Impacts of Migration on Urban Environmental Pollutant Emissions in China: A Comparative Perspective

In recent years,researchers have devoted considerable attention to identifying the causes of urban environmental pollution.To determine whether migrant populations significantly affect urban environments,we examined the relationship between urban environmental pollutant emissions and migrant populations at the prefectural level using data obtained for 90 Chinese cities evidencing net in-migration.By dividing the permanent populations of these cities into natives and migrants in relation to the population structure,we constructed an improved Stochastic Impacts by Regression on Population,Affluence and Technology model(STIRPAT)that included not only environmental pollutant emission variables but also variables on the cities’attributes.We subsequently conducted detailed analyses of the results of the models to assess the impacts of natives and migrants on environmental pollutant emissions.The main findings of our study were as follows:1)Migrant populations have significant impacts on environmental emissions both in terms of their size and concentration.Specifically,migrant populations have negative impacts on Air Quality Index(AQI)as well as PM2.5 emissions and positive impacts on emissions of NO2 and CO2.2)The impacts of migrant populations on urban environmental pollutant emissions were 8 to 30 times weaker than that of local populations.3)Urban environmental pollutant emissions in different cities differ significantly according to variations in the industrial structures,public transportation facilities,and population densities.

Study on the Environmental Quality Guarantee Ratio on the Basis of Total Air Pollutant Emission Amount Control

The hourly and daily air quality concentration in the total air pollutant emission amount control zone is not sure to be continuously up to national ambient air quality standard, even though the total annual air pollutant emission is permitted under the total air pollutant emission amount control (TAPEAC) on the basis of A-value method. So the concept of the environmental quality guarantee ratio (EQGR) for TAPEAC is advanced in this paper and its quantitative formula is figured out for both hourly and daily EQGR. It is concluded that the EQGR is related with the yearly arrangement of A-value besides the pollutant type. According to the meteorological data in a lower area along Yangtze River in 2000, the yearly A-value trend is analyzed. Based on the data, the hourly EQGR of SO 2 and NO 2 is respectively 97.4% and 90.2%, and daily EQGR respectively 90.2% and 79.5%.

A new prediction method of industrial atmospheric pollutant emission intensity based on pollutant emission standard quantification

Industrial emissions are the main source of atmospheric pollutants in China.Accurate and reasonable prediction of the emission of atmospheric pollutants from single enterprise can determine the exact source of atmospheric pollutants and control atmospheric pollution precisely.Based on China’s coking enterprises in 2020,we proposed a quantitative method for pollutant emission standards and introduced the quantification results of pollutant emission standards(QRPES)into the construction of support vector regression(SVR)and random forest regression(RFR)prediction methods for SO_(2) emission of coking enterprises in China.The results show that,affected by the types of coke ovens and regions,China’s current coking enterprises have implemented a total of 21 emission standards,with marked differences.After adding QRPES,it was found that the root mean squared error(RMSE)of SVR and RFR decreased from 0.055 kt/a and 0.059 kt/a to 0.045 kt/a and 0.039 kt/a,and the R2 increased from 0.890 and 0.881 to 0.926 and 0.945,respectively.This shows that the QRPES can greatly improve the prediction accuracy,and the SO_(2) emissions of each enterprise are highly correlated with the strictness of standards.The predicted result shows that 45%of SO_(2) emissions from Chinese coking enterprises are concentrated in Shanxi,Shaanxi and Hebei provinces in central China.The method created in this paper fills in the blank of forecasting method of air pollutant emission intensity of single enterprise and is of great help to the accurate control of air pollutants.

Biomass briquette fuel,boiler types and pollutant emissions of industrial biomass boiler:A review

Biomass is considered a renewable and cleaner energy source alternative to fossil fuels.In recent years,industrial biomass boilers have been rapidly developed and widely used in the industrial field.This work makes a review on the fuel types used in industrial biomass boilers,the fuel characteristics and the characteristics of air pollutants emitted from the combustion of industrial biomass boilers and other contents in different studies.However,the existing research still has many deficiencies.In the future,further research on biomass fuel,industrial biomass boiler combustion process and the pollutants emitted by industrial biomass boiler combustion,especially the carbonaceous aerosol emitted by in-dustrial biomass boiler and carbonaceous aerosol optical properties still need to be made.At the same time,the potential harm of carbonaceous aerosols emitted from industrial biomass boiler sources to human health and climate change needs to be studied in depth.This review provides a scientific basis for the accurate evaluation of industrial biomass boilers and the effective prevention and control of various pollutants of industrial biomass boilers.

An Integrated Analysis on the Synergistic Reduction of Carbon and Pollution Emissions from China’s Iron and Steel Industry

Decarbonization and decontamination of the iron and steel industry(ISI),which contributes up to 15%to anthropogenic CO_(2) emissions(or carbon emissions)and significant proportions of air and water pollutant emissions in China,are challenged by the huge demand for steel.Carbon and pollutants often share common emission sources,indicating that emission reduction could be achieved synergistically.Here,we explored the inherent potential of measures to adjust feedstock composition and technological structure and to control the size of the ISI to achieve carbon emission reduction(CER)and pollution emission reduction(PER).We investigated five typical pollutants in this study,namely,petroleum hydrocarbon pollutants and chemical oxygen demand in wastewater,particulate matter,SO_(2),and NO_(x) in off gases,and examined synergies between CER and PER by employing cross elasticity for the period between 2022 and 2035.The results suggest that a reduction of 8.7%-11.7%in carbon emissions and 20%-31%in pollution emissions(except for particulate matter emissions)could be achieved by 2025 under a high steel scrap ratio(SSR)scenario.Here,the SSR and electric arc furnace(EAF)ratio serve critical roles in enhancing synergies between CER and PER(which vary with the type of pollutant).However,subject to a limited volume of steel scrap,a focused increase in the EAF ratio with neglection of the available supply of steel scrap to EAF facilities would lead to an increase carbon and pollution emissions.Although CER can be achieved through SSR and EAF ratio optimization,only when the crude steel production growth rate remains below 2.2%can these optimization measures maintain the emissions in 2030 at a similar level to that in 2021.Therefore,the synergistic effects between PER and CER should be considered when formulating a development route for the ISI in the future.

Influence of Coal Nature and Structure on Ash Size Formation Characteristic and Related Pollutant Emissions During CFB Combustion

The size distribution of coal particles in a Circulating Fluidized Bed (CFB) boiler plays a crucial role in the complicated combustion, heat exchange and pollutant emissions in such a plat. Therefore, it is fundamental to study the different factors having influence on the size distribution of coal particles. Above all, the coal itself and in particular, the coal combination phenomenon is a very influent factor. In the frame of this work, the coal nature (elementary composition) and coal internal structure (mineral components) are studied in detail. At this intermediary stage, experiments on three typical Chinese coals on a l.5 MWt CFBC pilot plant have been made. Some primary fragmentation tests have also been made in a small lab scale fluidized bed reactor. The results from the hot pilot test show i) the variation of coal ash distributions and other CFB performance data due to the cyclone and the coal characteristics and ii) the variation of desulfurization efficiency with limestone. Whereas the bench scale primary fragmentation test, likely linked to the caking propriety of a coal, does not seem to change considerably the char size distribution.

Assessment of pollutant emissions and energy efficiency of four commercialized charcoal stoves with modified Chinese cooking stove protocol

Charcoal stove is widely used in the developing countries especially in Africa and Central America.Even reported to have a high impact on human health,stoves promoted in the related areas still mainly focus on fuel saving and little knowledge was reported for the stove performance in the field.This research evaluated four commercialized charcoal stoves with clay baseline stove using a modified Chinese cooking stove protocol that considered the local cooking habit to make the testing results more useful for the local stove promotion.The results showed that the thermal efficiency of tested charcoal stoves ranged from 38.7%to 47.5%,and the cooking power was around 640-1200 W.The CO emission factors of the improved stove had a 60%reduction compared with baseline stove.Different indicators reporting the same aspect of the stove were evaluated,and it suggested choosing the indicators according to the project requirements.

Pollutant emission characteristics of rice husk combustion in a vortexing fluidized bed incinerator

Rice husk with high volatile content was burned in a pilot scale vortexing fluidized bed incinerator. The fluidized bed incinerator was constructed of 6 mm stainless steel with 0.45 m in diameter and 5 m in height. The emission characteristics of CO, NO, and SO2 were studied. The effects of operating parameters, such as primary air flow rate, secondary air flow rate, and excess air ratio on the pollutant emissions were also investigated. The results show that a large proportion of combustion occurs at the bed surface and the freeboard zone. The SO2 concentration in the flue gas decreases with increasing excess air ratio, while the NOx concentration shows reverse trend. The flow rate of secondary air has a significant impact on the CO emission. For a fixed primary air flowrate, CO emission decreases with the secondary air flowrate. For a fixed excess air ratio, CO emission decreases with the ratio of secondary to primary air flow. The minimum CO emission of 72 ppm is attained at the operating condition of 40% excess air ratio and 0.6 partition air ratio. The NOx and SO2 concentrations in the flue gas at this condition are 159 and 36 ppm, which conform to the EPA regulation of Taiwan.

Achieving air pollutant emission reduction targets with minimum abatement costs:An enterprise-level allocation method with constraints of fairness and feasibility

For achieving air pollutant emission reduction targets,total pollutant amount control is being continuously promoted in China.However,the traditional pattern of pollutant emission reduction allocation regardless of economic cost often results in unreasonable emission reduction pathways,and industrial enterprises as the main implementers have to pay excessively high costs.Therefore,this study adopted economic efficiency as its main consideration,used specific emission reduction measures(ERMs)of industrial enterprises as minimum allocation units,and constructed an enterprise-level pollutant emission reduction allocation(EPERA)model with minimization of the total abatement cost(TAC)as the objective function,and fairness and feasibility as constraints for emission reduction allocation.Taking City M in China as an example,the EPERA model was used to construct a Pareto optimal frontier and obtain the optimal trade-off result.Results showed that under basic and strict emission reduction regulations,the TAC of the optimal trade-off point was reduced by 46.40%and 45.77%,respectively,in comparison with that achieved when only considering fairness,and the Gini coefficient was 0.26 and 0.31,respectively.The abatement target was attained with controllable cost and relatively fair and reasonable allocation.In addition,enterprises allocated different emission reduction quotas under different ERMs had specific characteristics that required targeted optimization of technology and equipment to enable them to achieve optimal emission reduction effects for the same abatement cost.

Air pollutant emissions induced by rural-to-urban migration during China's urbanization(2005-2015)

As the world's most populous country,China has witnessed rapid urbanization in recent decades,with population migration from rural to urban(RU)regions as the major driving force.Due to the large gap between rural and urban consumption and investment level,large-scale RU migration impacts air pollutant emissions and creates extra uncertainties for air quality improvement.Here,we integrated population migration assessment,an environmentally extended inputeoutput model and structural decomposition analysis to evaluate the NOx,SO2 and primary PM2.5 emissions induced by RU migration during China's urbanization from 2005 to 2015.The results show that RU migration increased air pollutant emissions,while the increases in NOx and SO2 emissions peaked in approximately 2010 at 2.4 Mt and 2.2 Mt,accounting for 9.2%and 8.7%of the national emissions,respectively.The primary PM2.5 emissions induced by RU migration also peaked in approximately 2012 at 0.3 Mt,accounting for 2.8%of the national emissions.The indirect emissions embodied in consumption and investment increased,while household direct emissions decreased.The widening gap between urban and rural investment and consumption exerted a major increasing effect on migration-induced emissions;in contrast,the falling emission intensity contributed the most to the decreasing effect benefitting from end-of-pipe control technology applications as well as improving energy efficiency.The peak of air pollutant emissions induced by RU migration indicates that although urbanization currently creates extra environmental pressure in China,it is possible to reconcile urbanization and air quality improvement in the future with updating urbanization and air pollution control policies.

Variation of toxic pollutants emission during a feeding cycle from an updraft fixed bed gasifier for disposing rural solid waste

The variation of toxic pollutants emission during a feeding cycle was examined by field monitoring from a batch feeding updraft fixed bed gasifier for disposing rural domestic solid waste. Results showed that the content of oxygen in flue gas gradually increased, while SO_2 and HCl in flue gas decreased with time after feeding in a whole feeding cycle. Although large amount of CO was produced during the gasifying, low CO content in flue gas could be obtained after the heat treatment with an electric heating device. The distribution characteristics of dioxin congeners in flue gas indicted the re-synthesis of dioxins after flue gas heating, and the increase of oxygen promoted the synthesis of dioxins. The emission content of dioxins could meet the standard(0.1 ng I-TEQ·m^(-3),GB18458-2014) of China when the oxygen content was controlled below 8.3%. Hence, for a batch feeding gasifier,low oxygen condition should be offered by reducing air intake at the later stage of feeding cycle in order to decrease the re-synthesis of dioxins after the flue gas heating.

Preliminary Study on the Emission Rules of Sulfur Derivative Pollutants in Putrefactive Cyanobacteria

[Objective]The aim was to study the characteristics of the emission of sulfur derivative pollutants in cyanobacteria.[Method]Based on water odor in drink water from Gonghu Bay in Lake Taihu,the sulfur derivatives pollutants were extracted by head space solid phase microextraction（HS-SPME） and the odor substance was identified by gas chromatography and mass spectrometry（GC-MS）.Decomposed simulation was conducted in closed tube of water and cyanobacteria samples collected from Gonghu Bay in Lake Taihu.The cyanobacteria rotten odor substances was analyzed and detected by HS-SPME-GC-MS for 10 days.The sulfur derivative pollutant was expounded.[Result]The primary or secondary metabolites by cyanobacteria in water samples such as β-cyclocitral,indol,methylphenol,mercaptan and thioether were detected with scan.During the decomposition process,the emission of β-cyclocitral changed little.The maximum emission of dimethyl trisulfide appeared on the seventh and eighth day.The maximum emission of dimethyl disulfide appeared on the forth day.The maximum emission of the diethyl sulfide was on the eighth and ninth day.The maximum concentration of dimethyl trisulfide was 2 344.79 ng/L,which was much more than the olfactory threshold.[Conclusion] The sewage in Gonghu Bay in the end of May in 2007 resulted from the accumulation of cyanobacteria.

Emission characteristics and combustion instabilities in an oxy-fuel swirl-stabilized combustor

This paper presents an experimental study on the emission characteristics and combustion instabilities of oxy-fuel combustions in a swirl-stabilized combustor. Different oxygen concentrations (Xoxy=25%～45%, where Xoxy is oxygen concentra- tion by volume), equivalence ratios (φ=0.75～1.15) and combustion powers (CP=1.08～2.02 kW) were investigated in the oxy-fuel (CH4/CO2/O2) combustions, and reference cases (Xoxy=25%～35%, CH4/N2/O2 flames) were covered. The results show that the oxygen concentration in the oxidant stream significantly affects the combustion delay in the oxy-fuel flames, and the equivalence ratio has a slight effect, whereas the combustion power shows no impact. The temperature levels of the oxy-fuel flames inside the combustion chamber are much higher (up to 38.7%) than those of the reference cases. Carbon monoxide was vastly produced when Xoxy>35% or φ>0.95 in the oxy-fuel flames, while no nitric oxide was found in the exhaust gases because no N2 participates in the combustion process. The combustion instability of the oxy-fuel combustion is very different from those of the reference cases with similar oxygen content. Oxy-fuel combustions excite strong oscillations in all cases studied Xoxy=25%～45%. However, no pressure fluctuations were detected in the reference cases when Xoxy>28.6% accomplished by heavily sooting flames which were not found in the oxy-fuel combustions. Spectrum analysis shows that the frequency of dynamic pressure oscillations exhibits randomness in the range of 50～250 Hz, therefore resulting in a very small resultant amplitude. Temporal oscillations are very strong with amplitudes larger than 200 Pa, even short time fast Fourier transform (FFT) analysis (0.08 s) shows that the pressure amplitude can be larger than 40 Pa.

Combustion and emission characteristics of diesel/n-butanol blends with split-injection and exhaust gas recirculation stratification

Oxygen fuels have broad application prospects and great potential for realizing efficient and clean combustion,and hence this study applies diesel/n-butanol blends to explore the influence of split-injection strategy on combustion and emission characteristics.Simultaneously,changing the way of exhaust gas recirculation(EGR)gas introduction forms uneven in-cylinder components distribution,and utilizing EGR stratification optimizes the combustion process and allows better emission results.The results show that the split-injection strategy can reduce the NO_(x)emissions and keep smoke opacity low compared with the single injection,but the rise in accumulation mode particles is noticeable.NO_(x)emissions show an upward trend as the injection interval expands,while soot emissions are significantly reduced.The increase in pre-injection proportion causes the apparent low-temperature heat release,and the two-stage heat release can be observed during the process of main combustion heat release.More pre-injection mass makes NO_(x)gradually increase,but smoke opacity reaches the lowest point at 15%pre-injection proportion.EGR stratification can optimize the emission results under the split injection strategy,especially the considerable suppression of accumulation mode particulate emissions.Above all,fuel stratification coupled with EGR stratification is beneficial for further realizing the in-cylinder purification of pollutants.

Analysis of the Influence of Fuel Additives on Automobile Exhaust Emission

In order to investigate the effect of a certain type of fuel additives on the emission and performance of vehicles,according to the Limits and Measurement Methods for Exhaust Pollutants from Vehicles Equipped Ignition Engine under Two-speed Idle Conditions and Simple Driving Mode Conditions(GB 18285-2005),the double idle method is used to detect the emission changes of different vehicles before and after the use of a certain type of fuel additives,and then the fuel consumption and power are evaluated.The results show that the use of fuel additives and the appropriate selection of fuel can effectively reduce the emissions of vehicle pollutants,which is of great significance for energy saving and emission reduction.

Life-Cycle Analysis of Bio-Ethanol Fuel Emissions of Transportation Vehicles in Greater Houston Area

Study is conducted on the life cycle assessment of bio-ethanol used for transportation vehicles and their emissions. The emissions that are analyzed include greenhouse gases, volatile organic compounds, sulfur oxide, carbon monoxide, nitrous oxide, particulate matter with the size less than 10 and 2.5 microns. Furthermore, various blends of bio-ethanol and gasoline are studied to learn about the impacts of higher blend on emissions. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model software are used to simulate for emissions. The research analyzes two pathways of emissions: Well-to-Pump and Pump-to-Vehicle analyses. It is found that the fuel cell vehicles using 100% bio-ethanol have shown the most reduction in the amount of all the pollutants from the Pump-to-Vehicle emission analysis. The Well-to-Pump analysis shows that only greenhouse gases (GHGs) reduce with higher blends of bio-ethanol. All other pollutants VOC, CO, NOx, SOx, PM10 and PM2.5 emissions increase with the higher blending ratios. The Pump-to-Vehicle analysis shows that all the pollutant emissions reduce with the percentage increase of bio-ethanol in the fuel blends.

Quantifying the emission＇s impact of coal mining activities on the environment and human health in process

Discharges and emissions in the coal mining process have a strong effect both on the environment and on human health. This problem is usually be a negative one and has only been recognized qualitatively, due to the lack of effective quantitative methods. Based on emergy theory and accounting methodology, a set of quantitative methods for accounting the environmental support due to pollutants emissions was first introduced. Then impacts on environment and effects on human health were quantified using the unified units. The results indicated that water pollutants caused more impacts on the environment than air pollutants did, i.e., more environmental contributions are needed to dilute and absorb water pollutants. The occupation of land caused by coal mining gangue waste stacking has led to a huge loss of environmental services over the years. Moreover, the potential damage on the human condition health caused by CO2 through climate change cannot be ignored. Finally, the impacts of mining activities on environmental and human health in unified units are shown to provide a quantitative insight into the disadvantage of coal mining. The comparable results of the method indicate the different influence of various pollutants and the contribution of ＇natural capital＇ directly. This work is a part of ongoing thermodynamic input-output analysis and life cycle analysis of coal mining systems （which are in process.）

Mercury emission and pollution in Chongqing City, China

Investigation showed that mercury emission in Chongqing City, China is about 2.1 t/a, 70% of which came from coal burning.Mercury in many water bodies have been detected, in vegetables and milk had exceeded the food standard value in some places.

Investigation of the Effects of a Large Percentage of Dried Sludge on the Operation of a Coal-Fired Boiler

A 600 MW coal-fired boiler with a four-corner tangential combustion mode is considered here to study the combustion features and pollutant emissions at different loads for large-percentages of blending dried sludges.The influence of the over-fired air(OFA)coefficient is examined and the impact of the blending ratio on the boiler operation is explored.The results show that for low blending ratios,a slight increase in the blending ratio can improve the combustion of bituminite,whereas a further increase leads to the deterioration of the combustion of blended fuels and thus reduces the boiler efficiency.Enhancing the supporting capability of the secondary air effectively reduces the slagging degree in the bottom ash hopper and improves the burnout rate of coals.For a large-percentage blending case at full load,it is found that the OFA coefficient must be reduced appropriately,otherwise,a secondary high-temperature combustion zone can be generated in the vicinity of the furnace arches,causing high temperature slagging and superheater tube bursting.Considering the influences of combustion and pollutant emissions,the recommended OFA coefficient is 0.2.Blending dried sludge under low loads increases the flue gas temperature at the furnace exit.While reducing the flue gas temperature in the main combustion region,which is beneficial to the safe operation of the denitrification system.Increasing the blending ratio and reducing load lead to an increase in NOx concentration at the furnace exit Sludges with low nitrogen content are suggested for the practical operation of boilers.

Quantifying China's iron and steel industry's CO2 emissions and environmental health burdens:A pathway to sustainable transformation

Assessing the iron and steel industry's(ISI)impact on climate change and environmental health is vital,particularly in China,where this sector significantly influences air quality and CO_(2)emissions.There is a lack of comprehensive analyses that consider the environmental and health burdens of manufacturing processes for ISI enterprises.Here,we present an integrated emission inventory that encompasses air pollutants and CO_(2)emissions from 811 ISI enterprises and five key manufacturing processes in 2020.Our analysis shows that sintering is the primary source of air pollution in the ISI.It contributes 71%of SO_(2),73%of NO_(x),and 54%of PM_(2.5)emissions.On the other hand,81%of total CO_(2)emissions come from blast furnaces.Significantly,the contributions of ISI have resulted in an increase of 3.6 mg m^(-3)in national population-weighted PM_(2.5)concentration,causing approximately 59,035 premature deaths in 2020.Emissions from Hebei,Jiangsu,Shandong,Shanxi,and Inner Mongolia provinces contributed to 48%of PM_(2.5)-related deaths in China.Moreover,the transportation of air pollutants across provincial borders highlights a concerning trend of environmental health inequality.Based on the research findings,it is crucial for ISI manufacturers to prioritize the removal of outdated production capacities and adopt energy-efficient and advanced techniques,along with ultra-low emission technologies.This is particularly important for those manufacturers with substantial environmental footprints.These transformative actions are essential in mitigating the environmental and health impacts in the affected regions.