Peroxyacetyl nitrate can be used as a comprehensive indicator of air pollution complex.

With the acceleration of air cleaning activities in China, air pollution has entered a new stage characterized by seasonal interplay and predominance of fine particulate matter (PM) and ozone (O) pollutants. However, the differing peak seasons of these two pollution preclude the use of a unified indicator for air pollution complex. Given that peroxyacetyl nitrate (PAN) originates from secondary formation and persists under low-temperature conditions for extended periods, it is vital to determine whether its concentration can be used as an indicator to represent air pollution, not only in summer but also in winter.

Intercomparison of equivalent black carbon (eBC) and elemental carbon (EC) concentrations with three-year continuous measurement in Beijing, China.

Due to the lack of black carbon (BC) measurement data in some cases, elemental carbon (EC) is often used as a surrogate of BC, with a simple assumption that they are interchangeable. Such assumption will inevitably lead to uncertainties in radiative forcing estimation and health impact assessment. In order to quantitatively and systematically evaluate the relationship between BC and EC as well as factors responsible for their difference, 3-year collocated equivalent BC (eBC) and EC measurements with 1-h resolution were performed in Beijing, China continuously from 2016 to 2019.

Annual nonmethane hydrocarbon trends in Beijing from 2000 to 2019.

High loads of ground-level ozone have occurred with the implementation of the Air Pollution Prevention and Control Action Plan. However, the long temporal variation in precursor nonmethane hydrocarbons (NMHCs) has rarely been studied. In this study, we examined the evolution of NMHCs in Beijing based on ambient measurements from 2000 to 2019.

Primary organic gas emissions from gasoline vehicles in China: Factors, composition and trends.

Continuous tightening emission standards (ESs) facilitate the reduction of organic gas emissions from gasoline vehicles. Correspondingly, it is essential to update the emissions and chemical speciation of total organic gases (TOGs), including volatile organic compounds (VOCs), intermediate volatility organic compounds (IVOCs), CH, and unidentified non-methane hydrocarbons (NMHCs) for assessing the formation of ozone and secondary organic aerosol (SOA). In this study, TOG and speciation emissions from 12 in-use light-duty gasoline vehicle (LDGV) exhausts, covering the ESs from China II to China V, were investigated on a chassis dynamometer under the Worldwide Harmonized Light-duty Test Cycle (WLTC) in China.

Preparation of ammonium polyphosphate and dye co-intercalated LDH/polypropylene composites with enhanced flame retardant and UV resistance properties.

In this paper, ammonium polyphosphate (APP) with flame retardant performance and acid red 88 (AR88) with UV absorption property were intercalated into layered double hydroxide (LDH) interlayers together, aiming to improve the flame retardancy and UV resistance properties of polypropylene (PP) simultaneous in one system. The synthesized LDHs and PP/LDH composites were characterized systematically and the results showed that AR88 and APP were intercalated into LDH interlayers successfully, and the content of APP and AR88 in LDH interlayers can be controlled through the synthesis process. Both APP-LDHs and AR88/APP-LDHs can greatly improve the flame retardancy performance of PP, with 25 wt% LDH addition, the peak heat release rate (PHRR) decreased by 42-63%, respectively.

Accumulation risk and source apportionment of heavy metals in different types of farmland in a typical farming area of northern China.

The types of land used for farmland can greatly influence the source and accumulation risk of heavy metals in soil. However, the apportioning quantitatively the source of soil heavy metals has been studied insufficiently, especially in terms of different types of farmland. In this study, a total of 252 soil samples were taken from dry land, paddy fields and greenhouse fields in the Jinyuan district of Taiyuan city, China, to assess the accumulation risk of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn).

Nitrous oxide (NO) emissions from a pilot-scale oxidation ditch under different COD/N ratios, aeration rates and two shock-load conditions.

Nitrous oxide (NO) generated from wastewater treatment plants (WWTPs) has drawn attention due to its high emission load and significant greenhouse effect. In the present study, NO emissions from a pilot-scale Carrousel oxidation ditch under various chemical oxygen demand (COD) to nitrogen ratio (COD/N) and aeration rates were systematically investigated. The highest NO emission factor was 0.

Contrasting seasonal variations of geochemistry and microbial community in two adjacent acid mine drainage lakes in Anhui Province, China.

Acid mine drainage (AMD) is generated by the bio-oxidation of sulfide minerals. To understand the AMD formation and evolution, it is necessary to determine the composition and variation of acidophilic community, and their role in AMD ecosystem. In this study, we compared seasonal variations of geochemistry and microbial composition of two adjacent AMD lakes with different formation histories in Anhui Province, China.

Vertically increased NO radical in the nocturnal boundary layer.

In the nocturnal boundary layer, nitrate radical (NO) has an important contribution to atmospheric chemistry through oxidation of nitrogen oxides and hydrocarbons. Vertical distributions of NO, O and NO were measured by four differential optical absorption spectroscopy instruments at meteorological tower in Beijing from June 1 to July 22, 2019. The results show the mean diurnal variations of NO, O, and NO display a single peak (up to 65.

[Concentration and Carbon Isotope Composition of DOC and DIC in the Miyun Reservoir Watershed in Summer].

This study aims to complement existing research on the carbon cycle of water in reservoirs, for the effective control of nutrient input in drinking water. The content and isotopic compositions of water dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) from the Miyun Reservoir watershed in Beijing were studied, and water from the Jingmi diversion canal was also studied as a baseline reference. The results showed that the content of DOC in the Miyun Reservoir watershed in summer varied from 1.

Different HONO Sources for Three Layers at the Urban Area of Beijing.

Gaseous nitrous acid (HONO) is a crucial precursor of the hydroxyl (OH) radical, which is a "detergent" in the atmosphere. Nowadays, HONO formation mechanisms at polluted urban areas are controversial, which restricts the understanding of atmospheric oxidative capacity and radical cycling. Herein, multiday vertical observation of HONO and NO was simultaneously performed at three heights at the urban area of Beijing for the first time.

Preparation of MnO decorated CoFeO powder/monolithic catalyst with improved catalytic activity for toluene oxidation.

In this paper, KMnO was used to pre-treat CoFe-layered double hydroxides (LDH) precursor to prepare MnO decorated CoFeO catalyst. The toluene oxidation performance of the catalyst was investigated systematically. The optimized 0.

Effects of different potassium and nitrogen pretreatment strategies on anaerobic digestion performance of rice straw.

The effects of different potassium and nitrogen pretreatment strategies on the anaerobic digestion (AD) performance of rice straw (RS) were investigated. KOH, NH·HO and KOH + NH·HO combined pretreatments were applied. The results showed that KOH + NH·HO combined pretreatment achieved the highest biomethane production and TS (TS: total solid) removal rate of 274 mL g VS and 43.

Aerosol optical properties under different pollution levels in the Pearl River Delta (PRD) region of China.

To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta (PRD) region, integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17, 2014. The concentrations and chemical compositions of PM, aerosol optical properties and meteorological parameters were measured. The mean value of PM increased from less than 35 (excellent) to 35-75 μg/m (good) and then to greater than 75 μg/m (pollution), corresponding to mean PM values of 24.

Drivers of improved PM air quality in China from 2013 to 2017.

From 2013 to 2017, with the implementation of the toughest-ever clean air policy in China, significant declines in fine particle (PM) concentrations occurred nationwide. Here we estimate the drivers of the improved PM air quality and the associated health benefits in China from 2013 to 2017 based on a measure-specific integrated evaluation approach, which combines a bottom-up emission inventory, a chemical transport model, and epidemiological exposure-response functions. The estimated national population-weighted annual mean PM concentrations decreased from 61.

Investigating the characteristics and source analyses of PM seasonal variations in Chengdu, Southwest China.

In 2015, comprehensive observations were carried out in Chengdu, Sichuan Province, China, to elucidate the seasonal variation characteristics of the concentrations, chemical compositions, and the sources of PM pollution. The meteorological parameters, gaseous pollutants and chemical compositions of PM were measured. The annual average concentration of PM in Chengdu was 67.

Intermediate-Volatility Organic Compound Emissions from Nonroad Construction Machinery under Different Operation Modes.

Intermediate-volatility organic compounds (IVOCs) have been found as important sources for secondary organic aerosol (SOA) formation. IVOC emissions from nonroad construction machineries (NRCMs), including two road rollers and three motor graders, were characterized under three operation modes using an improved portable emission measurement system. The fuel-based IVOC emission factors (EFs) of NRCMs varied from 245.

[Analysis of a Pollution Process in the Beijing-Tianjin-Hebei Region Based on Satellite and Surface Observations].

The air pollution control of the Beijing-Tianjin-Hebei region (BTH region) is gradually moving toward regional joint mode. Remote sensing technology can be used to realize real-time dynamic monitoring over a wide range of space and ground-based monitoring can obtain accurate point information. Combining satellite with ground-based data, the formation and dissipation of pollution can be traced in three dimensions.

[Variation in Pollutant Concentrations and Correlation Analysis with the Vegetation Index in Beijing-Tianjin-Hebei].

Based on 2017 hourly air quality monitoring data, NDVI 16 d synthetic data, and socio-economic data, the air pollution characteristics of Beijing-Tianjin-Hebei were systematically analyzed, and its variation, normalized vegetation index, and the relationship between the index (NDVI) and its impact on socio-economic factors, were analyzed by linear regression analysis and a geographically weighted regression model. The conclusions are as follows:①The overall air pollution in the Beijing-Tianjin-Hebei region is characterized by high-level pollution over the southern plain areas and low-level pollution over the northern mountainous areas. The air pollution increases from north to south, and shows significant spatial heterogeneity.