The spatial distribution of forest carbon sinks and sources in China

Forest ecosystems play an important role in the global carbon cycle.The implementation of the United Nations Framework Convention on Climate Change(UNFCCC) and the Kyoto Protocol has made the study of forest ecosystem carbon cycling a hot topic of scientific research globally.This paper utilized Chinese national forest inventory data sets(for the periods 1984-1988 and 1999-2003),the vegetation map of China(1:1000000),and the spatially explicit net primary productivity(NPP) data sets derived with the remote sensing-based light use efficiency model(CASA model).We quantitatively estimated the spatial distribution of carbon sinks and sources of forest vegetation(with a resolution of 1 km) using the spatial downscaling technique.During the period 1984 to 2003 the forest vegetation in China represented a carbon sink.The total storage of carbon increased by 0.77 PgC,with a mean of 51.0TgCa 1.The total carbon sink was 0.88PgC and carbon source was 0.11 PgC during the study period.The carbon sink and carbon source of forest vegetation in China showed a clear spatial distribution pattern.Carbon sinks were mainly located in subtropical and temperate regions,with the highest values in Hainan Province,Hengduan mountain ranges,Changbai mountain ranges in Jilin,and south and northwest of the Da Hinggan Mountains;carbon sources were mainly distributed from the northeast to southwestern areas in China,with the highest values mainly concentrated in southern Yunnan Province,central Sichuan Basin,and northern Da Hinggan Mountains.Increase in NPP was strongly correlated with carbon sink strength.The regression model showed that more than 80% of the variation in the modeled carbon sinks in Northeast,Northern,Northwest and Southern China were explained by the variation in NPP increase.There was a strong relationship between carbon sink strength and forest stand age.     

Application and Development of Biomass Fuels for Transportation in China

Biomass fuels have become a big concern due to the large increase in green house gases and the rapid rise of petroleum prices around the world. This paper reviews recent developments in biomass fuels, such as ethanol and biodiesel, in China. Ethanol-gasoline mixture (E10) for vehicles is currently distributed in nine provinces while biodiesel is under development. One way to extend the application of ethanol is to burn it in diesel engines to lower soot emissions. The effects of the different methods blending ethanol with fossil diesel, and blending biodiesel with fossil diesel and ethanol-diesel on the combustion and emissions are investigated. The test results show that ethanol and biodiesel can be mixed with fossil diesel to greatly reduce particulate matter and soot emissions from diesel engines. But the application of ethanol blending with fossil diesel is more difficult than that of ethanol blending with gasoline, and biodiesel blending with fossil diesel. The dual-fuel injection of ethanol and diesel systems has the highest smoke reduction effect for a high ethanol fraction.     

Estimation of provincial forest carbon sink capacities in Chinese mainland

Estimation of the capacity of provincial forest carbon sinks in Chinese mainland using the CO2FIX model provides data support for the effective management of provincial regions. According to China’s Sixth National Forest Inventory, we estimate the capacities of original and new afforestation carbon sinks under the assumption of using the country’s non-forest land for afforestation and reforestation to achieve a new forested area of 57323200 ha. The carbon absorption capacity of China’s forest ecosystems est...     

Evaluating the influences of measurement time and frequency on soil respiration in a semiarid temperate grassland

Soil respiration(Soil R)is one of the largest CO2fluxes from terrestrial ecosystems to the atmosphere.The largely seasonal and daily patterns of Soil R in semiarid grassland ecosystems indicate that measurement time and frequency would have significant influences on the assessment of seasonal soil carbon release.Based on a three-year continuous measurement of Soil R in a semiarid grassland,we found that the Soil R value measured at around 10:00 o’clock local time was the closest to its daily mean,while the value at 14:00 o’clock was found to be the highest daily rate.A measurement frequency higher than every 10 days was necessary for estimating the seasonal Soil R and its temperature sensitivity(Q10)reasonably.Our study would be useful as guidelines for manual Soil R measurements and model data selection in semiarid temperate grasslands.     

An analysis of the spatial and temporal changes in Chinese terrestrial ecosystem service functions

Since Westman(1977) and Ehrlich(1982) put forward the concepts of "the service of nature" and "ecosystem service functions",respectively,methods for conducting value accounting for them,and their practical application have become the subjects of intense study.Based on an overview of available research findings,we discuss three scientific hypotheses.First,the terrestrial ecosystem offers both positive and negative service functions.Second,changes in terrestrial ecosystem service functions lie not only in the number of ecosystem types and the coverage area of each type,but also in their quality.Third,the value of terrestrial ecosystem service functions should be assessed both in terms of the value stocked and the value added.We collected land use data from China during the period 1999-2008,and Normalized Difference Vegetation Index data based on remote sensing images from the Global Inventory Modeling and Mapping Studies for the same period.We then calculated and analyzed spatial and temporal changes in China’s terrestrial ecosystem service values over the 10-year period.Considering temporal change,the total value(stocked) of China’s terrestrial ecosystem service functions decreased from 6.82 trillion Yuan RMB in 1999 to 6.57 trillion Yuan RMB in 2008.During that period,the positive value decreased by 240.17 billion Yuan RMB and the negative value increased by 8.85 billion Yuan RMB.The decrease in total value lies mainly in the humidity control,soil formation,and waste recycling functions.The total value(added) of China’s terrestrial ecosystem service functions increased by 4.31 billion Yuan RMB in 2000,but decreased by 0.13 billion Yuan RMB in 2008(based on the constant price of China in 1999).The value(added) was a negative figure.From the perspective of spatial change,we can see that the supply of China’s terrestrial ecosystem service functions fell slightly over the past 10 years,mainly in Northeast and Southern China.As a result of human activities on ecosystems,the loss of ecosystem service functions’ value was relatively prominent in Shanxi and Gansu provinces,compared with an increase in value in Shaanxi Province.Terrestrial ecosystem service functions’ value per unit area was relatively high in mid-and East China,showing a prominent spatial change over the 10-year period,but low in Western China.Some conclusions are drawn after an in-depth analysis of the factors causing the spatial and temporal changes in China’s terrestrial ecosystem service functions,in the hope that our suggestions will be helpful for the management of China’s terrestrial ecosystems.     

Multimodel projections and uncertainties of net ecosystem production in China over the twenty-first century

Ecosystems in China have been absorbing anthropogenic CO2 over the last three decades. Here, we assess future carbon uptake in China using models from phase 5 of Coupled Model Intercomparison Project under four socio-economic scenarios. The average of China＇s carbon sink from 2006 to 2100 represented by multimodel mean net ecosystem production （NEP） is projected to increase （relative to averaged NEP from 1976 to 2005） in the range of 0.137 and 0.891 PgC a^-1 across different scenarios. Increases in NEP are driven by increases in net primary production exceeding increases in heterotrophic respiration, and future carbon sink is mainly attributed to areas located in eastern China. However, there exists a considerable model spread in the magnitude of carbon sink and model spread tends to be larger when future climate change becomes more intense. The model spread may result from intermodel discrepancy in the magnitude of CO2 fertilization effect on photosynthesis, soil carbon turnover time, presence of carbon-nitrogen cycle and interpretation of land-use changes. For better quantifying future carbon cycle, a research priority toward improving model representation of these processes is recommended.     

Preliminary estimation of the organic carbon pool in China’s wetlands

Accurate estimation of wetland carbon pools is a prerequisite for wetland resource conservation and implementation of carbon sink enhancement plans.The inventory approach is a realistic method for estimating the organic carbon pool in China’s wetlands at the national scale.An updated data and inventory approach were used to estimate the amount of organic carbon stored in China’s wetlands.Primary results are as follows:(1) the organic carbon pool of China’s wetlands is between 5.39 and 7.25 Pg,accounting for 1.3%-3.5% of the global level;(2) the estimated values and percentages of the organic carbon contained in the soil,water and vegetation pools in China’s wetlands are 5.04-6.19 Pg and 85.4%-93.5%,0.22-0.56 Pg and 4.1%-7.7%,0.13-0.50 Pg and 2.4%-6.9%,respectively.The soil organic carbon pool of China’s wetlands is greater than our previous estimate of 3.67 Pg,but is lower than other previous estimates of 12.20 and 8-10 Pg.Based on the discussion and uncertainty analysis,some research areas worthy of future attention are presented.     

Satellite remote sensing of changes in NO x emissions over China during 1996–2010

Satellite derived NO2 column data have been used to study Chinese national fossil fuel consumption and pollutant emissions.Based on NO 2 retrievals from two satellites (GOME and SCIAMACHY) for 1996-2010,we analyzed the characteristics and evolution of regional pollution related to NO x emissions in China.Satellite observations indicated that the highly polluted regions were expanding.Anthropogenic emission dominated areas have expanded from the east to central and western China,and new highly polluted regions have formed throughout the nation.Bottom-up emission estimates suggested a 133% increase in anthropogenic NOx emissions in East Central China during 1996 to 2010,which was lower than the 184% increase of the NO2 columns measured by the satellites.We found that growth rates of NOx emissions have slowed in Chinese megacities over recent years,in contrast to which,the NOx emissions were soaring in medium-sized cities,indicating that strict controls of NOx emissions from coal-fired facilities are required in China.     

Leaf cuticular characters of Ginkgo and implications for paleoatmospheric CO2 in the Jurassic

A combination of carbon isotope composition and stomatal characters of fossil leaves provides information about paleoatmospheric CO₂ levels and the physiology of fossil plants. Plant anatomy, physiology, and geochemistry have been employed to reconstruct the paleoatmospheric CO2 concentrations throughout Jurassic time and to investigate the physiological response of fossil Ginkgo to an atmosphere of much higher CO₂ than usual. Our results show that fossil Ginkgo in China lived in an atmosphere with a CO₂ concentration 3—5 times higher than that of today. It used a carbon isotopic discrimination similar to that of the living plant, but had much higher water use efficiency (3—5 times that of the extant). The physiological traits of Ginkgo in different atmospheres suggest that CO₂ might have played a contributory role in the rise and fall of maidenhair trees.     

Leaf cuticular characters of Ginkgo and implications for paleoatmospheric CO2 in the Jurassic

A combination of carbon isotope composition and stomatal characters of fossil leaves provides information about paleoatmospheric CO₂ levels and the physiology of fossil plants. Plant anatomy, physiology, and geochemistry have been employed to reconstruct the paleoatmospheric CO2 concentrations throughout Jurassic time and to investigate the physiological response of fossil Ginkgo to an atmosphere of much higher CO₂ than usual. Our results show that fossil Ginkgo in China lived in an atmosphere with a CO₂ concentration 3—5 times higher than that of today. It used a carbon isotopic discrimination similar to that of the living plant, but had much higher water use efficiency (3—5 times that of the extant). The physiological traits of Ginkgo in different atmospheres suggest that CO₂ might have played a contributory role in the rise and fall of maidenhair trees.     

Integrated modeling of nitrogen oxides formation in diesel engines

To account for the effects of both chemistry and flow turbulence, the present study proposes an integrated NO sub-model that combines the extended Zel’dovich mechanism and engine CFD computations to simulate the NO histories in a diesel engine. NOx sub-model parameters and pollutant formation mechanisms can be more easily investigated by solving the NOx sub-model. The new NO formation model incorporating the effects of both chemical kinetics and turbulent mixing was applied to simulate a diesel engine with a quiescent combustion chamber, and one with a re-entrant combustion chamber; the premise of the model being the reaction rate is mainly determined by a kinetic timescale and a turbulent timescale. The results indicate that the predicted NO formulation from the new model agrees well with the measured data. As the utilization of fossil fuels continues to increase, the control of NOx emissions is a worldwide concern; and it is imperative to understand fully the NOx reaction processes in combustion systems. This technology has the potential to enhance the application of various combustion techniques used to reduce NOx emissions from practical combustion systems.     

Carbon sequestration within millet phytoliths from dry-farming of crops in China

Phytoliths are noncrystalline minerals that form inside cells and cell walls of different parts of plants. Organic carbon in living cells can be occluded in phytoliths during plant growth. It has been documented that the occluded carbon within phytoliths is an important long-term terrestrial carbon reservoir that has a major role in the global carbon cycle. Common millet and foxtail millet have become typical dry-farming crops in China since the Neolithic Age. The study of carbon conservation within phytoliths in these crops could provide insights into anthropogenic influences on the carbon cycle. In this study, we analyzed the carbon content in phytoliths of common millet and foxtail millet. The results indicated that (1) common millet and foxtail millet contained 0.136% ± 0.070% and 0.129% ± 0.085% phytolith-occluded carbon (PhytOC) on a dry mass basis, respectively; (2) based on the mean annual production of common millet and foxtail millet in the last 10 years, the phytolith occluded carbon accumulation rate of common millet and foxtail millet was approximately 0.023 ± 0.015 and 0.020 ± 0.010 t CO 2 ha 1 a 1 , respectively; (3) assuming a similar phytolith occluded carbon accumulation rate as for common millet (the highest accumulation rate was 0.038 t CO 2 ha 1 a 1 ), this could result in the sequestration of 2.37 × 10 6 t CO 2 per year for the 62.4 × 10 6 ha dry-farming crops in China. Although there was a decline in the annual production rate and planting area of foxtail millet during 1949 to 2008, the total phytolith carbon sequestration rate was 7×10 6 t CO 2 within the 60-year period. However, phytolith occluded carbon has not yet been fully considered as a global carbon sink. Also, this carbon fraction is probably one of the best candidates for the missing carbon sink.     

Static slip model of the M w 9.0 Tohoku (Japan) earthquake: Results from joint inversion of terrestrial GPS data and seafloor GPS/acoustic data

Based on co-seismic displacements recorded by terrestrial GPS stations and seafloor GPS/acoustic stations, the static slip model of the 2011 Mw 9.0 Tohoku earthquake was determined by inverting the data using a layered earth model. According to a priori information, the rupture surface was modeled with a geometry that is close to the actual rupture, in which the fault dip angle increases with depth and the fault strike varies with the trend of the trench. As shown by the results inferred from the joint inversion, the "geodetic" moment is 3.68 × 10 22 Nm, corresponding to Mw 9.01, and the maximum slip is positioned at a depth of 13.5 km with a slip magnitude of 45.8 m. Rupture asperities with slip exceeding 10 m are mainly distributed from 39.6 to 36.97°N, over a length of almost 240 km along the trench. The slip was mostly concentrated at depths shallower than 40 km, up-dip of the hypocenter. "Checkerboard" tests reveal that a joint inversion of multiple datasets can resolve the slip distribution better than an inversion with terrestrial GPS data only-especially when aiming to resolve slip at shallow depths. Thus, the joint inversion results obtained by this work may provide a more reliable slip model than the results of other studies that are only derived from terrestrial GPS data or seismic waveform data.     

Sustainable Energy Development Strategy in China

Energy and electrical power is very important in economy and society. China has faced an increasingly serious energy shortage in the past decade. On the other hand, energy consumption and power generation, releasing carbon dioxide and other gaseous emissions from fossil fuels, may pollute the environment. Nuclear power, as an alternative energy source, would reduce these gaseous emissions. Both global wanning and sustainable energy supply can be solved to some extent by the application of nuclear power. In the aspects of regaining economic advantages, environmental protection, the security and reliability of energy, nuclear power has an obvious superiority. In this paper, we present the energy status in quo of China, and discuss ways to realize the sustainable development of energy and power.     

The discovery of Jurassic plants in Shenzhen of Guangdong,southern China and related significance

Investigations of major marine and non-marine geologic and biotic events across the Triassic-Jurassic transition rely predominantly on detailed stratigraphic frameworks and biodiversity analyses. The alternating sequences of marine and terrestrial Triassic-Jurassic for- mations in Guangdong Province represent one of the most remarkable coal-bearing series in southern China. The Lower Jurassic Jinji Formation is widely distributed in Guangdong, with continuously outcropped sections and rich marine and non-marine fossil fauna. However, as little research has been conducted on fossil plant remains in the Jinji Formation, it is difficult to understand the systematics, diversity, and floral aspects of the Jurassic. Here we report on the recent collection of rich fossil plants from the Jinji Formation in the Dapeng area of Shenzhen, southern Guangdong Province. Our studies demonstrate taxonomical affiliations, preservation status, and diversity features of these plant fossils, which are marked by the close associ- ation of densely preserved, pinnae and rachis connected leaves, and the bennettitalean reproductive organs of Wil- liamsoniella, which may represent an Early Jurassic plant community dominated by Otozamites of the bennettitales. This work not only represents the first discovery of fossil plants in the Shenzhen area, but is also the first docu- mentation of Jurassic plants in Guangdong and the Pearl River Delta regions. Research related to these plant fossils will be helpful in the correlation of the Early Mesozoiccoal-bearing strata in Guangdong, and will provide a dee- per understanding of variations in plant diversity of the Triassic and Jurassic transition in southern China. Addi- tionally, it will provide terrestrial plant evidence for explorations in Jurassic palaeoecology, palaeoclimatology, and palaeogeography of southern China.     

Preservation of black carbon in the shelf sediments of the East China Sea

Concentrations and carbon isotopic(14C,13C) compositions of black carbon(BC) were measured for three sediment cores collected from the Changjiang River estuary and the shelf of the East China Sea. BC concentrations ranged from 0.02 to 0.14 mg/g(dry weight) ,and accounted for 5% to 26% of the sedimentary total organic carbon(TOC) pool. Among the three sediment cores collected at each site,sediment from the Changjiang River estuary had relatively high BC contents compared with the sedi-ments from the East China Sea shelf,suggesting that the Changjiang River discharge played an im-portant role in the delivery of BC to the coastal region. Radiocarbon measurements indicate that the ages of BC are in the range of 6910 to 12250 years old B.P.(before present) ,that is in general,3700 to 9000 years older than the 14C ages of TOC in the sediments. These variable radiocarbon ages suggest that the BC preserved in the sediments was derived from the products of both biomass fire and fossil fuel combustion,as well as from ancient rock weathering. Based on an isotopic mass balance model,we calculated that fossil fuel combustion contributed most(60%―80%) of the BC preserved in these sediments and varied with depth and locations. The deposition and burial of this "slow-cycling" BC in the sediments of the East China Sea shelf represent a significant pool of carbon sink and could greatly influence carbon cycling in the region.     

Integrated modeling of nitrogen oxides formation in diesel engines

To account for the effects of both chemistry and flow turbulence, the present study proposes an integrated NO sub-model that combines the extended Zel'dovich mechanism and engine CFD computations to simulate the NO histories in a diesel engine. NOx sub-model parameters and pollutant formation mechanisms can be more easily investigated by solving the NOx sub-model. The new NO formation model incorporating the effects of both chemical kinetics and turbulent mixing was applied to simulate a diesel engine with a quiescent combustion chamber, and one with a re-entrant combustion chamber; the premise of the model being the reaction rate is mainly determined by a kinetic timescale and a turbulent timescale. The results indicate that the predicted NO formulation from the new model agrees well with the measured data. As the utilization of fossil fuels continues to increase, the control of NOx emissions is a worldwide concern; and it is imperative to understand fully the NOx reaction processes in combustion systems. This technology has the potential to enhance the application of various combustion techniques used to reduce NOx emissions from practical combustion systems.     

Recent advances in hydrogen storage technologies based on nanoporous carbon materials

Hydrogen is a promising energy carrier that can potentially facilitate a transition from fossil fuels to sustainable energy sources without producing harmful by-products. Prior to realizing a hydrogen economy, however, viable hydrogen storage materials must be developed. Physical adsorption in porous solids provides an opportunity for hydrogen storage under low-stringency conditions. Physically adsorbed hydrogen molecules are weakly bound to a surface and, hence, are easily released. Among the various surface candidates, porous carbons appear to provide efficient hydrogen storage, with the advantages that porous carbon is relatively low-cost to produce and is easily prepared. In this review, we summarize the preparation methods, pore characteristics, and hydrogen storage capacities of representative nanoporous carbons, including activated carbons, zeolite-templated carbon, and carbide-derived carbon. We focus particularly on a series of nanoporous carbons developed recently: metal–organic framework-derived carbons, which exhibit promising properties for use in hydrogen storage applications.     

Estimation and prediction of black carbon emissions in Beijing City

Black carbon is a by-product of incomplete combustion of carbon containing fuels. It can alter atmospheric radiation property and make adverse impacts on human health. The energy consumption in Beijing City depends largely on coal burning. Recently, Beijing City has been performing the municipal energy structure adjustment as a tool for air pollution abatement, aiming at the air quality goal for the Beijing 2008 Olympic Games. Based on Beijing energy use data in 2000, combined with emission factors of major sources of black carbon, the emission of black carbon in Beijing City is estimated to be 7.77 Gg. Coke, raw coal and biomass as non-commercial energy are the main contributors to municipal black carbon emissions. Based on Beijing energy planning in the year 2008, the emission of black carbon in 2008 will be 2.97 Gg if the contribution from biomass is not taken into account. Assuming that the black carbon emission from rural biomass in 2008 is the same as that in 2004, the biomass burning will be the largest emitter of black carbon to Beijing City in 2008.     

Protection efficacy of national wetland reserves in China

Wetlands have the most abundant biodiversity,the highest carbon sequestration capacity,and the highest values for ecological services per unit area,of all the world’s ecosystems.Practice has shown that establishing reserves is the most effective way of protecting typical ecosystems and their biodiversity,and saving rare or endangered wildlife.The Chinese government’s policy is to protect wetland systems by establishing reserves that encompass a massive network of wetlands,including wetland nature re-serves,internationally important wetlands,and wetland parks.Many are already established.The effect of protecting wetland nature reserves at the national level has not yet been reported.We used the latest database evaluating the protection value of wet-land reserves,and remotely sensed wetland maps(1978-2008) ,developed by the same mapping specialists and based on the same classification system,and related environmental data,to evaluate the effects of protecting China’s national wetland reserves over the last 30 years.We conclude that(i) the total area of wetland in the national wetland reserves has decreased over the last 30 years to 8152.47 km2,and just 8% of China’s net decrease in wetlands;(ii) about 79% of the 91 national wetland reserves are in a poor condition.These are generally located around the Yangtze River,Eastern Coast,the Three Rivers Source,and Southwest China.Protection measures should be undertaken urgently in these areas.Only 15% of national wetland reserves are under sound protection,and these are generally located in the upper reaches of the Songhua River;(iii) although 88% of national wetland re-serves are primitive(relatively natural) ,implying that the site selection has been scientific,a high percentage of national wetland reserves show early warning signs of decline and require urgent attention;(iv) based on our evaluation of protection effects and pressures on ecology,we have made a priority list of national wetland reserves,and propose several protection strategies.