长江三角洲区域大气PM_(2.5)和臭氧污染协同控制路径

国家“碳达峰、碳中和”战略目标(以下简称“双碳”目标)的提出对长江三角洲(以下简称长三角)高质量一体化发展赋予了新的要求.本文基于长三角区域精细化排放清单和WRF-CMAQ模型,模拟了不同政策情景下区域空气质量改善情况.结果显示,绿色低碳情景(CP)较趋势照常情景(BAU)和末端强化情景(EP)具有更大的减排潜力,是实现绿色美丽长三角目标的重要路径.CP情景下,与2017年相比,预计2025年SO_(2)、NO_(x)、NMVOCs(non-methane volatile organic compounds)、一次PM_(2.5)排放将分别下降55.1%、26.5%、25.2%、27%;2035年,则将分别下降66%、56.4%、36.1%、39.4%.截至2035年,区域PM_(2.5)年均值和臭氧日8 h最大值第90百分位数(O_(3)-8 h 90th)将分别达到26和129μg m^(−3),50%地级市PM_(2.5)年均浓度将达到世界卫生组织第二阶段指导值.综合模拟结果,中长期全国和区域持续同步推动主要污染物的减排,将有望实现PM_(2.5)浓度持续改善和臭氧浓度的同步改善,实现协同减排的目标.近中期,绿色美丽长三角政策驱动的以末端治理为主的大气污染治理措施仍将继续对污染减排具有重要贡献,而中长期,由“双碳”目标驱动的能源、产业、交通结构调整措施对污染减排具有关键作用.持续大力推动NO_(x)和NMVOCs全面减排是实现PM_(2.5)与臭氧协同控制的关键.在延续现有严格的末端控制政策的基础上,进一步强化工业涂装、石化化工、橡塑、医药等涉挥发性有机物排放行业的产业结构调整,以及深入推进交通运输结构调整与加强新能源车船推广是中长期区域协同控制PM_(2.5)和臭氧的重要抓手.

Chemical characteristics of fine particles and their impact on visibility impairment in Shanghai based on a 1-year period observation

In this work, a one-year observation focusing on high time resolution characteristics of components in fine particles was conducted at an urban site in Shanghai. Contributions of different components on visibility impairment were also studied. Our research indicates that the major components of PM2.5 in Shanghai are water-soluble inorganic ions and carbonaceous aerosol, accounting for about 60% and 30% respectively. Higher concentrations of sulfate （SO42-） and organic carbon （OC） in PM2.s occurred in fall and summer, while higher concentrations of nitrate （NO3-） were observed in winter and spring. The mass concentrations of Cl- and K＋ were higher in winter. Moreover, NO3- increased significantly during PM2.s pollution episodes. The high values observed for the sulfate oxidizing rate （SOR）, nitrate oxidizing rate （NOR） and secondary organic carbon （SOC） in OC indicate that photochemical reactions were quite active in Shanghai. The IMPROVE （Interagency Monitoring of Protected Visual Environments） formula was used in this study to investigate the contributions of individual PM2.5 chemical components to the light extinction efficient in Shanghai. Both NH4NO3 and （NH4）aSO4 had close relationships with visibility impairment in Shanghai. Our results show that the reduction of anthropogenic SO2, NOx and NH3 would have a significant effect on the improvement of air qualitv and visibility in Shanghai.

Chemical and optical properties of aerosols and their interrelationship in winter in the megacity Shanghai of China

A field campaign on air quality was carried out in Shanghai in winter of 2012. The concentrations of NO, NO2, NOx, SO2, CO, and PM2.5increased during haze formation. The average masses of SO4^2-, NO3^-and NH4^＋were 10.3, 11.7 and 6.7 μg/m^3 during the haze episodes, which exceeded the average（9.2, 7.9, and 3.4 μg/m3） of these components in the non-haze days. The mean values for the aerosol scattering coefficient（b sp）, aerosol absorption coefficient（b ap） and single scattering albedo（SSA） were 288.7, 27.7 and0.91 Mm-1, respectively. A bi-peak distribution was observed for the mass concentrations of CO, NO, NO2, and NOx. More sulfate was produced during daytime than that in the evening due to photochemical reactions. The mass concentration of NH4＋achieved a small peak at noontime. NO3-showed lower concentrations in the afternoon and higher concentrations in the early morning. There were obvious bi-peak diurnal patterns for b sp and b ap as well as SSA. b sp and b ap showed a positive correlation with PM2.5mass concentration.（NH4）2SO4, NH4NO3, organic mass, elemental carbon and coarse mass accounted for 21.7%, 19.3%, 31.0%, 9.3% and 12.3% of the total extinction coefficient during non-haze days, and 25.6%, 24.3%, 30.1%, 8.1% and 8.2% during hazy days. Organic matter was the largest contributor to light extinction. The contribution proportions of ammonium sulfate and ammonium nitrate to light extinction were significantly higher during the hazy time than during the non-haze days.

Do vehicular emissions dominate the source of C6–C8 aromatics in the megacity Shanghai of eastern China?

The characteristic ratios of volatile organic compounds（VOCs） to i-pentane, the indicator of vehicular emissions, were employed to apportion the vehicular and non-vehicular contributions to reactive species in urban Shanghai. Two kinds of tunnel experiments, one tunnel with more than 90% light duty gasoline vehicles and the other with more than 60% light duty diesel vehicles, were carried out to study the characteristic ratios of vehicle-related emissions from December 2009 to January 2010. Based on the experiments, the characteristic ratios of C6–C8aromatics to i-pentane of vehicular emissions were 0.53 ± 0.08（benzene）, 0.70 ± 0.12（toluene）,0.41 ± 0.09（m,p-xylenes）, 0.16 ± 0.04（o-xylene）, 0.023 ± 0.011（styrene）, and 0.15 ± 0.02（ethylbenzene）, respectively. The source apportionment results showed that around 23.3% of C6–C8 aromatics in urban Shanghai were from vehicular emissions, which meant that the non-vehicular emissions had more importance. These findings suggested that emission control of non-vehicular sources, i.e. industrial emissions, should also receive attention in addition to the control of vehicle-related emissions in Shanghai. The chemical removal of VOCs during the transport from emissions to the receptor site had a large impact on the apportionment results. Generally, the overestimation of vehicular contributions would occur when the VOC reaction rate constant with OH radicals（k OH） was larger than that of the vehicular indicator, while for species with smaller k OH than the vehicular indicator, the vehicular contribution would be underestimated by the method of characteristic ratios.

阅读障碍儿童双眼调节及集合功能的研究

目的:研究阅读障碍儿童双眼调节、集合功能的特点,为阅读障碍的预防和临床治疗提供依据。方法:病例对照研究。采用整群随机抽样法抽取天津市东丽区2所小学2301名3~5年级学生进行问卷调查。根据阅读障碍诊断标准及纳入标准筛选出102例阅读障碍儿童作为阅读障碍组,并在非阅读障碍儿童中选出年龄、性别、班级相匹配的102例正常儿童作为对照组。分别检查阅读障碍组和对照组儿童的视力、屈光不正度数、近立体视、隐斜视度数、双眼调节幅度(移近法)、双眼调节反应(FCC)、双眼调节灵敏度、双眼正负相对调节(PRA/NRA)、调节性集合/调节(AC/A)、集合近点(NPC)等情况。采用t检验及χ^(2)检验分析2组检查结果的差异性。结果:对照组和阅读障碍组儿童屈光不正度数分别为(-2.08±2.18)D和(-1.95±2.00)D,2组比较差异无统计学意义;对照组和阅读障碍组的调节反应量分别为(0.02±0.63)D和(0.21±0.35)D,2组比较差异有统计学意义(t=5.065,P=0.011);对照组与阅读障碍组的PRA分别为(-2.77±1.82)D和(-1.88±1.06)D,差异有统计学意义(t=-2.153,P=0.040);对照组和阅读障碍组的双眼调节灵敏度分别为(8.20±2.26)cpm和(5.43±4.25)cpm,2组比较差异有统计学意义(t=2.402,P=0.027);对照组和阅读障碍组的AC/A分别为(3.81±0.81)Δ/D和(3.09±0.84)Δ/D,差异有统计学意义(t=2.491,P=0.025)。结论:阅读障碍儿童与正常人群在调节及集合功能方面均存在差异,阅读障碍儿童主要存在的调节及集合问题是调节不足和集合不足。

A novel mitigator of enzymatic browning--hawthorn leaf extract and its application in the preservation of fresh-cut potatoes

Objectives:The purpose of this study was to evaluate the antibrowning functions of hawthorn leaf extract on fresh-cut potato and its possible mechanism.Materials and Methods:Fresh-cut potatoes were treated with different concentrations(0.01%,0.05%,and 0.1%)of hawthorn leaf extract and preserved at 4 C for 8 days.The appears nee and colour of potato slices were evaluated,along with the content of the phenol,malondialdehyde(MDA),and hydrogen peroxide(H2O2)during cold storage.Meanwhile,the activities of polyphenol oxidase(PPO),peroxidase(POD),phenylalanine ammonia-lyase(PAL),lipoxygenase(LOX),catalase(CAT),superoxide dismutase(SOD),and the antioxidant capacity were determ in ed.Furthermore,the composition of hawthorn leaf extract was analyzed by high-performance liquid chromatographytandem mass spectrometry(HPLC-MS/MS).Results:The addition of hawthorn leaf extract effectively delayed the browning process.It not only enhanced the CAT activity and antioxidant capacity but also reduced the LOX activity and accumulation of MDA and H_(2)O_(2).Meanwhile,the activities of PPO,POD,and PAL as well as the content of phe nol were con trolled.Additionally,25 phe nols,34 flavonoids,and 5 proa nthocya nidins were identified through high-performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS),ideluding caffeic acid,quercetin and catechol.Conelusion:Hawthorn leaf extract significantly alleviated the browning of fresh-cut potato.It could serve as a n atural an tibrowning alter native by stabilizing the membra ne and modulating reactive oxygen species and redox reactions.