Review on recent progress in on-line monitoring technology for atmospheric pollution source emissions in China

Emissions from mobile sources and stationary sources contribute to atmospheric pollution in China, and its components, which include ultrafine particles (UFPs), volatile organic compounds (VOCs), and other reactive gases, such as NH₃ and NO_x, are the most harmful to human health. China has released various regulations and standards to address pollution from mobile and stationary sources. Thus, it is urgent to develop online monitoring technology for atmospheric pollution source emissions. This study provides an overview of the main progress in mobile and stationary source monitoring technology in China and describes the comprehensive application of some typical instruments in vital areas in recent years. These instruments have been applied to monitor emissions from motor vehicles, ships, airports, the chemical industry, and electric power generation. Not only has the level of atmospheric environment monitoring technology and equipment been improving, but relevant regulations and standards have also been constantly updated. Meanwhile, the developed instruments can provide scientific assistance for the successful implementation of regulations. According to the potential problem areas in atmospheric pollution in China, some research hotspots and future trends of atmospheric online monitoring technology are summarized. Furthermore, more advanced atmospheric online monitoring technology will contribute to a comprehensive understanding of atmospheric pollution and improve environmental monitoring capacity.     

基于应力分解法的整机加速因子预计方法研究

提出了计算整机加速因子的新方法.将整机的失效率通过定量分析方法按照部件、失效模式和应力的顺序逐级下分,从而得到各敏感应力的失效率,再通过加速模型计算各失效模式在加速应力下的失效率.最终可以得到整机在加速应力下的失效率,进而计算出整机加速因子.以典型电子产品为例,预计了弹上计算机在温度、湿度、振动综合环境应力下的加速因子为153.5.     

Fe2O3纳米棒的制备及其H2S气敏性能研究

为快速检测H2S泄漏,以一步水热法制备的Fe2O3纳米棒为基础,制备了H2S气体传感器。研究表明,该传感器在300℃工作温度下对10μmol/mol的H2S的灵敏度为2左右,响应时间为12s左右,恢复时间约4s。而且该传感器具有优异的稳定性和选择性,对CH4、CO等多种气体响应较差,适合用于长时间快速检测H2S气体的泄漏。     

自吸式文丘里洗涤器雾化液滴尺寸影响因素的实验研究

为研究雾化液滴尺寸对自吸式文丘里洗涤效率的影响,从喉部气速、液面高度差以及文丘里扩散段结构等方面,研究了自吸式文丘里洗涤器雾化液滴平均直径(D_(32))的变化规律,并与Boll模型对D_(32)的预测值进行了对比。研究表明,随着喉部气速的增加,D_(32)的实验值和预测值均呈逐渐减小的趋势,且预测值略小于实验值。另外,液面高度差的增加会导致D_(32)的减小,当气相速度增大时,D_(32)加速减小。研究发现,当喉部气速大于54.6 m/s时,A_1挡板对液相流体具有更好的雾化效果,当喉部气速小于54.6 m/s时,在环形挡板内径为46～54 mm之间存在一个最佳内径,使得雾化液滴平均直径最小,文丘里洗涤器达到最佳雾化效果。     

Assessing the role of mineral particles in the atmospheric photooxidation of typical carbonyl compound

Mineral particles are ubiquitous in the atmosphere and exhibit an important effect on the photooxidation of volatile organic compounds (VOCs). However, the role of mineral particles in the photochemical oxidation mechanism of VOCs remains unclear. Hence, the photooxidation reactions of acrolein (ARL) with OH radical (OH) in the presence and absence of SiO₂ were investigated by theoretical approach. The gas-phase reaction without SiO₂ has two distinct pathways (H-abstraction and OH-addition pathways), and carbonyl-H-abstraction is the dominant pathway. In the presence of SiO₂, the reaction mechanism is changed, i.e., the dominant pathway from carbonyl-H-abstraction to OH-addition to carbonyl C-atom. The energy barrier of OH-addition to carbonyl C-atom deceases 21.33 kcal/mol when SiO₂ is added. Carbonyl H-atom of ARL is occupied by SiO₂ via hydrogen bond, and carbonyl C-atom is activated by SiO₂. Hence, the main product changes from H-abstraction product to OH-adduct in the presence of SiO₂. The OH-adduct exhibits a thermodynamic feasibility to yield HO₂ radical and carboxylic acid via the subsequent reactions with O₂, with implications for O₃ formation and surface acidity of mineral particles.     

Competing pathways of cresol formation in toluene photooxidation: OH-toluene adducts react with NO2 or with O2?

Methyl-hydroxy-cyclohexadienyl radicals (OTAs) are the key products of the photooxidation of toluene, with implications for the fate of toluene. Hence, we investigated the photooxidation mechanisms and kinetics of three main OTAs (o-OTA, m-OTA, and p-OTA) with NO₂ using quantum chemical calculations as well as the fate of OTAs under the different concentration ratios of NO₂ and O₂. The mechanism results show that the pathway of H-abstraction by NO₂ to anti-HONO (anti-H-abstraction) is more favorable than the syn-H-abstraction pathway, because the strong interaction between OTAs and NO₂ is formed in the transition states of the anti-H-abstraction pathways. The branching ratios of the anti-H-abstraction pathways are more than 99% in the temperature range of 216−298 K. The total rate constant of the OTA-NO₂ reaction is 9.9 × 10⁻¹² cm³/(molecule∙sec) at 298 K, which is contributed about 90% by o-OTA + NO₂, and the main products are o-cresol and anti-HONO. The half-lives of the OTA-NO₂ reaction in some polluted areas of China are 35 times longer than those of the OTA-O₂ reaction. In the atmosphere, the NO₂- and O₂- initiated reactions of OTAs have the same ability to form cresols as [NO₂] is up to 142.1 ppmV, which is impossible to achieve. It implies that under the experimental condition, the [NO₂]/[O₂] should be controlled to be less than 7.8 × 10⁻⁵ to simulate real atmospheric oxidation of toluene. Our results reveal that for the photooxidation of toluene, the yield of cresol is not affected by the concentration of NO₂ under the atmospheric environment.     

Remediation of preservative ethylparaben in water using natural sphalerite: Kinetics and mechanisms

As a typical class of emerging organic contaminants(EOCs), the environmental transformation and abatement of preservative parabens have raised certain environmental concerns. However, the remediation of parabens-contaminated water using natural matrixes(such as, naturally abundant minerals) is not reported extensively in literature. In this study, the transformation kinetics and the mechanism of ethylparaben using natural sphalerite(NS) were investigated. The results show that around 63% of ethy...     

聚苯乙烯微塑料和纳米塑料对萼花臂尾轮虫有性生殖的毒性影响

为探索不同粒径聚苯乙烯微塑料和纳米塑料对轮虫繁殖的影响规律,以萼花臂尾轮虫(Brachionus calyciflorus)为受试生物,探究了3种粒径(100 nm、0.5 μm和1 μm)聚苯乙烯塑料对轮虫有性生殖的影响. 结果表明:①暴露于粒径较小的聚苯乙烯纳米塑料对轮虫的急性毒性较大. ②与对照组相比,暴露于20 mg/L的100 nm聚苯乙烯纳米塑料和0.01、0.1、1、10和20 mg/L的1 μm聚苯乙烯微塑料均导致轮虫种群增长率显著降低(P<0.05). ③聚苯乙烯微塑料和纳米塑料暴露对萼花臂尾轮虫混交率和受精率均有显著影响. ④暴露于10和20 mg/L的100 nm聚苯乙烯纳米塑料均显著抑制萼花臂尾轮虫7 d休眠卵产量(P<0.05),而暴露于0.1 mg/L的1 μm聚苯乙烯微塑料以及0.01、0.1、1、10和20 mg/L的0.5 μm聚苯乙烯微塑料均显著增加轮虫7 d休眠卵产量(P<0.05). 研究显示,在评价聚苯乙烯微塑料和纳米塑料对萼花臂尾轮虫有性生殖影响时,轮虫混交率和休眠卵产量可以作为合适的毒性测试指标.      

Long-term winter observation of nitrous acid in the urban area of Beijing

The particulate matter (PM) pollution has been significantly improved by carrying out various valid emission control strategies since 2013 in China. Meanwhile the variation trend of nitrous acid (HONO) is worthy to investigate due to its vital role in the atmospheric oxidation process. In this study, field observation in the winter is conducted to investigate the concentration of HONO in an urban area of Beijing. In the winter of 2019, the mean HONO concentration is 1.38 ppbV during the whole winter. Photo-enhanced NO₂ heterogeneous reactions on the ground and aerosol surfaces were found as the possible daytime sources of HONO. Compared to O₃, photolysis of HONO dominates the primary OH sources during the winter time. To understand the HONO pollution patterns by years variation, multi-year data is summarized and finds that primary pollutants including CO and NO decreased, but secondary pollutants i.e., HONO (mostly generated via secondary process) increased. Our study highlights the requirement to mitigate secondary pollution by control HONO concentration.     

2005－2020年广西近岸海域表层沉积物重金属含量特征及风险评价

为了了解近15年来广西近岸海域表层沉积物的环境质量状况,本研究应用2005－2020年广西近岸海域表层沉积物重金属数据,运用统计、相关分析、因子分析及风险评价等方法,对广西近岸海域表层沉积物的重金属含量特征、变化趋势及生态风险进行了分析。分析结果表明:2005－2020年,广西近岸海域表层沉积物99.0%的As、98.1%的Cu、99.0%的Pb、99.6%的Cd、100%的Hg、97.9%的Zn、100%的Cr含量低于《海洋沉积物质量标准》（GB 18668—2002）的一类标准限值要求,且58%的站位沉积物重金属含量近15年来无统计意义上的年际变化。地累积指数评价结果显示,广西近岸海域约37.5%的站位表层沉积物存在轻度?中度污染,Hg、As及Cd是主要污染因子;潜在生态风险指数评价结果显示,广西近岸海域表层沉积物重金属总体处于低风险状态。