Spatial-temporal evolution characteristics of PM2.5 and its driving mechanism: spatially explicit insights from Shanxi Province, China.

In China, despite the fact that the atmospheric environment quality has continued to improve in recent years, the PM2.5 pollution still had not been controlled fundamentally and its driving mechanism was complex which remained to be explored. Based on the 1-km ground-level PM2.5 datasets of China from 2000 to 2020, this study combined spatial autocorrelation, trend analysis, geographical detector, and multi-scale geographically weighted regression (MGWR) model to explore the spatial-temporal evolution of PM2.5 in Shanxi Province and revealed its complex driving mechanism behind this process. The results reflected that (1) there was a pronounced spatial clustering of PM2.5 concentration within Shanxi Province, with PM2.5 concentrations decreasing from southwest to northeast. From 2000 to 2020, the levels of PM2.5 pollution demonstrated a decline over time, with its concentrations decreasing by 9.15 µg/m3 overall. The Hurst exponent indicated a projected decrease in PM2.5 concentrations in the central and northern areas of Shanxi Province, contrasting with an anticipated increase in other regions. (2) The geographical detector indicated that all drivers had significant influences on PM2.5 concentrations, with meteorological factors exerting the greatest effects then followed by human activity and vegetation cover showing the least effects. (3) Both gross domestic product and population density exhibited positive correlations with PM2.5 concentration, while vegetation fractional cover, wind speed, precipitation, and elevation exerted negative influences on PM2.5 concentration all over the space. This study enriched the research content and ideas on the driving mechanism of PM2.5 and provided a reference for similar studies.

The impacts of ship emissions on ozone in eastern China.

Tropospheric ozone (O3), which is one of the main pollutants impeding air quality compliance, has received considerable attention in China. As maritime transportation continues to expand, the effect of ship emissions on air quality is becoming increasingly important. In this study, the Weather Research and Forecast model (WRF), the Community Multiscale Air Quality model (CMAQ), and the integrated process rate (IPR) module provided in the CMAQ are applied to evaluate the impacts of ship emissions on O3 concentration at a national scale in China, including the spatiotemporal characteristics and influencing pathways. Ship emissions can increase or decrease O3 concentrations, with varying effects in different seasons and regions. In the winter, spring, and fall, ship emissions were predicted to decrease O3 concentrations in most areas, whereas in the summer, they increase the O3 concentration, even in regions far away from the coastline, thus adversely affecting the Yangtze River Delta (YRD) and Pearl River Delta (YRD). Additionally, owing to differences in the emissions of volatile organic compounds and nitrogen oxides, the northern and southern regions of the YRD respond differently to ship emissions. Additionally, the influence of ship emissions on the diurnal variation of O3 in the summer was investigated, where significant differences were indicated between cities. The IPR was used to investigate the individual processes contributing to changes in the O3 concentration caused by ship emissions. The transport process appears to be the primary contributor to O3 production, whereas chemistry and dry deposition played key roles in O3 loss. This study provides an in-depth insight into the impacts of ship emissions on O3 in China, which can facilitate the formulation of corresponding environmental policies.

Improving Dispersion of Carbon Nanotubes in Natural Rubber by Using Waterjet-Produced Rubber Powder as a Carrier.

Carbon nanotube (CNT), as reinforcing agents in natural rubber (NR), has gained a large amount of consideration due to their excellent properties. Uniform dispersion of CNT is the key to obtaining high-performance NR nanocomposites. In this contribution, a novel ultrasonic grinding dispersion method of CNT with waterjet-produced rubber powder (WPRP) as a carrier is proposed. Microscopic morphologies show that a Xanthium-like structure with WPRP as the core and CNTs as the spikes is formed, which significantly improves the dispersion of CNT in the NR matrix and simultaneously strengthens the bonding of the WPRP and NR matrix. With the increase in the WPRP loading, the Payne effect of CNT/WPRP/NR composites decreases, indicating the effectiveness of the dispersion method. The vulcanization MH and ML value and crosslinking density increase with the increase in the WPRP loading, whereas the scorch time and cure time exhibit a decreasing trend when the WPRP loading is less than 15 phr. It is found that the CNT/WPRP/NR composites filled with 5 phr WPRP have a 4% increase in 300% modulus, a 3% increase in tensile strength, while a 5% decrease in Akron abrasion loss, compared to CNT/NR composites.

Recycling of Flexible Polyurethane Foams by Regrinding Scraps into Powder to Replace Polyol for Re-Foaming.

In the context of protecting the ecological environment and carbon neutrality, high-value recycling of flexible polyurethane foam (F-PUF) scraps, generated in the production process, is of great significance to save petroleum raw materials and reduce energy consumption. In the present study, F-PUF scraps were ground into powder by strong shear regrinding using two-roll mill and then reused as a partial replacement of polyol for re-foaming. A series of characterizations were employed to investigate the effect of milling cycles, roller temperatures, and content of the powder on the properties of the powder and F-PUF containing powder. It was revealed that the mechanochemical effect induced breaking of the cross-linking structure and increased activity of the powder. The volume mean diameter (VMD) of powder prepared with 7 milling cycles, at room temperature, is about 97.73 µm. The microstructure and density of the F-PUF containing powder prepared in the above-mentioned manner to replace up to 15 wt.% polyol, is similar to the original F-PUF, with resilience 49.08% and compression set 7.8%, which indicates that the recycling method will play an important role in industrial applications.

Synergistic effect of reductions in multiple gaseous precursors on secondary inorganic aerosols in winter under a meteorology-based redistributed daily NH3 emission inventory within the Beijing-Tianjin-Hebei region, China.

Secondary inorganic aerosols (SIA) account for 20-60% of the total fine particulates in the Beijing-Tianjin-Hebei (BTH) region of China, indicating an urgent need to clarify the relationship among such compounds. The purpose of this study was to quantify the relationship between emissions of NH3, NOx, SO2, VOCs and SIA concentrations during a severe winter haze episode using an air quality model and a meteorology-based redistributed NH3 emission inventory within the BTH region. The results showed that the model performance regarding the NH3 simulations in January by the four emission inventories improved after the redistribution of daily NH3 emissions, with an increase of 0.02-0.13 in R, a 9-56% decrease in NMB, and a 7-51% decrease in NME. The updated simulations reproduced the daily observations of SIA, SO2, and NO2 well. A total of 125 sets of sensitivity simulations showed that a synergistic reduction in NH3 and VOCs was more efficient in terms of SIA control than simply reducing SO2 or NOx in the BTH region. If only NOx emissions were reduced, the SIA concentration would first increase and then decrease, and it could decline by another 0.86-8.03% in parallel with an equal NH3 emission cut. SIA could be reduced by approximately 22.68% with the most stringent inorganic precursors' control. Moreover, VOCs emission reductions could lead to a decrease in SIA, and the impact of VOCs on SIA was similar to that of NH3. The collaborative control of both inorganic precursors and VOCs was more effective than single-factor control measures for decreasing SIA, and the decline rate was approximately 29.26% under minimum emission conditions. This improved effectiveness was obtained because VOCs mitigation effectively decreases the ozone concentration, which in turn influences SIA formation. Finally, on the premise of a 60% SO2 cut, the reduction scheme NH3:VOCs:NOx = 4:4:1 was suggested for SIA control.

Low-Temperature Mechano-Chemical Rubber Reclamation Using Terpinene as a Swelling Agent to Enhance Bond-Breaking Selectivity.

Common swelling agents used in the mechano-chemical rubber devulcanization process usually require high temperatures to achieve satisfactory swelling effects, which results in severe production of pollutants and reduces the selectivity of bond scissions. This work presents an environmentally friendly swelling agent, terpinene, which can swell the rubber crosslink structures at low temperatures. Both a rubber swelling experiment and a rubber reclaiming experiment with a mechano-chemical devulcanization method are conducted to explore the swelling effects of terpinene. After soaking in terpinene at 60 °C for 90 min, the length elongation of the rubber sample reaches 1.55, which is much higher than that in naphthenic oil and is comparable to that in toluene. When adding 3 phr of terpinene for every 100 phr of waste rubber during the reclaiming process, the bond scissions exhibit high selectivity. After revulcanization, the reclaimed rubbers have a tensile strength of 17 MPa and a breaking elongation of 400%. Consequently, the application of terpinene as the swelling agent in the LTMD method can greatly improve the properties of reclaimed rubbers, thereby enhancing the dual value for the economy and environment.

Agricultural ammonia emissions and its impact on PM2.5 concentrations in the Beijing-Tianjin-Hebei region from 2000 to 2018.

Ammonia (NH3) discharged from agricultural activities to the atmosphere plays a crucial role in the formation of secondary inorganic aerosols. This study analyzed the temporal-spatial development of agricultural NH3 emissions from 2000 to 2018 in the Beijing-Tianjin-Hebei (BTH) region and assessed the effects of reducing PM2.5 by removing agricultural NH3 using an air quality model. The results showed that the interannual agricultural NH3 emissions in the BTH region exhibited a stairs trend from 2000 to 2018, with an average of 971.63 Gg. In particular, agricultural NH3 emissions in the BTH region reached a maximum in summer when the temperature was high and were more concentrated in the southern plains compared to the northern areas. Under the reduction scenario (RS), the agricultural NH3 emissions in the BTH region in 2015, 2016, 2017, and 2018 were reduced by 2.95%, 4.10%, 18.75%, and 10.21%, resulting in a reduction of 0.5%, 0.5%, 2.5%, and 1.2% of annual mean PM2.5 concentration, respectively, compared with the baseline scenario (BS). Furthermore, agricultural NH3 emissions contributed 12.6, 12.1, 11.9, and 11.3 µg m-3 to PM2.5 concentrations in 2015, 2016, 2017, and 2018 under the zero-emission scenario (ZS), respectively. However, the contribution rates exhibited a slightly increasing trend from 20.5% in 2015 to 24.6% in 2018. These findings could provide a new understanding of agricultural NH3 emission trends and their impacts on PM2.5 concentration based on actual NH3 mitigation ratios in recent years, thereby guiding the formulation of future control strategies.

Prediction and mitigation potential of anthropogenic ammonia emissions within the Beijing-Tianjin-Hebei region, China.

Large ammonia (NH3) emissions contribute approximately 8-30% to the fine particle pollution in China and highlight the need for understanding the emission trends and mitigation effects of NH3 in the future. The purpose of this study is to predict the NH3 emissions and analyze the mitigation potential up to year 2040 by scenario analysis based on the established new NH3 emission inventory from anthropogenic sources for the Beijing-Tianjin-Hebei (BTH) region. The results showed that the total NH3 emission in the BTH region was estimated at 966.14 Gg in 2016. Under the Business-as-Usual (BAU) scenario, the total NH3 emissions in 2030 and 2040 would increase by 13% and 26% compared with 2016 levels, with average annual growth rates of 0.9% and 1.0%, respectively. Livestock will continue to dominate NH3 emissions in the future, with the proportions of total emissions increasing from 57% in 2016 to 64% in 2030 and 68% in 2040. The share of the second-largest NH3 emission source, synthetic fertilizer application, will decrease from 36% in 2016 to 31% in 2030 and 27% in 2040. Among five other sources, the largest change occurred in waste disposal, increasing notably by 3.31 times from 2016 to 2040 owing to rapid urbanization. Under the Combined Options (CO) scenario, the total NH3 emissions could be reduced by as much as 34% by 2030 and 50% by 2040 compared with the BAU scenario, which is attributed to livestock (24% in 2030, 37% in 2040) and synthetic fertilizer application (10% in 2030, 13% in 2040), respectively. This study can give a reliable estimation of anthropogenic NH3 emission in the BTH region during 2020-2040 and provide a valuable reference for effective mitigation measures and control strategies for policy makers.

Estimation and prediction of pollutant emissions from agricultural and construction diesel machinery in the Beijing-Tianjin-Hebei (BTH) region, China☆.

Both agricultural and construction machinery are important non-road sources of atmospheric pollution, with total hydrocarbons (THC), nitrogen oxides (NOx) and particulate matter (PM) emissions accounting for more than 60% of the total emissions from all non-road mobile sources in China. However, there exist relatively few efforts to establish the emission inventory for these machineries. This study attempted to estimate and predict air pollutant emissions from agricultural and construction diesel machinery, using the Beijing-Tianjin-Hebei (BTH) region as the case study area. The results show that total emissions of PM10, PM2.5, THC, NOX, CO and SO2 in 2015 were 41.10, 38.80, 86.14, 520.41, 379.01 and 17.32 Kt respectively. The contribution of agricultural machinery was slightly higher than that of construction machinery, accounting for 60-71% of the total. Moreover, emissions of various pollutants (except SO2) from agricultural machinery were mainly distributed in central Hebei (Cangzhou, Shijiazhuang and Baoding), while emissions from construction machinery were mainly distributed in Beijing and Tianjin. The prediction suggest that the total emissions of agricultural and construction diesel machinery in the BTH region would increase by 6% in 2020 and 9% in 2025. Moreover, pollutant emissions from construction machinery would contribute from 29% to 40% in 2015 to 34%-61% in 2025. These results could provide important information for making effective mitigation measures of non-road mobile sources.

The impact of ship emissions on nitrogen and sulfur deposition in China.

A large amount of NOX and SO2 emitted from ships may elevate atmospheric N and S and eventually aggravate the deposition of N and S. The understanding of N and S deposition due to ship emissions is still limited, especially for China because it has a long coastline, busy shipping routes, and several large ports. To fill this gap, a comprehensive air quality model was employed in this study to quantify the contributions of ship emissions to N and S deposition on a national scale in China. Both the spatial and temporal variations of N and S deposition, as well as the major N and S species from ship traffic, were investigated. The results indicate that ship emissions contributed significantly to the deposition of N and S, especially in coastal and offshore areas, where the largest ship contribution to both N and S deposition could exceed 15 kg·ha-1·yr-1. For N deposition, ship emissions caused an increase in the total N deposition, not only in port areas and along shipping routes but also far inland, with evident seasonal variations. The contribution from dry N deposition was evidently larger than wet N deposition, especially over the coastal areas. S deposition, however, was generally higher along shipping routes but exhibited distinct seasonal variations. The total S deposition was dominated by dry deposition, especially over offshore areas. Ship-caused dry S deposition occurred mainly in offshore areas, while wet S deposition could be found over wider inland regions and inland waterways, although with a markedly smaller magnitude.

[Emission Characteristics and Ozone Formation Potential of VOCs in Printing Enterprises in Beijing-Tianjin-Hebei].

In this study, 23 typical printing enterprises were selected in Beijing-Tianjin-Hebei. Through gas chromatography-mass spectrometry/flame ionization detection (GC-MS/FID), 46 sets of analysis results were obtained to quantitatively analyze the emissions characteristics of volatile organic compounds (VOCs) and the ozone generation potential of these printing enterprises. The results show that the emission concentrations of total VOCs (TVOCs) in exhaust funnels of the printing enterprises varied greatly, ranging from 3.3 mg·m-3 to 755.0 mg·m-3. In the printing stations of printing enterprises, the emission concentrations of VOCs were 129.7-958.4 mg·m-3 and 19.1-113.7 mg·m-3 in packaging and printing enterprises and publications printing enterprises, respectively. The concentration of VOCs emitted by packaging and printing enterprises was significantly higher than that of publications printing enterprises, which is related to the use of solvent-based inks. In terms of VOC composition, oxygen-containing VOCs were the primary type of those emitted by the printing station of packaging and printing enterprises and publications printing enterprises, which accounted for a ratio of 32.6%-99.4%, followed by alkanes. In terms of ozone generation potential, the average of ozone formation potential (OFP) of the printing enterprises was 505.5 mg·m-3, in which the packaging and printing enterprises was 564.1 mg·m-3, and the publication printing enterprises was 52.9 mg·m-3. The average VOC source reactivity (SR) emitted from the printing process was 1.24 g·g-1; that is, 1.24 g of O3 was formed owing to the unit mass of VOC emission, of which the packaging and printing enterprises was 1.70 g·g-1, and the publication printing enterprises was 0.89 g·g-1. According to the OFP and SR, the use of environmentally friendly ink can reduce the generation of O3 and promote air quality improvement.

The impact of ship emissions on PM2.5 and the deposition of nitrogen and sulfur in Yangtze River Delta, China.

Ship emissions contribute significantly to the deterioration of air quality, while their impacts on ambient PM2.5 and depositions have not been comprehensively evaluated. This is especially true for China because it has a long coastline, busy shipping routes and many large ports. To fill this gap, this study applied the SMOKE/WRF/CMAQ modeling system to quantifying the impacts of ships on PM2.5 compositions, annual and seasonal contribution to PM2.5 as well as the wet and dry deposition of nitrogen and sulfur compounds over the land areas in YRD region for 2014. The results showed that 4.0% of annual PM2.5 concentrations over the land areas could be explained by ship emissions and the largest contribution could reach up to 35.0% in port areas. Temporally, the contribution to PM2.5 exhibited an obviously seasonal variation. The highest contribution was predicted in autumn (6.2%), followed by summer (5.4%), spring (3.6%) and winter (1.2%) for the land areas. Spatially, the contribution reached up to 13.6% along the coastline and dropped to 2.1% 300 km inland. As for the impacts on PM2.5 components, the primary components were relatively small and increased mainly along the shipping routes and the Yangtze River, whereas the secondary components played a more important role in both water and land areas. The sulfur deposition due to ship emissions was occurred generally along the shipping routes and was dominated by the dry SO2 deposition. The nitrogen depositions, on the contrary, was observed not only along the shipping routes but also extend to wide land areas. Further investigation revealed that ship emissions have caused an evident increase of dry nitrogen deposition in NO2 and HNO3, while a slight decrease in NH3 over YRD region. These results indicated that comprehensive regulations of ship emissions are required considering their adverse effects on the ambient concentration of PM2.5 and the deposition of sulfur and nitrogen.

Air quality improvement and health benefit of PM2.5 reduction from the coal cap policy in the Beijing-Tianjin-Hebei (BTH) region, China.

Large amounts of air pollutants emitted from massive coal combustion result in the air quality deterioration and threaten public health in China. To improve air quality, the Chinese government released the coal cap policy to reduce coal consumption. So it is important and necessary to understand the possible environmental impact and relevant health benefits from the coal cap policy. The purpose of this paper is to quantify the air quality improvement and to evaluate the health benefits from the implementation of the coal cap policy, with the Beijing-Tianjin-Hebei (BTH) region as the study area. The results showed that the emissions of SO2, NOx, CO, VOCs, PM10, and PM2.5 could be reduced by 20-40% in the BTH region in 2020 and all pollutants from industrial boilers notably decreased. Under the coal cap policy, the PM2.5 concentration in the whole region would fall by 11.27%, and the total economic benefit from health impacts could achieve 26.61 (13.29 to 39.14) billion RMB (3.9 billion USD) in the BTH region in 2020, accounting for 0.43% (0.21 to 0.63%) of regional GDP in 2013. This study demonstrated the quantification of environmental effect and health benefit from the coal cap policy, which could be used for the complete cost-benefit analysis and provide the sufficient support for policy makers to implement the coal cap policy in the BTH region and other areas of China.

Prediction of reduction potential of pollutant emissions under the coal cap policy in BTH region, China.

The coal cap policy is one of the most important measures to address the severe air pollution in China. To quantify the impact of the coal cap policy on emissions reduction, we designed four scenarios to predict the effect of energy saving and pollutant emissions reduction from coal-fired stationary sources in the BTH (Beijing-Tianjin-Hebei) region from 2014 to 2030. The results demonstrated that the coal cap strategy would significantly affect energy consumption structure and result in 15% of energy savings in 2020 and 25% in 2030. Moreover, the reduction potential of main pollutants from stationary coal combustion sources would achieve 36-45% in 2020 and 60-79% in 2030 relative to BAU (Business As Usual). For the whole BTH region the BPE (Backward Productivity Elimination) scenario could get a better effect for SO2 and NOX than CES (Clean Energy Strategy) scenario, while the effect is opposite for CO and PM2.5, and similar for VOCs and PM10. For Beijing, there would be very significant reduction for all pollutants under the CES scenario. For Tianjin and Hebei, there is little difference in the pollutants reduction between the BPE and CES scenarios. Power plants and industrial boilers are major contributors under the BPE scenario, and emissions from the heating boilers and residential sources are greatly reduced under the CES scenario. The findings in this study are of considerable value for the policymakers to implementing the coal cap policy in BTH region and other Chinese cities.

[Impact of the Electric Power Industry on Air Quality in Winter of Urban Agglomerations Along the Middle Reaches of the Yangtze River].

A WRF-CAMx-PSAT model was applied to analyze the impact of the electric power industry on urban agglomerations along the middle reaches of the Yangtze River. A high-resolution emission inventory based on a bottom-up approach was developed for air quality simulation. A typical month with heavy air pollution in this region (i.e., January) was chosen for simulation, and two mitigation scenarios were set for assessing lower capacity power units' impact on regional air quality. One scenario was for shutting down the lower capacity power units, and the other was for replacing lower capacity power units with higher capacity power units. Results showed that lower capacity power units contributed bigger pollutant concentrations to the regional contribution of the electric power industry. The concentration contributions of SO2, NOx, and PM2.5 in the two mitigation scenarios were reduced by 36.2%-39.8%、30.5%-33.5%, and 25.9%-30.7%, respectively, than those under the current situation. Meanwhile, the decreases in pollutant concentration contribution for different regions were very similar for the two mitigation scenarios. In addition, lower capacity power units in four regions (i.e., northwest of Hubei province, west of Hunan province, Xiang-Jing-Yi economic belt region, and Hefei-centered urban agglomerations) contributed obviously to the regional pollutant concentration contributions of the electric power industry. Regional pollutant concentration contributions in the two mitigation scenarios were reduced by 40%-70%. Therefore, lower capacity power units make a bigger impact on the air quality of urban agglomerations along the middle reaches of the Yangtze River and should be paid special attention to achieve better regional air quality.

Contribution of ship emissions to the concentration of PM2.5: A comprehensive study using AIS data and WRF/Chem model in Bohai Rim Region, China.

Compared with on-road vehicles, emission from ships is one of the least-regulated anthropogenic emission sources and non-negligible source of primary aerosols and gas-phase precursors of PM2.5. The Bohai Rim Region in China hosts dozens of large ports, two of which ranked among the top ten ports in the world. To determine the impact of ship emissions on the PM2.5 concentrations over this region, two parts of works have been conducted in this study. First, a detailed ship emission inventory with high spatiotemporal resolution was developed based on Automatic Identification System (AIS) data. Then the WRF/Chem model was applied to modeling the impact of ship emissions by comparing two scenarios: with and without ship emissions. The results indicate that the total estimated ship emissions of SO2, NOX, PM10, PM2.5, CO, HC, and CO2 from Bohai Rim Region in 2014 are 1.9×105, 2.9×105, 2.6×104, 2.4×104, 2.5×104, 1.2×104, and 1.3×107tonnes, respectively. The modeling results indicate that the annual PM2.5 concentrations increased by 5.9% on land areas of Bohai Rim Region (the continent within 115.2°E-124.3°E and 36.1°N-41.6°N) due to ship emissions. The contributions show distinctive seasonal variations of contributions, presenting highest in summer (12.5%) followed by spring (6.9%) and autumn (3.3%), and lowest in winter (0.9%). The contribution reaches up to 10.7% along the shoreline and down to 1.0% 200km inland. After examining the statistics of the modeling results during heavy and non-heavy haze days in July, it was found that 6 out of 9 cities around the Bohai Rim Region were observed with higher contributions from ship emissions during heavy haze days compared with non-heavy haze days. These results indicate that the impacts of ship emissions on the ambient PM2.5 are non-negligible, especially for heavy haze days for most coastal cities in the Bohai Rim Region.

High-spatiotemporal-resolution ship emission inventory of China based on AIS data in 2014.

Ship exhaust emissions have been considered a significant source of air pollution, with adverse impacts on the global climate and human health. China, as one of the largest shipping countries, has long been in great need of in-depth analysis of ship emissions. This study for the first time developed a comprehensive national-scale ship emission inventory with 0.005°×0.005° resolution in China for 2014, using the bottom-up method based on Automatic Identification System (AIS) data of the full year of 2014. The emission estimation involved 166,546 unique vessels observed from over 15billion AIS reports, covering OGVs (ocean-going vessels), CVs (coastal vessels) and RVs (river vessels). Results show that the total estimated ship emissions for China in 2014 were 1.1937×106t (SO2), 2.2084×106t (NOX), 1.807×105t (PM10), 1.665×105t (PM2.5), 1.116×105t (HC), 2.419×105t (CO), and 7.843×107t (CO2, excluding RVs), respectively. OGVs were the main emission contributors, with proportions of 47%-74% of the emission totals for different species. Vessel type with the most emissions was container (~43.6%), followed by bulk carrier (~17.5%), oil tanker (~5.7%) and fishing ship (~4.9%). Monthly variations showed that emissions from transport vessels had a low point in February, while fishing ship presented two emission peaks in May and September. In terms of port clusters, ship emissions in BSA (Bohai Sea Area), YRD (Yangtze River Delta) and PRD (Pearl River Delta) accounted for ~13%, ~28% and ~17%, respectively, of the total emissions in China. On the contrast, the average emission intensities in PRD were the highest, followed by the YRD and BSA regions. The establishment of this high-spatiotemporal-resolution ship emission inventory fills the gap of national-scale ship emission inventory of China, and the corresponding ship emission characteristics are expected to provide certain reference significance for the management and control of the ship emissions.

Investigating the contribution of shipping emissions to atmospheric PM2.5 using a combined source apportionment approach.

Many studies have been conducted focusing on the contribution of land emission sources to PM2.5 in China; however, little attention had been paid to other contributions, especially the secondary contributions from shipping emissions to atmospheric PM2.5. In this study, a combined source apportionment approach, including principle component analysis (PCA) and WRF-CMAQ simulation, was applied to identify both primary and secondary contributions from ships to atmospheric PM2.5. An intensive PM2.5 observation was conducted from April 2014 to January 2015 in Qinhuangdao, which was close to the largest energy output port of China. The chemical components analysis results showed that the primary component was the major contributor to PM2.5, with proportions of 48.3%, 48.9%, 55.1% and 55.4% in spring, summer, autumn and winter, respectively. The secondary component contributed higher fractions in summer (48.2%) and winter (36.8%), but had lower percentages in spring (30.1%) and autumn (32.7%). The hybrid source apportionment results indicated that the secondary contribution (SC) of shipping emissions to PM2.5 could not be ignored. The annual average SC was 2.7%, which was comparable to the primary contribution (2.9%). The SC was higher in summer (5.3%), but lower in winter (1.1%). The primary contributions to atmospheric PM2.5 were 3.0%, 2.5%, 3.4% and 2.7% in spring, summer, autumn and winter, respectively. As for the detailed chemical components, the contributions of shipping emissions were 2.3%, 0.5%, 0.1%, 1.0%, 1.7% and 0.1% to elements & sea salt, primary organic aerosol (POA), element carbon (EC), nitrate, sulfate and secondary organic carbon (SOA), respectively. The results of this study will further the understanding of the implications of shipping emissions in PM2.5 pollution.

Estimating the contribution of regional transport to PM2.5 air pollution in a rural area on the North China Plain.

PM2.5 air pollution in metropolises as well as some medium-sized cities in the North China Plain have aroused many researchers' interest, but less attention has been paid to the rural areas of this region. In this study, four months of daily PM2.5 samples were collected from a rural site in Lingcheng (a district of Dezhou City in Shandong Province) during different seasons in 2013 and 2014. Analysis of the samples indicates that the PM2.5 air pollution was severe over this area with the four-month average concentration of 105.9µg/m3, three times higher than China's guideline for this pollutant (35µg/m3). In winter, the monthly average concentration was as high as 151.2µg/m3. In order to identify the potential source regions, the Integrated Source Apportionment Method within Community Multiscale Air Quality model (CMAQ-ISAM) was applied during the wintertime. The regional source apportionment results show that local emissions in Lingcheng only contributed 15.4% to PM2.5 concentrations, with 12.6% and 28.1% from its circumjacent areas in Dezhou City and the six surrounding cities, respectively. Regional transport from areas farther away and the boundaries account for 31.6% and 11.1%, respectively. This indicates that the ambient PM2.5 at Lingcheng is not affected only by emissions from local and circumjacent areas; regional and long-range transport should also be considered. Further analysis indicated that with increasing degrees of pollution, the contributions from local and circumjacent regions showed a clear downward trend, while the contributions from northern and southwestern areas, which most of the trajectories passed through during periods of heavy haze, showed an obvious upward trend.

Scenario analysis to vehicular emission reduction in Beijing-Tianjin-Hebei (BTH) region, China.

Motor vehicle emissions are increasingly becoming one of the important factors affecting the urban air quality in China. It is necessary and useful to policy makers to demonstrate the situation given the relevant pollutants reduction measures are taken. This paper predicted the reduction potentials of conventional pollutants (PM10, NOx, CO, HC) under different control strategies and policies in the Beijing-Tianjin-Hebei (BTH) region during 2011-2020. There are the baseline and 5 control scenarios designed, which presented the different current and future possible vehicular emissions control measures. Future population of different kinds of vehicles were predicted based on the Gompertz model, and vehicle kilometers travelled estimated as well. After that, the emissions reduction under the different scenarios during 2011-2020 could be estimated using emission factors and activity level data. The results showed that, the vehicle population in the BTH region would continue to grow up, especially in Tianjin and Hebei. Comparing the different scenarios, emission standards updating scenario would achieve a substantial reduction and keep rising up for all the pollutants, and the scenario of eliminating high-emission vehicles can reduce emissions more effectively in short-term than in long-term, especially in Beijing. Due to the constraints of existing economical and technical level, the reduction effect of promoting new energy vehicles would not be significant, especially given the consideration of their lifetime impact. The reduction effect of population regulation scenario in Beijing cannot be ignorable and would keep going up for PM10, CO and HC, excluding NOx. Under the integrated scenario considering all the control measures it would achieve the maximum reduction potential of emissions, which means to reduce emissions of PM10, NOx, CO, HC, by 56%, 59%, 48%, 52%, respectively, compared to BAU scenario for the whole BTH region in 2020.