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Turnover of dissolved organic carbon fuels nocturnal CO_(2) emissions from a headwater catchment reservoir, Southeastern China: Effects of ecosystem metabolism on source partitioning of CO2 emissions

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Journal of Environmental Sciences 2022年第11期34卷 98-111页

作者： Peipei Zhang Ruyuan Jiao Chen Gong Fang Wang Weijin Yan Qingqian Li Dongsheng Wang Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing100101China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Yangtze River Delta Branch Research Center for Eco-Environmental SciencesChinese Academy of SciencesZhejiang 322000China

Dam reservoirs in headwater catchments, as critical zones for their proximity to terrestrial sources, play important roles in dissolved organic carbon(DOC) cycling. However, the effects of ecosystem metabolism(EM) on DOC cycling are not well known. Here, in-situ diurnal and monthly observations were conducted to measure EM(including gross primary production(GPP), ecosystem respiration(ER) and heterotrophic respiration(HR)), DOC turnover and CO_(2)emissions in a headwater catchment reservoir in Southeastern China in 2020. Our study showed the nocturnal CO_(2)emission rate was about twice as high as in daytime, and was strongly driven by EM. The values for DOC turnover velocity ranged from 0.10 to 1.59 m/day,and the average DOC turnover rate was 0.13 day-1, with the average removal efficiency of 12%. The contribution of respired DOC to daily CO_(2)emissions ranged from 17% to 61%. The accumulated efficiencies were estimated to be 13% for the selected 15 reservoirs throughout the Changjiang River network, corresponding to about 0.34 Tg C/year of the respired DOC.The modified CO_(2)flux was 0.75 Tg C/year, and respired DOC accounted for about 45% of total emitted CO_(2)from the 15 larger reservoirs. Our research emphasizes the necessity of incorporating the effects of EM into studies of reservoir DOC removal and COemissions.

关键词： Ecosystem metabolism DOC turnover CO_(2)emission rate Source partitioning of CO_(2) emissions δ13CDIC

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Combustion and emissions of RP-3 jet fuel and diesel fuel in a single-cylinder diesel engine

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Frontiers in Energy 2023年第5期17卷 664-677页

作者： Tongbin ZHAO Zhe REN Kai YANG Tao SUN Lei SHI Zhen HUANG Dong HAN Key Laboratory for Power Machinery and Engineering of the Ministry of Education Shanghai Jiao Tong UniversityShanghai 200240China

The combustion characteristics and emission behaviors of RP-3 jet fuel were studied and compared to commercial diesel fuel in a single-cylinder compression ignition(CI)engine.Engine operational parameters,including engine load(0.6,0.7,and 0.8 MPa indicating the mean effective pressure(IMEP)),the exhaust gas recirculation(EGR)rate(0%,10%,20%,and 30%),and the fuel injection timing(–20,–15,–10,and–5°crank angle(CA)after top dead center(ATDC))were adjusted to evaluate the engine performances of RP-3 jet fuel under changed operation conditions.In comparison to diesel fuel,RP-3 jet fuel shows a retarded heat release and lagged combustion phase,which is more obvious under heavy EGR rate conditions.In addition,the higher premixed combustion fraction of RP-3 jet fuel leads to a higher first-stage heat release peak than diesel fuel under all testing conditions.As a result,RP-3 jet fuel features a longer ignition delay(ID)time,a shorter combustion duration(CD),and an earlier CA50 than diesel fuel.The experimental results manifest that RP-3 jet fuel has a slightly lower indicated thermal efficiency(ITE)compared to diesel fuel,but the ITE difference becomes less noticeable under large EGR rate conditions.Compared with diesel fuel,the nitrogen oxides(NOx)emissions of RP-3 jet fuel are higher while its soot emissions are lower.The NOx emissions of RP-3 can be effectively reduced with the increased EGR rate and delayed injection timing.

关键词： RP-3 jet fuel diesel engine combustion emissions

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Quantifying the impacts of emissions and meteorology on the interannual variations of air pollutants in major Chinese cities from 2015 to 2021

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Science China Earth Sciences 2023年第8期66卷 1725-1737页

作者： Qili DAI Tianjiao DAI Linlu HOU Linxuan LI Xiaohui BI Yufen ZHANG Yinchang FENG State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control College of Environmental Science and EngineeringNankai UniversityTianjin 300350China China Meteorological Administration-Nankai University Cooperative Laboratory for Atmospheric Environment-Health Research Tianjin 300350China

Air pollutant concentration is a function of emission rates and meteorology.To accurately evaluate the effect of control measures,the meteorological covariate must be corrected from the observations.This study quantified the impacts of emission abatement and meteorological condition on the interannual variations of SO_(2),NO_(2),CO,O_(3),PM_(10) and PM_(2.5) concentrations in 31 major Chinese cities using an optimized machine learning-based meteorological normalization technique.Overall,the annual average concentrations of SO_(2),NO_(2),CO,PM_(10)and PM_(2.5)were reduced by 86%,51%,99%,86% and 88%from 2015 to 2020,respectively,in the studied cities,attributable to their emission reductions.However,the concentration of O_(3) was found with no significant decrease with the reduction of precursors.Emission abatement notably improved air quality between 2015 and 2018.Such a decline in emissions tended to progressively slow down since 2018.Overall,the meteorological conditions in 2016–2017 and 2018–2019 were unfavorable for a better air quality,while it became favorable in 2020–2021.Specifically,emission abatement in 2021 further lowered the concentrations of SO_(2),NO_(2),CO,and PM_(2.5),while the emission of PM_(10) increased.And changes in precursors emissions worsened O_(3) air quality.To meet the demand of improving air quality,more aggressive abatement measures need to be formulated to synergistically reduce NOx,volatile organic compounds,and coarse particles.

关键词： Air pollution Air quality Machine learning Meteorology emissions Policy evaluation

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The relationship between fire severity and burning efficiency for estimating wildfire emissions in Mediterranean forests

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林业研究:英文版 2023年第5期34卷 1195-1206页

作者： Bountouraby Balde Cristina Vega-Garcia Pere Joan Gelabert Aitor Ameztegui Marcos Rodrigues Department of Agriculture and Forest Engineering University of LleidaAv.Alcalde Rovira Roure19125198 LleidaSpain Department of Geography and Land Management University of ZaragozaPedro Cerbuna 1250009 SaragossaSpain

Forests are exposed to changing climatic conditions reflected by increasing drought and heat waves that increase the risk of wildfire ignition and spread.Climatic variables such as rain and wind as well as vegetation structure,land configuration and forest management practices are all factors that determine the burning potential of wildfires.The assessment of emissions released by vegetation combustion is essential for determining greenhouse gases and air pollutants.The estimation of wildfire-related emissions depends on factors such as the type and fraction of fuel(i.e.,live biomass,ground litter,dead wood)consumed by the fire in a given area,termed the burning efficiency.Most approaches estimate live burning efficiency from optical remote sensing data.This study used a data-driven method to estimate live burning efficiency in a Mediterranean area.Burning severity estimations from Lands at imagery(dNBR),which relate to fuel consumption,and quantitative field data from three national forest inventory data were combined to establish the relationship between burning severity and live burning efficiency.Several proxies explored these relationships based on dNBR interval classes,as well as regres sion models.The correlation results between live burning efficiency and dNBR for conifers(R=0.63)and broad-leaved vegetation(R=0.95)indicated ways for improving emissions estimations.Median estimations by severity class(low,moderate-low,moderate-high,and high)are provided for conifers(0.44-0.81)and broad-leaves(0.64-0.86),and regression models for the live fraction of the tree canopy susceptible to burning(7 branches,and leaves).The live burning efficiency values by severity class were higher than previous studies.

关键词： Forest wildfires emissions Greenhouse gases Satellite images

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Numerical Simulation of the High-Boosting Influence on Mixing,Combustion and emissions of High-Power-Density Engine

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Journal of Thermal Science 2023年第3期32卷 933-946页

作者： WANG Can YUE Zongyu ZHAO Yuanyuan YE Ying LIU Xinlei LIU Haifeng State Key Laboratory of Engines Tianjin UniversityTianjin 300072China Clean Combustion Research Center King Abdullah University of Science and TechnologyThuwal 23900Saudi Arabia

Future high-power-density engines require high level of intake boost.However,the effects of boosting on mixing,combustion and emissions in existing studies are inconsistent.In this paper,the mixing,combustion and emission characteristics with intake pressures of 100-400 kPa at low,medium and high loads are studied.The results show that the increase of intake pressures is conducive to the enhancement of air entrainment,while the air utilization ratios are reduced,thus requiring injection pressure to be optimized to effectively improve the mixing.For the intake pressures of 100 kPa,the average chemical reaction path is low-temperature reaction route,while the path of higher intake pressures is dominated by high-temperature pyrolysis.For soot emissions,when the equivalence ratio is lower than 0.175,the oxygen in the cylinder is suficient,so the effect of temperature decrease is more significant,which leads to the increase of soot emissions with the increase of intake pressures.Otherwise,the effect of increasing oxygen concentration is more significant,so soot decreases accordingly.When the peak of global temperature is lower than 1800 K,the effect of the increase of oxygen concentration is more dominant,so the NO_(x)emission increases with the increase of intake pressures.Otherwise,the rule of NOxemissions is consistent with temperature changes.

关键词： high-power-density engines high boosting mixing process combustion process emissions

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The UAE’s energy system and GHG emissions: pathways to achieving national goals by 2050

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Clean Energy 2023年第5期7卷 962-980页

作者： Ammar Hummieda Ali Bouabid Karim Moawadand Ahmad Mayyas Engineering Systems and Management Khalifa UniversityAbu DhabiUAE Institute of Education Sciences Mohammed VI Polytechnic UniversityRabatMorocco

In recent years,the United Arab Emirates(UAE)has developed strategies to increase renewable power generation and reduce emis-sions to net zero by 2050.Electricity generation and energy-intensive industries(EII)have the largest potentials for emission reduc-tion.Therefore,an up-to-date inventory of greenhouse gas emissions and a study of the pathways to achieving the 2050 targets are essential.This study focuses on power production and EII(aluminium,steel and cement).The structure of these sectors is modelled and simulated up to 2050 using a system dynamics(SD)methodology.The SD model is validated to reflect the real-world state of the system using the emissions inventory projections as reference modes.Nineteen mitigation policies are considered in the selected sectors and four policy scenarios were simulated.The results show that implementing the Energy Strategy 2050 in the power sector can result in a reduction of 63.5%in emissions in that sector,which translates into a reduction of 33.5%overall by 2050.Additionally,implementing all identified mitigation strategies to full utilization in EII yields a 94%reduction in that sector,which translates into a 78%reduction overall.Decarbonizing the aluminium industry yields the highest emissions reductions,followed by power produc-tion,then cement and finally steel.In the best-case scenario,22.1%of the business-as-usual emissions are still released and further decarbonization—mainly in the power sector—will be required.This is achievable given the trajectory of the UAE’s successful nuclear energy programme and the prospect of utilizing carbon capture,utilization and storage even further.

关键词： climate change emissions UAE energy strategy energy-intensive industry net zero

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海事能源转型:未来燃料和未来排放

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哈尔滨工程大学学报（英文版） 2023年第4期22卷 681-692页

作者： William Ramsay Erik Fridell Mario Michan Daphne Technology SA Chemin de la Venoge 7 CH-1025 Saint-Sulpice Switzerland IVL Swedish Environmental Research Institute Valhallavägen 8111428 Stockholm Sweden

The lifecycle greenhouse gas(GHG)emissions(Well-to-Wake)from maritime transport must be reduced by at least 50%in absolute values by 2050 to contribute to the ambitions of the Paris Agreement(2015).A transition from conventional fuels to alternative fuels with zero or lower GHG emissions is viewed as the most promising avenue to reach the GHG reductions.Whereas GHG and toxic pollutants emitted from the use of fossil fuels(heavy fuel oil(HFO)and marine gas/diesel oil(MGO/MDO))are generally well understood,the emissions associated with the new fuel options are only now being measured and communicated.This review provides an outlook on fuels that could help shipping respond to the decarbonization effort including Liquefied Petroleum Gas(LPG),Liquefied Natural Gas(LNG),methanol,ammonia,and hydrogen.A quantification of the pollutants associated from the use of these fuels is provided and challenges and barriers to their uptake are discussed.

关键词： Greenhouse gas emissions Maritime transport Future fuels Future emissions Life-cycle assessment Energy transition

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Factor decomposition of carbon emissions in Chinese megacities

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Journal of Environmental Sciences 2019年第1期31卷 209-215页

作者： Longyu Shi Jing Sun Jianyi Lin Yang Zhao Institute of Urban Environment Chinese Academy of Sciences University of Chinese Academy of Sciences

In this article, per capita urban carbon emissions were decomposed into manufacturing,transportation, and construction sectors using logarithmic mean Divisia index(LMDI)method. This new decomposition method can provide information about specific drivers of carbon emissions, including urban growth and resident living standards, rather than general demographic and economic factors identified by traditional methods. Using four Chinese megacities(Beijing, Tianjin, Shanghai, and Chongqing) as case studies, we analyzed the factors that influenced per capita carbon emissions from 2010 to 2015. The results showed that per capita carbon emissions increased in Tianjin and Chongqing whereas decreased in Beijing and Shanghai, and that manufacturing was a key driving force. In these four megacities,energy conservation strategies were successfully implemented despite poor energy structure optimization during 2010–2015. Development of manufacturing and improvement of resident living standards in the cities led to an increase in carbon emissions. The unique dual-core urban form of Tianjin might mitigate the increased carbon emissions caused by the transportation sector. Reductions in carbon emissions could be achieved by further optimizing energy structures, limiting the number of private cars, and controlling per capita construction.

关键词： Per capita carbon emissions Factor decomposition LMID China megacities

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Performance,emissions and exergy analyses of adding CNTs to various biodiesel feedstocks

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Propulsion and Power Research 2022年第4期11卷 511-526页

作者： M.S.Gad Mostafa M.Abdel Aziz Hatem Kayed Mechanical Engineering Department Faculty of EngineeringFayoum UniversityEgypt Mechanical Engineering Department Institute of Aviation Engineering and TechnologyGizaEgypt Mechanical Power Engineering Department Faculty of EngineeringCairo University12613Egypt

Extraction of biodiesel from waste cooking oil,jatropha,and corn oils is done by transesterification.Diesel and biodiesel were blended at 20%volume ratio to make methyl ester.At doses of 25,50,and 100 mg/l,carbon nanotubes(CNTs)was mixed with biodiesel blend.The objective of the present research is to examine experimentally a diesel engine performance,combustion characteristics,exergy and emissions analyses with inclusion of nano additive to various methyl ester feedstocks.Methyl ester blend is enriched with CNTs as JB20C100,WB20C100 and CB20C100 where the improvements in thermal efficiency are raised about biodiesel mixture by 9%,13%and 15%,respectively.Addition of 100 ppm of CNTs to biodiesel blends achieves the greatest reductions in CO(14%,22%and 30%),HC(16%,20%and 25%),and smoke emissions(15%,19%and 23%)for JB20C100,WB20C100 and CB20C100,respectively.By comparing with B20,blending 100 ppm CNTs with JB20,CB20,and WB20 obtained the highest increases in cylinder pressure of 3%,5%,and 10%,as well as the highest increases in heat release of 4%,7%,and 11%,respectively.The downside of CNTs addition achieves a rise in NOx emissions by 10%,17%,and 22%for JB20C100,WB20C100,and CB20C100,respectively.Exergetic efficiency increases by 8%,19%,and 24%for B20T100,B20A100,and B20C100,respectively.Sustainability index improvements achieve 1.5%,5%and 6.5%,for B20T100,B20A100,and B20C100,respectively.WB20 with CNTs of 100 ppm is highly recommended for improving engine performance,combustion,and exergy characteristics with considerable emissions reduction.

关键词： Biodiesel Carbon nanotubes(CNTs) Engine performance Exergy Combustion characteristics emissions

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Impact of different nano additives on performance, combustion, emissions and exergetic analysis of a diesel engine using waste cooking oil biodiesel

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Propulsion and Power Research 2022年第2期11卷 209-223页

Biodiesel is derived from waste cooking oil (WCO) by transesterification. Methylester was prepared by mixing diesel and biodiesel oils as 20% by volume. Nano particles asTiO2, Al2O3 and CNTs were blended with biodiesel blend at different concentrations of 25,50, and 100 mg/l to enhance the physicochemical fuel characteristics to obtain clean and effi-cient combustion performance. An experimental setup was incorporated into a diesel engine toinvestigate the influence of these nano-materials on engine performance, exergy analysis, combustion characteristics and emissions using WCO biodiesel-diesel mixture. Enriching methylester mixture with 100 ppm titanium, alumina and CNTs (B20T100, B20A100 andB20C100) increased the thermal efficiency by 4%, 6% and 11.5%, respectively compared toB20. Biodiesel blending with nano additives B20T100, B20A100 and B20C100 decreasedthe emissions of CO (11%, 24% and 30%, respectively), HC (8%, 17% and 25%, respectively)and smoke (10%, 13% and 19%, respectively) compared to B20. However, the noticeable increase of NOx was estimated by 5%, 12% and 27% for B20T100, B20A100 and B20C100,respectively. Finally, the results showed the rise in peak cylinder pressure by 5%, 9% and 11% and increase in heat release rate by 4%, 8% and 13% for B20T100, B20A100 andB20C100, respectively. The fuel exergy of B20T100, B20A100 and B20C100 are lower thanbiodiesel blend B20 by 6.5%, 16% and 23% but the exergetic efficiency are increased by 7%,19% and 30% at full load about B20.

关键词： Waste cooking oil(WCO) Nano additives Engine performance Exergy Combustion characteristics emissions

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