采用静态箱-气相色谱法研究了氮肥施用水平及种类对生菜产量和土壤N_2O排放的影响。试验设7个处理:不施氮肥(N0),施氮112.5 kg N·hm^(-2)(N1),施氮225 kg N·hm^(-2)(N2),施氮337.5 kg N·hm^(-2)(N3),控释氮肥(CRU-N2),...采用静态箱-气相色谱法研究了氮肥施用水平及种类对生菜产量和土壤N_2O排放的影响。试验设7个处理:不施氮肥(N0),施氮112.5 kg N·hm^(-2)(N1),施氮225 kg N·hm^(-2)(N2),施氮337.5 kg N·hm^(-2)(N3),控释氮肥(CRU-N2),稳定性氮肥(SN-N2),有机无机氮肥配施(MN-N2)。对比研究了不同施氮水平和等氮量不同氮种类处理对N_2O排放特征和生菜产量的影响。结果表明,随着氮肥用量的增加N_2O排放通量增加。在试验条件下,生菜获得最高产量时的施氮量为125 kg N·hm^(-2),适量降低生菜施氮水平能有效降低N_2O气体累积排放量。相同氮水平下,SN-N2与MN-N2处理较N2处理分别增产达13.3%和17.2%,但差异未达显著水平。SN-N2处理N_2O排放总量和N_2O排放系数仅为0.80 kg N·hm^(-2)和0.36%,较常规施肥处理分别降低了84.8%和1.97个百分点。综上,在不降低生菜产量的前提下,优化氮肥施用水平并采用稳定性氮肥技术是菜地N_2O减排和减少蔬菜种植氮素损失的重要途径。展开更多
China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road vehicles.This study provides the first la...China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road vehicles.This study provides the first large-scale review and evaluation of China’s NDMM policies,along with emission measurements and an investigation on diesel fuel quality.The sulfur contents of the investigated diesel declined from 430 ppm(median value)in 2011 to6-8 ppm during the 2017-2018 period.The emission control of NO_(x)and PM greatly improved with the shift from the China II to China IV standards,as demonstrated by engine tests and field NO_(x)measurements.However,the NO_(x)emission factors for non-type-approved engines were approximately twice the limits of the China II standards.Emission compliance based on bench tests was not sufficient to control actual emissions because the field-measured NO_(x)emission factors of all machinery ranged from 24%to 225%greater than the respective emission limits for the engines.These circumstances adversely affected the effectiveness of the regulations and policies for China’s emission control of NDMM.Nevertheless,the policies on new and in-use NDMM,as well as diesel fuel quality,prevented NO_(x)and PM emissions amounting to 4.4 Tg and 297.8 Gg during the period 2008-2017,respectively.The emission management strategy contributed to enhancing the international competitiveness of China’s NDMM industries by promoting advanced technologies.For effective NDMM emission control in the future,portable testing and noncontact remote supervision should be strengthened;also,the issue of noncompliant diesel should be addressed through rigorous control measures and financial penalties.展开更多
The transportation industry is an essential sector for carbon emissions mitigation.This paper firstly used the LMDI(Logarithmic Mean Divisia Index)decomposition method to establish factors decomposition model on China...The transportation industry is an essential sector for carbon emissions mitigation.This paper firstly used the LMDI(Logarithmic Mean Divisia Index)decomposition method to establish factors decomposition model on China's transportation carbon emission.Then,a quantitative analysis was performed to study the factors influencing China's transportation carbon emissions from 1991 to 2008,which are identified as transportation energy efficiency,transportation structure and transportation development.The results showed that:(1)The impact of transportation development on transportation carbon emissions showed pulling function.Its contribution value to carbon emissions remained at high growth since 1991 and showed an exponential growth trend.(2)The impact of transportation structure on transportation carbon emissions showed promoting function in general,but its role in promoting carbon emissions decreased year by year.And with the continuous optimization of transportation structure,the promoting effect decreased gradually and showed the inversed"U"trend.(3)The impact of transportation energy efficiency on transportation carbon emissions showed a function of inhibition before pulling.In order to predict the potential of carbon emission reduction,three scenarios were set.Analysis of the scenarios showed that if greater intensity emission reduction measures are taken,the carbon emissions will reduce by 31.01 million tons by 2015 and by 48.81 million tons by 2020.展开更多
This study is primarily focused on Cleveland-Akron-Lorain nonattainment area in northeastern Ohio. The base year 2002 considered in this study witnessed one of the worst cases of ozone pollution in this region with oz...This study is primarily focused on Cleveland-Akron-Lorain nonattainment area in northeastern Ohio. The base year 2002 considered in this study witnessed one of the worst cases of ozone pollution in this region with ozone values exceeding previous 8-hour ozone standards of 84 ppb. The photochemical modeling system CAMx was applied to compute relative reduction factors, which were used subsequently to scale the base year (2002) values at the ozone monitoring sites to estimate the ozone design values for the year 2009 in Cleveland area for different emissions reduction scenarios. The results disclose that the largest change in the 2009 ozone design values consequent to applying auxiliary emission control strategies is between 1 and 1.5 ppb, which still left certain counties in northeastern Ohio unable to demonstrate attainment. The results are important in the development of emission control strategies in today’s context with instillation of even more stringent ozone standards and potential future increases in ozone concentrations due to climate change.展开更多
文摘采用静态箱-气相色谱法研究了氮肥施用水平及种类对生菜产量和土壤N_2O排放的影响。试验设7个处理:不施氮肥(N0),施氮112.5 kg N·hm^(-2)(N1),施氮225 kg N·hm^(-2)(N2),施氮337.5 kg N·hm^(-2)(N3),控释氮肥(CRU-N2),稳定性氮肥(SN-N2),有机无机氮肥配施(MN-N2)。对比研究了不同施氮水平和等氮量不同氮种类处理对N_2O排放特征和生菜产量的影响。结果表明,随着氮肥用量的增加N_2O排放通量增加。在试验条件下,生菜获得最高产量时的施氮量为125 kg N·hm^(-2),适量降低生菜施氮水平能有效降低N_2O气体累积排放量。相同氮水平下,SN-N2与MN-N2处理较N2处理分别增产达13.3%和17.2%,但差异未达显著水平。SN-N2处理N_2O排放总量和N_2O排放系数仅为0.80 kg N·hm^(-2)和0.36%,较常规施肥处理分别降低了84.8%和1.97个百分点。综上,在不降低生菜产量的前提下,优化氮肥施用水平并采用稳定性氮肥技术是菜地N_2O减排和减少蔬菜种植氮素损失的重要途径。
基金supported by the National Key Research and Development Program(Nos.2019YFC0214800 and 2016YFC0208004)the National Natural Science Foundation of China(Nos.41822505 and 42061130213)+1 种基金supported by the Royal Society of the UK through the Newton Advanced Fellowship(No.NAFR1201166)the Tsinghua University Initiative Scientific Research Program(No.2019Z02CAU)。
文摘China’s emission control for nonroad diesel mobile machinery(NDMM)must deal with a fast increase in stock as well as regulations that are two decades behind those for on-road vehicles.This study provides the first large-scale review and evaluation of China’s NDMM policies,along with emission measurements and an investigation on diesel fuel quality.The sulfur contents of the investigated diesel declined from 430 ppm(median value)in 2011 to6-8 ppm during the 2017-2018 period.The emission control of NO_(x)and PM greatly improved with the shift from the China II to China IV standards,as demonstrated by engine tests and field NO_(x)measurements.However,the NO_(x)emission factors for non-type-approved engines were approximately twice the limits of the China II standards.Emission compliance based on bench tests was not sufficient to control actual emissions because the field-measured NO_(x)emission factors of all machinery ranged from 24%to 225%greater than the respective emission limits for the engines.These circumstances adversely affected the effectiveness of the regulations and policies for China’s emission control of NDMM.Nevertheless,the policies on new and in-use NDMM,as well as diesel fuel quality,prevented NO_(x)and PM emissions amounting to 4.4 Tg and 297.8 Gg during the period 2008-2017,respectively.The emission management strategy contributed to enhancing the international competitiveness of China’s NDMM industries by promoting advanced technologies.For effective NDMM emission control in the future,portable testing and noncontact remote supervision should be strengthened;also,the issue of noncompliant diesel should be addressed through rigorous control measures and financial penalties.
基金supported by the National Science and Technology Ministry(Grant No.2011BAJ07B01)
文摘The transportation industry is an essential sector for carbon emissions mitigation.This paper firstly used the LMDI(Logarithmic Mean Divisia Index)decomposition method to establish factors decomposition model on China's transportation carbon emission.Then,a quantitative analysis was performed to study the factors influencing China's transportation carbon emissions from 1991 to 2008,which are identified as transportation energy efficiency,transportation structure and transportation development.The results showed that:(1)The impact of transportation development on transportation carbon emissions showed pulling function.Its contribution value to carbon emissions remained at high growth since 1991 and showed an exponential growth trend.(2)The impact of transportation structure on transportation carbon emissions showed promoting function in general,but its role in promoting carbon emissions decreased year by year.And with the continuous optimization of transportation structure,the promoting effect decreased gradually and showed the inversed"U"trend.(3)The impact of transportation energy efficiency on transportation carbon emissions showed a function of inhibition before pulling.In order to predict the potential of carbon emission reduction,three scenarios were set.Analysis of the scenarios showed that if greater intensity emission reduction measures are taken,the carbon emissions will reduce by 31.01 million tons by 2015 and by 48.81 million tons by 2020.
文摘This study is primarily focused on Cleveland-Akron-Lorain nonattainment area in northeastern Ohio. The base year 2002 considered in this study witnessed one of the worst cases of ozone pollution in this region with ozone values exceeding previous 8-hour ozone standards of 84 ppb. The photochemical modeling system CAMx was applied to compute relative reduction factors, which were used subsequently to scale the base year (2002) values at the ozone monitoring sites to estimate the ozone design values for the year 2009 in Cleveland area for different emissions reduction scenarios. The results disclose that the largest change in the 2009 ozone design values consequent to applying auxiliary emission control strategies is between 1 and 1.5 ppb, which still left certain counties in northeastern Ohio unable to demonstrate attainment. The results are important in the development of emission control strategies in today’s context with instillation of even more stringent ozone standards and potential future increases in ozone concentrations due to climate change.
