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Chemical characteristics of long-term acid rain and its impact on lake water chemistry:A case study in Southwest China

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Journal of Environmental Sciences 2024年第4期138卷 121-131页

作者： Liuyi Zhang JiaWang Shuxiao Wang Chunbo Wang fumo yang Tingzhen Li Chongqing Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir Chongqing Three Gorges UniversityWanzhou 404000China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China College of Carbon Neutrality Future Technology Sichuan UniversityChengdu 610065China National Engineering Research Center on Flue Gas Desulfurization Chengdu 610065China

The chemical composition of acid rain and its impact on lake water chemistry in Chongqing,China,from 2000 to 2020 were studied in this study.The regional acid rain intensity is affected jointly by the acid gas emissions and the neutralization of alkaline substances.The pH of precipitation experienced three stages of fluctuating decline,continuous improvement,and a slight correction.Precipitation pH showed inflection points in 2010,mainly due to the total control actions of SO_(2)and NO_(x)implemented in 2011.The total ion concentrations in rural areas and urban areas were 489.08μeq/L and 618.57μeq/L,respectively.The top four ions were SO_(4)^(2-),Ca^(2+),NH_(4)^(+)and NO_(3)^(-),which accounted for more than 90%of the total ion concentration,indicating the anthropogenic effects.Before 2010,SO_(4)^(2-)fluctuated greatly while NO_(3)^(-)continued to rise;however,after 2010,both SO_(4)^(2-)and NO_(3)^(-)began to decline rapidly,with the rates of-12.03μeq/(L·year)and-4.11μeq/(L·year).Because the decline rate of SO_(4)^(2-)was 2.91 times that of NO_(3)^(-),the regional acid rain has changed from sulfuric acid rain to mixed sulfuric and nitric acid rain.The lake water is weakly acidic,with an average pH of 5.86,and the acidification frequency is 30.00%.Acidification of lake water is jointly affected by acid deposition and acid neutralization capacity of lake water.Acid deposition has a profound impact on water acidification,and nitrogen(N)deposition,especially reduced N deposition,should be the focus of future research.

关键词： Acid rain Chemical composition Neutralization Nitrogen deposition Water acidification

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An observed nocturnal ozone transport event in the Sichuan Basin,Southwestern China

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Journal of Environmental Sciences 2024年第4期138卷 10-18页

作者： Ruyue Guo Guangming Shi Dan Zhang yang Chen Chao Peng Chongzhi Zhai fumo yang Department of Environmental Science and Engineering Sichuan UniversityChengdu 610065China College of Carbon Neutrality Future Technology Sichuan UniversityChengdu 610065China National Engineering Research Center on Flue Gas Desulfurization Chengdu 610065China Chongqing Academy of Eco-Environmental Science Chongqing 401147China Research Center for Atmospheric Environment Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China Key Laboratory for Urban Atmospheric Environment Integrated Observation&Pollution Prevention and Control of Chongqing Chongqing 401147China

The ozone(O_(3))pollution in China drew lots of attention in recent years,and the Sichuan Basin(SCB)was one of the regions confronting worsening O_(3)pollution problem.Many previous studies have shown that regional transport is an important contributor to O_(3)pollution.However,very few features of the O_(3)profile during transport have been reported,especially in the border regions between different administrative divisions.In this study,we conducted tethered balloon soundings in SCB during the summer of 2020 and captured a nocturnal O_(3)transport event during the campaign.Vertically,the O_(3)transport occurred in the bottom of the residual layer,between 200 and 500 m above ground level.Horizontally,the transport pathway was directed from southeast to northwest based on the analysis of the wind field and air mass trajectories.The effect of transport in the residual layer on the surface O_(3)concentration was related to the spatial distribution of O_(3).For cities with high O_(3)concentrations in the upwind region,the transport process would bring clean air masses and abate pollution.For downwind lightly polluted cities,the transport process would slow down the decreasing or even increase the surface O_(3)concentration during the night.We provided observational facts on the profile features of a transboundary O_(3)transport event between two provincial administrative divisions,which implicated the importance of joint prevention and control measures.However,the sounding parameters were limited and the quantitative analysis was preliminary,more integrated,and thorough studies of this topic were called for in the future.

关键词： Ozone Sichuan basin Transport event Vertical profile

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Biogenic volatile organic compounds dominated the near-surface ozone generation in Sichuan Basin,China,during fall and wintertime

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Journal of Environmental Sciences 2024年第7期141卷 215-224页

作者： Dasheng Huang Qing Li Yan Han Shi-Yong Xia Jiawei Zhou Hanxiong Che Keding Lu fumo yang Xin Long yang Chen Research Center for Atmospheric Environment Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China College of Resources and Environment Chongqing SchoolUniversity of the Chinese Academy of Sciences(UCAS Chongqing)Chongqing 400714China College of Environmental and Chemical Engineering Chongqing Three Gorges UniversityChongqing 404199China Key Laboratory for Urban Habitat Environmental Science and Technology School of Environment and EnergyPeking University Shenzhen Graduate SchoolLishui RoadNanshan DistrictShenzhen 518055China SKL-ESPC and BIC-ESAT College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China College of Architecture&Environment Sichuan UniversityChengdu 610065China

The complex air pollution driven by both Ozone(O_(3))and fine particulate matter(PM2.5)sig nificantly influences the air quality in the Sichuan Basin(SCB).Understanding the O_(3)for mation during autumn and winter is necessary to understand the atmospheric oxidative capacity.Therefore,continuous in-site field observations were carried out during the late summer,early autumn and winter of 2020 in a rural area of Chongqing.The total volatile organic compounds(VOCs)concentration reported by a Proton-Transfer-Reaction Time-of Flight Mass Spectrometry(PTR-ToF-MS)were 13.66±9.75 ppb,5.50±2.64 ppb,and 9.41±5.11 ppb in late summer,early autumn and winter,respectively.The anthropogenic VOCs(AVOCs)and biogenic VOCs(BVOCs)were 8.48±7.92 ppb and 5.18±2.99 ppb in late sum mer,3.31±1.89 ppb and 2.19±0.93 ppb in autumn,and 6.22±3.99 ppb and 3.20±1.27ppb in winter.A zero-dimensional atmospheric box model was employed to investigate the sensitivity of O_(3)-precursors by relative incremental reactivity(RIR).The RIR values of AV OCs,BVOCs,carbon monoxide(CO),and nitrogen oxides(NOx)were 0.31,0.71,0.09,and-0.36 for late summer,0.24,0.59,0.22,and-0.38 for early autumn,and 0.30,0.64,0.33 and-0.70 for winter,and the results showed that the O_(3)formation of sampling area was in the VOC-limited region,and O_(3)was most sensitive to BVOCs(with highest RIR values,>0.6)This study can be helpful in understanding O_(3)formation and interpreting the secondary formation of aerosols in the winter.

关键词： VOCs PTR-MS Model Ozone

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Data augmentation for bias correction in mapping PM_(2.5) based on satellite retrievals and ground observations

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Geoscience Frontiers 2024年第1期15卷 17-28页

作者： Tan Mi Die Tang Jianbo Fu Wen Zeng Michael L.Grieneisen Zihang Zhou Fengju Jia fumo yang Yu Zhan College of Carbon Neutrality Future Technology Sichuan UniversityChengduSichuan 610065China Department of Environmental Science and Engineering Sichuan UniversityChengduSichuan 610065China Institute for Disaster Management and Reconstruction Sichuan UniversityChengduSichuan 610200China Department of Land Airand Water ResourcesUniversity of CaliforniaDavisCA 95616United States Chengdu Academy of Environmental Sciences ChengduSichuan 610072China Sichuan Chengdu Ecological and Environment Monitoring Center ChengduSichuan 610011China

As most air quality monitoring sites are in urban areas worldwide,machine learning models may produce substantial estimation bias in rural areas when deriving spatiotemporal distributions of air pollutants.The bias stems from the issue of dataset shift,as the density distributions of predictor variables differ greatly between urban and rural areas.We propose a data-augmentation approach based on the multiple imputation by chained equations(MICE-DA)to remedy the dataset shift problem.Compared with the benchmark models,MICE-DA exhibits superior predictive performance in deriving the spatiotemporal distributions of hourly PM2.5 in the megacity(Chengdu)at the foot of the Tibetan Plateau,especially for correcting the estimation bias,with the mean bias decreasing from-3.4µg/m3 to-1.6µg/m3.As a complement to the holdout validation,the semi-variance results show that MICE-DA decently preserves the spatial autocorrelation pattern of PM2.5 over the study area.The essence of MICE-DA is strengthening the correlation between PM2.5 and aerosol optical depth(AOD)during the data augmentation.Consequently,the importance of AOD is largely enhanced for predicting PM2.5,and the summed relative importance value of the two satellite-retrieved AOD variables increases from 5.5%to 18.4%.This study resolved the puzzle that AOD exhibited relatively lower importance in local or regional studies.The results of this study can advance the utilization of satellite remote sensing in modeling air quality while drawing more attention to the common dataset shift problem in data-driven environmental research.

关键词： Aerosol optical depth Dataset shift Spatiotemporal Distribution Air quality monitoring Multiple imputation by chained equations

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Exhaust emission inventory of typical construction machinery and its contribution to atmospheric pollutants in Chengdu, China

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Journal of Environmental Sciences 2023年第3期125卷 761-773页

作者： Wubo Fan Wenju Jiang Junhui Chen fumo yang Jun Qian Hong Ye Institute of New Energy and Low-Carbon Technology Sichuan University(Wangjiang Campus)Chengdu 610207China Sichuan Academy of Environmental Sciences Chengdu 610041China Tsinghua University Beijing 100084China

To study the emission characteristics of typical construction machinery in Chengdu,12 construction machinery (excavators,bulldozers,loaders,and forklifts) under idling mode,moving mode,and working mode,were tested using a portable emission measurement system(PEMS).Under three operating modes,the typical construction machinery in the working mode was higher in the fuel-based average emission factors of PM_(2.5)and NOx,while the fuel-based average emission factors of HC and CO were higher in idling mode.Integrated the results of investigation on ownership and activity levels of construction machinery,an exhaust emission inventory of typical construction machinery of Chengdu in 2018 was established according to the recommendation method.The annual emission of PM_(2.5),NOx,HC,and CO were 1.67×106,1.61×108,3.83×106,and 1.26×107kg,respectively,and the excavator contributed the maximum emissions,accounting for an average proportion of 43.95%.The emission of construction machinery in Chengdu exhibited a clear monthly trend,with the highest from April to October and the lowest from November to March.In addition,the exhaust emissions presented an obvious spot-like characteristics,and the high-value areas were mainly concentrated in the surrounding suburban counties such as Shuangliu Wenjiang etc.To reduce pollution from construction machinery and improve the quality of the atmospheric environment,more effective measures on housing construction and municipal construction should be taken in those districts in Chengdu.

关键词： Construction equipment PEMS Emission factor Emission inventory Contribution Chengdu

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Characteristics of ambient volatile organic compounds during spring O_(3) pollution episode in Chengdu,China

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Journal of Environmental Sciences 2022年第4期34卷 115-125页

作者： Dongyang Chen Li Zhou Chen Wang Hefan Liu yang Qiu Guangming Shi Danlin Song Qinwen Tan fumo yang College of Architecture and Environment Sichuan UniversityChengdu 610065China Chengdu Academy of Environmental Sciences Chengdu 610000China

Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.

关键词： Volatile organic compounds Ozone sensitivity Observation-based box model Source apportionments Chengdu

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Progressively narrow the gap of PM_(2.5) pollution characteristics at urban and suburban sites in a megacity of Sichuan Basin, China

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Journal of Environmental Sciences 2023年第4期126卷 708-721页

作者： Ning Wang Li Zhou Miao Feng Tianli Song Zhuoran Zhao Danlin Song Qinwen Tan fumo yang College of Architecture and Environment Sichuan UniversityChengdu 610065China Chengdu Academy of Environmental Sciences Chengdu 610072China

Nowadays,the fine particle pollution is still severe in some megacities of China,especially in the Sichuan Basin,southwestern China.In order to understand the causes,sources,and impacts of fine particles,we collected PM_(2.5)samples and analyzed their chemical composition in typical months from July 2018 to May 2019 at an urban and a suburban (background) site of Chengdu,a megacity in this region.The daily average concentrations of PM_(2.5)ranged from5.6-102.3μg/m^(3)and 4.3-110.4μg/m^(3)at each site.Secondary inorganics and organic matters were the major components in PM_(2.5)at both sites.The proportion of nitrate in PM_(2.5)has exceeded sulfate and become the primary inorganic component.SO_(2)was easier to transform into sulfate in urban areas because of Mn-catalytic heterogeneous reactions.In contrast,NO_(2)was easily converted in suburbs with high aerosol water content.Furthermore,organic carbon in urban was much greater than that in rural,other than elemental carbon.Element Cr and As were the key cancer risk drivers.The main sources of PM_(2.5)in urban and suburban areas were all secondary aerosols (42.9%,32.1%),combustion (16.0%,25.2%) and vehicle emission (15.2%,19.2%).From clean period to pollution period,the contributions from combustion and secondary aerosols increased markedly.In addition to tightening vehicle controls,urban areas need to restrict emissions from steel smelters,and suburbs need to minimize coal and biomass combustion in autumn and winter.

关键词： PM_(2.5) Seasonal variation Regional characteristics Chemical compositions Source apportionment Chengdu

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Biogenic volatile organic compound emission patterns and secondary pollutant formation potentials of dominant greening trees in Chengdu,southwest China

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Journal of Environmental Sciences 2022年第4期34卷 179-193页

作者： Liping Liu Barnabas C.Seyler Hefan Liu Li Zhou Dongyang Chen Song Liu Chang Yan fumo yang Danlin Song Qinwen Tan Fengju Jia Cheng Feng Qiuwei Wang Yunchun Li College of Architecture and Environment Sichuan UniversityChengdu 610065China College of Science Sichuan Agricultural UniversityYa’an 625014China Chengdu Academy of Environmental Sciences Chengdu 610000China Chengdu Ecological and Environmental Monitoring Center Chengdu 610000China Longquanyi Ecology and Environment Bureau Chengdu 610000China

Integral to the urban ecosystem,greening trees provide many ecological benefits,but the active biogenic volatile organic compounds(BVOCs)they release contribute to the production of ozone and secondary organic aerosols,which harm ambient air quality.It is,therefore,necessary to understand the BVOC emission characteristics of dominant greening tree species and their relative contribution to secondary pollutants in various urban contexts.Consequently,this study utilized a dynamic enclosure system to collect BVOC samples of seven dominant greening tree species in urban Chengdu,Southwest China.Gas chromatography/mass spectrometry was used to analyze the BVOC components and standardized BVOC emission rates of each tree species were then calculated to assess their relative potential to form secondary pollutants.We found obvious differences in the composition of BVOCs emitted by each species.Ficus virens displayed a high isoprene emission rate at31.472μgC/(gdw(g dry weight)·hr),while Cinnamomum camphora emitted high volumes of D-Limonene at 93.574μgC/(gdw·hr).In terms of the BVOC emission rates by leaf area,C.camphora had the highest emission rate of total BVOCs at 13,782.59μgC/(m^(2)·hr),followed by Cedrus deodara with 5466.86μgC/(m^(2)·hr).Ginkgo biloba and Osmanthus fragrans mainly emitted oxygenated VOCs with lower overall emission rates.The high BVOC emitters like F.virens,C.camphora,and Magnolia grandiflora have high potential for significantly contributing to environmental secondary pollutants,so should be cautiously considered for future planting.This study provides important implications for improving urban greening efforts for subtropical Chinese urban contexts,like Chengdu.

关键词： Biogenic volatile organic compounds(BVOCs) Dynamic enclosure system Emission characteristics Secondary pollutants

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Effects of relative humidity and PM2.5 chemical compositions on visibility impairment in Chengdu, China

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Journal of Environmental Sciences 2019年第12期31卷 15-23页

作者： Fan Liu Qinwen Tan Xia Jiang fumo yang Wenju Jiang College of Architecture&Environment Sichuan UniversityChengdu 610065China Chengdu Academy of Environmental Sciences Chengdu 610072China National Engineering Research Center/or Flue Gas Desul/Urization Chengdw 610065China

To better understand the potential causes of visibility impairment in autumn and winter in Chengdu,relative humidity(RH),visibility,the concentrations of PM2.5 and its chemical components were on-line measured continuously in Chengdu from Nov.2016 to Jan.2017.Six obvious haze episodes occurred in Chengdu,with the total time of haze episodes accounted for more than 90%of the total observation period,and higher NO2 concentrations and RH were related to the high particle concentrations in haze episodes.The visibility decreased in a non-linear tendency under different RH conditions with the increase of PM2.5 concentrations,which was more sensitive to RH under lower PM2.5 concentrations.The threshold concentration of PM2.5 got more smaller with the increase of RH.During the entire observation period,organic matter(OM)was the largest contributor(31.12%to extinction coefficient(bext)),followed by NH4NO3 and(NH4)2SO4 with 28.03%and 23.01%,respectively.However,with the visibility impairment from Type I(visibility>10 km)to Type IV(visibility≤2 km),the contribution of OM to bextdecreased from 38.12%to 26.77%,while the contribution of NH4NO3 and(NH4)2SO4 to bextincreased from 19.09%and 20.20%to 34.29%and 24.35%,respectively,and NH4NO3 became the largest contributor to bextat Type IV.The results showed that OM and NH4NO3 were the key components of PM2.5 for visibility impairment in Chengdu,indicating that the control of precursors emissions of carbonaceous species and NH4NO3 could effectively improve the visibility in Chengdu.

关键词： Visibility impairment PM2.5 chemical composition Relative humidity Light extinction coefficient Secondary formation

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中国大气逆温的时空分布特征

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高原气象 2024年第2期43卷 434-449页

作者：万超悦徐婷婷王艳刘甚蓝杨复沫成都理工大学生态环境学院四川成都610059 四川大学建筑与环境学院四川成都610065

大气逆温在气象研究和空气质量研究中有非常重要的意义。本研究采用2011-2020年ERA5逐时温度廓线数据分析西北、华北、东北、西南、华东、华南六个地区的低空大气逆温特征。从日变化来看,逆温频率、逆温强度多在07:00(北京时,下同)达到... 详细信息

大气逆温在气象研究和空气质量研究中有非常重要的意义。本研究采用2011-2020年ERA5逐时温度廓线数据分析西北、华北、东北、西南、华东、华南六个地区的低空大气逆温特征。从日变化来看,逆温频率、逆温强度多在07:00(北京时,下同)达到最大,最高分别可达70%和2℃左右,逆温厚度多在11:00-18:00达到最大值。从月变化上看,站点逆温特征均在1-2月和12月达到最大值,6-8月达到最小值,部分站点1月逆温频率最高可到90%,逆温强度可达3℃以上,逆温厚度整体多集中在200~400 m。从年变化上看,多数站点逆温特征变化较小,逆温频率、逆温强度、逆温厚度年份波动分别约在10%、0.4℃、60 m之间,东北各站点逆温特征总体呈下降趋势,华东、华南各站点逆温特征总体无明显上升或下降趋势。逆温特征在时间上的差异多与地面辐射冷却和天气气候相关。从空间分布来看,东北、华东和华南临海地区,受海洋上空环流所带来的暖空气影响,逆温更易于形成,逆温频率区域均值(分别为44.5%、48.7%、48.65%)总体高于西北(23.4%)、西南(13.4%)和华北地区(21.84%)。西北、华东及华南沿海地区逆温强度最大,厚度最厚,逆温强度和厚度整体在1.5℃和300 m以上,西南地区环境潮湿多云不利于形成逆温层,逆温强度和厚度最小。本研究可为后续探究我国不同地区大气污染物在垂直方向上的累积和扩散提供科学参考。

关键词：逆温逆温频率逆温强度逆温厚度逆温区域特征

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