The optical absorption of large molecular compounds HULIS(humic-like substances)can significantly impact the aerosol light absorption and radiative forcing,influencing cloud condensation nuclei formation and thus the ...The optical absorption of large molecular compounds HULIS(humic-like substances)can significantly impact the aerosol light absorption and radiative forcing,influencing cloud condensation nuclei formation and thus the climate and atmospheric environment.This study collected aerosol(PM_(2.5))samples from the summit of Mount Tai in North China to investigate the concentration,molecular composition,and optical properties of HULIS.The average concentration of HULIS in the PM_(2.5) in this study was 1.26±0.54μg/m^(3),comprising for 56%of the water-soluble organic carbon(WSOC),with levels lower than urban areas but higher than other mountainous regions.Mass spectrometry revealed that CHO and CHON components,with high aromaticity and phenolic groups,are major contributors to absorption and fluorescence.These results indicate that HULIS is mainly composed of lignin and proteins/amino sugars,derived from combustion and secondary formation,and possesses a high light absorption capacity(withMAE365(mass absorption efficiency)and AAE(A˚ngstrom exponent)indices of 0.62m^(2)/g and 4.99,respectively).Parallel factor analysis identified three fluorescence components of HULIS,with proportions of 60.8%for less oxygen humic-like substances,21.0%for high oxygen humic-like substances,and 18.2%for protein-like substances.Our study highlights the significance of the light-absorbing capacity and secondary formation of HULIS at Mount Tai,laying the groundwork for investigation into the climate effects,formation mechanisms,and sources of HULIS generation.展开更多
Humic-like substances(HULIS),a class of macromolecular photosensitizers,are major components of light-absorbing aerosols in the atmosphere.Due to the amphiphilic nature of HULIS,they tend to appear at the air-water in...Humic-like substances(HULIS),a class of macromolecular photosensitizers,are major components of light-absorbing aerosols in the atmosphere.Due to the amphiphilic nature of HULIS,they tend to appear at the air-water interface of atmospheric water.However,there have been limited studies on the photosensitized chemistry of HULIS at the air-water interface owing to the lack of methods with high interface selectivity.Here,a unique field-induced droplet ionization mass spectrometry(FIDI-MS)technique was used to investigate the photosensitized chemistry of several samples at the air-water interface.These samples include commercially available humic acid and the PM_(2.5)sample collected during Beijing′s severe winter haze in December 2016.Ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was also applied to analyze the atomic compositions,the degree of unsaturation and the aromaticity of these samples.Both TypeⅠand TypeⅡphotosensitized oxidation pathways were observed,which were postulated to be dictated by the packing density of the molecules at the air-water interface.These findings reveal that the photosensitization of HULIS at the air-water interface contributes greatly to the formation of atmospheric aerosols,further advancing our understanding of the important roles played by photosensitized chemistry in the atmosphere.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22176112 and 42307134)the Natural Science Foundation of Shandong Province(No.ZR2021MD028)the Natural Science Foundation of Qingdao(No.23–2-1–74-zyyd-jch).
文摘The optical absorption of large molecular compounds HULIS(humic-like substances)can significantly impact the aerosol light absorption and radiative forcing,influencing cloud condensation nuclei formation and thus the climate and atmospheric environment.This study collected aerosol(PM_(2.5))samples from the summit of Mount Tai in North China to investigate the concentration,molecular composition,and optical properties of HULIS.The average concentration of HULIS in the PM_(2.5) in this study was 1.26±0.54μg/m^(3),comprising for 56%of the water-soluble organic carbon(WSOC),with levels lower than urban areas but higher than other mountainous regions.Mass spectrometry revealed that CHO and CHON components,with high aromaticity and phenolic groups,are major contributors to absorption and fluorescence.These results indicate that HULIS is mainly composed of lignin and proteins/amino sugars,derived from combustion and secondary formation,and possesses a high light absorption capacity(withMAE365(mass absorption efficiency)and AAE(A˚ngstrom exponent)indices of 0.62m^(2)/g and 4.99,respectively).Parallel factor analysis identified three fluorescence components of HULIS,with proportions of 60.8%for less oxygen humic-like substances,21.0%for high oxygen humic-like substances,and 18.2%for protein-like substances.Our study highlights the significance of the light-absorbing capacity and secondary formation of HULIS at Mount Tai,laying the groundwork for investigation into the climate effects,formation mechanisms,and sources of HULIS generation.
基金the National Natural Science Foundation of China(42221001)the National Natural Science Foundation of China(22325402,22174073)+4 种基金the National Key R&D Program of China(2023YFE0124200)the Natural Science Foundation of Tianjin City(21JCJQJC00010)the Natural Science Foundation of Tianjin City(23ZYJDSS00030)the Nankai Cangzhou Chemistry(NCC)Fund(NCC2022PY05)the Haihe Laboratory of Sustainable Chemical Transformations and the Frontiers Science Center for New Organic Matter at Nankai University(63181206)。
文摘Humic-like substances(HULIS),a class of macromolecular photosensitizers,are major components of light-absorbing aerosols in the atmosphere.Due to the amphiphilic nature of HULIS,they tend to appear at the air-water interface of atmospheric water.However,there have been limited studies on the photosensitized chemistry of HULIS at the air-water interface owing to the lack of methods with high interface selectivity.Here,a unique field-induced droplet ionization mass spectrometry(FIDI-MS)technique was used to investigate the photosensitized chemistry of several samples at the air-water interface.These samples include commercially available humic acid and the PM_(2.5)sample collected during Beijing′s severe winter haze in December 2016.Ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was also applied to analyze the atomic compositions,the degree of unsaturation and the aromaticity of these samples.Both TypeⅠand TypeⅡphotosensitized oxidation pathways were observed,which were postulated to be dictated by the packing density of the molecules at the air-water interface.These findings reveal that the photosensitization of HULIS at the air-water interface contributes greatly to the formation of atmospheric aerosols,further advancing our understanding of the important roles played by photosensitized chemistry in the atmosphere.
