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.     

A new RICEs model with the global emission reduction schemes

Taking into account the fact of global economic integration,this paper improves the RICE model and the MRICES model,and establishes a new integrated assessment model MRICES-2012,which takes Ramsey utility as the standard of fairness.Based on the model,schemes which meet the global emission mitigation targets as well as the interests of developing countries are simulated to assess the international fairness of emission reduction.Therefore,a new feasible scheme is proposed,which can not only reach the Copenhagen Consensus but also ensure interests of every country.Specifically speaking,the US and Japan cut emissions 80% and 70% respectively by 2050 relative to the 1990 level;the EU and other developed countries cut 80% by 2050 relative to 1990 level;high human development countries cut 50% by 2050 relative to 1990 level;all above-mentioned countries start emission reduction from 2020 and keep emission on 2050 level by 2100;China begins emission reduction from 2030 and cuts emission 15% by 2050 and 25% by 2100 relative to 2005 level;medium human development countries keep emission on 2020 level by 2100;low human development countries do not take part in reduction on emission intensity and global emission.     

Influence of the carbon cycle on the attribution of responsibility for climate change

The carbon cycle is one of the fundamental climate change issues.Its long-term evolution largely affects the amplitude and trend of human-induced climate change,as well as the formulation and implementation of emission reduction policy and technology for stabilizing the atmospheric CO2concentration.Two earth system models incorporating the global carbon cycle,the Community Earth System Model and the Beijing Normal University-Earth System Model,were used to investigate the effect of the carbon cycle on the attribution of the historical responsibility for climate change.The simulations show that when compared with the criterion based on cumulative emissions,the developed(developing)countries’responsibility is reduced(increased)by 6%–10%using atmospheric CO2concentration as the criterion.This discrepancy is attributed to the fact that the developed world contributed approximately61%–68%(61%–64%)to the change in global oceanic(terrestrial)carbon sequestration for the period from 1850 to2005,whereas the developing world contributed approximately 32%–49%(36%–39%).Under a developed world emissions scenario,the relatively larger uptake of global carbon sinks reduced the developed countries’responsibility for carbon emissions but increased their responsibility for global ocean acidification(68%).In addition,the large emissions from the developed world reduced the efficiency of the global carbon sinks,which may affect the long-term carbon sequestration and exacerbate global warming in the future.Therefore,it is necessary to further consider the interaction between carbon emissions and the carbon cycle when formulating emission reduction policy.     

Estimation of emissions from field burning of crop straw in China

Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000-2003 from the government statistics, taking into account the ratio of residue and grain, the total amount of crop straw production is estimated to be about 600 Tg per year, 76% of which are rice, wheat and corn straw. With reference to the data of living standards, the percentage of crop straw burnt in fields for counties are obtained and consequently the total amount of burnt straws is approximately 140 Tg/year. With the emission factors from literature and experiments, appropriate emission factors have been obtained. The total amounts of PM, SO2, NOx3, NH3, CH4, BC, OC, VOC, CO, CO2 emissions from field burning of crop straw in China are estimated. All emissions are presented at county level. Some pollutants, such as BC, VOC, OC, CO and CO2, are contributing a major portion to the total emissions of China. This paper uses a map with resolution of 0.2°×0.2°to present the PM emissions distribution from crop straw burnt in 2003. The results show a significant regional unevenness of emissions, with larger amounts of pollutions coming from the provinces in eastern and northeast China. The regions with higher emissions per unit area are located as a belt stretching from northeast China to eastern China.     

Assessment of urinary concentration of cotinine in Chinese pregnant women exposed to environmental tobacco smoke

Environmental tobacco smoke （ETS） is a well- known reason of many adverse health consequences in pregnant women. Exposure of ETS during pregnancy may increase the risk of some fetal diseases in pregnant women and/or birth defects in neonates. Many countries have implemented laws to control smoking and free of second hand smoke in all enclosed workplaces. In China, anti- smoking law was enforced in March 2010. We aimed to assess the exposure of pregnant women to cotinine after anti-smoking law was implemented in China. The urine samples were collected from 2,100 volunteers from Zhejiang Province, China and urinary concentration of cotinine was measured using gas chromatography and mass spectrometry. Cotinine was detected in 87 % of the pregnant women. The GM and 95th percentile concentration in pregnant women were 4.28 and 44.00 μg/L, respectively. Similarly, the GM and 95th concentration of cotinine were significantly higher in smoking group than in non-smoking group （P 〈 0.0001）. Our results indicate that pregnant women in China are at the high risk of exposure ETS. Further attempts are required to make strategies to find out the sources of ETS exposure and prevent smoking at public places especially during pregnancy.     

Emission inventories of primary particles and pollutant gases for China

Detailed high-resolution emission inventories of primary particles(PM2.5,BC and OC) and pollutant gases(SO2,NOx,NH3,CO and VOCs) for China in 2007 were constructed on the basis of the latest fuel consumption data,mostly at the county level,and from socio-economic statistics and data on fossil and biomass fuels obtained from government agencies.New emission factors reflecting local features were also used.The calculated emissions were 13.212 Mt PM2.5,1.4 Mt BC,2.946 Mt OC,31.584 Mt SO2,23.248 Mt NOx,16.017 Mt NH3,164.856 Mt CO and 35.464 Mt VOCs.The national and regional emissions were gridded with 0.5°× 0.5° resolution for use in air quality models.Larger emissions were found in eastern and central China than in western China.The emissions estimated here are roughly equal to those obtained in previous studies,but with different contributions from because of seasonal changes in residential heating and biomass combustion.Finally,uncertainties in inventories were analyzed.     

He and Ar isotope geochemistry of pyroxene megacrysts and mantle xenoliths in Cenozoic basalt from the Changle–Linqu area in western Shandong

We performed a combined study of He–Ar isotopes and element geochemistry for pyroxene megacrysts and mantle xenoliths from Cenozoic basalt in the Changle–Linqu area in western Shandong.The results are used to trace the evolution of subcontinental lithospheric mantle after destruction of the North China Craton.The3He/4He ratios of pyroxene megacrysts,websterite,and dunites are 7.0–7.7 Ra,7.4 Ra,and 7.0–7.7 Ra,respectively.They are related to the origin of host basalts,and are slightly lower than that of mid-ocean ridge basalts(MORB).Their40Ar/36Ar ratios are much lower than that of MORB and close to that of air.The lherzolites and wehrlites represent the fragments of the newly accreted lithospheric mantle,and their REE and trace elements indicate that they experienced melt metasomatism and partial melting.The3He/4He ratios of their olivine are slightly lower than that of MORB,but3He/4He ratios of their clinopyroxene are low(2.3–7.1 Ra)and display an inverse correlation with(La/Yb)N.The40Ar/36Ar ratios of these clinopyroxene are much lower than that of MORB and close to the air ratio.Combining existing studies of petrology,Sr–Nd–Pb isotopes,O isotopes,trace elements,and Mg isotopes,we infer that the juvenile lithospheric mantle in the Changle–Linqu area was metasomatized by oceanic crust-derived melts,which transfer the supracrustal Ar isotope signatures to the mantle sources.The low4He abundance and low3He/4He ratios of clinopyroxene in the lherzolites and wehrlites are ascribed to metasomatism by crustal melts from the subducted Pacific plate.     

China’s urban expansion from 1990 to 2010 determined with satellite remote sensing

Based on the same data source of Landsat TM/ETM+ in 1990s,2000s and 2010s,all urban built-up areas in China are mapped mainly by human interpretation.Mapping results were checked and refined by the same analyst with the same set of criteria.The results show during the last 20 years urban areas in China have increased exponentially more than 2 times.The greatest area of urbanization changed from Northeastern provinces in 1990s to the Southeast coast of China in Jiangsu,Guangdong,Shandong,and Zhejiang in 2010s.Urban areas are mostly converted from croplands in China.Approximately 17750 km 2 croplands were converted into urban lands.Furthermore,the conversion from 2000 to 2010 doubled that from 1990 to 2000.During the 20 years,the most urbanized provinces are Jiangsu,Guangdong,Shandong and Zhejiang.We also analyzed built-up areas,gross domestic production (GDP) and population of 147 cities with a population of greater than 500000 in 2009.The result shows coastal cities and resource-based cities are with high economic efficiency per unit of built-up areas,resource-based cities have the highest population density,and the economic efficiency of most coastal provinces are lower than central provinces and Guangdong.The newly created urban expansion dataset is useful in many fields including trend analysis of urbanization in China;simulation of urban development dynamics;analysis of the relationship among urbanization,population growth and migration;studies of carbon emissions and climate change;adaptation of climate change;as well as land use and urban planning and management.     

Spatiotemporal characteristics of freezing and thawing of the active layer in the source areas of the Yellow River （SAYR）

Based on the analysis of data on temperatures and moisture of soils in the active layer at four different permafrost sites in the source areas of the Yellow River(SAYR)in 2010–2012,the freeze–thaw processes of soils in the active layer were compared and contrasted for understanding the spatiotemporal variations.At the four studied sites,the thickness and mean annual temperature of permafrost are different.The temperatures at the top of permafrost(TTOP),i.e.,the maximum depth(s)of seasonal frost and/or thaw penetration,are-1.9°C at the Chalaping site(CLP),-0.9°C at the site on the southern bank of the Zhaling Lake(ZLH),-0.4°C at the Maduo Town site(MDX),and 1.1°C at the site on the northern bank of the Eling Lake(ELH).Differences in the mean annual ground temperature of permafrost and TTOPs may be responsible for the differentiations in the freeze–thaw processes of soils in the active layer.With rising TTOPs,the ground thawing started earlier:CLP in early June,ZLH in late May,MDX in early May,and ELH in mid-April,while the freezing began later:CLP in early October,ZLH in early to midOctober,MDX in mid-October,and ELH in the mid-to late October.With increasing TTOPs,the freeze-up periods for permafrost sites were shortened:202 days at CLP,130 days at ZLH,100 days at MDX,and the period of complete thaw was 89 days at ELH.At the CLP and ZLH sites,the two-directional ground freezing(downwards from ground surfaces and upwards from the permafrost table)and thawing finished in the same year,but the ground freezing at the MDX continued to the end of the nextJanuary,with very slow freezing rates in the end.At the ELH site,ground freezing kept on until early May when thawing began on the surface,and upward and downward thawing became increasingly stable in late June to early July.At each site,with rising TTOPs,the downward freezing accelerated in comparison with the upward freezing,and with an increasing proportion of downward frozen depth,and with the larger ratios of freezing to thawing duration.In summary,the patterns of thawing and freezing processes in the active layer in the SAYR differ from those in other parts of the Qinghai–Tibet Plateau to a noticeable extent.     

Super solar particle event around AD775 was found

A rapid radiocarbon14C increase of 120/00in AD774–775 has been reported in cedar and oak tree rings.So far,the origin of the14C increase is still uncertain and the possible origin is either supernova or solar particle event.The most possible origin of14C increase is strong solar flares and Coronal Mass Ejections(CMEs)with strong particles emission.Comprehensive approaches to identify the strong historical solar particle events based on the rapid14C/10Be increase in tree/coral rings and ice cores,long duration strong auroras and geomagnetic storms are introduced.Evidence of the super auroras in AD775 was first found in a Chinese Chronicles Jiutangshu and it supports the views that the rapid14C increase and strong auroras around AD775 are most possibly caused by strong solar storms with intense particles emission.It was identified that the solar event around AD775 would be the strongest solar particle event in the past 11400 years.The discovery is significant for the research on the history of solar activities,space weather and forecast,radiation of solar energetic particles and protection.     

Changes in tropospheric ozone levels over the Three Representative Regions of China observed from space by the Tropospheric Emission Spectrometer (TES), 2005–2010

Tropospheric ozone observations over China from 2005 to 2010 at three pressure levels (484,681 and 825 hPa) from the Tropospheric Emission Spectrometer on board the NASA Aura satellite have been analyzed.Fourier Transform analysis revealed the trends and seasonality of regionally-averaged,monthly-mean ozone concentrations over western,northern and southern China.Significant increases in ozone levels are found over all three regions at 464 hPa and the rate of increase is fastest over northern China,reaching 0.89±0.059 nL/(La).At 681 hPa,ozone shows increases over northern and western China,at a rate of 0.57± 0.065 nL/(La) and 0.41±0.041 nL/(La) respectively,but is constant over southern China.At 825 hPa,ozone increases at a rate of 0.36±0.074 nL/(La) over northern China,while decreasing over southern China at a rate of 0.21±0.061 nL/(La).Over the three regions,ozone levels are generally higher in summer and lower in winter.Over southern China at all three pressure levels and northern China at the 825 hPa level,ozone shows double peaks occurring in spring and autumn as a result of the combined effects of atmospheric chemistry and global transport.This work provides a useful observational dataset and tools for future analysis of changes in tropospheric ozone over China.     

U-Pb ages of zircon grains reveal a proximal dust source of the Xiashu loess,Lower Yangtze River region,China

Deciphering the eolian sources is critical to understand the paleo-significance of the Quaternary eolian deposits （the Xiashu loess） in the lower reaches of the Yangtze River. Both a local source from the fluvial sediments of the Yangtze River and a distal source from the northern deserts similar to that of the loess on the Chinese Loess Plateau （CLP） have been proposed. Recent researches show great advantages of detrital zircon ages as a source tracer for Asian dust based on the laser ablation U-Pb isotopic dating technique. This work presents the U-Pb ages of zircon grains extracted from the Xiashu loess. The results indicate that the Xiashu loess has a very different age distribution of zircon grains from that of the loess on the CLP as well as the materials in the arid lands of the Asian Interior. Instead, the zircon ages of the Xiashu loess are indistinguishable from the fluvial sediments of the Yangtze River, indicating the dominance of proximal dust source. Proximal source of the Xiashu loess implies that extensive eolian processes might have existed in the currently wet South China, possibly in response to the full glacial conditions after the middle Pleistocene transition of global climate.     

Vulnerability assessment of areas affected by Chinese cryospheric changes in future climate change scenarios

Using the definition of vulnerability provided by the Intergovernmental Panel on Climate Change,this paper assesses the vulnerability of areas affected by Chinese cryospheric changes from 2001 to 2020 and from 2001 to 2050 in A1 and B1scenarios.Seven indices are used in the vulnerability assessment:glacial area fraction,interannual variability of permafrost depth,interannual variability of surface snow area fraction,interannual variability of surface runoff,interannual variability of surface temperature,interannual variability of vegetation growth,and interannual variability of the human development index.Assessment results show that the overall vulnerability of the studied areas in China increases from east to west.The areas in the middle and eastern parts of China are less vulnerable compared with western parts and parts of the Tibetan Plateau.The highest vulnerability values are found from 1981 to 2000,and the least ones are found from 2001 to 2050.The vulnerable areas increase from the period of 1981 to 2000 to the period of 2001 to 2050,and the less vulnerable areas decrease.The highly vulnerable areas increase from the period of 1981 to 2000 to the period of 2001 to 2020 and then decrease from the period of 2001 to 2020 to the period of 2001 to 2050.This decrease in vulnerability is attributed to the decrease in exposure and sensitivity to Chinese cryospheric changes along with a concomitant increase in adaptation.     

NO and N2O fluxes from agricultural soils in Beijing area

Chinese agriculture represents one of the most intensively managed agroecosystems in the world. Typical nitrogen fertilization rates are more than three times those of the world' s average, resulting in dramatically accelerated nitrogen cycling in China. In this study, we have examined NO and N2O exchange in the upland agricultural systems of Beijing area. Inorganic and organic fertilizer treatments were arranged in order to evaluate their impact on the magnitude and proportion of trace gas emissions. Increasing inorganic fertilization rates showed a highly significant impact upon emissions of both NO and N2O. Organic matter amendment did not have a statistically significant impact on the N-gas fluxes examined here. Overall losses of added nitrogen by NO and N2O emission averaged 1.24% and 0.22% respectively over the range of treatments in this study. Results from our field study indicate that compared with other studies done elsewhere, emissions of reactive nitrogen from agricultural systems in Beijing area are not so large as expected before.     

Simulated change in the near-surface soil freeze/thaw cycle on the Tibetan Plateau from 1981 to 2010

The near-surface freeze/thaw cycle in cold regions plays a major role in the surface energy budget,hydrological activity,and terrestrial ecosystems.In this study,the Community Land Model,Version 4 and a suite of high-resolution atmospheric data were used to investigate the changes in the near-surface soil freeze/thaw cycle in response to the warming on the Tibetan Plateau from1981 to 2010.The in situ observations-based validation showed that,considering the cause of scale mismatch in the comparison,the simulated soil temperature,freeze start and end dates,and freeze duration at the near-surface were reasonable.In response to the warming of the Tibetan Plateau at a rate of approximately 0.44°C decade-1,the freeze start-date became delayed at an area-mean rate of1.7 days decade-1,while the freeze end-date became advanced at an area-mean rate of 4.7 days decade-1.The delaying of the freeze start-date,which was combined with the advancing of the freeze end-date,resulted in a statistically significant shortening trend with respect to the freeze duration,at an area-mean rate of 6.4 days decade-1.Such changes would strongly affect the surface energy flux,hydrological processes,and vegetation dynamics.We also found that the rate of freeze-duration shortening at the near-surface soil layer was approximately 3.0 days decade-1lower than that at a depth of 1 m.This implied that the changes in soil freeze/thaw cycles at the near surface cannot be assumed to reflect the situation in deeper soil layers.The significant correlations between freeze duration and air temperature indicated that the shortening of the near-surface freeze duration was caused by the rise in air temperature,which occurred especially in spring,followed by autumn.These results can be used to reveal the laws governing the response of the near-surface freeze/thaw cycle to climate change and indicate related changes in permafrost.     

CH4 emission and recovery from municipal solid waste in China

Methane (CH4) is an important greenhouse gas and a major environmental pollutant, second only to carbon dioxide (CO2) in its contribution to potential global wanning. In many cases, methane emission from landfills otherwise emitted to the atmosphere can be removed and utilized, or significantly reduced in quantity by using cost-effective management methods. The gas can also be used as a residential, commercial,or industrial fuel. Therefore, emission reduction strategies have the potential to become low cost, or even profitable. The annual growth rate of Municipal Solid Waste (MSW) output in China is 6.24% , with the highest levels found in South China, Southwest China and East China. Cities and towns axe developing quickly in these regions. MSW output was only 76.36 Mt in 1991 and increased to 109.82 Mt in 1997, registering an average increase of 43.8% . In China, methane emission from landfills also increased from 5.88 Mt in 1991 to 8.46 Mt in 1997; so the recovery of methane from landfills is a profitable project.     

A new method to calculate monthly CO emissions using MOPITT satellite data

A new method is developed to calculate monthly CO emission data using MOZART modeled and MOPITT observed CO data in 2004. New CO emission data were obtained with budget analysis of the processes controlling CO concentration such as surface emission, transport, chemical transform and dry deposition. MOPITT data were used to constrain the model simulation. New CO emission data agree well with Horowitz’s emissions in the spatial distributions. Horowitz’s emissions are found to underes- timate CO emissions significantly in the industrial areas of Asia and North America, where high CO emissions are mainly due to the anthropogenic activities. New CO emissions can better reflect the more recent CO actual emissions than Horowitz’s.     

Projected change in extreme rainfall events in China by the end of the 21st century using CMIP5 models

Projection of future climate changes and their regional impact is critical for long-term planning at the national and regional levels aimed at adaptation and mitigation. This study assesses the future changes in precipitation in China and the associated atmospheric circulation patterns using the Couple Model Intercomparison Project 5 Phase (CMIP5) simulations under the RCP4.5 and RCP8.5 scenarios. The results consistently indicate that the annual precipitation in China is projected to significantly increase at the end of the 21st century compared to the present-day levels. The number of days and the intensity of medium rain, large rain and heavy rain are obviously increased, while the number of trace rain days is projected to decrease over the entire area of China. Further analysis indicates that the significant increase of annual precipitation in Northwest China is primarily due to the increase of light rain and the increases in North and Northeast China are primarily due to the increase of medium rain. In the region of southern China, the increases of large rain and heavy rain play an important role in the increase of annual precipitation, while light rain events play a negative role. Analysis of the changes in atmospheric circulation indicates that the East Asian summer monsoon circulation is projected to be considerably stronger, and the local atmospheric stratification is projected to be more unstable, all of which provide a background benefit for the increase of precipitation and extreme rainfall events in China under global warming scenarios.     

Spatiotemporal pattern and regional characteristics of visibility in China during 1976–2010

Degradation in visibility occurs extensively across China,creating the urgent need to better understand visibility patterns and characteristics in China.Using daily observation data from the U.S.National Climatic Data Center(NCDC)during 1976–2010,the spatial distribution and temporal trends of visibility in China,as well as seasonal and regional characteristics,were determined.The distribution of visibility was characterized by a longitudinal gradient between west and east China.The northwest of China generally experienced consistent high visibility of[20 km,while central and eastern China experienced visibility degradation and increase in haziness.The 133stations with significant downward trends in visibility were clustered around central-east China and the average reduction rate was-1.65 km/decade(from 18.5 km).The96 stations with increasing trends of visibility were mostly on the Qinghai–Tibet Plateau and Xinjiang and were closely related to a reduction in local sand storms.The average visibility in 12 key regions in China varied between9.9–17.8 km(except for 23.9 km in Urumqi),which was lower than the national average of 18.7 km.The Taiyuan–Hohhot,Guanzhong,Yangtze River Delta,Pearl River Delta and Fuzhou–Xiamen areas all encountered significant decreases in visibility,while minor increases were observed in Beijing–Tianjin–Hebei and the Cheng-Yu region.At most stations,the worst visibility was measured in winter,but the season with best visibility varied between regions.A comparison of visibility trends with the emission trends of various pollutants revealed that SO2emissions dominated the visibility degradation in eastern Chinawith NOxand volatile organic compounds playing ascending roles during the 2000s.     

Characterization and assessment of volatile organic compounds (VOCs) emissions from typical industries

VOCs play an increasingly important role in affecting air quality and threatening human health in China in recent years,where industry activities show a significant contribution to VOCs emission.In this article we report our long term study of industrial VOCs emissions of six major industries (vehicle manufacturing,printing,equipment coating,electronic manufacturing,furniture manufacturing and bio-pharming) on the aspects of emission characteristics,environmental impact and health risk assessment,and control challenge analysis with the purpose to obtain in-depth understanding of industry VOCs emissions and offer some original basements for national control and management of industry VOCs emissions.This study shows that all these industries give middle or low emission with total VOCs concentration less than 1000 mg/m3 at each exhaust pipe.Benzenes,esters,alcohols,ketones,alkanes,chloroalkanes and alkenes were detected as the major emission components and the most frequently monitored VOCs were benzenes,which varied obviously with different processes and industries.The environmental impact assessments indicate that vehicle manufacturing and benzenes should be prior controlled with the purpose to reduce air pollution.While,health risk assessments suggest that furniture manufacturing and chloroalkanes should be firstly controlled.Control analysis indicates that developing technologies with low cost and high efficiency and establishing and completing specific industry emission standards/regulations are the two key issues in VOCs emission management at present stage.