Response of organic aerosol characteristics to emission reduction in Yangtze River Delta region

● The emission reduction causes significant change in organic aerosol composition. ● The atmospheric oxidizing capacity improved during emission reduction. ● The mixed oxygenated organic aerosol contributed higher during emission reduction. Organic aerosol (OA) is a major component of atmospheric particulate matter (PM) with complex composition and formation processes influenced by various factors. Emission reduction can alter both precursors and oxidants which further affects secondary OA formation. Here we provide an observational analysis of secondary OA (SOA) variation properties in Yangtze River Delta (YRD) of eastern China in response to large scale of emission reduction during Chinese New Year (CNY) holidays from 2015 to 2020, and the COVID-19 pandemic period from January to March, 2020. We found a 17% increase of SOA proportion during the COVID lockdown. The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions. Two types of oxygenated OA (OOA) influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region. Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.     

新型冠状病毒肺炎疫情医疗废物应急管理与处置

基于我国新型冠状病毒肺炎疫情医疗废物应急管理与处置体系建立过程,分析疫情初期医疗废物管理与处置短板,预测医疗废物产生量随患者人数发展的变化,提出医疗废物突出问题的解决方案。结果表明：及时构建重大疫情医疗废物全过程应急管理与处置技术体系有利于促进医疗废物分类分流管理与处置,迅速提升医疗废物应急处置能力;修正湖北省涉疫情医疗废物和医疗废物平均产生系数分别为3.35 kg/（人·d）和5.15 kg/（人·d）;截至2020年6月6日,全国医疗废物处置能力从疫情前的4 902.8 t/d增至6 245.4 t/d,湖北省具备的医疗废物处置能力由疫情前的180 t/d增至667.4 t/d;疫情期间积累的医疗废物应急管理与技术经验对后疫情时期建立和强化医疗废物应急管理与处置机制具有借鉴意义。     

中国大气环境治理的新启示--来自武汉疫情管控期间的自然实验

在武汉疫情管控期间,企业经济活动和机动车活动水平明显大幅下降,大部分污染源基本停止排放,意味着在此期间全国各地区应该出现优良天气,但是事实上在我国部分地区却出现了严重雾霾天气,这种反预期现象引起人们的普遍关注,甚至怀疑我国大气环境治理是否存在失误。根据这种反预期现象,提出环境污染应当是由流量污染和存量污染共同决定的猜想。为验证这一猜想,分别假设了两种情况:第一种只有流量污染,第二种既有流量污染又有存量污染,并用武汉疫情管控前后的实际排放数据模拟得到空气质量状况,寻找雾霾形成的规律,然后与武汉疫情管控前后实际监测数据进行对比,确定反预期现象的原因。实际数据和模拟数据对比发现,实际情况与假设1不符,与假设2相符。据此认为,大气污染是由当期排放的污染与积累的存量污染共同决定。在此基础上,进一步分析存量污染造成的经济损失,分析表明:2007年被低估1.64亿元,到2017年被低估3.83亿元;在消散率为0.05、贴现率为0.01时,流量、存量和流量与存量损失的差额分别为6.5亿元、50.5亿元和44.0亿元,这意味着2007—2017年总的经济损失被低估44.0亿元。在消散率为0.3、贴现率为0.1时,流量、存量和流量与存量损失的差额分别为4.6亿元、10.5亿元和5.9亿元,这意味着2007—2017年总的经济损失被低估5.9亿元。研究发现,长期累积形成的存量污染是一个被忽视的大气污染源,从而解释了在武汉疫情管控期间低水平经济活动条件下仍然会出现重度大气污染的经验事实。其政策含义在于,制定反污染政策需要根据存量污染的特征进一步完善相关政策设计。     

Methodology for risk assessment of COVID-19 pandemic propagation

This paper proposes a methodology to perform risk analysis of the virus spread. It is based on the coupling between CFD modelling of bioaerosol dispersion to the calculation of probability of contact events. CFD model of near-field sneeze droplets dispersion is developed to build the SARS-CoV-2 effect zones and to adequately capture the safe distance. The most shared classification of droplets size distribution of sneezes was used.Droplets were modeled through additive heating/evaporation/boiling laws and their impact on the continuous phase was examined. Larger droplets move behind the droplet nuclei front and exhibit greater vertical drop due to the effect of gravity. CFD simulations provided the iso-risk curves extension (i.e., the maximum distance as well as the angle) enclosed by the incident outcome effect zone. To calculate the risk indexes, a fault tree was developed and the probability of transmission assuming as of the top event “COVID-19 infection” was calculated starting from the virus spread curve, as main base case. Four phases of virus spread evolution were identified: initiation, propagation, generalised propagation and termination. For each phase, the maximum allowable close contact was computed, being fixed the values of the acceptable risk index. In particular, it was found that during the propagation case, the maximum allowable close contacts is two, suggesting that at this point lockdown should be activated. The here developed methodology could drive policy containment design to curb spread COVID-19 infection.     

疫情期间人为源减排对城市大气氧化性的影响

近年来,中国经济发达地区以细颗粒物（PM_2.5）和臭氧（O₃）共同引发的区域性复合型大气污染事件频发,大气氧化性（AOC）在其中发挥着重要作用.基于WRF-CMAQ模型,以2020年疫情管控期为案例探究人为源减排对AOC的影响,选取中国东部3个典型城市（石家庄、南京和广州）进行深入分析,量化排放变化及气象变化对氧化剂和AOC变化的贡献,探讨AOC变化对二次污染物生成的影响.结果表明,与2019年同期相比,2020年石家庄、南京和广州的城市平均AOC分别增加了60%、48.7%和12.6%;氧化剂臭氧、羟基自由基和硝酸根自由基的浓度均有不同程度的增加（1.6%~26.4%、14.8%~73.3%和37.9%~180%）.排放变化使3个城市AOC分别增加了0.06×10^-4、0.12×10^-4和0.33×10^-4 min^-1,气象变化导致石家庄和南京AOC增加（分别为20%和17.9%）,但在广州却相反（-9.3%）.增强的AOC导致氮氧化速率和挥发性有机物氧化速率升高,即促进了一次污染物向二次污染物的转化,并抵消了部分一次减排的影响,造成了管控期间二次污染物相对排放的非线性变化.     

Linking empirical estimates of body burden of environmental chemicals and wellness using NHANES data

Biomonitoring of industrial chemicals in human tissues and fluids has shown that all people carry a “body burden” of synthetic chemicals. Although measurement of an environmental chemical in a person's tissues/fluids is an indication of exposure, it does not necessarily mean the exposure concentration is sufficient to cause an adverse effect. Since humans are exposed to multiple chemicals, there may be a combination effect (e.g., additive, synergistic) associated with low-level exposures to multiple classes of contaminants, which may impact a variety of organ systems. The objective of this research is to link measures of body burden of environmental chemicals and a “holistic” measure of wellness. The approach is demonstrated using biomonitoring data from the National Health and Nutrition Examination Surveys (NHANES). Forty-two chemicals were selected for analysis based on their detection levels. Six biological pathway-specific indices were evaluated using groups of chemicals associated with each pathway. Five of the six pathways were negatively associated with wellness. Three non-zero interaction terms were detected which may provide empirical evidence of crosstalk across pathways. The approach identified five of the 42 chemicals from a variety of classes (metals, pesticides, furans, polycyclic aromatic hydrocarbons) as accounting for 71% of the weight linking body burden to wellness. Significant interactions were detected indicating the effect of smoking is exacerbated by body burden of environmental chemicals. Use of a holistic index on both sides of the exposure-health equation is a novel and promising empirical “systems biology” approach to risk evaluation of complex environmental exposures.     

基于社会燃烧理论的突发公共卫生事件网络情绪传播模型

为有效引导和管控突发公共卫生事件网络舆情,考虑社会相关性和网络群体间情绪状态转移的不确定性,基于社会燃烧理论研究突发公共卫生事件网络情绪传播机制.首先基于社会燃烧理论分析网络用户群体的社会影响因素,建立未燃-阴燃-燃烧-抑燃-稳定(UDBFS)网络情绪传播模型和考虑干预措施的网络情绪传播模型;然后以新冠肺炎(COVID...     

疫情前后太原市主城区空气质量时空变化特征及影响因素研究

深入探讨城市新冠疫情管控期间大气环境质量及影响因素,对空气质量的改善与治理具有重要意义。以太原市主城区为研究对象,采用克里金插值法、Pearson相关性分析、HYSPLIT轨迹模型对太原市主城区2022年疫情前后空气质量时空变化特征及影响因素进行研究。结果表明：（1）在时间上,O₃浓度呈逐月递增趋势。其他污染物在管控期间浓度有所下降,与2021年同期相比,PM_2.5下降了23.6%,PM₁₀下降了32.7%,NO₂下降了2.6%。（2）在空间分布上,PM_2.5、CO、SO₂呈“西北低、东南高”的分布特点,PM₁₀浓度则呈“西部低、东部高”的特点。（3）太原市污染物在疫情前及管控期间主要受来自西北方向长距离传输及山西省内晋中地区短距离传输影响。在常态化时期,气流轨迹更分散,来自晋中市和临汾市的短距离传输占比最高,为21.45%。（4）管控期间重点工业企业仍保持较快增长,工业用电量达到28.33亿kW·h,工业活动受管控影响较小;但移动源污染排放减少,缓解了大气污染。     

The secret life of pets: The intersection of animals and organizational life

Although often overlooked, pets and other animals intersect with organizations in interesting, important ways. We seek to define how various animals intersect with organizations, highlight opportunities for theory development, and illustrate important areas for future research. We also explore how pandemics such as COVID-19 might affect the animals we highlight.     

上海市PM2.5中重金属元素对COVID-19控制的高频响应

为研究城市大气重金属元素在新冠控制前、中（与春节重叠）、后的演化和来源,利用多金属在线分析仪于2020年1月1日至2月26日测定了上海市PM_2.5中重金属元素的小时浓度.利用PMF模型确定了8个来源.结果表明,大部分元素的浓度呈现"V"字型的变化趋势,主要受烟花爆竹（特征性元素有K、Cu、Ba）、Se工业、道路扬尘（Ca、Fe、Ba）和机动车（Mn、Zn、Fe、Cu）等排放源影响.但在新冠控制期间,K、Ba和Cu浓度仍较高.以Cu元素为例的特殊事件分析表明,其浓度高值在控制期前显著受到外来传输的影响,在控制期内主要来自于本地烟花爆竹排放的影响.