Spatiotemporal variations of ambient air pollutants and meteorological influences over typical urban agglomerations in China during the COVID-19 lockdown

To investigate the air quality change during the COVID-19 pandemic, we analyzed spatiotemporal variations of six criteria pollutants in nine typical urban agglomerations in China using ground-based data and examined meteorological influences through correlation analysis and backward trajectory analysis under different responses. Concentrations of PM_2.5, PM₁₀, NO₂, SO₂ and CO in urban agglomerations respectively decreased by 18%–45% (30%–62%), 17%–53% (22%–39%), 47%-64% (14%–41%), 9%–34% (0%–53%) and 16%-52% (23%–56%) during Lockdown (Post-lockdown) period relative to Pre-lockdown period. PM_2.5 pollution events occurred during Lockdown in Beijing-Tianjin-Hebe (BTH) and Middle and South Liaoning (MSL), and daily O₃ concentration rose to grade Ⅱ standard in Post-lockdown period. Distinct from the nationwide slump of NO₂ during Lockdown period, a rebound (～40%) in Post-lockdown period was observed in Cheng-Yu (CY), Yangtze River Middle-Reach (YRMR), Yangtze River Delta (YRD) and Pearl River Delta (PRD). With slightly higher wind speed compared with 2019, the reduction of PM_2.5 (51%–62%) in Post-lockdown period is more than 2019 (15%–46%) in HC (Harbin-Changchun), MSL, BTH, CP (Central Plain) and SP (Shandong-Peninsula), suggesting lockdown measures are effective to PM_2.5 alleviation. Although O₃ concentrations generally increased during the lockdown, its increment rate declined compared with 2019 under similar sunlight duration and temperature. Additionally, unlike HC, MSL and BTH, which suffered from additional (> 30%) air masses from surrounding areas after the lockdown, the polluted air masses reaching YRD and PRD mostly originated from the long-distance transport, highlighting the importance of joint regional governance.     

A large-scale outdoor atmospheric simulation smog chamber for studying atmospheric photochemical processes: Characterization and preliminary application

Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China. Thus, a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences (the CRAES Chamber), which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment. The chamber consisted of a 56-m³ fluorinated ethylene propylene (FEP) Teflon film reactor, an electrically-driven stainless steel alloy shield, an auxiliary system, and multiple detection instrumentations. By performing a series of characterization experiments, we obtained basic parameters of the CRAES chamber, such as the mixing ability, the background reactivity, and the wall loss rates of gaseous compounds (propene, NO, NO₂, ozone) and aerosols (ammonium sulfate). Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol (SOA), including α-pinene ozonolysis, propene and 1,3,5-trimethylbenzene photooxidation. Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work: higher temperature and the presence of seed could reduce the vapor wall loss; SOA yield was found to depend inversely on temperature, and the presence of seed could increase SOA yield. The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls. The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.     

Application of FeIII-TAML/H2O2 system for treatment of fluoroquinolone antibiotics

Over the recent past, fluoroquinolone antibiotics (FQs) have raised extensive attention due to their potential to induce the formation of resistance genes and “superbugs”, thus various advanced oxidation techniques have been developed to eliminate their release into the environment. In the present study, the prototype tetraamido macrocyclic ligand (Fe^III-TAML)/hydrogen peroxide (H₂O₂) system is employed to degrade FQs (i.e., norfloxacin and ciprofloxacin) over a wide pH range (i.e., pH 6-10), and the reaction rate increases with the increase in pH level. The effect of dosage of Fe^III-TAML and H₂O₂ on the degradation of FQs is evaluated, and the reaction rate is linearly correlated with the added amount of chemicals. Moreover, the impact of natural organic matters (NOM) on the removal of FQs is investigated, and the degradation kinetics show that both NOM type and experimental concentration exhibit negligible influence on the oxidative degradation of selected antibiotics. Based on the results of liquid chromatography-high resolution mass spectrometry and theoretical calculations, the reaction sites and pathways of FQs by Fe^III-TAML/H₂O₂ system are further predicted and elucidated.     

基坑开挖影响下下卧盾构隧道变形及控制措施研究

近年来地铁建设不断加快,在地铁隧道上方施工已成常态。为研究基坑开挖影响下下卧盾构隧道的隆起变形,评价不同变形控制措施的实际控制效果,以武汉市轨道交通6号线琴台变电站地下电缆通道工程为例,采用两阶段法计算了基坑开挖影响下下卧盾构隧道的隆起变形,同时采用数值模拟方法对无加固、压力注浆加固、水泥土搅拌桩加固和压力注浆+水泥土搅拌桩综合加固控制措施4种工况下下卧隧道的隆起变形值进行了数值模拟计算,并将数值模拟结果与实际工程监测数据进行了对比分析。结果表明:对于初步预测基坑开挖引起下卧盾构隧道的隆起变形,该理论计算方法可靠、实用;压力注浆+水泥土搅拌桩综合加固控制措施使下卧盾构隧道的隆起变形和横断面收敛变形值分别减小至2.3 mm和0.35 mm,控制效果良好,具有一定的实际推广意义,可为类似工程提供参考。     

假微型海链藻对不同氮培养条件的响应

本文选取假微型海链藻为目标微藻,研究其在不同氮源（硝酸盐、亚硝酸盐、铵盐和尿素）和氮饥饿条件下的生长速率和光合作用,以期为阐述海洋微藻对近岸复杂多变的氮环境适应机制提供依据。结果表明,在氮饥饿条件下,假微型海链藻的种群生长受阻,细胞内色素分解,光合作用被显著抑制;在不同氮源条件下,假微型海链藻均能生长但表现出不同的生长模式,但高浓度的铵盐能够对其产生抑制,各条件下藻细胞叶绿素a、叶绿素c 和总类胡萝卜素含量在指数生长期无显著差异,而在平台末期,尿素处理组各色素水平显著提高;假微型海链藻光系统Ⅱ的不同光合作用参数在实验末期均表现为铵盐处理组显著高于其他处理组。综上所述,假微型海链藻能够利用不同氮源进行生长,但在不同氮源条件下,种群增长的变化模式与光合作用的响应并不一致,由此推测假微型海链藻在不同氮源条件下光合作用并不是导致其生长模式差异的主要原因。     

油田井口加热炉烟尘排放超标原因分析及治理方法

针对井口加热炉燃用套管气出现的烟尘排放超标问题,从燃烧方式及燃料组成方面分析发现,加热炉所采用的扩散式燃烧,火焰面燃料侧缺少氧气,燃料产生热分解生成炭黑颗粒;另外,套管气含有大量的重碳烷烃,其稳定性差、分解温度低,加剧了热分解反应。因此,控制套管气质量和改变燃烧方式是治理烟尘排放超标的基本途径。但是井口加装轻烃回收装置,分离出套管气中的重碳烷烃,成本高不可行。最终,基于预混燃烧理论,设计了双调风预混燃烧装置,现场实施结果表明,不仅烟尘排放降低了87.8%,而且NOx排放降低了58.6%、热效率提升了8.2%。实践证明,预混燃烧是治理井口加热炉烟尘排放超标的有效方法。     

焦化废水处理技术的发展

焦化废水主要来自焦化厂和煤气厂，污染物组成复杂，含有挥发酚、许多难以生物降解的芳香族有机物、多环化合物和氧硫氮等杂环化合物，属较难生化降解的高浓度有机工业废水。因此焦化废水的处理难度大，已引起国内外人士的关注，一直是国内外废水处理领域的一大难题。文章阐述了焦化废水的处理技术发展及其近年来发展的新技术。     

驾驶人危险感知能力影响因素及干预方式综述

为探究外部干预对驾驶人危险感知能力的作用效果,梳理不同理论描述驾驶人危险感知过程,并总结驾驶人危险感知行为机制;然后,从危险感知行为要素出发,分析驾驶风格、驾驶经验、交通环境、驾驶状态对危险感知能力的影响;其次,介绍5种危险感知能力干预方式的研究成果,归纳各方式特点;最后,从干预效果持续性、评价指标、迁移效应等方面总结...     

A Highly Efficient Adsorbent Based on Starch-Graphene Oxide Architecture for Scavenging Aqueous Pb(II): Isotherms,Kinetics, Thermodynamics and Interaction Mechanism

Journal of Polymers and the Environment - Heavy metal pollution stems from the modern industry is a severe environmental problem. In this work, a highly efficient adsorbent based on starch-graphene...     

我国文化和旅游产业融合效率的时空动态演化及其驱动机理

采用仁慈型交叉DEA效率模型、冷热点分析、Tobit模型等方法对2010—2019年我国文化产业和旅游产业融合效率的时空动态演化及驱动机理进行了全面探析,结果发现:①2010—2019年我国文化产业和旅游产业融合效率呈波动上升趋势。②研究期内,文化和旅游产业融合效率呈“东部—中部—西部”依次递减,而融合效率增长率呈“东部—西部—中部”依次递减,但融合增长率都不高。③研究期内,文化产业和旅游产业融合效率呈区域差异性和集聚性。④从文化和旅游产业融合效率驱动机制剖析来看,经济发展、居民消费水平、地区城市化水平、信息发达程度、创新能力、政府政策支持力度是我国文化和旅游产业融合效率的驱动因素,促使效率时空动态演化。