大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知...大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知和对其指标的量化描述。本文作者通过承担国家重点研发计划“区域大气氧化能力与空气质量的定量关系及调控原理”研究等项目,从大气化学基本理论入手,对AOC开展了系列研究,并在其量化表达方面取得了突破性进展。本文将围绕“大气氧化能力量化研究”这一科学问题,对这些进展进行简要的描述。首先在深入认知AOC内涵的基础上,分别从大气化学的热力学和动力学基本原理出发,构建了大气氧化能力表观指数(AOIe)和潜势指数(AOIp),并通过二者归一化指数日变化闭合研究,发现了非均相化学过程对AOC的贡献不容忽视。随着PM2.5污染的加重,无论夏季还是冬季,AOIe亦随之增加,但在冬季AOIp则出现了相反的情景,表现出AOIp的变化受气象条件的影响更大。AOC闭合研究思路用于大气OH自由基的储库分子HONO“未知源”研究,发现了北京大气HONO的重要非均相来源,阐释了MCM(Master Chemical Mechanism)机制对冬季AOC低估的重要原因。AOIp用于预测我国大气臭氧污染潜势格局,发现臭氧光化学生成表观潜势(AOIp_O_(3))与NO_(2)的光解系数[J(NO_(2))]直接相关,全国J(NO_(2))的年均值为4.39×10^(-3)s^(-1),高值区主要分布在四川、贵州、重庆和湖南等地。与其他化学反应氧化性指数对比,AOIe与AOIp组合指数更具准确性、普适性和实用性,可评价已发生的污染过程AOC的变化,亦可预测城市或区域重污染发生的可能性及其变化和格局。展开更多
Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-develo...Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-developed region in western China,while the rural Qinghai-Tibetan Plateau(QTP)lies west of the SCB.Previous regional and national atmospheric modeling studies have sug-gested that large areas in the SCB-to-QTP transect region experience excessive deposition of sulfur and nitrogen.In this study,we applied a passive monitoring method at 11 sites(one in urban Chengdu and 10 from fivenature reserves)in this transect region from September 2021 to October 2022 to confirm the high sulfur and nitrogen deposition fluxes and to understand the gaps between the modeling and observation results for this transect region.These observations suggest that the five reserves are under eutrophication risk,and only two reserves are partially under acidification risk.Owing to the complex topography and landscapes,both sulfur and nitrogen deposition and critical loads exhibit large spatial variations within a reserve,such as Mount Emei.Regional atmospheric modeling may not accurately capture the spatial variations in deposition fluxes within a reserve;however,it can capture general spatial patterns over the entire transect.This study demonstrates that a combination of state-of-the-art atmospheric chemical models and low-cost monitoring methods is helpful for ecological risk assessments at a regional scale.展开更多
Using the observation data in Yongxing Island,South China Sea(SCS)from December 2013 to November 2018,the multiple time scales variation of atmospheric CO_(2)and CH_(4)were analyzed to understand their temporal variat...Using the observation data in Yongxing Island,South China Sea(SCS)from December 2013 to November 2018,the multiple time scales variation of atmospheric CO_(2)and CH_(4)were analyzed to understand their temporal variation characteristics and controlling factors.The regional-averaged background mole fractions of CO_(2)and CH_(4)both show a single-period sinusoidal variation with a lower value at noon and a higher value in the wee hours.In the seasonal scale,they exhibited a significant seasonal difference with higher values in winter and lower values in summer.In the annual scale,CO_(2)and CH_(4)both show an increasing trend,with an annual growth rate of approximately 3.2 ppm and 12 ppb,respectively.The annual growth rate at this site was higher than the global average.The change in atmospheric CO_(2)and CH_(4)in Yongxing Island was probably caused by the higher emission of the surrounding areas and the airflows driven by monsoon.Hopefully,the long-term and high-resolution greenhouse gases(GHGs)dataset will aid relevent researchers and decision-makers in performing more in-depth studies for GHG sources in order to derive effective strategies.展开更多
During the 36th Chinese National Antarctic Research Expedition,aerosol samples were gathered from the Ross Sea in Antarctic to assess the climatic impact of the Australian fires that occurred in 2019-2020.The chemical...During the 36th Chinese National Antarctic Research Expedition,aerosol samples were gathered from the Ross Sea in Antarctic to assess the climatic impact of the Australian fires that occurred in 2019-2020.The chemical compositions,including levoglucosan(Lev)and its isomers,galactosan(Gan)and mannosan(Man),were analyzed.Principal component analysis helped identify the potential sources of these chemical components.By combining backward trajectories with the ratios of CLev/CMan and CMan/CGan,it was further inferred that Australia might be the potential source region for biomass burning.The radiative forcing resulting from biomass burning was evaluated using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART)model,which revealed that black carbon emitted from biomass burning could slightly warm the atmosphere(+0.52 W·m^(-2))while causing slightly cooling at the surface(-0.73 W·m^(-2))and the top of the atmosphere(-0.22 W·m^(-2))over the Ross Sea.展开更多
文摘大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知和对其指标的量化描述。本文作者通过承担国家重点研发计划“区域大气氧化能力与空气质量的定量关系及调控原理”研究等项目,从大气化学基本理论入手,对AOC开展了系列研究,并在其量化表达方面取得了突破性进展。本文将围绕“大气氧化能力量化研究”这一科学问题,对这些进展进行简要的描述。首先在深入认知AOC内涵的基础上,分别从大气化学的热力学和动力学基本原理出发,构建了大气氧化能力表观指数(AOIe)和潜势指数(AOIp),并通过二者归一化指数日变化闭合研究,发现了非均相化学过程对AOC的贡献不容忽视。随着PM2.5污染的加重,无论夏季还是冬季,AOIe亦随之增加,但在冬季AOIp则出现了相反的情景,表现出AOIp的变化受气象条件的影响更大。AOC闭合研究思路用于大气OH自由基的储库分子HONO“未知源”研究,发现了北京大气HONO的重要非均相来源,阐释了MCM(Master Chemical Mechanism)机制对冬季AOC低估的重要原因。AOIp用于预测我国大气臭氧污染潜势格局,发现臭氧光化学生成表观潜势(AOIp_O_(3))与NO_(2)的光解系数[J(NO_(2))]直接相关,全国J(NO_(2))的年均值为4.39×10^(-3)s^(-1),高值区主要分布在四川、贵州、重庆和湖南等地。与其他化学反应氧化性指数对比,AOIe与AOIp组合指数更具准确性、普适性和实用性,可评价已发生的污染过程AOC的变化,亦可预测城市或区域重污染发生的可能性及其变化和格局。
基金Under the auspices of National Natural Science Foundation of China(No.41929002)Science and Technology Department of Sichuan Province(No.2021YFS0338)。
文摘Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-developed region in western China,while the rural Qinghai-Tibetan Plateau(QTP)lies west of the SCB.Previous regional and national atmospheric modeling studies have sug-gested that large areas in the SCB-to-QTP transect region experience excessive deposition of sulfur and nitrogen.In this study,we applied a passive monitoring method at 11 sites(one in urban Chengdu and 10 from fivenature reserves)in this transect region from September 2021 to October 2022 to confirm the high sulfur and nitrogen deposition fluxes and to understand the gaps between the modeling and observation results for this transect region.These observations suggest that the five reserves are under eutrophication risk,and only two reserves are partially under acidification risk.Owing to the complex topography and landscapes,both sulfur and nitrogen deposition and critical loads exhibit large spatial variations within a reserve,such as Mount Emei.Regional atmospheric modeling may not accurately capture the spatial variations in deposition fluxes within a reserve;however,it can capture general spatial patterns over the entire transect.This study demonstrates that a combination of state-of-the-art atmospheric chemical models and low-cost monitoring methods is helpful for ecological risk assessments at a regional scale.
基金supported by the National Natural Science Foundation of China(No.41907180).
文摘Using the observation data in Yongxing Island,South China Sea(SCS)from December 2013 to November 2018,the multiple time scales variation of atmospheric CO_(2)and CH_(4)were analyzed to understand their temporal variation characteristics and controlling factors.The regional-averaged background mole fractions of CO_(2)and CH_(4)both show a single-period sinusoidal variation with a lower value at noon and a higher value in the wee hours.In the seasonal scale,they exhibited a significant seasonal difference with higher values in winter and lower values in summer.In the annual scale,CO_(2)and CH_(4)both show an increasing trend,with an annual growth rate of approximately 3.2 ppm and 12 ppb,respectively.The annual growth rate at this site was higher than the global average.The change in atmospheric CO_(2)and CH_(4)in Yongxing Island was probably caused by the higher emission of the surrounding areas and the airflows driven by monsoon.Hopefully,the long-term and high-resolution greenhouse gases(GHGs)dataset will aid relevent researchers and decision-makers in performing more in-depth studies for GHG sources in order to derive effective strategies.
基金supported by the National Natural Science Foundation of China (Grant nos. 41941014 and 41930532)financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change”(Grant no. IRASCC 01-01-02E)。
文摘During the 36th Chinese National Antarctic Research Expedition,aerosol samples were gathered from the Ross Sea in Antarctic to assess the climatic impact of the Australian fires that occurred in 2019-2020.The chemical compositions,including levoglucosan(Lev)and its isomers,galactosan(Gan)and mannosan(Man),were analyzed.Principal component analysis helped identify the potential sources of these chemical components.By combining backward trajectories with the ratios of CLev/CMan and CMan/CGan,it was further inferred that Australia might be the potential source region for biomass burning.The radiative forcing resulting from biomass burning was evaluated using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART)model,which revealed that black carbon emitted from biomass burning could slightly warm the atmosphere(+0.52 W·m^(-2))while causing slightly cooling at the surface(-0.73 W·m^(-2))and the top of the atmosphere(-0.22 W·m^(-2))over the Ross Sea.
