Triplet-State Organic Matter in Atmospheric Aerosols: Formation Characteristics and Potential Effects on Aerosol Aging

2021 ◽  
pp. 118343
Author(s):  
Qingcai Chen ◽  
Zhen Mu ◽  
Li Xu ◽  
Mamin Wang ◽  
Jin Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Triplet State ◽  
Atmospheric Aerosols ◽  
Aerosol Aging

scholarly journals Triplet State Formation of Chromophoric Dissolved Organic Matter in Atmospheric Aerosols: Characteristics and Implications

2020 ◽  
Author(s):  
Qingcai Chen ◽  
Zhen Mu ◽  
Li Xu ◽  
Mamin Wang ◽  
Jin Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Triplet State ◽  
Atmospheric Aerosols ◽  
Formation Rate ◽  
Chromophoric Dissolved Organic Matter ◽  
Biomass Combustion ◽  
Triplet States ◽  
Ambient Aerosols ◽  
Paramagnetic Resonance

Abstract. There is chromophore dissolved organic matter (CDOM) in the atmosphere, which may form triplet-state chromophoric dissolved organic matter (3CDOM*) to further driving the formation of reactive oxygen species (ROS) under solar illumination. 3CDOM* contributes significantly to aerosol photochemistry and plays an important role in aerosol aging. We quantify the ability to form 3CDOM* and drive the formation of ROS by primary, secondary and ambient aerosols. Biomass combustion has the strongest 3CDOM* generation capacity and the weakest vehicle emission capacity. Ambient aerosol has a stronger ability to generate 3CDOM* in winter than in summer. Most of the triplet states generation conform to first-order reaction, but some of them do not due to the different quenching mechanism. The structural-activity relationship between the CDOM type and the 3CDOM* formation capacity shows that the two types of CDOM identified, which similar to the nitrogen-containing chromophores contributed 88 % to the formation of 3CDOM*. The estimated formation rate of 3CDOM* can reach ~ 100 μmol m−3 h−1 in the atmosphere in Xi'an, China, which is approximately one hundred thousand-times the hydroxyl radical (•OH) production. This study verified that 3CDOM* drives at least 30 % of the singlet oxygen (1O2) and 31 % of the •OH formed by aerosols using the spin trapping and electron paramagnetic resonance technique.

scholarly journals Formation characteristics of aerosol triplet state and coupling effect between the separated components with different polarity

2021 ◽  
Author(s):  
Dongjie Guan ◽  
Qingcai Chen ◽  
Jinwen Li ◽  
Hao Li ◽  
Lixin Zhang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Triplet State ◽  
Atmospheric Aerosols ◽  
Coupling Effect ◽  
Critical Role ◽  
High Energy ◽  
Water Soluble ◽  
Ros Generation ◽  
Triplet States ◽  
Leading Role

Abstract. Atmospheric aerosols contain organic matter that can form triplet state (3C*) excited by sunlight, which plays a critical role in the aging process of aerosols. In order to understand the triplet state reaction mechanism of complex aerosol components, the formation characteristics of 3C* in the aerosol components with different polarity, i.e., the highly polar water-soluble matter (HP-WSM), humic-like substances (HULIS) and methanol-soluble matter (MSM) were investigated. The coupling effect of generation of 3C* and reactive oxygen species (ROS) between different aerosol components was also examined. The results show that the 3C* generation characteristics is strongly dependent on the polarity of these components. HULIS has the strongest generation ability of 3C*, and the MSM contribute the most to the total generation of 3C*. It is found that the high-energy triplet states (ET ≥ 250 kJ mol−1) of HULIS and HP-WSM components account for up to 80 %. These 3C* has an important contribution to the photochemically generation of ROS, and the generated ROS of different components are also different, which is determined by the chromophore composition of complex organic matter. Tyrosine-like chromophore is the main substance leading to the formation of water-soluble 3C*, whilethe highly oxidized HULIS chromophore plays a leading role in the water-insoluble component. This study also found that there is a coupling effect between HP-WSM and HULIS on 3C* and ROS generation. The 3C* generation rate increases by about 40 % after mixing, but the generation of 1O2 is severely reduced. Overall, this study provides deep insights into the generation characteristics of the triplet state of atmospheric aerosols.

scholarly journals Impact of in-cloud aqueous processes on the chemical compositions and morphology of individual atmospheric aerosols

2020 ◽  
Vol 20 (22) ◽  
pp. 14063-14075
Author(s):  
Yuzhen Fu ◽  
Qinhao Lin ◽  
Guohua Zhang ◽  
Yuxiang Yang ◽  
Yiping Yang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atmospheric Aerosols ◽  
Chemical Reactivity ◽  
Chemical Compositions ◽  
Refractory Mixture ◽  
Cloud Processing ◽  
Microphysical Properties ◽  
Heterogeneous Chemical ◽  
Individual Particles

Abstract. The composition, morphology, and mixing structure of individual cloud residues (RES) and interstitial particles (INT) at a mountaintop site were investigated. Eight types of particles were identified, including sulfate-rich (S-rich), S-organic matter (OM), aged soot, aged mineral dust, aged fly ash, aged metal, refractory, and aged refractory mixture. A shift of dominant particle types from S-rich (29 %) and aged soot (27 %) in the INT to aged refractory mixture (23 %) and S-OM (22 %) in the RES is observed. In particular, particles with organic shells are enriched in the RES (27 %) relative to the INT (12 %). Our results highlight that the formation of more oxidized organic matter in the cloud contributes to the existence of organic shells after cloud processing. The fractal dimension (Df), a morphologic parameter to represent the branching degree of particles, for soot particles in the RES (1.82 ± 0.12) is lower than that in the INT (2.11 ± 0.09), which indicates that in-cloud processes may result in less compact soot. This research emphasizes the role of in-cloud processes in the chemistry and microphysical properties of individual particles. Given that organic coatings may determine the particle hygroscopicity, activation ability, and heterogeneous chemical reactivity, the increase of OM-shelled particles upon in-cloud processes should have considerable implications.

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