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Nitrophenols have received extensive attention due to their strong light-absorbing ability in the near-ultraviolet-visible region, which could be influenced by the atmospheric processes of nitrophenols. However, our knowledge and understanding of the formation and evolution of nitrophenols are still in the nascent stages. In the present study, the mixing states of four mononitrophenol particles (i.e., nitrophenol, methynitrophenol, nitrocatechol, and methoxynitrophenol), and one nitropolycyclic aromatic hydrocarbon particles (i.e., nitronaphthol (NN)) were investigated using a single-particle aerosol mass spectrometer (SPAMS) in November 2019 in Qingdao, China. The results showed, for the first time, that mononitrophenols and NN exhibit different mixing states and diurnal variations. Four mononitrophenols were internally mixed well with each other, and with organic acids, nitrates, potassium, and naphthalene. The diurnal variation in the number fraction of mononitrophenols presented two peaks at 07:00 to 09:00 and 18:00 to 20:00, and a valley at noon. Atmospheric environmental conditions, including NO 2 , O 3 , relative humidity, and temperature, can significantly influence the diurnal variation of mononitrophenols. Multiple linear regression and random forest regression models revealed that the main factors controlling the diurnal variation of mononitrophenols were photochemical reactions during the day and aqueous-phase reactions during the night. Unlike mononitrophenols, about 62–83% of NN were internally mixed with [NH 4 ]+ and [H(NO 3) 2 ]-, but not with organic acids and potassium. The diurnal variation of NN was also different from that of mononitrophenols, generally increased from 17:00 to 10:00 and then rapidly decreaed from 11:00 to 16:00. These results imply that NN may have sources and atmospheric processes that are different from mononitrophenols. We speculate that this is mostly controlled by photochemical reactions and mixing with [NH 4 ]+, which may influence the diurnal variation of NN in the ambient particles; however, this requires further confirmation. These findings extend our current understanding of the atmospheric formation and evolution of nitrophenols. [Display omitted] • Five nitrophenols were analyzed by a single-particle aerosol mass spectrometer. • Mononitrophenols and nitronaphthol have different mixing state and diurnal variation. • Photochemistry and aqueous-phase reactions control the diurnal variation of mononitrophenols. • [NH 4 ]+ can significantly influence the diurnal variation of nitronaphthol. [ABSTRACT FROM AUTHOR]

Studies have shown that water-insoluble organic matter (WIOM) accounts for a large part of the organic components in cloud water and significantly contributes to brown carbon. However, the molecular characteristics of WIOM in cloud droplets remain unclear, hampering the understanding of their climate effects. In this study, cloud water was collected at a remote mountain site in South China during the winter of 2020, and WIOM was separated by membrane filtration, extracted by methanol, and characterized using Fourier transform ion cyclotron resonance mass spectrometry coupled with an electrospray ionization source. A total of 697–1637 molecules were identified in WIOM. WIOM is characterized by lower oxidation states of carbon atoms (−1.10 ∼ −0.84 in WIOM vs. −0.58 ∼ −0.51 in water-soluble organic matter (WSOM) on average), higher carbon number (14.12–20.59 vs. 9.87–10.56) and lower unsaturation (double-bond equivalent 4.55–4.95 vs. 4.84–5.23) relative to WSOM. More abundant lipid-like compounds (12.2–41.9% in WIOM vs. <2% in WSOM) but less highly oxygenated compounds (<7% vs. 28.6–35.3%) exist in WIOM. More than 30% of WIOM molecules in cloud water are common with interstitial particles, implying that WIOM in cloud water may originate from aerosol activation and/or collision. Some unique molecules in WIOM in cloud water are identified as aqueous-phase oligomerization products, indicating the aqueous-phase formation of WIOM. Further analysis of the intermolecular relationship shows that WIOM has the potential to transform into WSOM by partitioning into the dissolved phase, oxidation and functionalization by heteroatom-containing groups, representing a previously unidentified pathway for WSOM formation in cloud water. The results provide new insights into the in-cloud chemistry, which would assist in the understanding of the aqueous formation and evolution of WIOM. [Display omitted] • Molecular composition of water-insoluble organics in cloud water was studied. • Water-insoluble organics originate from aerosol activation and oligomerization. • Water-insoluble organics can transform into water-soluble organics in cloud. [ABSTRACT FROM AUTHOR]

The coexistence of Zn-Pb deposits and oil/gas reservoirs demonstrates that a close genetic link between them. The Nanmushu is a large Mississippi Valley-Type (MVT) Zn-Pb deposit discovered on the northern margin of the Yangtze block in recent years. The deposit is hosted in the Ediacaran Dengying Formation dolostone, accompanied by large amount of bitumen in the orebodies. The MVT Zn-Pb deposit overlaps with the paleo-oil/gas reservoir horizontally, and sandwiched in the paleo-oil/gas reservoirs at depth. The Cambrian Guojiaba Formation may have provided not only the oil for paleo-oil/gas reservoirs, but also ore metals for the Zn-Pb mineralization. With increasing burial depth, the Guojiaba Formation may have become more mature to form metal-rich fluids, and the metals migrated and accumulated with hydrocarbons to form a paleo-oil reservoir. Large-scale Zn-Pb mineralization may have occurred in the destruction process of paleo-gas reservoir. With the deep burial of paleo-oil reservoir, the paleo-oil reservoir may have transformed into a paleo-gas reservoir. Decoupling of metals and hydrocarbons during the paleo-gas reservoir formation may have provided the ore metals. Thermal sulfate reduction (TSR) during the paleo-oil/gas reservoirs formation may have provided the hydrogen sulfide for mineralization. Decompression and cooling during the paleo-gas reservoir destruction may have formed extensive metal sulfide precipitation and mineralization. • Zn-Pb deposit overlaps with the paleo-oil/gas reservoir horizontally and vertically. • Orebodies are rich in bitumen. • Source rock provides not only the oil source but also the ore metals. • Hydrocarbon fluid is also the ore-forming fluid. • Zn-Pb deposit formed in the process of the destruction of paleo-gas reservoir [ABSTRACT FROM AUTHOR]

The effect of the mixing state of black carbon (BC) on light absorption is of enduring interest due to its close connection to regional/global climate. Herein, we present concurrent measurements of both BC absorption enhancement (E abs) and the chemical mixing state in southern China. E abs was obtained by simultaneous measuring the light absorption coefficient using an aethalometer before and after being heated. The observed E abs was categorized into non- (E abs ≤ 1.0), slight (1.0 < E abs ≤ 1.2), and higher (E abs > 1.2) enhancement groups, and it was compared to the mixing state of elemental carbon (EC) particles detected by a single particle aerosol mass spectrometer (SPAMS). The individual EC-containing particles were classified into four types, including EC with sodium and potassium ion peaks (NaK-EC), long EC cluster ions (C n +/−, n ≥ 6) with sulfate (EC-Sul1), short EC cluster ions (C n +/−, n < 6) with sulfate (EC-Sul2), and EC with OC and sulfate (ECOC-Sul). NaK-EC and EC-Sul2 are the dominant EC types. Slight enhancement group is mainly explained by the photochemical production of ammonium sulfate and organics on EC-Sul2 during afternoon hours. In contrast, the higher E abs is primarily attributed to the enhanced mixing of ammonium chloride with NaK-EC during morning hours, without photochemistry. The characterization of source emissions indicates that NaK-EC is likely from coal combustion and is associated with a relatively higher amount of ammonium chloride. To our knowledge, this is the first report to state that EC particles associated with ammonium chloride have a relatively higher E abs. Unlabelled Image • Both BC absorption enhancement (E abs) and mixing state were measured in real-time. • The morning E abs peak is explained by primary emission. • Secondary composition contributes to the afternoon E abs peak. • Internally mixed ammonium chloride is more responsible for the higher E abs. [ABSTRACT FROM AUTHOR]

Fog/Cloud processing of atmospheric particles changes their physiochemical properties, with profound impacts on atmospheric compositions, climate, and human health. These processes involve intricate physical and chemical processes of individual particles, which are often inadequately represented in current models that assume uniformly mixed aerosol compositions. The activation of particles as cloud condensation nuclei (CCN) or ice nuclei (IN), as well as their subsequent modification during fog/cloud processing, are greatly influenced by the unique physiochemical properties of individual particles. Since the 1990s, numerous observations have been conducted to investigate the physiochemical properties of individual droplet residual particles—those particles remaining after droplet evaporation. These particles serve as valuable tracers for understanding the fog/cloud processing of aerosols. In this review, we first compile the various sampling methods employed to collect individual fog/cloud residual particles and summarize the current understanding of the diverse particle types observed in various regions, including urban/industrial, marine/coastal, dusty, and remote areas. Specifically, we explore the size and chemically segregated activation of these particles, as well as the potential role of complex compositions in the aqueous formation of secondary components. We highlight the impact of mixed secondary compositions on the activation of particle types, including soot-containing, organic matters, sea salt, and dust particles. These works also emphasize the importance of understanding the heterogeneous compositions across individual particles for accurately assessing the formation of secondary species during fog/cloud processing. Furthermore, this review underscores the modification of microphysical properties of individual particles and their potential implications for optical properties and CCN/IN activities. Finally, we outline the limitations of current research on individual fog/cloud residual particles and identify areas for future investigation. • The chemical compositions and mixing structures of individual fog/cloud droplet residuals in various types of regions are summarized. • The activation and modification of particles involved in fog/cloud processing are tightly associated with individual particle properties. • The modification of cloud-processed individual particles and potential implications for evaluating their impacts are highlighted. [ABSTRACT FROM AUTHOR]

Inland transported sea spray aerosol (SSA) particles along with multiphase reactions are essential to drive the regional circulation of nitrogen, sulfur and halogen species in the atmosphere. Specially, the physicochemical properties of SSA will be significantly affected by the displacement reaction of chloride. However, the role of organic species and the mixing state on the chloride depletion of SSA during long-range inland transport remains unclear. Hence, a single particle aerosol mass spectrometer (SPAMS) was employed to investigate the particle size and chemical composition of individual SSA particles over inland southern China during the East Asian summer monsoon. Based on the variation of chemical composition, SSA particles were clustered into SSA-Aged, SSA-Bio and SSA-Ca. SSA-Aged was regarded as the aged Na-rich SSA particles. In comparison to the SSA-Aged, SSA-Bio involved some extra organic species associated with biological origin (i.e., organic nitrogen and phosphate). Each type occupies for approximately 50% of total detected SSA particles. Besides, SSA-Ca may relate to organic shell of Na-rich SSA particles, which is negligible (~3%). Tight correlation between Na and diverse organic acids was exhibited for the SSA-Aged (r2 = 0.52, p < 0.01) and SSA-Bio (r2 = 0.61, p < 0.01), reflecting the impact of organic acids to the chloride displacement during inland transport SSA particles. The chloride depletion occupied by organic acids is estimated to be up to 34%. It is noted that distinctly different degree of chloride depletion was observed between SSA-Aged and SSA-Bio. It is more likely to be attributed to the associated organic coatings for the SSA-Bio particles, which inhibits the displacement reactions between acids and chloride. As revealed from the mixing state of SSA-Bio, defined hourly mean peak area ratio of Cl / Na increases with the increasing phosphate and organic nitrogen. This finding provides additional basis for the improvement of modeling simulations in chlorine circulation and a comprehensive understanding of the effects of organics on chloride depletion of SSA particles. Unlabelled Image • Organic acids considerably contribute to chloride depletion of sea spray aerosol (SSA) particles. • The SSA particles are heavily internally mixed with biological compositions. • Biological organic coatings may inhibit heterogeneous reactions of SSA particles. [ABSTRACT FROM AUTHOR]

Interactions between clouds and black carbon (BC) represent a significant uncertainty in aerosol radiative forcing. To investigate the influence of cloud processing on the scavenging of BC, concurrent measurement of individual cloud droplet residue particles (cloud RES) and interstitial particles (cloud INT) throughout a cloud event was deployed at Mt. Tianjing (1690 m a.s.l.) in southern China. An aethalometer (AE-33), a single particle aerosol mass spectrometer (SPAMS) and a scanning mobility particle sizer (SMPS) were used to investigate the mass concentration of equivalent BC (EBC), size-resolved number of BC-containing particles, and size-resolved number concentration of submicron particles in real-time, respectively. The number-based SEs of the submicron particles varied between 2.7 and 31.1%. Mass scavenging efficiency (MSE) ranged from 4.7% to 52.6% for EBC, consistent with the number-based SE (from 11.3% to 59.6%) of the BC-containing particles throughout the cloud event. Several factors that may influence the SEs of the BC-containing particles are considered and examined. SEs are most likely determined by a single factor, i.e., liquid water content (LWC), with R2 > 0.8 in a power function throughout the cloud event. Stage-resolved investigation of SEs further reveals that particle size matters more than other factors in the cloud formation stage, whereas there is an increasing role of the mixing state in the development and stability stage. We also observed lower SEs for the BC-containing particles internally mixed organics, consistent with previous literature. • The stage-resolved scavenging efficiency of BC particles is firstly reported. • Scavenging efficiency (SE) is dominantly controlled by liquid water content (LWC). • Key factors influencing the in-cloud SE of BC-containing particles are assessed. [ABSTRACT FROM AUTHOR]

The formation mechanism of oxalate in the aqueous phase remains uncertain. Approximately 600 000 oxalate-containing particles and 450 000 its precursors-containing particles (e.g., acetate, glyoxylate, pyruvate and malonate) were obtained using a single particle aerosol mass spectrometer at a mountain site in southern China from 9 May to 4 June, 2018. The number fraction of oxalate or its precursors was compared within three representative aerosols with different liquid water contents including cloud droplet residues (RES), cloud interstitial particles (INTER) and cloud-free ambient particles (AMB). Lower number fraction of oxalate was found in the RES relative to INTER and AMB, mostly attributed to the decrease in precursors. This was conflicted with the enhancement of in-cloud oxalate formation previously reported. Further analysis indicated that the aerosol acidity had a major influence on the formation of precursors and their conversion to oxalate. With the increase of relative aerosol acidity (defined as the sum of sulfate and nitrate peak areas divided by ammonium peak area), the formation of precursors was increased while the conversion of precursors to oxalate was suppressed. Meanwhile, this influence was more pronounced in the INTER and AMB relative to RES. This work highlighted the roles of aerosol acidity and liquid water content in the aqueous phase formations of oxalate and its precursors. • Reduction of oxalate was found in cloud droplets residues relative to wet particles. • Enhanced relative aerosol acidity increased the formation of oxalate precursors. • Enhanced relative aerosol acidity suppressed the conversion of precursors to oxalate. [ABSTRACT FROM AUTHOR]

Abstract Amines play an important role in the formation and transformation of atmospheric aerosols. Gaseous phase and PM 2.5 samples were collected simultaneously at Nanling Mountains, southern China during autumn 2016 and summer 2017. The site is strongly affected by long distance transport from marine and continental air masses. Five amines, methylamine (MA), dimethylamine (DMA), diethylamine (DEA), dibutylamine (DBA) and morpholine (MOR), were detected by gas chromatography-mass spectrometry (GC-MS) after derivatization. The backward trajectory analyses suggested that different origins of air masses led to seasonal variation of amines. In gaseous phase samples, the average concentrations of total measured amines (Ʃamines) were 193.4 ± 111.7 ng m−3 in autumn 2016 and 307.5 ± 196.7 ng m−3 in summer 2017. In PM 2.5 samples, the average concentrations of Ʃamines were 12.4 ± 10.8 ng m−3 in autumn 2016 and 20.7 ± 11.0 ng m−3 in summer 2017. MA and DMA were the dominant amines, together contributing approximately 70% to gaseous amines and 80% to particulate amines. A strong linear relationship was found between Ʃamines and NO 3 − in PM 2.5 , implying that amines might mainly exist in the form of aminium nitrate. Ammonium (NH 4 +) was found mostly likely in the form of ammonia sulfate. Approximately 7.4% of the gaseous total amines partitioned to PM 2.5. A good linear relationship between the fraction of total atmospheric concentration sorbed by PM 2.5 (Φ) and the concentrations of O 3 was found, suggesting that O 3 likely played an important factor in the gas-to-particle partitioning of amines. Additionally, under high relative humidity circumstances (92% ± 7.0%), direct dissolution was a crucial step for gaseous amines partitioning into particles. The ratios of amines-C to water-soluble organic carbon (WSOC) and amines-N to water-soluble organic nitrogen (WSON) were 0.21% and 1.57% in autumn 2016 and 0.54% and 2.08% in summer 2017, respectively. The results of this study provide essential information on the formation mechanism of particulate amines. Highlights • Gaseous and particulate amines were detected simultaneously at a remote mountain site in southern China. • Amines were mostly likely in the form of aminium nitrate. • Approximately 7.4% of the total gaseous amines partitioned into the particulate phase. • Direct dissolution was a crucial step for gas-to-particle partitioning under high relative humidity circumstances. [ABSTRACT FROM AUTHOR]

Abstract The formation of secondary organic aerosol (SOA) from isoprene ozonolysis was investigated using a FEP Teflon reactor with and without the presence of H 2 O, CO, SO 2 and UV-light irradiation (365 nm) to reveal their possible influence on SOA formation. Compared with the base experiment (isoprene + O 3) under dark condition, the presence of 2000 ppm H 2 O and 1000 ppm CO could remarkably suppress SOA formation from isoprene ozonolysis, with SOA yields reduced from 2.96% to 1.47% and 2.08%, respectively. The evident reduction of SOA yields from isoprene ozonolysis with the presence of H 2 O and CO was mainly ascribed to the suppression of Stable Criegee Intermediates (SCIs). In contrast, the particle yield from isoprene ozonolysis with the presence of SO 2 pronouncedly increased from 2.96% to 57.9%, suggesting that the oxidation of SO 2 by SCIs made great contribution to the particle formation. The SOA or particle yields from all the reaction systems with and without presence of H 2 O, CO and SO 2 reduced more than 27% under the UV-light irradiation with respect to dark condition, which were mainly attributed to the SCIs photolysis. The contribution of OH channel to SOA formation from isoprene ozonolysis was estimated to be less than 30%. Considering the 50% reduction of SOA yield from isoprene ozonolysis under light irradiation, the disappearance of the component with low O:C and H:C and high molecule weight in the SOA sample collected under light irradiation indicated the polymerization of unsaturated SCIs might be an important SOA formation channel besides the oligomerization of SCIs, HCHO, and MACR from isoprene ozonolysis under dark condition. Graphical abstract Image 1 Highlights • UV-light could remarkably reduce SOA formation from isoprene ozonolysis. • SCIs formed from isoprene ozonolysis played key role in SOA formation. • Polymers with high C/H and O/H ratios were found in the SOA from isoprene ozonolysis. [ABSTRACT FROM AUTHOR]

Size-segregated PM 10 samples were collected in Guangzhou, China during autumn of 2014. Nine amines, including seven aliphatic amines and two heterocyclic amines, were detected using a gas chromatography-mass spectrometer after derivatization by benzenesulfonyl chloride. The total concentration of the nine amines (Ʃamines) was 79.6–140.9 ng m −3 in PM 10 . The most abundant species was methylamine (MA), which had a concentration of 29.2–70.1 ng m −3 . MA, dimethylamine (DMA), diethylamine (DEA) and dibutylamine (DBA) were the predominant amines in the samples and accounted for approximately 80% of Ʃamines in each size segment. Two heterocyclic amines, pyrrolidine (PYR) and morpholine (MOR), were detected in all samples and had average concentrations of 1.14 ± 0.37 and 1.89 ± 0.64 ng m −3 , respectively, in particles with aerodynamic diameters < 3 μm. More than 80% of Ʃamines were found in particles with diameters <1.5 μm, indicating that amines are mainly enriched in fine particles. All amines exhibited a bimodal distribution with a fine mode at 0.49–1.5 μm and a coarse mode at 7.2–10 μm. The maximum contributions of amines to particles (0.21%) and amines-N to water-soluble organic nitrogen (WSON) (3.1%) were found at the sizes < 0.49 μm. The maximum contribution of amines-C to water-soluble organic carbon (WSOC) was 1.6% over the size range of 0.95–1.5 μm. The molar ratio of Ʃamines to ammonium ranged from 0.0068 to 0.0107 in particles with diameters <1.5 μm, and the maximum ratio occurred in the smallest particles (diameter< 0.49 μm). The average dry deposition flux and velocity of Ʃamines in PM 10 were 7.9 ± 1.6 μg m −2 d −1 and 0.084 ± 0.0021 cm s −1 , respectively. The results of this study provide essential information on the contribution of amines to secondary organic aerosols and dry removal mechanisms in urban areas. [ABSTRACT FROM AUTHOR]

While aerosol plays a significant role in the formation of cloud, the in-cloud scavenging of chemically segregated particle types were still insufficiently investigated and the controlling factors remain ambiguous. Several field observations were carried out during 2018–2021 at Mt. Tianjing (1690 m a.s.l.) in southern China, based on ground-based counterflow virtual impactor (GCVI)-single particle aerosol mass spectrometer (SPAMS), to investigate the in-cloud scavenging (activation) of various particle types, including black carbon (BC), organic-containing particles (OC), mineral dust (Dust), metal-containing particles (Metal), potassium-rich particles (K-rich) and sea salt (SS). GCVI was used to sample cloud droplet residual particles (Res) while PM 2.5 inlet sampled interstitial particles (Inter) during cloud events and ambient particles (Amb) on sunny days, respectively. Different types of particles were recognized based on spectral characteristics obtained by the SPAMS. Based on the coupled GCVI-SPAMS measurements, the number-based scavenging efficiencies (NSEs) of various particle types could be quantified. Besides, the influence of liquid water content (LWC), PM 2.5 , particle size, and mixing state on the NSEs were discussed. The NSE of SS was the highest (32.4%) while OC showed the lowest NSE (9.1%). Other particle types shared similar NSEs with all the detected particles, with an average of ∼20–25%. Apart from OC, NSEs of other types of particles increased with the increase of LWC and decreased with the increase of the concentration of PM 2.5 , suggesting that numerous PM 2.5 suppressed particles entering cloud droplets via competing for water vapor. The annual variations of NSEs were generally in accordance with LWC and PM 2.5 , reflecting the certain role of these environment conditions. The NSEs typically increased with particle size in a range of 0.2–2.0 μm, reflecting the dominant nucleation mechanism during in-cloud scavenging. Particles mixed with sulfate and nitrate were easier to be scavenged than those coated with organic compounds, e.g., the discrepancy reached 11.8% for the K-rich particles. [Display omitted] • In-cloud scavenging efficiencies for six chemically segregated aerosol types are firstly reported. • SS displayed the highest NSE (32.4% on average) while OC's NSE was the lowest (9.1%). • The annual variations of NSEs were generally in accordance with LWC and PM 2.5 level. • Sulfate and nitrate enhance the NSEs of BC and K-rich particles by ∼10% compare with organics. [ABSTRACT FROM AUTHOR]

In-cloud brown carbon (BrC) can change cloud lifetimes and radiative effects. However, little is known regarding its molecular-level composition. Herein, the molecular characteristics of water-soluble organic matter (WSOM) in cloud water were analyzed by Fourier transform ion cyclotron resonance mass spectrometry coupled with electrospray ionization (ESI) in negative mode. CHON formulas were dominant in WSOM and exhibited the highest level of aromaticity. Combined with the water-soluble BrC (WS-BrC) light-absorption coefficient (Abs 365), the principal component analysis indicated that WS-BrC light absorption was mainly affected by unsaturation, aromaticity, highly oxygenated compounds, and N-containing formulas. Thirteen important potential WS-BrC were identified based on a random forest regression model, which could explain 61.7% of the variation in Abs 365. Among them, C 7 H 6 N 2 O 5 , C 8 H 8 N 2 O 5 , C 9 H 10 N 2 O 5 , C 10 H 12 N 2 O 5 , C 8 H 10 O 5 S, and C 8 H 9 NO 7 S were identified as WS-BrC for the first time in clouds, and these may belong to dinitrophenols or nitrotyrosine, organosulfates, and their derivatives. These findings would improve our understanding of cloud WS-BrC composition. [Display omitted] • Molecular characteristics and optical properties of cloud water were simultaneously obtained. • CHON and CHO are the dominant groups of organics in cloud water. • CHON has relatively abundant aromatic structures and unsaturated bonds in cloud water. • A series of –N 2 O 5 and S-containing formulas were identified as brown carbon in cloud water. [ABSTRACT FROM AUTHOR]

Amines are ubiquitous in the environment and pose potential impacts on atmospheric chemistry; however, their seasonal variations and atmospheric processes remain unclear. In this study, a single-particle aerosol mass spectrometer is employed to investigate the seasonal variations of amine-containing particles as well as the oxidation of trimethylamine (TMA) in the urban region of Guangzhou, China. Number fractions of the amine-containing particles exhibit distinct seasonal variations, with higher fractions in spring and summer. Four amines, namely, TMA, diethylamine (DEA), dipropylamine, and tripropylamine are observed over all the seasons. DEA and TMA are the most dominant and account for approximately 90% of all these amine-containing particles. They are mainly clustered into eight types, comprised of internally mixed organics and elemental carbon (OCEC), OC–K, EC, Metal–rich, Dust, NaK–EC, Amine–rich, and high molecular weight organic compounds. DEA and TMA distribute differently over particle types and exhibit a distinct mixing state because of their different physicochemical properties. Compared with TMA, DEA is associated with more sulfate. The possible oxidation of TMA is also investigated, and the results indicate the potential contribution of aqueous oxidation or NO 3 radical oxidation to the formation of TMA oxide. Overall, the results improve the comprehension of the formation and evolution processes of amines in atmospheric environment. • The number fraction of amine-containing particles in spring/summer is higher. • Trimethylamine and diethylamine distribute differently over particle types. • Compared with trimethylamine, diethylamine is associated with more sulfate. • A large fraction of trimethylamine is observed to be oxidized mainly at night. [ABSTRACT FROM AUTHOR]