[Atmospheric HONO Concentration Levels and Generation Mechanisms in Nanjing in Winter and Summer].

HONO, or gaseous nitrous acid, has a significant impact on air quality and climate. An atmospheric gaseous nitrous acid （HONO） observation study was carried out in December 2021 （winter） and July 2022 （summer） in the Jiangbei New District of Nanjing City, respectively. Using the HONO concentration observation data, combined with the atmospheric NO and O concentrations during the sampling period as well as the reaction rate of the HONO generation process and other parameters, we compared and analyzed the change rule of the atmospheric HONO concentration during winter and summer in the Nanjing area, quantitatively investigated the sources of diurnal atmospheric HONO and its generation mechanism, and explored the unknown sources of atmospheric HONO during the daytime.

Insights into anthropogenic impact on atmospheric inorganic aerosols in the largest city of the Tibetan Plateau through multidimensional isotope analysis.

Particulate inorganic nitrogen aerosols (PIN) significantly influence air pollution and pose health risks worldwide. Despite extensive observations on ammonium (pNH) and nitrate (pNO) aerosols in various regions, their key sources and mechanisms in the Tibetan Plateau remain poorly understood. To bridge this gap, this study conducted a sampling campaign in Lhasa, the Tibetan Plateau's largest city, with a focus on analyzing the multiple isotopic signatures (δN, ∆O).

[Analysis of Formation Processes and Sources of PM Ammonium During Winter and Summer in Suburban Area of the Yangtze River Delta].

As the main pollutants of secondary inorganic aerosols(SIAs) in fine particulate matter(PM), aerosol ammonium(p-NH) plays a significant role in the formation of haze. However, the contribution ratio of each potential source of atmospheric NH(p-NH and NH) still remains controversial. In this study, 3 h high-frequency PM samples were collected in Dongshan, Suzhou during winter and summer in 2015, respectively.

Effects of contrasting tillage managements on the vertical distribution of plant- and microbial-derived carbon in rice paddy.

Soil microbial necromass is considered a persistent component of soil organic carbon (SOC), constituting the final product of the microbial carbon pump (MCP). However, the mechanisms involved in the effects of tillage and rice residue managements on the vertical distribution of microbial necromass and plant residues in rice paddy soils remain unclear, limiting knowledge of SOC sequestration mechanisms. Therefore, we estimated microbial- and plant-derived C by biomarker amino sugars (AS) and lignin phenols (VSC) at the 0-30 cm soil depth, as well as their relationships with SOC contents and mineralization in a rice paddy soil under contrasting tillage practices, namely no-tillage (NT), reduced tillage (RT), and conventional tillage (CT).

Increasing Nonfossil Fuel Contributions to Atmospheric Nitrate in Urban China from Observation to Prediction.

China's nitrogen oxide (NO) emissions have undergone significant changes over the past few decades. However, nonfossil fuel NO emissions are not yet well constrained in urban environments, resulting in a substantial underestimation of their importance relative to the known fossil fuel NO emissions. We developed an approach using machine learning that is accurate enough to generate a long time series of the nitrogen isotopic composition (δN) of atmospheric nitrate using high-level accuracies of air pollutants and meteorology data.

Vertical measurements of stable nitrogen and oxygen isotope composition of fine particulate nitrate aerosol in Guangzhou city: Source apportionment and oxidation pathway.

Nowadays, the emission source and formation mechanism of fine particulate nitrate (pNO) in China are mired in controversy. In this study, the stable nitrogen isotope (δN-NO) and triple oxygen isotope (ΔO-NO) were determined for the pNO samples collected at three heights under different atmospheric oxidation capacity (AOC) (O = O + NO: 107 ± 29 μg m at ground, 102 ± 28 μg m at 118 m, 122 ± 23 μg m at 488 m) conditions during the sampling period based on the Canton Tower, Guangzhou, China. The Bayesian mixing model showed that coal combustion was the largest contributor to pNO in this city, followed by biomass burning, vehicle exhaust, and soil emission.

Seasonal variations of low molecular alkyl amines in PM in a North China Plain industrial city: Importance of secondary formation and combustion emissions.

Atmospheric amines have unique acid-neutralizing capacity and play an important role in atmospheric chemical reactions. An integrated observation of PM samples (from Dec 2015 to Nov 15, 2016) was conducted in a typical industrial city (Xuzhou), China. Concentrations of total measured amines (∑amines, including methylamine (MA), ethylamine (EA), dimethylamine (DMA), propanamine (PA) and trimethylamine (TMA) + diethylamine (DEA)) were 172.

Isotopic imprints of aerosol ammonium over the north China plain.

Atmospheric PM poses a variety of health and environmental risks to urban environments. Ammonium is one of the main components of PM, and its role in PM pollution will likely increase in the coming years as NH emissions are still unregulated and rising in many cities worldwide. However, partitioning urban NH sources remains challenging.

[Analysis on the Characteristics of Oxidation Potential and Influence Sources of PM in Baoding City in Winter].

In order to explore the characteristics of PM oxidation potential and its impact sources in the suburbs of Baoding City in the winter of 2018, the dithiothreitol (DTT) method was used to determine the reactive oxygen species in PM. Pearson correlation was used to analyze the relationship between the chemical components in PM and the oxidation potential. PMF was used to analyze the pollution source of DTT.

[Changes in Carbonaceous Aerosol in the Northern Suburbs of Nanjing from 2015 to 2019].

Carbonaceous aerosol is an important component of atmospheric fine particles that has an important impact on air quality, human health, and climate change. In order to explore the long-term changes in carbonaceous aerosol under the background of emission reduction, this study measured the mass concentrations of organic carbon (OC) and elemental carbon (EC) of PM, which collected in the northern suburbs of Nanjing for five years (December 17, 2014 to January 5, 2020). The results showed that the five-year average (OC) and (EC) were (10.

Light absorption and source apportionment of water soluble humic-like substances (HULIS) in PM at Nanjing, China.

Humic-like substances (HULIS), as important components of brown carbon (BrC), play an important role in climate change. In this study, one-year PM samples from 2017 to 2018 were collected at Nanjing, China and the water soluble HULIS and other chemical species were analyzed to investigate the seasonal variations, optical properties and possible sources. The HULIS concentrations exhibited highest in winter and lowest in summer.

Impacts of chemical degradation of levoglucosan on quantifying biomass burning contribution to carbonaceous aerosols: A case study in Northeast China.

Biomass burning (BB) is an important source of carbonaceous aerosols in Northeast China (NEC). Quantifying the original contribution of BB to organic carbon (OC) [BB-OC] can provide an essential scientific information for the policy-makers to formulate the control measures to improve the air quality in the NEC region. Daily PM samples were collected in the rural area of Changchun city over the NEC region from May 2017 to May 2018.

Formation Mechanisms and Source Apportionments of Airborne Nitrate Aerosols at a Himalayan-Tibetan Plateau Site: Insights from Nitrogen and Oxygen Isotopic Compositions.

Formation pathways and sources of atmosphere nitrate (NO) have attracted much attention as NO had detrimental effects on Earth's ecosystem and climate change. Here, we measured nitrogen (δN-NO) and oxygen (δO-NO and ΔO-NO) isotope compositions in nitrate aerosols at the Qomolangma station (QOMS) over the Himalayan-Tibetan Plateau (HTP) to quantify the formation mechanisms and emission sources of nitrate at the background site. At QOMS, the enhanced NO concentrations were observed in the springtime.

Important Role of NO Radical to Nitrate Formation Aloft in Urban Beijing: Insights from Triple Oxygen Isotopes Measured at the Tower.

Until now, there has been a lack of knowledge regarding the vertical profiles of nitrate formation in the urban boundary layer (BL) based on triple oxygen isotopes. Here, we conducted vertical measurements of the oxygen anomaly of nitrate (ΔO-NO) on a 325 m meteorological tower in urban Beijing during the winter and summer. The simultaneous vertical measurements suggested different formation mechanisms of nitrate aerosols at ground level and 120 and 260 m in the winter due to the less efficient vertical mixing under stable atmospheric conditions.

Substantial decreases of light absorption, concentrations and relative contributions of fossil fuel to light-absorbing carbonaceous aerosols attributed to the COVID-19 lockdown in east China.

To prevent spreads of Coronavirus disease-2019 (COVID-19), China adopted the lockdown measures in late January 2020, providing a platform to study the response of air quality and atmospheric chemical and physical properties to strict reduced emissions. In this study, the continuous measurements of aerosol light absorption were conducted in Nanjing, east China, from January 3 to March 31, 2020. Our results showed that the contribution of black carbon (BC) to light absorption at the different wavelengths was more than 75% and the rest light absorption was contributed by brown carbon (BrC), which was mainly originated from primary emissions.

Source apportionments of atmospheric volatile organic compounds in Nanjing, China during high ozone pollution season.

Atmospheric volatile organic compounds (VOCs) are not only harmful to human health, but also lead to ozone (O) formation. From July 3 to August 1 of 2018, online measurements of atmospheric VOCs were conducted in Nanjing City, in order to investigate the source apportionments to VOCs since the Empirical Kinetic Modelling Approach (EKMA) suggested that O formation was VOC-limited at the receptor site. Using positive matrix factorization (PMF) model, we quantified eight sources of VOCs, including vehicle exhausts (23%), industrial source (18%), fuel evaporation (17%), petrochemical industry (12%), solvent usage (12%), biogenic emission (8%) and liquefied petroleum gas (7%) along with gasoline additive (3%).

Development of a Monitoring System for Semicontinuous Measurements of Stable Carbon Isotope Ratios in Atmospheric Carbonaceous Aerosols: Optimized Methods and Application to Field Measurements.

Carbon content constitutes a major fraction of atmospheric particulate matter (PM) and directly influences the earth's climate and human health. The stable carbon isotope ratios (δC) can be used to track potential sources and atmospheric processes of carbonaceous aerosols. Previously, determination of δC was always conducted in offline carbonaceous aerosol samples.

[Source Apportionment and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in PM in Changchun City, Autumn of 2017].

In this study, 30 PM samples were collected from the atmosphere in Changchun City in the autumn of 2017. The concentration and composition characteristics of 17 polycyclic aromatic hydrocarbons (PAHs) in the samples were analyzed by gas chromatography mass spectrometry (GC-MS). The diagnostic ratio and principal component analysis method were used to determine the source of PAHs pollution.

[Chemical Characteristics and Source Apportionment of Water-Soluble Ions in Atmosphere Aerosols over the East China Sea Island During Winter and Summer].

A total of 70 total suspended particulate (TSP) samples were collected from December 2017 to February 2018 and June to August 2018 in Shengsi Islet, East China Sea. In this study, the mass concentrations of water-soluble ions in the TSP (including Na, K, NH, Mg, Ca, Cl, SO, NO, and MSA) samplers were determined by ion chromatography. The chemical characteristics, seasonal differences, and main sources of water-soluble ions in this background aerosol site were investigated by a multiple-technique analysis combining a HYSPLIT model, correlation analysis of water-soluble ions, and primary component analysis.

Specific sources of health risks caused by size-resolved PM-bound metals in a typical coal-burning city of northern China during the winter haze event.

High particulate matter (PM) pollution frequently occurs in winter over northern China , resulting in threats to human health. To date, there are limited studies to link source apportionments and health risk assessments in the different size-resolved PM samples during high PM events. In this study, size-segregated PM samples were collected in Linfen, a typical coal-burning city, in northern China during a wintertime haze pollution.

Stable Sulfur Isotopes Revealed a Major Role of Transition-Metal Ion-Catalyzed SO Oxidation in Haze Episodes.

Secondary sulfate aerosols played an important role in aerosol formation and aging processes, especially during haze episodes in China. Secondary sulfate was formed via atmospheric oxidation of SO by OH, O, HO, and transition-metal-catalyzed (TMI) O. However, the relative importance of these oxidants in haze episodes was strongly debated.

[High-frequency Evolution of Urban Atmospheric Ammonia and Ammonium and Its Gas-to-Particle Conversion Mechanism in Nanjing City].

In this study, hourly mass concentrations of atmospheric gases (mainly NH) and secondary inorganic aerosols (mainly NH, NO, and SO) in Nanjing City were continuously measured during the fall of 2018 by an online gas and aerosol chemical component monitor. The dataset was used to investigate the variation characteristics of ambient NH and NH during polluted and non-polluted periods, and to explore the potential chemical mechanism during gas-to-particle conversion between NH and NH. The results show that throughout the sampling period, the mean values (±1) of the mass concentrations of NH and NH were (15.

[Molecular Composition and Source Apportionment of Fine Organic Aerosols in Autumn in Changchun].

Organic aerosols have attracted increasing attention recently due to their significant contribution to fine particles (PM) and their complex components and sources. In this study, a total of 40 PM samples were collected simultaneously with high-volume samplers in Changchun from 16 Oct to 29 Nov 2016. Organic carbon (OC), elemental carbon (EC), non-polar organic compounds including -alkanes, polycyclic aromatic hydrocarbons (PAHs), and hopanes, and levoglucosan in atmospheric fine particles were analyzed.

[Characteristics and Sources of Water Soluble Inorganic Ions in Fine Particulate Matter During Winter in Xuzhou].

A total of 32 daily PM samples were collected from December 2016 to February 2017 in the urban area of Xuzhou city. Water-soluble inorganic ions (WSⅡs), including F, Cl, NO, SO, Na, Mg, NH, K and Ca, were determined by ion chromatography. The average mass concentration of PM was (164.