₂ emission and its effect on the atmosphere and climate change. Based on the result, timber scheme is the best choice due to releasing less CO₂ emissions to the atmosphere. However, house builders in Malaysia have almost completely neglected timber as a building material, with timber use as building components reduced to 5%. In this study, LCA Software was used to assess CO₂ emissions from different wall construction. The alternative building scheme has been made by reinforce steel stud, wooden beam and timber wall (S8) to improve the scheme deficiency while releasing less CO₂ emissions compared to other schemes. Therefore, S8 has a decreased CO₂ effect by 85% less than precast concrete frame and 90% less than brick over their lifetime. (S8) increased the load bearing compared to conventional timber beam. Thus, new scheme S8 could be replaced by current scheme and promote more adjustable scheme for Malaysian housing.     

Effect of sewage sludge amendment on soil microbial activity and nutrient mineralization

An incubation experiment was performed to study the effect of sewage sludge on microbial respiration and nutrient mineralization in a sandy soil as an indication of its effects on soil biological properties and nutrient transformation. Sewage sludge was amended with a sandy soil at 0, 25, 50, 150 and 350 g kg⁻¹ fresh weight. An increase in the sludge amendment rate caused an increase in both pH and electrical conductivity (EC). However, pH decreased while EC increased and then decreased along the incubation time. Nevertheless salinity and heavy metal contents of the soil sludge mixture were all within the safety guidelines. Soluble NH₄⁺, NO₃²⁻ and PO₃²⁻ increased after amending the soil with sewage sludge, but increasing the application rate to 350 g kg⁻¹ of sludge decreased the N and P mineralization efficiency and created an adverse effect on nitrification. The daily CO₂ evolution pattern was the same in all treatments that CO₂ evolution increased initially and then decreased till the end of the incubation period. All the treatments had peak CO₂ evolution at day 7, except for the soil amended with 350 g kg⁻¹ of sludge which had peak CO₂ evolution at day 2. Similarly, the percentage of C-mineralization decreased with an increase in sludge amendment rate. The present experiment indicated that an application rate of 50–150 g kg⁻¹ sludge for sandy soil would have the optimal beneficial effect on the soil in terms of microbial activity and nutrient transformation.     

Soil respiration in model plantations under conditions of elevated CO<Subscript>2</Subscript> in the atmosphere (Hokkaido Island,Japan)

The influence of long-term exposure of model plantations at elevated atmospheric CO₂ (550 ppm) on soil respiration under natural conditions has been studied using an automated Free-Air CO₂ Enrichment (FACE) system at the Hokkaido University, Japan. In the course of the experiment, an attempt has been made to simulate the effect of forthcoming climate change on the process of CO₂ emission from different soil types.     

Assessment of uncertainties in greenhouse gas emission profiles of livestock sectors in Africa,Latin America and Europe

The global animal food chain has a large contribution to the global anthropogenic greenhouse gas (GHG) emissions, but its share and sources vary highly across the world. However, the assessment of GHG emissions from livestock production is subject to various uncertainties, which have not yet been well quantified at large spatial scale. We assessed the uncertainties in the relations between animal production (milk, meat, egg) and the CO₂, CH₄, and N₂O emissions in Africa, Latin America and the European Union, using the MITERRA-Global model. The uncertainties in model inputs were derived from time series of statistical data, literature review or expert knowledge. These model inputs and parameters were further divided into nine groups based on type of data and affected greenhouse gas. The final model output uncertainty and the uncertainty contribution of each group of model inputs to the uncertainty were quantified using a Monte Carlo approach, taking into account their spatial and cross-correlation. GHG emissions and their uncertainties were determined per livestock sector, per product and per emission source category. Results show large variation in the GHG emissions and their uncertainties for different continents, livestock sectors products or source categories. The uncertainty of total GHG emissions from livestock sectors is higher in Africa and Latin America than in the European Union. The uncertainty of CH₄ emission is lower than that for N₂O and CO₂. Livestock parameters, CH₄ emission factors and N emission factors contribute most to the uncertainty in the total model output. The reliability of GHG emissions from livestock sectors is relatively high (low uncertainty) at continental level, but could be lower at country level.