[Effects of Meteorological Conditions in Summer and Early Autumn on PM2.5 and O3 Pollution in Beijing-Tianjin-Hebei and Surrounding Areas].

PM2.5 pollution remains prominent in autumn, whereas O3 pollution gradually manifests in summer. To understand the dual high characteristics and meteorological effects of PM2.5 and O3 in the summer and early autumn of 2021 in the Beijing-Tianjin-Hebei and surrounding areas, the spatiotemporal distribution characteristics of PM2.5 and O3 concentrations, as well as meteorological conditions, subtropical high index, and weather situation in the Beijing-Tianjin-Hebei and surrounding areas were analyzed. The results showed that PM2.5 concentration and DPO3 （O3 daily maximum 8h mean minus O3 concentration at 06：00） from June to September 2021 decreased compared with those in the same period in 2020 and 2022, and high concentrations were mainly occurring in June. The overall PM2.5 concentration and DPO3 showed a gradual decrease from the middle to the north and south, with synchronous spatiotemporal changes. The hourly value of PM2.5 concentration presented a multimodal distribution, reaching the peak at 07：00-10：00 and 22：00-24：00. O3 concentration showed an opposite trend of change with PM2.5 concentration, reaching their peak from 14：00-16：00. When DPO3 and the concentration of PM2.5 were high, the characteristics of near-surface meteorological elements were characterized by temperatures ranging from 24.0-28.0℃, relative humidity concentrated at 58.4%-76.3%, and wind speeds ranging from 1.5-3 m·s-1. There was a high lag correlation between the subtropical high index and DPO3. When the subtropical high was farther and stronger from the Beijing-Tianjin-Hebei and surrounding areas, DPO3 was higher. The major weather patterns with both high PM2.5 and O3 concentrations in the study area were near surface low-pressure front, high-pressure type, and frontal type. The high altitude was controlled by high-pressure ridges, and the subtropical high ridge line was stable between 21°-28°N.

Hourly emission amounts and concentration of water-soluble ions in primary particles from residential coal burning in rural northern China.

Residential coal burning (RCB) stands as an important contributor to ambient pollutants in China. For the effective execution of air pollution control policies, it is essential to maintain precise emission inventories of RCB. The absence of hourly emission factors (EFs) combined with the inaccuracies in the spatial-temporal distribution of activity data, constrained the quality of residential coal combustion emission inventories, thereby impeding the estimation of air pollutant emissions. This study revised the hourly EFs for PM2.5 and water-soluble ions (WSIs) emitted from RCB in China. The hourly emission inventories for PM2.5 and WSIs derived from RCB illustrate the diurnal fluctuations in emission patterns. This study found that the emissions of PM2.5, NH4+, Cl-, and SO42- showed similar emission features with emission of 106.8 Gg, 1417.6, 356.8, and 5868.5 ton in erupt period. The results provide basic data for evaluating RCB emission reduction policies, simulating particles, and preventing air pollution in both sub-regions and time periods. The spatial emission and simulated concentration distribution of PM2.5 and WSIs indicated that emission hotspot shifted from North China Plain (NCP) to Northeast region in China. The emissions in China were well-controlled in '2 + 26' region (R28) priority region, with hotspots decreasing by 99.6% in BTH region. The RCB became the dominant contributor to ambient PM2.5 with a ratio in the range of 16.2-23.7% in non-priority region.

[Dual-Perspective Analysis of the Warming Effect of the Methane Emissions from Animal Husbandry in China].

Accurate quantitative evaluation of the greenhouse effects of methane(CH4) is the foundation for developing effective mitigation strategies. This study was the first to quantitatively evaluate the warming effects of the CH4 emissions from animal husbandry in China using the recently proposed climate metric GWP-star(GWP*), which is designed for short-lived climate pollutants(SLCP), and to compare the results with the commonly used climate metric global warming potential(GWP). The results showed:CH4emissions from animal husbandry in China decreased from 957.0×105 t in 2000 to 764.0×105 t. The GWP results showed that the greenhouse effect of CH4 emissions from animal husbandry in China was increasing between 2015 and 2019, and the GWP* results showed that it decreased compared to that 20 years ago. The amount of reduction was equivalent to removing the warming of 2.1×108 t of carbon dioxide. Under the GWP evaluation system, achieving carbon neutrality in the livestock industry in China requires eliminating or offsetting stable annual CH4 emissions from increased carbon sinks. Instead, under the GWP* evaluation system, China's livestock industry could achieve its carbon neutrality in the short term by effectively reducing CH4 emissions by only 0.3% per year. In the case that the livestock industry in China continues to take effective emission reduction measures, the reduction target under the GWP* metric will be reached earlier than that under GWP. Still, the choice of GWP or GWP* requires careful consideration of the objectives of evaluation, the time scale of assessment, and practical operability.

[Emission Inventory of Air pollutants for the Harmless Treatment of Municipal Solid Waste].

In order to comprehensively assess the emission status of air pollutes from domestic waste treatment plants in mainland China, the basic statistical information of 31 provinces and cities in China was systematically collected and collated. The emission factor method was adopted to establish the 2016 list of air pollutants for the harmless treatment of domestic garbage in mainland China. The results showed that in 2016, the total amount of CH4, VOCs, NH3, TSP, PM10, and PM2.5 gaseous pollutants discharged from domestic waste landfills was 3472084.50, 185117.10, 66.45, 54.94, 25.99, and 3.92 t, respectively. The total amount of CH4, SO2, NOx, NH3, VOCs, CO, TSP, PM10,PM2.5, and BC of gaseous pollutants discharged from incineration facilities was 25389.10, 6419.30, 70923.84, 221.36, 435.33, 3025.19, 221.36, 221.36, 2.21, and 2.86 t, respectively. Through the analysis of solid waste treatment sources, partial, and temporal distribution characteristics of air pollutants, and the proportion of incineration plants in the provinces and municipalities to the number of household harmless waste treatment plants, it was determined that the total amount of gaseous pollutants discharged from domestic waste incineration sources and landfill sources had an upward trend during the period 2010-2016. In 2016, domestic landfill treatment was the most important waste treatment method in China, and mainly concentrated in areas with moderate population density and large land resources, such as central and western regions. Domestic waste incineration treatment facilities are mainly concentrated in developed cities in the Yangtze River Delta, Pearl River Delta, and the Beijing-Tianjin-Hebei Region.

Seasonal CH4 and CO2 effluxes in a final covered landfill site in Beijing, China.

As the main solid waste disposal method in China, landfill sites are considerable sources of methane (CH4) and carbon dioxide (CO2). This study characterized the seasonal variation of CH4 and CO2 effluxes at a large and well-managed final covered landfill site in China. A three-year monitoring program was conducted. There were two different seasonal variation patterns for hotspot and non-hotspot' CH4 and CO2 effluxes. For non-hotspots, the CH4 and CO2 effluxes' seasonal variations were mainly affected by the seasonal change of the landfill's cover soil respiration activity, particularly the CH4 oxidation capability. CH4 had a higher efflux in winter; in other seasons, the CH4 efflux fluctuated around 0; the CO2 effluxes were (1) increased in spring and peaked in summer or early autumn; (2) then, they decreased to a minimum value in late autumn or early winter; and (3) fluctuated with the CH4 efflux in winter. The CH4 emissions in winter account for 60.4-84.4% of the all year outputs. For the hotspots', the CH4 and CO2 effluxes seasonal variations were mainly determined by the seasonal change of the landfill cover's soil gas permeability. The ratio of CH4 emissions in winter to the all year outputs range from 17.4 to 68.7%.

CH4 mitigation potentials from China landfills and related environmental co-benefits.

China's CH4 emissions from 1955 existing (old) and 495 planned (new) landfills are estimated and projected by adopting a bottom-up method, targeting a 2012 baseline year and a 2030 projected target year. Nine key CH4 mitigation measures are proposed for the CH4 mitigation assessment from landfills. Approximately 0.66 million metric tons (Mt) of CH4 and 1.14 Mt of CH4 will be released, respectively, from new and existing landfills under a 2030 business-as-usual (BAU) scenario, which is 23.5% lower than a U.S. Environmental Protection Agency estimation. It is estimated that 0.60 and 0.97 Mt of CH4 can be reduced under new policies (NP) and low-carbon (LC) policy scenarios, respectively. The combined biocover and landfill gas collection and flaring system is the most promising mitigation measure, while mechanical biological treatment and mineral landfill also contribute substantially to CH4 reduction. The odor-affected population under NP and LC scenarios will decrease by 39.5 and 64.2%, respectively, when compared to the 2030 BAU scenario. The LC scenario is a recommended policy for meeting China's nationally determined contribution targets and reducing the not-in-my-backyard impact due to this policy's significant reduction of CH4 emissions.

The Temporal and Spatial Distribution Characteristics of Air Pollution Index and Meteorological Elements in Beijing, Tianjin, and Shijiazhuang, China.

With rapid economic development and continuous population growth, several important cities in China suffer serious air pollution, especially in the Beijing-Tianjin-Hebei economic developing area. Based on the daily air pollution index (API) and surface meteorological elements in Beijing, Tianjin, and Shijiazhuang (the capital of Hebei province) from 2001 to 2010, the relationships between API and meteorological elements were analyzed. The statistical analysis focused on the relationships at seasonal and monthly average scales, on different air pollution grades and air pollution processes. The results revealed that the air pollution conditions in the 3 areas gradually improved from 2001 to 2010, especially during summer; the worst conditions in air quality were recorded in Beijing in spring due to the influences of dust, and in Tianjin and Shijiazhuang in winter due to household heating. Meteorological elements exhibited different influences on air pollution, showing similar relationships between API in monthly averages and 4 meteorological elements (i.e., the average, maximum, and minimum temperatures; maximum air pressure; vapor pressure; and maximum wind speed), whereas the relationships on a seasonal average scale demonstrated significant differences. Compared with seasonal and monthly average scales of API, the relation coefficients based on different air pollution grades were significantly lower, whereas the relationship between API and meteorological elements based on air pollution processes reduced the smoothing effect due to the average processing of seasonal and monthly API and improved the accuracy of the results. Finally, statistical analysis of the distribution of pollution days in different wind directions indicated the directions of extreme and maximum wind speeds that mainly influence air pollution, representing valuable information that could support the definition of air pollution control strategies through the identification of the regions (and the located emission sources) where the implementation of emission reduction actions should be focused. Integr Environ Assess Manag 2018;14:710-721. © 2018 SETAC.

Evaluating the impact of odors from the 1955 landfills in China using a bottom-up approach.

Landfill odors have created a major concern for the Chinese public. Based on the combination of a first order decay (FOD) model and a ground-level point source Gaussian dispersion model, the impacts from odors emitted from the 1955 landfills in China are evaluated in this paper. Our bottom-up approach uses basic data related to each landfill to achieve a more accurate and comprehensive understanding of impact of landfill odors. Results reveal that the average radius of impact of landfill odors in China is 796 m, while most landfills (46.85%) are within the range of 400-1000 m, in line with the results from previous studies. The total land area impacted by odors has reached 837,476 ha, accounting for 0.09% of China's land territory. Guangdong and Sichuan provinces have the largest land areas impacted by odors, while Tibet Autonomous Region and Tianjin Municipality have the smallest. According to the CALPUFF (California Puff) model and an analysis of social big data, the overall uncertainty of our calculation of the range of odor impacts is roughly -32.88% to 32.67%. This type of study is essential for gaining an accurate and detailed estimation of the affected human population and will prove valuable for addressing the current Not In My Back Yard (NIMBY) challenge in China.

[Comparative Analysis and Inspiration of Air Quality Index Between China and America].

Research on the differences of air quality index (AQI) especially AQI of particulate matters between China and America and analysis of hourly monitored readings from April to December in 2013 released by Environmental Monitoring Station of China indicated that: (1) Although China lagged behind America in formulating and publishing of AQI standards, the AQI standards published in 2012 in China covered more pollutant indexes than before and could objectively reflect the characteristics of air pollution in China, and were more close to the residens's feeling about air quality. (2) The methods adopted for calculation of particulate matter hourly AQI were different in China and America, and the comparison revealed that the calculation method adopted by China using the 24 h average concentration breakpoint of particulate matters to replace the 1 h average concentration breakpoint would enhance the severity of the pollution level. (3) The breakpoint of PM2.5 -24 h in China was less rigorous than that in America when AQI < 200, which led to the inconsistence between the ratio of PM2.5/PM10 and the real situation in China. (4) Analysis on the monitoring readings from station of Beijing Olympic Sports Center showed that when AQI < 50, the ratio of PM2.5/PM10 was less than 0.5 and increased with.the increasing of AQI. Correction and adjustment of particulate matter real-time calculation method and breakpoints of PM2.5 and PM10 were suggested in China.

[Comparative Analysis on the Improvement of Air Quality in Beijing During APEC].

In order to evaluate the effects of the implementation of emission reduction measures and the revolution of air quality of Beijing during APEC, the evolution characteristics of air quality was analyzed based on the hourly monitored readings of Olympic Sports Center from 1 to 15 November 2014 released by Environmental Monitoring Station of China, and compared with that in 2013. The results showed that: (1) PM2.5 was the main pollutant in Beijing. The air quality was good during the period of APEC with three obvious pollution events, and it was better than that in the same period in 2013, indicating that the implementation of emission reduction measures had made significant contribution to the improvement of air quality. (2) During the period of APEC, the concentrations of PM2.5 of 5 days were below the World Health Organization (WHO) standard (25 µg · m⁻³), and the concentration of SO2 met the WHO standard during this time. (3) During the period of APEC, the ratio of PM2.5, and PM10 was less than 0.5 when the air quality was good, and gradually increased with the increasing pollution level. The ratio reached 0.9 when the air was seriously polluted. (4) Compared with the same time in 2013, although the implementation of emission reduction measures made contribution to the reduction of the concentration of PM2.5, its contributions to the reduction of SO2 and CO concentration were much more obvious than that of PM2.5, and it had little impact on the reduction of NO2 concentration, and the reduction order of pollutants emission was SO2 > CO > PM > NO2, indicating that the sources, effects and emission reduction of PM2.5 were complex, and further studies are required.

[Analysis on Regional Characteristics of Air Quality Index and Weather Situation in Beijing and Its Surrounding Cities During the APEC].

Analysis on the revolution and regional characteristics of air quality by hourly monitored readings from 1 to 15 November 2014 released by Environmental Monitoring Station of China and research of the impacts of weather situation and meteorological elements released by China Meteorological Administration towards air quality of Beijing and its surrounding cities during the Asia-Pacific Economic Cooperation (APEC) indicated that: (1) The air quality was good because of the implementation of mitigation measures, while the Air Quality Index (AQI) increased along with the termination of mitigation measures. Thus it can be seen that mitigation measures made a great contribution to the improvement of air quality of Beijing and its surrounding cities. (2) Affected by thermal inversion layer, AQI of Beijing and its surrounding cities increased quickly during the initial of the implemental of reducing measures which proved that pollutants would accumulate in the context of unfavourable weather, hence the influence of weather situation towards air quality could not be ignored. (3) Although affected by thermal inversion layer, the concentration of pollutants of Beijing was not accumulated to a high degree at the end period of reducing measures, while Tianjin, Tangshan, Baoding and Xingtai suffered from moderate and severe pollution at the same time which further illustrated that the implementation of mitigation measures have made a great contribution to the improvement of air quality in Beijing during APEC.

Mitigation of global greenhouse gas emissions from waste: conclusions and strategies from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. Working Group III (Mitigation).

Greenhouse gas (GHG) emissions from post-consumer waste and wastewater are a small contributor (about 3%) to total global anthropogenic GHG emissions. Emissions for 2004-2005 totalled 1.4 Gt CO2-eq year(-1) relative to total emissions from all sectors of 49 Gt CO2-eq year(-1) [including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and F-gases normalized according to their 100-year global warming potentials (GWP)]. The CH4 from landfills and wastewater collectively accounted for about 90% of waste sector emissions, or about 18% of global anthropogenic methane emissions (which were about 14% of the global total in 2004). Wastewater N2O and CO2 from the incineration of waste containing fossil carbon (plastics; synthetic textiles) are minor sources. Due to the wide range of mature technologies that can mitigate GHG emissions from waste and provide public health, environmental protection, and sustainable development co-benefits, existing waste management practices can provide effective mitigation of GHG emissions from this sector. Current mitigation technologies include landfill gas recovery, improved landfill practices, and engineered wastewater management. In addition, significant GHG generation is avoided through controlled composting, state-of-the-art incineration, and expanded sanitation coverage. Reduced waste generation and the exploitation of energy from waste (landfill gas, incineration, anaerobic digester biogas) produce an indirect reduction of GHG emissions through the conservation of raw materials, improved energy and resource efficiency, and fossil fuel avoidance. Flexible strategies and financial incentives can expand waste management options to achieve GHG mitigation goals; local technology decisions are influenced by a variety of factors such as waste quantity and characteristics, cost and financing issues, infrastructure requirements including available land area, collection and transport considerations, and regulatory constraints. Existing studies on mitigation potentials and costs for the waste sector tend to focus on landfill CH4 as the baseline. The commercial recovery of landfill CH4 as a source of renewable energy has been practised at full scale since 1975 and currently exceeds 105 Mt CO2-eq year(-1). Although landfill CH4 emissions from developed countries have been largely stabilized, emissions from developing countries are increasing as more controlled (anaerobic) landfilling practices are implemented; these emissions could be reduced by accelerating the introduction of engineered gas recovery, increasing rates of waste minimization and recycling, and implementing alternative waste management strategies provided they are affordable, effective, and sustainable. Aided by Kyoto mechanisms such as the Clean Development Mechanism (CDM) and Joint Implementation (JI), the total global economic mitigation potential for reducing waste sector emissions in 2030 is estimated to be > 1000 Mt CO2-eq (or 70% of estimated emissions) at costs below 100 US$ t(-1) CO2-eq year(-1). An estimated 20-30% of projected emissions for 2030 can be reduced at negative cost and 30-50% at costs < 20 US$ t(-) CO2-eq year(-1). As landfills produce CH4 for several decades, incineration and composting are complementary mitigation measures to landfill gas recovery in the short- to medium-term--at the present time, there are > 130 Mt waste year(-1) incinerated at more than 600 plants. Current uncertainties with respect to emissions and mitigation potentials could be reduced by more consistent national definitions, coordinated international data collection, standardized data analysis, field validation of models, and consistent application of life-cycle assessment tools inclusive of fossil fuel offsets.