We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),org...We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.展开更多
随着数字音源的普及,数模转换器(Digital to Analog Converter, DAC)成为音频设备中不可或缺的元件,其精度往往决定着整个系统的信号保真度。基于此,利用噪声整形技术对用于高精度音频DAC的Sigma-Delta调制器进行设计和现场可编程门阵列...随着数字音源的普及,数模转换器(Digital to Analog Converter, DAC)成为音频设备中不可或缺的元件,其精度往往决定着整个系统的信号保真度。基于此,利用噪声整形技术对用于高精度音频DAC的Sigma-Delta调制器进行设计和现场可编程门阵列(Field Programmable Gate Array, FPGA)实现。通过搭建测试系统,测试结果表明,所设计的Sigma-Delta调制器在输入信号为1 411.2 kHz采样频率、1 kHz频率、0 dBFS(Full Scale)幅度的正弦信号条件下,其输出信噪比(Signal to Noise Ratio, SNR)可达107.4 dB;当输入信号频率在音频频带内时(输入信号幅度为0dBFS),其输出SNR稳定保持在104 dB以上;并可用于WAV音乐播放器中。展开更多
This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data fr...This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and 2020.The spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural activities.NH_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to 2020.The highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to 2020.Agricultural emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban zones.Regions within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)VCDs.The rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem model.The concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)VCDs.This emphasizes the crucial role of environmental policies targeting the reduction of these acidic gases.Effective emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.展开更多
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20240036)the National Natural Science Foundation of China(Grant Nos.U24A20515,22276099,and 22361162668)Guangxi Key Research and Development Program,China(Grant No.Guike AB24010074)。
文摘We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.
基金supported by the Joint Funds of the National Natural Science Foundation of China(No.U21A2027)the New Cornerstone Science Foundation through the XPLORER PRIZE(2023-1033).
文摘This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and 2020.The spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural activities.NH_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to 2020.The highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to 2020.Agricultural emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban zones.Regions within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)VCDs.The rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem model.The concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)VCDs.This emphasizes the crucial role of environmental policies targeting the reduction of these acidic gases.Effective emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.
