The M/G values of different sodium alginate were studied by means of H-NMR. The alginate fiber was prepared via wet-spinning technology. The effects of M/G, the concentration of sodium-alginate, the concentration of ...The M/G values of different sodium alginate were studied by means of H-NMR. The alginate fiber was prepared via wet-spinning technology. The effects of M/G, the concentration of sodium-alginate, the concentration of the coagulation bath and coagulating time on the absorptive ability of alginate fiber were discussed. The results show that the absorptive ability to different substances varies in such order： physiological saline 〉 blood 〉 tap water 〉distilled water. The absorptive ability of the alginate fiber increases with the increase of M/G value and the concentration of sodium-alginate. Gradually increasing the concntration of coagulation bath, it increases until the concentration is up to 5%. However, it reduces with lasting coagulating tine.展开更多
The ambient air quality has improved significantly under strict emission controls in Beijing,China over the last decade.Black carbon(BC),as a short-lived climate forcer in ambient aerosols,profoundly impacts the air q...The ambient air quality has improved significantly under strict emission controls in Beijing,China over the last decade.Black carbon(BC),as a short-lived climate forcer in ambient aerosols,profoundly impacts the air quality and climate.Previous studies have demonstrated a decline in the mass concentration of BC.In this study,we characterized the chemical compositions and size distributions of BC-containing particles during the cold season of 2022 in Beijing using state-of-the-art instruments capable of exclusively measuring BCcontaining particles.The optical properties of BC-containing particles were further calculated based on the Mie theory.Moreover,we compared the properties of BC-containing particles in 2022 with the results of previous studies.The results showed that the diameters of BC cores became larger while the coating thickness of BC-containing particles became thinner in 2022.For the coating materials,the mass fraction of nitrate increased obviously,and even replaced organic matter as the dominant component during the peak of the pollution period.Variations in chemical compositions and size distributions resulted in lower mass absorption cross-sections(MAC)of BC-containing particles from 10.5±1.1 m^(2)/g in 2016 to 7.3±0.8 m^(2)/g in 2022,reduced by 30.5%.Our results demonstrate the synergistic benefits of air pollution control in improving air quality and mitigating climate change.Therefore,the MAC of BC adopted in climate models should vary with the changing air pollution levels.This study emphasizes that it is imperative to conduct long-term observations of BC-containing particles to better estimate BC’s climate effects.展开更多
As an important component of carbonaceous matters,dissolved organic carbon(DOC)can absorb and scatter the solar radiation at ultraviolet and blue wavelengths.The wet deposition process has great impact on the con-cent...As an important component of carbonaceous matters,dissolved organic carbon(DOC)can absorb and scatter the solar radiation at ultraviolet and blue wavelengths.The wet deposition process has great impact on the con-centration and light absorption ability of precipitation DOC,affecting the climatic effect caused by DOC in the atmosphere.In this study,light absorption and fluorescence characteristics of precipitation DOC was investigated in the central Tibetan Plateau(TP).The results showed that the mean DOC concentration and mass absorption cross-section measured at 365 nm(MAC_(365))in Tanggula(TGL)station were 0.59±0.42 mg/L and 0.37±0.19 m^(2)/g,respectively,while both values showed much higher volatilities than those of aerosols.DOC concentrations had significant negative correlation with the precipitation amount,while MAC_(365)values increase with the precipitation amount in TGL station.Therefore,DOC with high light-absorbing ability was preferred to be retained in the atmosphere during wet deposition.In this study,precipitation DOC contained three fluorescent components(one humic-like component and two tyrosine-like components)mainly from local biomass burning sources.DOC concentration showed a negative relationship with MAC_(365)value in TGL station.The wet deposition of DOC with low light-absorbing ability can reduce the strong negative radiative forcing caused by secondary organic aerosol due to high proportion of DOC in secondary organic carbon.Similar phenomenon was also found in Nam Co,Lulang and Everest stations of previous study,which may have a potential impact on radiative forcing in the atmosphere of TP.展开更多
基金The Research Fund for the Doctoral Program of Higher Education(No. 20061065002)The Research on Science and Technology Item of Shandong Province (No. 2006GG3205005)
文摘The M/G values of different sodium alginate were studied by means of H-NMR. The alginate fiber was prepared via wet-spinning technology. The effects of M/G, the concentration of sodium-alginate, the concentration of the coagulation bath and coagulating time on the absorptive ability of alginate fiber were discussed. The results show that the absorptive ability to different substances varies in such order： physiological saline 〉 blood 〉 tap water 〉distilled water. The absorptive ability of the alginate fiber increases with the increase of M/G value and the concentration of sodium-alginate. Gradually increasing the concntration of coagulation bath, it increases until the concentration is up to 5%. However, it reduces with lasting coagulating tine.
基金supported by the National Key Research and Development Program of China(No.2022YFC3701000,task 1&4)the National Natural Science Foundation of China(Nos.22221004 and 41977179).
文摘The ambient air quality has improved significantly under strict emission controls in Beijing,China over the last decade.Black carbon(BC),as a short-lived climate forcer in ambient aerosols,profoundly impacts the air quality and climate.Previous studies have demonstrated a decline in the mass concentration of BC.In this study,we characterized the chemical compositions and size distributions of BC-containing particles during the cold season of 2022 in Beijing using state-of-the-art instruments capable of exclusively measuring BCcontaining particles.The optical properties of BC-containing particles were further calculated based on the Mie theory.Moreover,we compared the properties of BC-containing particles in 2022 with the results of previous studies.The results showed that the diameters of BC cores became larger while the coating thickness of BC-containing particles became thinner in 2022.For the coating materials,the mass fraction of nitrate increased obviously,and even replaced organic matter as the dominant component during the peak of the pollution period.Variations in chemical compositions and size distributions resulted in lower mass absorption cross-sections(MAC)of BC-containing particles from 10.5±1.1 m^(2)/g in 2016 to 7.3±0.8 m^(2)/g in 2022,reduced by 30.5%.Our results demonstrate the synergistic benefits of air pollution control in improving air quality and mitigating climate change.Therefore,the MAC of BC adopted in climate models should vary with the changing air pollution levels.This study emphasizes that it is imperative to conduct long-term observations of BC-containing particles to better estimate BC’s climate effects.
基金supported by the National Natural Science Foundation of China(42201158,42177366)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0605)+1 种基金Natural Science Foundation of Gansu Province,China(23JRRA656)the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2022).
文摘As an important component of carbonaceous matters,dissolved organic carbon(DOC)can absorb and scatter the solar radiation at ultraviolet and blue wavelengths.The wet deposition process has great impact on the con-centration and light absorption ability of precipitation DOC,affecting the climatic effect caused by DOC in the atmosphere.In this study,light absorption and fluorescence characteristics of precipitation DOC was investigated in the central Tibetan Plateau(TP).The results showed that the mean DOC concentration and mass absorption cross-section measured at 365 nm(MAC_(365))in Tanggula(TGL)station were 0.59±0.42 mg/L and 0.37±0.19 m^(2)/g,respectively,while both values showed much higher volatilities than those of aerosols.DOC concentrations had significant negative correlation with the precipitation amount,while MAC_(365)values increase with the precipitation amount in TGL station.Therefore,DOC with high light-absorbing ability was preferred to be retained in the atmosphere during wet deposition.In this study,precipitation DOC contained three fluorescent components(one humic-like component and two tyrosine-like components)mainly from local biomass burning sources.DOC concentration showed a negative relationship with MAC_(365)value in TGL station.The wet deposition of DOC with low light-absorbing ability can reduce the strong negative radiative forcing caused by secondary organic aerosol due to high proportion of DOC in secondary organic carbon.Similar phenomenon was also found in Nam Co,Lulang and Everest stations of previous study,which may have a potential impact on radiative forcing in the atmosphere of TP.
