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With the expansion of urbanisation, the total amount of solid waste produced by urban residents has been increasing, and the problem of municipal solid waste disposal has also been aggravated. Landfill leachate treatment technologies could be divided into three categories: biological, physical and advanced oxidation treatment technology. Among them, advanced oxidation treatment technology has a good effect on the treatment of landfill leachate with little secondary pollution and has excellent application potential. Three-dimensional (3D) electrode technology, as a new type of advanced oxidation technology, could remove refractory pollutants in water and has attracted considerable attention. This article aims to (1) compare existing landfill leachate treatment technologies, (2) summarise 3D electrode technology application scenarios, (3) discuss the advantages of 3D electrode technology in landfill leachate treatment and (4) look ahead the future directions of 3D electrode technology in landfill leachate treatment. We hope that this article will be helpful to researchers who are interested in the field of landfill leachate treatment.

In order to reduce foodborne diseases caused by bacterial infections, antibacterial membranes have received increasing research interests in recent years. In this study, highly effective antibacterial membranes were prepared using biodegradable polymers, including polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), and carboxymethyl cellulose (CMC). The cation exchange property of CMC was utilized to introduce silver to prepare antibacterial materials. The presence of silver in the membranes was confirmed by EDS mapping, and the reduction of silver ions to metallic silver was confirmed by the Ag3d XPS spectrum which displayed peaks at 374.46 eV and 368.45 eV, revealing that the oxidation state of silver changed to zero. Two common pathogenic bacteria, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), were used to investigate the antibacterial performance of the prepared membranes. Zone of inhibition and bacteria-killing tests revealed that the antibacterial membranes were efficient in inhibiting the growth of bacteria (diameters of inhibition zone ranged from 16 mm to 19 mm for fresh membranes) and capable of killing 100% of bacteria under suitable conditions. Furthermore, after 10 cycles of continuous zone of inhibition tests, the membranes still showed noticeable antibacterial activities, which disclosed the sustainable antibacterial properties of the membranes.

The real-world exhaust emissions and fuel consumption of on-road diesel vehicles, fueled by waste cooking oil biodiesel blends, were measured using a portable emission measurement system (PEMS). Two light-duty diesel trucks (LDDTs) and two heavy-duty diesel trucks (HDDTs) filled with four mixed fuels with blend ratios of 0% (neat diesel), 5% (B5), 20% (B20), and 100% (B100) (biodiesel in traditional fossil diesel) were tested. The results show that the total fuel consumption (biodiesel + traditional fossil diesel) did not clearly decrease, but blending biodiesel into traditional fossil diesel could clearly decreased the consumption of traditional fossil diesel, reduce the countries' dependence on oil imports. Converting waste cooking oil into biofuel and blending with diesel is a three-win alternative, dealing simultaneously with greenhouse gas (GHG) emission, food security, and energy security. The CO, HC, NOX and PM2.5 emissions for all of the tested vehicles decreased with increasing biodiesel content in the blend, with the exception of PM2.5 and NOX for D3, the NOX emissions showed a decrease with increasing biodiesel content in the blend for most vehicles in this study. The effect of emission reduction for all biodiesel blending proportions under highway (HW) condition is better than that under Non-highway (NHW) condition. The degree of reduction in CO, HC, NOX, and PM2.5 emission increased with increasing biodiesel content in the blend under HW section. Under the NHW section, the emission factors for lower biodiesel blend proportions (below 12.5%) especially for B5 were higher than those for neat diesel. The biodiesel blend reduced CO, HC, NOX and PM2.5 emissions compared with neat diesel under different driving modes except for individual condition (especially for B5 under acceleration mode). Increasing the biodiesel content of the blend lowered the CO, HC, NOX, and PM2.5 emissions for acceleration and deceleration modes.

Diesel vehicle is an important source of black carbon (BC). A portable emission measurement system including a photo-acoustic extinctiometer and SEMTECH-LDV was used to measure the real-world emissions of 14 light-duty and heavy-duty diesel trucks (LDDTs and HDDTs, meeting the China IV and China V standards) in Beijing. BC emission factors and the BC/PM2.5 ratio were obtained, and the effects of the vehicle type, emission standard and driving cycle on emissions were analyzed. The tightening of emission standards and the advancement of vehicle technology have reduced BC emissions from the China II standard to the China V standard. The emission reductions of BC are lower than those of other components of PM2.5 from the China II standard to the China IV standard but higher from the China IV standard to the China V standard. The BC and PM2.5 had the same main sources for the HDDTs and China IV LDDTs but had different sources for the China V LDDTs having diesel particulate filters. The BC/PM2.5 ratios of LDDTs, and HDDTs decreased from the China IV standard to the China V standard by 97.2% and 38.2%, respectively. The BC/PM2.5 ratio for China V LDDTs was 10 to 20 times lower than that for other diesel vehicles. The BC emissions tested under the highway driving cycle were 39.4% ± 16.7% lower than those under the no-highway driving cycle, but the BC/PM2.5 ratios had the opposite tendency. More China V and China VI heavy-duty diesel vehicles equipped with diesel particulate filters need to be tested to obtain more accurate BC/PM2.5 data and to improve the readiness of emission inventory calculations. The findings of this study help clarify the BC emission characteristics of diesel vehicles on actual roads and provide scientific basis for the formulation of emission control strategies for diesel vehicles in China.

Ion exchange membranes (IEMs) are undergoing prosperous development in recent years. More than 30,000 papers which are indexed by Science Citation Index Expanded (SCIE) have been published on IEMs during the past twenty years (2001-2020). Especially, more than 3000 papers are published in the year of 2020, revealing researchers' great interest in this area. This paper firstly reviews the different types (e.g., cation exchange membrane, anion exchange membrane, proton exchange membrane, bipolar membrane) and electrochemical properties (e.g., permselectivity, electrical resistance/ionic conductivity) of IEMs and the corresponding working principles, followed by membrane synthesis methods, including the common solution casting method. Especially, as a promising future direction, green synthesis is critically discussed. IEMs are extensively applied in various applications, which can be generalized into two big categories, where the water-based category mainly includes electrodialysis, diffusion dialysis and membrane capacitive deionization, while the energy-based category mainly includes reverse electrodialysis, fuel cells, redox flow battery and electrolysis for hydrogen production. These applications are comprehensively discussed in this paper. This review may open new possibilities for the future development of IEMs.

Rural vehicles (RVs) could contribute significantly to on-road vehicle emissions, especially PM2.5 and NOx; This study tested 10 three-wheeled (3-W) RVs and 8 four-wheeled (4-W) RVs on real roads in Hebei Province using a portable emissions measurement system to investigate gaseous concentrations (CO, NOx, and HC) and the carbonaceous composition (EC and OC) of the PM2.5 emitted. The results showed that the tightening emission standards resulted in the CO, HC, and PM2.5 emissions for China II RVs decreasing, but may increasing NOx emission for China II 3-W RVs. The emission level of PM2.5 for China II RVs is between Euro II LDDTs and Euro III LDDTs. The emission factors (EFs) of OC and EC for 3-W RVs were 0.035 ± 0.019 and 0.058 ± 0.055 g km-1, respectively, and for 4-W RVs, they were 0.046 ± 0.018 and 0.031 ± 0.024 g km-1, respectively. The carbonaceous component represents the main fraction of PM2.5 emitted from RVs (84.6% and 87.2% for 3-W and 4-W RVs, respectively), similar to other diesel vehicles. The average distance-based EFs of OC increased with increasing vehicle size (3-W RVs < 4-W RVs). The CO2-based EFs of OC and EC decreased with increasing vehicle mass, consistent with the emission laws of light-, medium-, and heavy-duty diesel trucks. Driving cycles that included more cruise mode and less creep mode resulted in a higher average EC/OC ratio (1.57) for 3-W RVs than for 4-W RVs (0.63), and resulted in the average EC/OC ratios for both types of RV were lower than for highway LDDTs.

Biofuel stoves are an important source of black carbon (BC) emissions, which have adverse effects on the environment and human health, especially in rural areas. However, there have been only limited studies of BC emissions from residential biofuel stoves based on real-time measurements. In this study, a photo-acoustic extinctiometer (PAX)-based real-time measurement system was employed to monitor the emission characteristics of corncobs, corn stalks, cotton stalks and poplar branches in simple or improved stoves (with a total of 16 units) in Hebei Province, China. The real-time and phased emissions of BC, fine particulate matter (PM2.5), carbon monoxide (CO) and carbon dioxide (CO2) were assessed, and the effects of stove type and fuel on emissions were analyzed. Under the same conditions, polar branches were associated with the highest BC emission factors (EFs) of up to 2.64 ± 0.42 g kg−1, while the EFs for improved stoves were higher than those for simple stoves. During the ignition phase, BC emissions were found to be low, while the later addition of fuel dramatically increased emissions, followed by a gradual decrease until the next fuel addition. The phased results show that the flaming phase had the highest BC emission rate, the fuel addition phase was associated with the highest BC EF. The BC emission rates and EFs for the ignition, fuel addition, flaming and smoldering phases ranged from 0.0014–0.014, 0.11–6.32, 0.18–2.24 and 0.03–0.32 mg s−1, and from 0.04–0.18, 0.38–9.53, 0.45–3.55 and 0.12–1.01 g kg−1, respectively. This study assessed the BC emissions from residential biofuel stoves using a larger sample size than in prior work. The results increase our understanding of the BC emissions process, which is helpful in terms of improving the accuracy of BC EF estimations. The real-time measurement process described herein is also expected to provide new approaches to minimizing BC emissions.

Microorganisms play important roles in the degradation of volatile organic compounds. Aeromonas salmonicida strain (AEP-3) generated from biomass in the citric acid fermentation industry was screened and subjected to denaturing gradient gel electrophoresis (DGGE) fingerprinting and 16S rDNA gene sequencing. The growth conditions of AEP-3 in Luria-Bertani broth were optimized at 25 °C and approximately pH 7. AEP-3 was used to degrade ethyl formate, propionic aldehyde, or acetone alone and their mixture. The concentrations of ethyl formate, propionic aldehyde, and acetone were below 7500, 600, and 800 mg L-1, respectively, and their maximum degradation efficiencies were 100%, 92.41%, and 34.75%. AEP-3 first degraded acetone and propionic aldehyde in the mixture, followed by ethyl formate. The degradation pathways of these organic compounds in the mixture and their substrate interactions during degradation were explored. Propionic aldehyde was first converted into propionic acid in the metabolic process and was involved in the subsequent carboxylic acid cycle. By contrast, ethyl formate was first hydrolyzed into formic acid and ethanol. Then, formic acid participated in the cyclic metabolism of carboxylic acid, whereas, ethanol was hydrolyzed into acetaldehyde and acetic acid through alcohol and aldehyde dehydrogenase. Additionally, acetone directly interacted with nitrate in the medium under the action of hydrogen ions and produced carbon dioxide, water, and nitrogen. Overall, this study provides a new degrading bacterium biodegradability toward the exhaust gas of citric acid fermentation.

To study the formation process of secondary organic aerosols (SOA) in a vehicle exhaust plume near the exhaust gas discharge outlet, a new multipoint sampling system was established. The system has five sampling heads and includes a particulate matter multi-channel film sampling system, a CO2/CO analyzer system, a volatile organic compound (VOC) sampling system, a particulate matter real-time analyzer system, and sensor interfaces. The vehicle exhaust near the exhaust nozzle can be sampled at multiple locations simultaneously using the new multipoint sampling system. Additionally, the system can be used to measure and analyze variations in the fine particulate matter, including the carbonaceous and ionic components, and organic compounds in the plume near the exhaust nozzle. This paper introduces the construction and application of the multipoint sampling system. The motor vehicle exhaust multipoint sampling system is reliable and can accurately capture the characteristics of the exhaust plume near the discharge outlet area. Changes in the CO2 concentration were used to determine whether exhaust was accurately collected at the sampling points. The relationship between the dilution rate and distance was calculated on the basis of on-road test results using the following equation: DR = 21.4X1.16. This equation can be used for modeling purposes, especially in comparisons of model results and observations and in the evaluation of dispersion models.

Polycyclic aromatic hydrocarbon (PAH) and nitro-polycyclic aromatic hydrocarbon (NPAH) emissions from 18 diesel trucks of different sizes and with different emission standards were tested in Beijing using a portable emission measurement system (PEMS). Both the gaseous- and particulate-phase PAHs and NPAHs were quantified by high-performance liquid chromatography (HPLC) in the laboratory. The emission factors (EFs) of the total PAHs from light-duty diesel trucks (LDDTs), medium-duty diesel trucks (MDDTs) and heavy-duty diesel trucks (HDDTs) were 82229.11 ± 41906.06, 52867.43 ± 18946.47 and 93837.35 ± 32193.14 μg/km, respectively, much higher than the respective values of total NPAHs from their counterpart vehicles. The gaseous phase had an important contribution to the total PAHs and NPAHs, with a share rate of approximately 69% and 97% on average, respectively. The driving cycle had important impacts on the emissions of PAHs and NPAHs, especially for LDDTs and HDDTs. Higher emissions of PAHs and NPAHs were detected on non-highway roads compared to that on highways for these two types of vehicles. Compared to the results of different studies, the difference in the EFs of PAHs and NPAHs can reach several orders of magnitudes, which would introduce errors in the development of an emission inventory of PAHs and NPAHs.

The concentrations and characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in 48 oil samples randomly collected from 30 catering services that employ six cooking methods were quantified via high-performance liquid chromatography (HPLC). These 16 PAHs were detected in almost all of the samples. The levels of Σ16PAHs, Σ4PAHs, benzo[a]pyrene (BaP), and total BaP equivalents (ΣBaPeq) for the six cooking methods exceeded the legal limit. The concentrations of Σ4PAHs were approximately 9.5 to 16.4 times the legal limit proposed by the European Commission (Off J Eur Union 215:4-8, 2011), and the level of BaP exceeded the national standard in China by 4.7- to 10.6-fold, particularly in oil from fried foods. Low molecular weight PAHs (LMW PAHs) were predominant in fried food oil from different catering services and accounted for 94.8 % of these oils, and the ΣBaPeq of the high molecular weight PAHs (HMW PAHs) was 11.5-fold higher than that of the LMW PAHs. The concentrations of Σ16PAHs (3751.9-7585.8 μg/kg), Σ4PAHs (144.6-195.7 μg/kg), BaP (79.7-135.8 μg/kg), and ΣBaPeq (231.0-265.4 μg/kg) were highest in the samples from fast food restaurants/buffets (FB), followed by those from fried food stalls (FS) and then cooking restaurants/cafeterias (RC). The results of this study suggest that the government should strengthen control and supervision of PAH contamination in food and edible oils.

Changes in the 16 PAHs in rapeseed, soybean, peanut and olive oil during deep-frying were examined to evaluate PAH levels in edible oils and the effects of deep-frying time. Chicken nuggets and potatoes were deep-fried in four types of oil for 15, 30 and 45 min. PAH concentrations were quantified via high-performance liquid chromatography (HPLC). The results show that all four fresh (unused) edible oils contain PAHs (189.9–2754.8 μg/kg) and mainly low-ring (2- to 4-ring) PAHs. PAH concentrations in the edible oils increased with increasing deep-frying time, especially among the high-ring (5-ring and above) PAHs. The mean values of high-ring PAHs (5-ring and above) in the samples deep-fried for 45 min were 1.9-fold higher than the oil samples that were deep-fried for 15 min and 31.5-fold higher than the levels for the fresh oils. The mean concentrations of benzo[a]pyrene in the deep-fried peanut and olive oils were 6.1- and 5.2-fold, respectively, the control value established in China (10 μg/kg). Average levels of ∑4PAH (consisting of benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) for the two deep-fried oils also exceeded the maximum permitted limit (10 μg/kg) set by the European Union (9.2- and 6.8-fold higher, respectively). At present, regulations imposed in China limit only concentrations of benzo[a]pyrene. The results of this study show that more standards and regulations on PAHs in edible oils must be established. In addition, the repeated use of edible oils must be avoided.

With the increasingly strict supervision of road mobile sources and the ongoing progress in research, the relative contribution of non-road mobile sources to the total emissions has grown in prominence. Therefore, accurately estimating the emissions from non-road mobile sources is essential to developing effective policies for improving air quality. Hence, this study established an inventory of nine air pollutants, viz., CO, NOx, HC, PM2.5, PM10, BC, OC, VOCs, and SO2, emitted by four types of non-road mobile sources, viz., construction machinery, agricultural machinery, vessels, and diesel locomotives, in China for the period 1990–2017. These emissions increased continually from 1990 till 2014, after which they decreased before increasing again during 2017. With the exception of SO2, which primarily originated from vessels, agricultural machinery accounted for the largest proportion of emissions for all of the pollutants, contributing 67.7% (1472.5 Gg) and 46.1% (2170.4 Gg) of the total CO and NOx from non-road mobile sources, respectively. Additionally, the spatial distribution of the investigated pollutants revealed high concentrations on the North China Plain and in the Southeast China coastal area. Our findings demonstrate the necessity of improving the registration system for non-road mobile sources as well as the urgency of obtaining accurate emission factors for them by further researching their emission characteristics.

The development of efficient materials and processes is a long-term goal for the integrated flue gas purification in industry. In this study, a large-size V-based catalytic filter (L3000 mm &times, &Phi, 150 mm) was prepared by loading the catalyst emulsion into a blank filter, which demonstrated excellent performance for simultaneously removing NOx, SOx and dust. The laboratory investigation found that the small catalytic particles, high catalyst loading and low face velocity could improve the DeNOx efficiency, and above 80% NO conversion could be achieved in the temperature range of 250&ndash, 400 &deg, C on the condition of &lt, 300 nm catalytic particle size, &gt, 7.41 wt % catalyst loading and &lt, 1.00 Nm/min face velocity. The negative effect of SO2/H2O was only observed below 300 &deg, C, and the dust had little negative effects on DeNOx efficiency except for the increase of pressure drop. Moreover, a 90-day industrial test of 2380 catalytic filters over 100,000 Nm3/h of flue gas (0.50 Nm/min) from a glass kiln demonstrated that the removal efficiency of both NOx and SOx could be maintained above 95% with great stability at 320&ndash, 350 &deg, C, and 99% dust could be removed with a pressure drop of less than 1.40 KPa. The results reported herein indicate the promising application prospect of large-size V-based catalytic filters for integrated flue gas purification in industry.

This work assessed the effects of biodiesel on carbonyl emissions from diesel trucks. Biodiesel converted from waste cooking oil was employed and mixed with commercial fossil diesel to produce four blends: B0 (pure conventional diesel fuel), B5 (5% v/v biodiesel), B20 (20% v/v biodiesel) and B100 (pure biodiesel). Four diesel trucks were tested under real-world conditions using a portable emissions measurement system, including one China III light-duty diesel truck (LDDT), one China IV LDDT, one China III heavy-duty diesel truck (HDDT) and one China IV HDDT. A driving cycle including highway (HW) and non-highway (NHW) driving conditions was employed and carbonyls were sampled using 2,4-dinitrophenylhydrazine cartridges and analyzed via high performance liquid chromatography. Seven carbonyl compounds were detected, and formaldehyde, acetaldehyde, acetone and butyraldehyde were the primary carbonyls. Total carbonyl emissions from the China III LDDT, China III HDDT and China IV HDDT vehicles with selective catalytic reduction decreased monotonically with increases in the biodiesel proportion, while the China IV LDDT with a particle oxidation catalyst system showed an increasing trend. With increases in the biodiesel proportions, complementary variations were observed in the proportions of formaldehyde and butyraldehyde obtained using the China III LDDT, China IV LDDT and China III HDDT vehicles. However, in the case of the China IV HDDT trials, the formaldehyde and acetaldehyde emissions exhibited complementary variations. Under different driving conditions, the effects of adding biodiesel on carbonyl emission factors were different. In China III LDDT trials, biodiesel reduced carbonyl emissions to a greater extent under HW conditions, but the opposite occurred in China III HDDT tests. Using the China IV LDDT vehicle, the emission factors did not increase as much during HW trials compared with NHW trials when the B5 and B20 fuels were used, but were significantly higher than the NHW values when pure biodiesel was employed. In China III LDDT data, the proportions of formaldehyde, acetaldehyde and butyraldehyde showed opposite variations under the two driving conditions. Using the China IV LDDT vehicle, a significant increase in formaldehyde and decrease in butyraldehyde were found during HW trials, but not NHW trials. Ozone formation potentials were obtained from carbonyls emission factors using the maximum incremental reactivity method and their variations were similar to those of the carbonyl emission factors.

A considerable amount of volatile organic compounds (VOCs) is emitted, and a vast amount of citric acid residue (CAR) waste is simultaneously produced during citric acid production. Thus, a suitable method realizing the clean production of citric acid must be developed. This study investigated the adsorption of the multicomponent VOCs in a homemade CAR waste-based activated carbon (CAR-AC). A fixed-bed experimental setup was used to explore the adsorption and desorption of single- and multi-component VOCs. Surface adsorption and diffusion molecular models with different defects were built to study the underlying adsorption and diffusion mechanisms of multicomponent VOCs on CAR-AC. The adsorption amount of ethyl acetate in CAR-AC from multicomponent VOCs was 3.04 and 5.91 times higher than those of acetone and acetaldehyde, respectively, and the interaction energy between ethyl acetate and C surfaces was low at −13.41 kcal/mol. During desorption, the most weakly adsorbed acetaldehyde desorbed from the surface of CAR-AC first, followed by acetone and ethyl acetate. The regeneration efficiencies of acetaldehyde, acetone, and ethyl acetate reached 88.77, 85.55, and 91.46 %, respectively, after four adsorption/desorption cycles. We aimed to provide a new strategy to realize the recycle use of CAR and the clean production of citric acid.

The polycyclic aromatic hydrocarbon (PAH) and nitro-polycyclic aromatic hydrocarbon (NPAH) emissions from 16 gasoline passenger cars, encompassing five emission standards and two driving conditions, were tested using a portable emission measurement system (PEMS) in Beijing under on-road conditions. In total, 16 PAHs and 9 NPAHs were quantified in both the gaseous and particulate phases by high-performance liquid chromatography (HPLC). The results indicated that lower PAH and NPAH emissions were observed with improved emission standards, especially for China 3 to China 5 vehicles (P 0.05). Higher emission factors (EFs) were detected on nonhighway roads than on highway roads due to incomplete combustion. Although most PAHs and NPAHs were in the gas-phase, the TEQ

This study is the third in a series of three papers aimed at characterizing the VOC emissions of vehicles in Beijing. In this study, 30 light-duty vehicles fueled with gasoline were evaluated using a portable emission measurement system (PEMS) as they were driven on a predesigned, fixed test route. All of the tested vehicles were rented from private vehicle owners and spanned regulatory compliance guidelines ranging from Pre-China I to China IV. Alkanes, alkenes, aromatics and some additional species in the exhaust were collected in Tedlar bags and analyzed using gas chromatography/mass spectrometry (GC–MS). Carbonyls were collected on 2,4-dinitrophenyhydrazine (DNPH) cartridges and analyzed using high-performance liquid chromatography (HPLC). Overall, 74 VOC species were detected from the tested vehicles, including 22 alkanes, 6 alkenes, 1 alkyne, 16 aromatics, 3 cyclanes, 10 halohydrocarbons, 12 carbonyls and 4 other compounds. Alkanes, aromatics and carbonyls were the dominant VOCs with weight percentages of approximately 36.4%, 33.1% and 17.4%, respectively. The average VOC emission factors and standard deviations of the Pre-China I, China I, China II, China III and China IV vehicles were 469.3 ± 200.1, 80.7 ± 46.1, 56.8 ± 37.4, 25.6 ± 11.7 and 14.9 ± 8.2 mg/km, respectively, which indicated that the VOC emissions significantly decreased under stricter vehicular emission standards. Driving cycles also influenced the VOC emissions from the tested vehicles. The average VOC emission factors based on the travel distances of the tested vehicles under urban driving cycles were greater than those under highway driving cycles. In addition, we calculated the ozone formation potential (OFP) using the maximum incremental reactivity (MIR) method. The results of this study will be helpful for understanding the true emission levels of light-duty gasoline vehicles and will provide information for controlling VOC emissions from vehicles in Beijing, China.

To mitigate NOx and other emissions from diesel vehicles, China I, China II, China III and China IV emissions standards for new vehicles have been implemented nationwide. However, recent on-road measurements using a portable emission measurement system (PEMS) have revealed no significant reductions in the NOx emissions factors of diesel trucks due to the change from China II emissions standards to the more stringent China III standards. Thus, it is important to understand the effect of the China IV emissions standard on NOx emissions. In this study, nine China III and nine China IV diesel trucks of three sizes (light-duty diesel trucks (LDDTs), medium-duty diesel trucks (MDDTs) and heavy-duty diesel trucks (HDDTs)) were tested on real roads in Beijing using a PEMS. Compared to the tested China III diesel trucks, the China IV diesel trucks showed significant reductions of the average NOx emissions factors in terms of both distance travelled and fuel consumption. However, the driving conditions had an important impact on the reduction. Under non-highway driving (NHD), several of the tested China IV diesel trucks experienced no reduction or an increase in NOx emissions compared to their China III counterparts. The NOx emissions factors of the 18 tested diesel trucks under NHD were on average 1.5-times greater than those under highway driving (HD), and the effects on NOx emissions removal from China III to China IV diesel trucks were greater under HD than under NHD. In addition, no significant reduction of NOx based on fuel consumption for China IV diesel trucks was observed for MDDTs and HDDTs compared to the test results for similar China II vehicles reported in a previous study. To reduce NOx emissions in China, additional control measures of vehicular NOx emissions should be formulated.

Heavy-duty diesel trucks (HDDTs) are gaining more attention because of their contribution to NOX and PM2.5 emissions. To evaluate their contribution to ambient fine particulate matter (PM2.5), not only their emission factors, but also their source profile is required. We conducted on-road emissions tests to characterize the PM2.5 emission, documenting per second mass emission rates from in-use HDDTs in China, using portable emissions measurement systems. The average PM2.5 emission factors for pre-EURO and EURO 1 HDDTs were 1.104 g/km and 0.822 g/km, equivalent to 6.106 g/kg and 3.132 g/kg based on fuel consumption. Element carbon (EC) and organic carbon (OC) were the major components: EC accounted for 45–65% of PM2.5 for pre-EURO HDDTs and 36–69% for EURO 1 HDDTs, while the OC fraction for pre-EURO and EURO 1 HDDTs ranged from 20 to 31% and 19–31%, respectively. Thus, the average EC emission factors for pre-EURO and EURO 1 HDDTs were 0.667 g/km and 0.502 g/km, showing that implementation of tighter emission standards resulted in a 25% EC output reduction from pre-EURO to EURO 1 vehicles. Sulfate, comprising about 1% of PM2.5 mass, is still an abundant species in PM2.5 from HDDTs because of the high sulfur content in diesel fuel in China. Using these data, we updated national PM2.5 emission profiles for pre-EURO and EURO 1 HDDTs.

Fine particulate matter (PM2.5) has attracted increasing attention due to its impacts on air quality and human health. As an important source of PM2.5, diesel vehicles are often the focus of research. In this study, we characterized the carbonaceous composition of PM2.5 that is emitted from on-road China III diesel trucks (DTs). Organic carbon (OC), elemental carbon (EC), and PM2.5 emission characteristics were determined for 17 China III DTs, including 6 light-duty diesel trucks (LDDTs), 5 medium-duty diesel trucks (MDDTs), and 6 heavy-duty diesel trucks (HDDTs), based on real-world measurements in Beijing, China, using a portable emissions measurement system (PEMS). The average distance-based PM2.5 emission factors (EFs) (g km−1) generally increased and the average CO2-based PM2.5 EFs (g (kg of CO2)−1) generally decreased with increased vehicle size from LDDTs to MDDTs to HDDTs. The effects of driving conditions on the EFs for carbonaceous PM2.5 were analyzed. The results show that distance-based and CO2-based EFs strongly depend on driving conditions. Generally, greater amounts of PM2.5 and OC are emitted from non-highway driving cycles, and greater amounts of EC are emitted from highway driving cycles for vehicles of the same size. For LDDTs, MDDTs, and HDDTs, no significant differences were observed between vehicles with different EC/OC ratios; therefore, the EC/OC ratio is not useful for distinguishing between the emissions generated by differently sized vehicles. The EC/OC, OC/PM2.5, and EC/PM2.5 mass ratios are strongly dependent on driving conditions for vehicles of the same size. The results of this study provide EFs for the carbonaceous composition of PM2.5 that are more appropriate for China; these results will be helpful for improving policies that are designed to control the carbonaceous composition of PM2.5 emitted from on-road DTs in China.

Cooking fumes are an important indoor source of polycyclic aromatic hydrocarbons (PAHs). Because indoor pollution has a more substantial impact on human health than outdoor pollution, PAHs from cooking fumes have drawn considerable attention. In this study, 16 PAHs emitted through deep-frying and frying methods using rapeseed, soybean, peanut, and olive oil were examined under a laboratory fume hood. Controlled experiments were conducted to collect gas- and particulate-phase PAHs emitted from the cooking oil fumes, and PAH concentrations were quantified via high-performance liquid chromatography (HPLC). The results show that deep-frying methods generate more PAHs and benzo[a]pyrene (B[a]P) (1.3 and 10.9 times, respectively) because they consume greater volumes of edible oil and involve higher oil temperatures relative to those of frying methods. In addition, the total B[a]Peq concentration of deep-frying is 2.2-fold larger than that of frying. Regarding the four types of edible oils studied, rapeseed oil produced more PAH emission than the other three oil varieties. For all of the cooking tests, three- and four-ringed PAHs were the main PAH components regardless of the food and oil used. Concerning the PAH partition between gas and particulate phase, the gaseous compounds accounted for 59-96 % of the total. Meanwhile, the particulate fraction was richer of high molecular weight PAHs (five-six rings). Deep-frying and frying were confirmed as important sources of PAH pollution in internal environments. The results of this study provide additional insights into the polluting features of PAHs produced via cooking activities in indoor environments.

A database of real-world diesel vehicle emission factors, based on type and technology, has been developed following tests on more than 300 diesel vehicles in China using a portable emission measurement system. The database provides better understanding of diesel vehicle emissions under actual driving conditions. We found that although new regulations have reduced real-world emission levels of diesel trucks and buses significantly for most pollutants in China, NOx emissions have been inadequately controlled by the current standards, especially for diesel buses, because of bad driving conditions in the real world. We also compared the emission factors in the database with those calculated by emission factor models and used in inventory studies. The emission factors derived from COPERT (Computer Programmer to calculate Emissions from Road Transport) and MOBILE may both underestimate real emission factors, whereas the updated COPERT and PART5 (Highway Vehicle Particulate Emission Modeling Software) models may overestimate emission factors in China. Real-world measurement results and emission factors used in recent emission inventory studies are inconsistent, which has led to inaccurate estimates of emissions from diesel trucks and buses over recent years. This suggests that emission factors derived from European or US-based models will not truly represent real-world emissions in China. Therefore, it is useful and necessary to conduct systematic real-world measurements of vehicle emissions in China in order to obtain the optimum inputs for emission inventory models.

This paper is the second in a series of papers aimed at understanding volatile organic compound (VOC) emissions from motor vehicles in Beijing using on-board emission measurements, focusing specifically on rural vehicles (RVs). In this work, 13 RVs, including 6 different 3-wheel (3-W) RVs and 7 different 4-wheel (4-W) RVs, were examined using a portable emissions measurement system (PEMS) as the vehicles were driven on predesigned fixed test routes in rural areas of Beijing. Overall, 50 VOC species were quantified in this study, including 18 alkanes, 5 alkenes, 11 aromatics, 13 carbonyls and 3 other compounds. The average emission factor (EF) of the total VOCs for the 4-W RVs based on the distance traveled was 326.2 ± 129.3 mg/km, which is 2.5 times greater than that of the 3-W RVs. However, the VOC emissions for the 3-W RVs had higher EFs based on their CO2 emissions due to the different fuel economies of the two types of RVs. Formaldehyde, toluene, acetaldehyde, m-xylene, p-xylene, isopentane, benzene, ethylbenzene, n-pentane, 2-methoxy-2-methylpropane and butenal were the dominant VOC species from the RVs, accounting for an average of 68.6% of the total VOC emissions. Overall, the RVs had high proportions of aromatics and carbonyls. The ozone formation potentials (OFPs) were 670.6 ± 227.2 and 1454.1 ± 643.0 mg O3/km for the 3-W and 4-W RVs, respectively, and approximately 60%–70% of the OFP resulted from carbonyls. We estimated that the 3-W and 4-W RVs accounted for approximately 50% and 10%, respectively, of the total OFP caused by diesel vehicles (including diesel trucks and RVs) in Beijing in 2012. Thus, more attention should be given to VOC emissions and their impact on ozone formation.

This paper is the first in our series of papers aimed at understanding the volatile organic compound (VOC) emissions of vehicles in Beijing by conducting on-board emission measurements. This paper focuses on diesel vehicles. In this work, 18 China III diesel vehicles, including seven light-duty diesel trucks (LDDTs), four medium-duty diesel trucks (MDDTs) and seven heavy-duty diesel trucks (HDDTs), were examined when the vehicles were driven on predesigned fixed test routes in Beijing in China using a portable emissions measurement system (PEMS). Tedlar bag sampling and 2,4-dinitrophenyhydrazine (DNPH) cartridge sampling were used to collect VOC species, and gas chromatography-mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC) were used to analyze these samples. We obtained the VOC emission factors and relative compositions for diesel trucks of different sizes under different driving patterns. In total, 64 VOC species were quantified in this study, including 25 alkanes, four alkenes, 13 aromatics, 13 carbonyls and nine other compounds. The emission factors of the total VOCs based on mileage traveled for HDDTs were higher than those of LDDTs and MDDTs. Carbonyls, aromatics and alkanes were the dominant VOC species. Carbonyls accounted for 42.7%–69.2% of the total VOCs in the three types of tested diesel trucks. The total VOC emission factors of the tested vehicles that were driven on non-highway routes were 1.5–2.0 times higher than those of the vehicles driven on the highway. As for the OFP calculation results, with increased vehicle size, the ozone formation potential presented an increasing trend. Among the VOC components, carbonyls were the primary contributor to OFP. In addition, the OFPs under non-highway driving cycles were 1.3–1.7 times those under highway driving cycles. The results of this study will be helpful in improving our understanding of VOCs emitted from on-road diesel trucks in China.

To study the emission characteristics of carbonyl compounds for in-use diesel vehicles on real roads, nine in-use heavy-duty diesel trucks (HDDTs) representing different emission standards from China 0 to China 3 were tested on roads in Xiamen using an on-board carbonyl compound sampling system with a 2,4-DNPH cartridge. High-performance liquid chromatography (HPLC) was used to quantify the carbonyl compound emission factors. In total, 10 carbonyl compounds were detected for all the tested vehicles in this work. Formaldehyde, acetaldehyde and propanal were the three largest contributors of carbonyl emissions, accounting for 47.9%, 21.0% and 9.9% of the total carbonyls, respectively. The emission standards had a significant effect on the emission factors and profiles of the carbonyl compounds from the test vehicles. The total emissions of carbonyls from the test vehicles with China 0, China 1, China 2 and China 3 emission standards were 318.4, 232.8, 108.1 and 88.8 mg/km, respectively. The relative contribution of formaldehyde to the total carbonyl emissions increased with increasing stringency of the emission standards. Driving patterns also affected the vehicular carbonyl emissions. The total carbonyl emissions under highway driving cycles were lower than those under non-highway driving cycles. In addition, the ozone-formation potential of the carbonyls from the tested diesel vehicles was analyzed. This work represents a preliminary step in measuring carbonyl emission characteristics using portable emission measurement systems (PEMS). More attention should be paid to carbonyl emissions from HDDTs.

This study is the first in a series of papers that aim to develop high-resolution emission databases for different anthropogenic sources in China. Here we focus on on-road transportation. Because of the increasing impact of on-road transportation on regional air quality, developing an accurate and high-resolution vehicle emission inventory is important for both the research community and air quality management. This work proposes a new inventory methodology to improve the spatial and temporal accuracy and resolution of vehicle emissions in China. We calculate, for the first time, the monthly vehicle emissions for 2008 in 2364 counties (an administrative unit one level lower than city) by developing a set of approaches to estimate vehicle stock and monthly emission factors at county-level, and technology distribution at provincial level. We then introduce allocation weights for the vehicle kilometers traveled to assign the county-level emissions onto 0.05° × 0.05° grids based on the China Digital Road-network Map (CDRM). The new methodology overcomes the common shortcomings of previous inventory methods, including neglecting the geographical differences between key parameters and using surrogates that are weakly related to vehicle activities to allocate vehicle emissions. The new method has great advantages over previous methods in depicting the spatial distribution characteristics of vehicle activities and emissions. This work provides a better understanding of the spatial representation of vehicle emissions in China and can benefit both air quality modeling and management with improved spatial accuracy.

To alleviate air pollution and lessen the petroleum demand from the motor vehicle sector in China, natural gas vehicles (NGVs) have been rapidly developed over the last several years. However, the understanding of the real-world emissions of NGVs is very limited. In this study, the emissions from 20 compressed-natural-gas-fueled bi-fuel taxis were measured using a portable emission measurement system (PEMS) under actual driving conditions in Yichang, China. The emission characteristics of the tested vehicles were analyzed, revealing that the average CO2, CO, HC and NOx emissions from the tested compressed-natural-gas (CNG) taxis under urban driving conditions were 1.6, 4.0, 2.0 and 0.98 times those under highway road conditions, respectively. The CO, HC and NOx emissions from Euro 3 CNG vehicles were approximately 40%, 55% and 44% lower than those from Euro 2 vehicles, respectively. Compared with the values for light-duty gasoline vehicles reported in the literature, the CO2 and CO emissions from the tested CNG taxis were clearly lower; however, significant increases in the HC and NOx emissions were observed. Finally, we normalized the emissions under the actual driving cycles of the entire test route to the New European Driving Cycle (NEDC)-based emissions using a VSP modes method developed by North Carolina State University. The simulated NEDC-based CO emissions from the tested CNG taxis were better than the corresponding emissions standards, whereas the simulated NEDC-based HC and NOx emissions greatly exceeded the standards. Thus, more attention should be paid to the emissions from CNG vehicles. As for the CNG-fueled bi-fuel taxis currently in use, the department of environmental protection should strengthen their inspection and supervision to reduce the emissions from these vehicles. The results of this study will be helpful in understanding and controlling emissions from CNG-fueled bi-fuel vehicles in China.

As stricter standards for diesel vehicles are implemented in China, and the use of diesel trucks is forbidden in urban areas, determining the contribution of light-duty gasoline vehicles (LDGVs) to on-road PM2.5 emissions in cities is important. Additionally, in terms of particle number and size, particulates emitted from LDGVs have a greater health impact than particulates emitted from diesel vehicles. In this work, we measured PM2.5 emissions from 20 LDGVs in Beijing, using an improved combined on-board emission measurement system. We compared these measurements with those reported in previous studies, and estimated the contribution of LDGVs to on-road PM2.5 emissions in Beijing. The results show that the PM2.5 emission factors for LDGVs, complying with European Emission Standards Euro-0 through Euro-4 were: 117.4 ± 142, 24.1 ± 20.4, 4.85 ± 7.86, 0.99 ± 1.32, 0.17 ± 0.15 mg/km, respectively. Our results show a significant decline in emissions with improving vehicle technology. However, this trend is not reflected in recent emission inventory studies. The daytime contributions of LDGVs to PM2.5 emissions on highways, arterials, residential roads, and within urban areas of Beijing were 44%, 62%, 57%, and 57%, respectively. The contribution of LDGVs to PM2.5 emissions varied both for different road types and for different times.

The Guangzhou government adopted many vehicle emission control policies and strategies during the five-year preparation (2005–2009) to host the 2010 Asian Games. This study established a multi-year emission inventory for vehicles in Guangzhou during 2005–2009 and estimated the uncertainty in total vehicle emissions by taking the assumed uncertainties in fleet-average emission factors and annual mileage into account. In 2009, the estimated total vehicle emissions in Guangzhou were 313 000 (242 000–387 000) tons of CO, 60 900 (54 000–70 200) tons of THC, 65 600 (56 800–74 100) tons of NOx and 2740 (2100–3400) tons of PM10. Vehicle emissions within the urban area of Guangzhou were estimated to be responsible for ∼40% of total gaseous pollutants and ∼25% of total PM10 in the entire city. Although vehicle use intensity increased rapidly in Guangzhou during 2005–2009, vehicle emissions were estimated to have been reduced by 12% for CO, 21% for THC and 20% for PM10 relative to those in 2005. NOx emissions were estimated to have remained almost constant during this period. Compared to the “without control” scenario, 19% (15%–23%) of CO, 20% (18%–23%) of THC, 9% (8%–10%) of NOx and 16% (12%–20%) of PM10 were estimated to have been mitigated from a combination of the implementation of Euro III standards for light-duty vehicles (LDVs) and heavy-duty diesel vehicles and improvement of fuel quality. This study also evaluated several enhanced vehicle emission control actions taken recently. For example, the enhanced I/M program for LDVs was estimated to reduce 11% (9%–14%) of CO, 9% (8%–10%) of THC and 2% (2%–3%) of NOx relative to total vehicle emissions in 2009. Total emission reductions by temporary traffic controls for the Asian Games were estimated equivalent to 9% (7%–11%) of CO, 9% (8%–10%) of THC, 5% (5%–6%) of NOx and 10% (8%–13%) of PM10 estimated total vehicle emissions in 2009. Those controls are essential to further vehicle emission mitigation in Guangzhou required by the new National Ambient Air Quality Standards.

This paper estimates the energy consumption and CO2 emissions from China’s urban passenger transportation sector up to year 2030. A “bottom-up” methodology is developed to estimate the emissions based upon passenger travel behaviors in cities, which is notably different from popular existing approaches that calculate emissions from vehicular population. This methodology enables policy analysts to (1) quantify how different urban development strategies and patterns would affect about CO2 emissions; (2) directly link behavioral changes with urban development patterns and policies; and (3) analyze and understand the sensitivities of the urban passenger transportation sector in responding to both national- and city-level policies for carbon mitigation, thus helping the policy evaluation and development. Detailed information regarding urban passenger travels are collected in grouped Chinese cities of six categories. With the newly developed methodology, total carbon emissions from China’s urban passenger transportation sector under three scenarios are considered. The results showed that mode choice changes are the most sensitive to policies. Promoting public transportation and limiting car usage can contribute 21% of the total energy reduction of China’s transportation sector in 2030. Enhancing the above by optimizing street network and urban form, this contribution can be doubled in size.

This paper, which focuses on diesel trucks, is the third in a series of three papers published in Atmospheric Environment to understand vehicle emissions in China by conducting on-board emission measurements. Diesel trucks are a significant source of emissions in ambient air, especially for NOx. Recently, China announces an aggressive target to reduce national NOx emissions by 10% from 2010 to 2015 in the “Twelfth Five-Year Plan (2011–2015)” and diesel vehicles are identified as a key target for NOx control. However, the understanding of the real-world emissions of diesel trucks is limited. In this study, we measured HC, CO, NOx, and PM 2.5 emissions from 175 diesel trucks of different sizes and technologies in five Chinese cities during 2007 and 2011, and generated emission factors on the basis of the measurements. The results show that the HC, CO, and PM 2.5 emission factors have been reduced significantly as the emission standards become more stringent from Euro 0 to Euro IV, but the NOx emission factors change differently. Euro II trucks have 3–6% higher NOx emission levels than Euro I technologies and Euro III trucks fail to show a reduction as regulated by the standards. More stringent NOx requirements (e.g. Euro IV) for diesel vehicles need to be enforced. The comparison with the emission factors used in recent emission inventory studies shows that these inventories may have overestimated or underestimated diesel emissions for the years after 2006. This study emphasizes the importance of conducting local measurement research to improve the accuracy of the estimates of mobile emissions in China.

Vehicle-use intensity (kilometers traveled per vehicle per year or VKT) is important because it directly affects simulation results for vehicle fuel use and emissions, but the poor understanding of VKT in China could significantly affect the accuracy of estimation of total fuel use and CO2 emissions, and thus impair precise evaluation of the effects of associated energy and environmental policies. As an important component of our work on the Fuel Economy and Environmental Impacts (FEEI) model, we collected VKT survey data in China from available sources and conducted additional surveys during 2004 and 2010, from which we derived VKT values and VKT-age functions by vehicle type for China. We also projected the future VKT for China by examining the relationship of vehicle use to per-capita GDP in 20 other countries worldwide. The purpose of this work is to achieve a better understanding of vehicle-use intensity in China and to generate reliable VKT input (current and future VKT levels) for the FEEI model. The VKT results obtained from this work could also benefit other work in the field associated with vehicle energy use and emissions.

One of the principal ways to reduce transport-related energy use is to reduce fuel-consumption rates of motor vehicles (usually measured in liters of fuel per 100 km). Since 2004, China has implemented policies to improve vehicle technologies and lower the fuel-consumption rates of individual vehicles. Policy evaluation requires accurate and adequate information on vehicle fuel-consumption rates. However, such information, especially for Chinese vehicles under real-world operating conditions, is rarely available from official sources in China. For each vehicle type we first review the vehicle technologies and fuel-economy policies currently in place in China and their impacts. We then derive real-world (or on-road) fuel-consumption rates on the basis of information collected from various sources. We estimate that the real-world fuel-consumption rates of vehicles in China sold in 2009 are 9 L/100 km for light-duty passenger vehicles, 11.4 L/100 km for light-duty trucks, 22 L/100 km for inter-city transport buses, 40 L/100 km for urban transit buses, and 24.9 L/100 km for heavy-duty trucks. These results aid in understanding the levels of fuel consumption of existing Chinese vehicle fleets and the effectiveness of policies in reducing on-road fuel consumption, which can help in designing and evaluating future vehicle energy-efficiency policies.

This paper is the second in a series of three papers aimed at understanding the emissions of vehicles in China by conducting on-board emission measurements. This paper focuses on light-duty gasoline vehicles. In this study, we measured 57 light-duty gasoline vehicles (LDGVs) in three Chinese mega-cites (Beijing, Guangzhou, and Shenzhen), covering Euro 0 through Euro IV technologies, and generated CO, HC, and NOx emission factors and deterioration rates for each vehicle technology. The results show that the vehicle emission standards have played a significant role in reducing vehicle emission levels in China. The vehicle emission factors are reduced by 47–81%, 53–64%, 46–71%, and 78–82% for each phase from Euro I to Euro IV. Euro 0 vehicles have a considerably high emission level, which is hundreds of times larger than that of Euro IV vehicles. Three old taxis and four other Euro I and Euro II LDGVs are also identified as super emitters with equivalent emission levels to Euro 0 vehicles. Of the measured fleet, 23% super emitters were estimated to contribute 50–80% to total emissions. Besides vehicle emission standards, measures for restricting super emitters are equally important to reduce vehicle emissions. This study is intended to improve the understanding of the vehicle emission levels in China, but some key issues such as emission deterioration rates are yet to be addressed with the presence of a sufficient amount of vehicle emission measurements.

Recently, China has implemented many policy measures to control the oil demand of on-road vehicles. In 2010, China started to report the fuel consumption rates of light-duty vehicles tested in laboratory and to require new vehicles to show the rates on window labels. In this study, we examined the differences between the test and real-world fuel consumption of Chinese passenger cars by using the data reported by real-world drivers on the internet voluntarily. The sales-weighted average fuel consumption of new cars in China in 2009 was 7.80 L/100 km in laboratory and 9.02 L/100 km in real-world, representing a difference of 15.5%. For the 153 individual car models examined, the real-world fuel consumption rates were −8 to 60% different from the test values. The simulation results of the International Vehicle Emission model show that the real-world driving cycles in 22 selected Chinese cities could result in −8 to 34% of changes in fuel consumption compared to the laboratory driving cycle. Further government effort on fuel consumption estimates adjustment, local driving cycle development, and real-world data accumulation through communication with the public is needed to improve the accuracy of the labeling policy.

We propose a method to simulate vehicle emissions in Chinese cities of different sizes and development stages. Twenty two cities are examined in this study. The target year is 2007. Among the cities, the vehicle emission factors were remarkably different (the highest is 50–90% higher than the lowest) owing to their distinct local features and vehicle technology levels, and the major contributors to total vehicle emissions were also different. A substantial increase in vehicle emissions is foreseeable unless stronger measures are implemented because the benefit of current policies can be quickly offset by the vehicle growth. Major efforts should be focused on all cities, especially developing cities where the requirements are lenient. This work aims a better understanding of vehicle emissions in all types of Chinese cities. The proposed method could benefit national emission inventory studies in improving accuracy and help in designing national and local policies for vehicle emission control.

Rural vehicles (RVs) could contribute significantly to air pollutant emissions throughout Asia due to their considerable population, extensive usage, and high emission rates, but their emissions have not been measured before and have become a major concern for the accuracy of regional and global emission inventories. In this study, we measured CO, HC, NOx and PM emissions of RVs using a combined on- board emission measurement system on real roads in China. We also compared the emission levels of the twenty RVs to those of nineteen Euro II light-duty diesel trucks (LDDTs) that we measured for previous studies. The results show that one-cylinder RVs have lower distance-based emission factors compared to LDDTs because of their smaller weight and engine power, but they have significantly higher fuel-based PM emission factors than LDDTs. Four-cylinder RVs have equivalent emission levels to LDDTs. Based on the emission factors and the activity data obtained, we estimate that the total emissions of RVs in China in 2006 were 1049 Gg of CO, 332 Gg of HC, 933 Gg of NOx, and 54 Gg of PM, contributing over 40% to national on-road diesel CO, NOx, and PM emissions. As RVs are a significant contributor to national emissions, further research work is needed to improve the accuracy of inventories at all levels, and the government should strengthen the management of RVs to facilitate both policy making and research work.

Three lab-scale horizontal subsurface flow constructed wetlands (HSSF CWs) were installed to demonstrate the use of constructed wetlands as a viable low-cost treatment option to purify the polluted scenery water. The goals of this study were to determine the effectiveness of the wetland treatment technology in reducing contaminants in polluted natural water body and to characterize bacterial composition present in 3 constructed wetlands. Water samples were collected periodically for 12 months from three wetlands to determine the efficiency of the treatment system in removal of chemical pollutants. The reduction by the treatment was greatest for chemical oxygen demand (COD), total nitrogen and total phosphorus, but the removal of nutrients obviously varied with seasons. Plant uptake was highly responsible for nitrogen and phosphorus removal. Denaturing gradient gel electrophoresis (DGGE) was used to study the diversity of microbial community in the constructed wetland. Changes in the total bacterial community and ammonia-oxidizing bacterial composition were examined by DGGE and sequencing of polymerase chain reaction (PCR)-amplified fragments of the gene carrying the ammonia monooxygenase subunit A gene (amoA) recovered from matrix samples and DGGE bands. DGGE analysis of wetlands samples revealed that seasonal change had an effect on the diversity and composition of microbial communities in constructed wetlands. The sequence analysis showed ammonia-oxidizing bacteria (AOB) in constructed wetlands were uncultivable and the population of AOB had a higher percentage of Nitrosomonas-like sequences from wetlands, while no Nitrosospira-like sequences were found.

Current driving cycles used in China are not able to accurately assess vehicle emissions due to their inadequate representation of real-world driving. We in this study analyzed the driving characteristics and developed the driving cycles in Chinese cities, then compared them to the European test cycle and the American Federal Test Procedure. Eleven cities were selected, covering different city sizes and geographical locations. Car chasing technique was employed in each city to collect speed-time data on freeways, arterials, and residential roads during traffic peak and non-peak periods. The data collected were adjusted by the traffic adjustment factors to reflect the overall traffic. Eleven driving parameters were used to characterize driving characteristics and develop driving cycles. The results indicate that city size, local road infrastructure, and driving behavior are the most important factors that lead to the significant differences in vehicle driving patterns among the cities. The comparison with the European and US cycles suggests that the emission factors produced from the European or US cycles-based tests could be significantly different than those from the driving cycles in China.

As stricter standards for diesel vehicles are implemented in China, and the use of diesel trucks is forbidden in urban areas, determining the contribution of light-duty gasoline vehicles (LDGVs) to on-road PM2.5 emissions in cities is important. Additionally, in terms of particle number and size, particulates emitted from LDGVs have a greater health impact than particulates emitted from diesel vehicles. In this work, we measured PM2.5 emissions from 20 LDGVs in Beijing, using an improved combined on-board emission measurement system. We compared these measurements with those reported in previous studies, and estimated the contribution of LDGVs to on-road PM2.5 emissions in Beijing. The results show that the PM2.5 emission factors for LDGVs, complying with European Emission Standards Euro-0 through Euro-4 were: 117.4 ± 142, 24.1 ± 20.4, 4.85 ± 7.86, 0.99 ± 1.32, 0.17 ± 0.15 mg/km, respectively. Our results show a significant decline in emissions with improving vehicle technology. However, this trend is not reflected in recent emission inventory studies. The daytime contributions of LDGVs to PM2.5 emissions on highways, arterials, residential roads, and within urban areas of Beijing were 44%, 62%, 57%, and 57%, respectively. The contribution of LDGVs to PM2.5 emissions varied both for different road types and for different times.

This study is the first in a series of papers that aim to develop high-resolution emission databases for different anthropogenic sources in China. Here we focus on on-road transportation. Because of the increasing impact of on-road transportation on regional air quality, developing an accurate and high-resolution vehicle emission inventory is important for both the research community and air quality management. This work proposes a new inventory methodology to improve the spatial and temporal accuracy and resolution of vehicle emissions in China. We calculate, for the first time, the monthly vehicle emissions (CO, NMHC, NOx, and PM2.5) for 2008 in 2364 counties (an administrative unit one level lower than city) by developing a set of approaches to estimate vehicle stock and monthly emission factors at county-level, and technology distribution at provincial level. We then introduce allocation weights for the vehicle kilometers traveled to assign the county-level emissions onto 0.05° × 0.05° grids based on the China Digital Road-network Map (CDRM). The new methodology overcomes the common shortcomings of previous inventory methods, including neglecting the geographical differences between key parameters and using surrogates that are weakly related to vehicle activities to allocate vehicle emissions. The new method has great advantages over previous methods in depicting the spatial distribution characteristics of vehicle activities and emissions. This work provides a better understanding of the spatial representation of vehicle emissions in China and can benefit both air quality modeling and management with improved spatial accuracy.

To guarantee good traffic and air quality during the 16th Asian Games in Guangzhou, China, the government carried out two traffic control Drills before the Games and adopted traffic control measures during the Games. Vehicle activities before and during the first and second Drills, and during the Games, were surveyed. Based on the data under investigation, the impacts of control measures on traffic volumes and driving characteristics were analyzed during the first and second Drills, and the Games. The emission reduction of traffic control measures was also evaluated during the three stages using the MOBILE-China model. The results show that there were significant effects of implementing temporary traffic control measures on transportation activity and vehicular emissions. During the first and second Drills, and the Games, the average traffic volumes in monitored roads decreased, and the average speed of vehicles increased significantly The co-effects of traffic flow reduction, traffic congestion improvement, and the banning of high-emitting vehicles helped to greatly reduce the estimated emissions from motor vehicles in Guangzhou during the first and second Drills, and the Games. Estimated vehicular emissions were reduced by 38-52% during the first Drill and 28-36% for the second Drill. During the Asian Games, vehicular emissions of carbon monoxide (CO), hydrocarbon (HC), oxides of nitrogen (NO), and particulate matter with an aerodynamic diameter10 microm (PM10) reduced by an estimated 42%, 46%, 26%, and 30%, respectively, compared with those before the Games. Both the banning of high-emitting vehicles and the travel restrictions imposed by use of odd-even licenses had significant effects on the reduction of vehicular emissions of CO, HC, NOx, and PM10.Motor vehicles have become the most prevalent source of emissions and subsequently air pollution within Chinese cities. Understanding the impacts that different control measures have on vehicular emissions is very important in order to be able to control vehicle emissions. The results of this study will be very helpful for the further control of vehicle emissions in Guangzhou in the future. In addition, the effects of temporary transportation control measures will provide important awareness to other cities that will be hosting large-scale activities similar to the Asian Games.

We propose a new link-based, bottom-up vehicle emission inventory method for Chinese cities using available on-road emission measurement data and activity survey data. This study uses Beijing as a case study and focuses on CO, HC, and NOx emissions from hot-stabilized activities of light-duty vehicles. The target year is 2004. The total quantity of emissions, emission intensity, temporal distribution of emissions by hour, and spatial distribution of emissions at 1 km x 1 km resolution are presented and compared with results from other inventory methods commonly used in China. The results show that the total emissions from light-duty vehicles in the Beijing urban area in 2004 were 1141 Mg of CO per day, 48 Mg of HC per day, and 32 Mg of NOx per day. Pollutant emissions from mobile sources show temporal and spatial variation trends that are consistent with the characteristics of people's activities. The inventory developed in this study reflects the influences of vehicle driving patterns in traffic on vehicle emissions on a road link basis, and it could be used to evaluate the impacts of traffic-related emission control measures in China.

On-board emission measurements were performed on 49 light-duty gasoline vehicles in seven cities of China. Vehicle-specific power mode distribution and emission characteristics were analyzed based on the data collected. The results of our study show that there were significant differences in different types of roads. The emission factors and fuel consumption rates on arterial roads and residential roads were approximately 1.4-2 times those on freeways. The carbon monoxide, hydrocarbon, and nitrogen oxides emission factors of Euro II vehicles were on average 86.2, 88.2, and 64.5% lower than those of carburetor vehicles, respectively. The new vehicle emission standards implemented in China had played an important role in reducing individual vehicle emissions. More comprehensive measures need to be considered to reduce the total amount of emissions from vehicles.

[1] A rapid increase of NO2 columns over China has been observed by satellite instruments in recent years. We present a 10-a regional trend of NOx emissions in China from 1995 to 2004 using a bottom-up methodology and compare the emission trends with the NO2 column trends observed from GOME and SCIAMACHY, the two spaceborne instruments. We use a dynamic methodology to reflect the dramatic change in China's NOx emissions caused by energy growth and technology renewal. We use a scenario analysis approach to identify the possible sources of uncertainties in the current bottom-up inventory, in comparison with the satellite observation data. Our best estimates for China's NOx emissions are 10.9 Tg in 1995 and 18.6 Tg in 2004, increasing by 70% during the period considered. NOx emissions and satellite-based NO2 columns show broad agreement in temporal evolution and spatial distribution. Both the emission inventory data and the satellite observations indicate a continuous and accelerating growth rate between 1996 and 2004 over east central China. However, the growth rate from the emission inventory is lower than that from the satellite observations. From 1996 to 2004, NOx emissions over the region increased by 61% according to the inventory, while a 95% increase in the NO2 columns measured by satellite was observed during the same period. We found good agreement during summertime but a large discrepancy during wintertime. The consistency between the summertime trends suggests that the bias cannot be due to systematic error of activity data or emission factors. The reasons for the discrepancy cannot yet be fully identified, but possible explanations include an underestimation in seasonal emission variations, variability of meteorology, NOx injection height, and the increasing trend of sulfate aerosols.

Researches are made to find out the active tracing measurement strategy of crankshaft roundness error during noncircular grinding process. This paper makes a detailed study on the tracing motion equations of the measurement system. Aiming at the request of three sensors' linear dependence in frequency-domain analysis, this paper also describes the constraint condition of uniform sampling. For improve the in-situ measurement precision, the three-sensor tracing principle of roundness error separation (TTPRES) is proposed under motion stage. Furthermore, the method for avoiding harmonic suppression by adjusting the installation angles of three sensors is discussed. Finally, the data processed by error separating are calculated using Least Square Method (LSM), and contrasted the compute result with the measurement result of Roundness Measuring Instrument. The experiment proves the validity of in-situ tracing measurement strategy of crankshaft roundness error during noncircular grinding process.

The assembly line can be regarded as a system consisted of complex disperse events considering the assembly process exists not only time sequence relations but also parallel and competitive relation. This article investigates the methods of modeling the product assembly line system based on information of assembly process flow, combined with the requirement that the auto electrical machine assembly should be adopted to multi-production, and the materiel flow and information flow change complicatedly in product assembly line, the system model of auto electrical machine assembly line is set up based on Petri net. The structure configurations and dynamic properties of the system are investigated by intuitionistic graphics format using Petri net. The operation performance of the system through reachability method is analyzed to optimize the system ensuring the key actions and the pivotal resources. Heuristic scheduling arithmetic is put forward and the emulation results are presented, the auto electrical machine assembly line recombining construction and optimization is achieved. The methods proved to be feasible and effective through the practice run of the product line.