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1.
近年来,大气化学研究工作有着飞跃的发展,现就其中若干方面简介如下: 一、对现今大气的组成、污染物地面浓度以及它们的来源有了新的资料和认识,特别是对背景大气中许多痕量气体,如NH3、HNO3、O3、HCN、CH4、CO、NOx、H2S、SO2、H2SO4、HCl、HNO2和CH3Cl等等,有了新的定量资料。这是一大批现代的物理、化学分析等测试方法得到运用的结果。  相似文献   

2.
中美大气化学联合考察实验结果的初步分析与比较   总被引：1，自引：0，他引：1  
根据临安区域本底站观测资料分析结果得出,中国中纬度地区秋、冬季O3及其前体物NOx等浓度偏高,可以对农作物和地表生态系统产生影响.观测结果表明:近地层大气O3浓度主要决定于地面总辐射量控制下的光化学反应过程;O3的生成受到前体物NOx的控制,但O3与NOx存在着明显的非线性关系.从PEM-WESTA和B的实验及1995年的观测资料表明,O3的生成效率随着NOx浓度的增大而减小.尽管O3的生成速率秋季比冬季的大,但由于秋季较高的NOx抑制了过氧基的生成,因此冬季O3的累积量几乎可以和秋季相比拟.在临安观测的NMHC和NOx的比值比国外同纬度地区测值要大.这说明在临安本底站O3的光化学生成中,NMHC不是控制物种.从而提示我们,在这些季节临安O3光化学产物能够被NOx浓度所控制.中美大气化学联合考察(PEM-WEST-B)实验期间,台湾省的卡盯站SO2的平均浓度为0.29ppb,O3的平均浓度为42.2ppb,可以认为此值为低纬度海岛的本底值.1994年PEM-WEST-B实验期间临安站的观测资料和台湾省的卡盯站资料相比,临安站SO2的浓度约为卡盯站SO2浓度的50倍左右,从而可以看出人类活动对大气本底的显着影响.  相似文献   

3.
南京地区大气颗粒物影响近地面臭氧的个例研究   总被引：4，自引：0，他引：4  
通过对2008年4月2～7日南京地区地面气象观测数据以及两个站点空气质量(O3、NOx、PM10)监测资料的分析, 发现O3和PM10之间存在一定程度的反相关。利用一个光化学箱模式对该个例中大气颗粒物影响近地面臭氧的过程进行模拟, 结果发现大气颗粒物浓度的升高使得气溶胶光学厚度增加20％～40%, 导致NO2和O3近地面光解率下降20%～30%, OH和HO2自由基浓度分别减少20%～50%, 造成O3净生成率下降30%～40%。研究表明, 颗粒物对光化学过程的抑制造成了大气氧化能力的降低, 是近地面臭氧浓度减少的可能原因。  相似文献   

4.
基于中国环境空气质量监测站观测数据、区域空气质量模式（CMAQ）模拟数据和卫星反演数据,利用数据融合方法获得了2014、2018年地表大气O3质量浓度水平变化及其空间分布,通过空气污染控制健康效益评估工具（BenMAP-CE）评估了2014、2018年中国O3导致的过早死亡人数。结果表明：2018年中国O3日8 h最大（O3-MDA8）质量浓度年均值为98.0 μg/m3,较2014年的87.9 μg/m3增长了11.5%,其中安徽省、山西省和山东省的O3-MDA8质量浓度增加最为明显;2014和2018年O3相关过早死亡人数分别为17.4万和26.7万,过早死亡人数增长率约为57%;中国9个区域中的中部区域O3质量浓度和O3相关过早死亡人数较其他几个区域增长最多,并且人口密度为1 000人/km2左右的区域过早死亡人数增加最多;河南省、河北省和四川省的O3相关过早死亡增加人数比其他省份多;近年来中国地表大气O3的健康危害的增加程度远大于O3质量浓度的增加程度,应尽快加强对O3污染的控制。  相似文献   

5.
【目的】为揭示边界层O3异常升高及大气热力、动力条件对其影响的机理。【方法】该文基于多源观测资料,采用天气分型、统计合成和物理量诊断等方法,探究了2022年9月福建邵武（国家级气象探空站、O3探空观测科学试验基地）出现边界层O3异常升高的特征及大气热动力的综合作用。【结果】2022年9月邵武近地层O3-8h异常正距平最高达125.4%;在非光化学时段（21时—次日07时）O3较多年平均值增长137.1%;边界层O3体积混合比（OVMR）明显高于不同季节的平均状态,21日O3探空观测到边界层O3总量为全年同层探空观测的极大值。O3异常升高是副热带高压和3个台风外围共同影响的结果,导致全月较30 a气候态平均呈现：太阳辐射偏强、低云量偏少、地面气温升高,相对湿度偏低、降水量偏少,偏北风持续时间长且风速偏大;7日和21日边界层O3总量高值日的气象探空廓线呈现大气层结稳定、空气干燥、湿层薄,同时下沉对流有效位能DCAPE值较高,在200～800 J·kg-1之间,即存在明显的下沉气流;低层主导风为偏东风,风速在4～8m·s-1之间。【结论】气象要素配置与大气的热力、动力条件一方面有利于O3光化学生成,另一方面有利于上风向高浓度O3水平输送和边界层高浓度O3垂直下沉侵入,而后者是O3异常升高的主要来源。  相似文献   

6.
Using a detailed, fully coupled chemistry climate model (CCM), the effect of increasing stratospheric H2O on ozone and temperature is investigated. Different CCM time-slice runs have been performed to investigate the chemical and radiative impacts of an assumed 2 ppmv increase in H2O. The chemical effects of this H2O increase lead to an overall decrease of the total column ozone (TCO) by ～1% in the tropics and by a maximum of 12% at southern high latitudes. At northern high latitudes, the TCO is increased by only up to 5% due to stronger transport in the Arctic. A 2-ppmv H2O increase in the model's radiation scheme causes a cooling of the tropical stratosphere of no more than 2 K, but a cooling of more than 4 K at high latitudes. Consequently, the TCO is increased by about 2%--6%. Increasing stratospheric H2O, therefore, cools the stratosphere both directly and indirectly, except in the polar regions where the temperature responds differently due to feedbacks between ozone and H2O changes. The combined chemical and radiative effects of increasing H2O may give rise to more cooling in the tropics and middle latitudes but less cooling in the polar stratosphere. The combined effects of H2O increases on ozone tend to offset each other, except in the Arctic stratosphere where both the radiative and chemical impacts give rise to increased ozone. The chemical and radiative effects of increasing H2O cause dynamical responses in the stratosphere with an evident hemispheric asymmetry. In terms of ozone recovery, increasing the stratospheric H2O is likely to accelerate the recovery in the northern high latitudes and delay it in the southern high latitudes. The modeled ozone recovery is more significant between 2000--2050 than between 2050--2100, driven mainly by the larger relative change in chlorine in the earlier period.  相似文献   

7.
采用盱眙县环境监测站 2014年1—12月PM10、PM2.5、SO2、NO2、O3逐日质量浓度资料及盱眙国家基本气象站同期气象资料,分析不同气象条件下盱眙县空气质量变化.结果表明:盱眙县主要污染物是PM2.5、PM10,污染较轻的是SO2、NO2、O3;盱眙县空气质量变化趋势为春冬季污染严重,夏秋季污染较轻.气象条件中的降水因子对改善空气质量、清除颗粒物具有明显作用;当温度在0 ℃以下或30 ℃以上时空气质量相对较好,0～20 ℃时空气污染情况较为严重;偏东风时大气环境质量较差,偏北风时大气环境质量较好.  相似文献   

8.
大气污染严重威胁了我国陆地生态系统的固碳能力,但随着减污降碳协同治理的快速推进,减缓大气污染将有利于提升陆地碳汇,并切实推动碳达峰碳中和目标的实现。为了更好地理解大气污染与生态系统固碳的关系,本文以主要空气污染物臭氧（O3）为例,基于田间控制实验的整合分析、剂量响应关系及机理模型三种评估方法综述了近地层O3污染对植被碳固定影响的最新进展。尽管不同作物种类以及品种、不同功能型木本植物对O3的响应有着显著的差异,且各种方法的评估结果也不尽相同,但目前O3浓度造成我国粮食作物减产、森林生产力降低已是不争的事实。持续升高的O3浓度将严重威胁我国陆地生态系统的固碳能力。利用我国作物和树木的O3剂量响应方程进行评估的结果表明,在CO2减排和O3污染协同治理下,预计2060年我国树木生物量和作物产量将比当前显著提高,增加陆地生态系统碳汇,助力碳中和目标。最后,对如何提高O3污染环境下植物固碳能力也进行了展望。  相似文献   

9.
为研究云贵高原城市遵义新冠期间大气污染物变化特征,利用2015—2020年遵义市空气质量监测数据、地面气象观测资料,分析新冠肺炎疫情防控期间遵义市主要大气污染物和气象要素的变化情况,研究空气质量对污染物减排和气象要素变化的响应。结果表明：疫情防控导致遵义市PM2.5、PM10和NO2质量浓度明显下降,但O3质量浓度小幅增加;PM2.5和NO2对人为减排的响应更敏感;防控期内遵义市气象条件比较有利于污染物的清除,防控减排措施导致PM2.5质量浓度下降25.34%。在疫情防控的背景下,O3浓度较2015—2019年明显偏高,PM2.5显著下降,这与疫情防控期间人员车辆外出明显减少有关,导致夜间滴定消耗O3的气体减少。减排措施对防控期间颗粒物污染浓度有明显的削弱作用。  相似文献   

10.
利用风云2号卫星TBB资料、多普勒天气雷达和常规观测资料,分析了近10a影响中国天眼FAST的7次冰雹个例的降雹持续时间、冰雹直径、移动速度等特征,揭示了其源地和移动路径,并初步建立基于卫星和雷达的FAST冰雹识别指标。结果表明：影响FAST冰雹主要发生在春季的傍晚到夜间,冰雹云从初生到降雹平均时间为112 min,平均移动速度为45.5 km/h,降雹持续时间主要为2 min左右,冰雹直径以小于等于10 mm的小冰雹和中冰雹为主;冰雹云源地主要在安顺市,移动路径为西北和偏西路径为主。在降雹前1 h,FAST区域TBB呈西南—东北走向分布,云团中心TBB＜46 ℃,TBB梯度密集的对流区会产生降雹;降雹前30 min识别指标为Zmax≥55 dBz,VILmax≥30 kg/m2,H45 dBz≥8 km,H45dBz- H0℃＞4 km,H45dBz- H-20℃＞1 km。  相似文献   

11.
The photodegradation of naphthalene (NPH), chosen as a model of polynuclear aromatic pollutants, has been studied in the presence of a layer of four water-insoluble inorganic solids which can be found in the troposphere (TiO2, Fe2O3, muscovite, and a fly ash sample). Direct photolysis of NPH is negligible at >340 nm. Dark adsorption of NPH on TiO2 (mainly anatase, nonporous, 50 m2 g–1) at 293 K corresponds to a surface coverage ofca. 50% at equilibrium. Under these conditions (saturated surface), the stationary-state photocatalytic degradation reaches 0.4 molecule nm–2 h–1 (>340 nm, radiant fluxca. 22 mW cm–2). Dioxygen is required and its partial pressure in air is such that the degradation is zero order in O2. Water vapor markedly increases the rate. The other particulates have also an effect, less important than that of TiO2, however quite noticeable with respect to surface area unit for the fly ash sample which contains 3.2% Fe2O3. Apart from 1,4-naphthoquinone, which is the main intermediate product in all cases, 2-naphthol, phthalide, phthaldialdehyde, phthalic acid, acetophenone, benzaldehyde, benzoic acid are also formed on dry TiO2. Depending on their volatility, these compounds are transferred to the gas phase or remain principally adsorbed on the solid particles where they are further transformed. For instance, phthalic acid (or anhydride) and benzoic acid are generated from 1,4-naphthoquinone. Degradation mechanisms are briefly discussed.  相似文献   

12.
大气过氧化氢（H2O2）是一种重要的光化学产物,也是硫酸盐气溶胶生成及降水酸化过程的关键氧化剂。然而,我国对H2O2的观测研究较少,尤其对雾霾期间H2O2浓度变化特征认识不足。该文介绍了冬春时段（2016年12月-2017年4月）在北京城区中国气象局的H2O2观测结果,并结合同期O3,PAN,NOX,PM2.5等污染物和气象要素观测数据,分析H2O2浓度变化特征与影响因素。观测结果表明:观测期间H2O2体积混合比（简称为浓度）为（0.65±0.59）×10-9,其中,春季浓度（0.83±0.67）×10-9高于冬季浓度（0.51±0.47）×10-9;H2O2平均日变化基本呈现单峰特征,峰值出现在18:00-21:00,比其他地区峰值出现稍晚,并滞后于O3峰值时间4~7 h;相对湿度对H2O2日峰值时间和浓度水平有影响,小于55%时日峰值出现于18:00-24:00,平均峰值浓度1.52×10-9;大于65%时日峰值出现于11:00-16:00,日峰值浓度均小于1×10-9。H2O2,O3和PAN虽然同属光化学产物,但在不同污染状况下浓度水平和变化趋势差异明显;H2O2清洁日峰值浓度高于污染日,但11:00-15:00污染日浓度略高于清洁日。  相似文献   

13.
Hydrogen peroxide (H2O2) and organic hydroperoxides (ROOH) were measured on board of theRV Polarstern during its cruise across the Atlantic Ocean from 20 October to 12 November 1990 (54° N to 51° S latitude) by the enzyme fluorometric method. The H2O2 mixing ratio varied from below the detection limit of about 0.12 ppbv up to 3.89 ppbv, showing a latitudinal dependence with generally higher values around the equator and decreasing values poleward. The shape of the latitudinal H2O2 distribution agrees well with an analytical steady state expression for H2O2 using the measured H2O and O3 distribution and a wind dependent H2O2 deposition rate. The ROOH mixing ratio varied from below the detection limit of about 0.08 ppbv up to 1.25 ppbv with qualitatively the same latitudinal dependence as H2O2. The observed ratio ROOH/(ROOH + H2O2) varied between 0.17 and 0.98 showing higher values at the lowest H2O2 mixing ratios at high latitudes. The measured H2O2 mixing ratio shows a significant diurnal variation with a maximum around 14:00 local time, explicable by a superposition of the photochemical H2O2 production with a constant H2O2 deposition rate. Four independent estimations of the average effective H2O2 deposition rate inferred from the H2O2 decrease in the night, from the midday H2O2 production deficit (as derived from comparison with a photochemical model and from the daily ozone loss), and from the offset in the latitudinal H2O2 distribution, were consistent. An episode of maximum H2O2 concentration suggests the possibility of its formation in clouds.  相似文献   

14.
In order to study the concentrations of hydrogen peroxide (H2O2) and the factors controlling its concentrations, we monitored concentrations of H2O2 and other gases such as sulfur dioxide, ozone, and NO x as well as meteorological factors such as air temperature, relative humidity, and wind direction/speed during eight measurement periods from 2000 to 2002 in a Japanese red pine forest in Japan. The H2O2 concentrations ranged from below 0.01 to 1.64 ppb, and analysis of the diurnal variation in H2O2 concentration showed high concentrations around noon, and low concentrations in the morning and late afternoon. The H2O2 concentrations were high in early summer, when O3 concentration, temperature, and solar radiation were high, and were low in fall, when O3 concentration, temperature, and solar radiation were low. We propose that O3 concentration affects the production of H2O2 in the monitored region during the period under study, but that high H2O2 concentrations were sometimes caused by the transport of polluted air from urban regions. H2O2 concentrations decreased remarkably when SO2 concentrations increased by transported volcanic emission on Miyake Island. In the absence of the effects of SO2, H2O2 concentrations increased with increasing O3 concentration and temperature.  相似文献   

15.
《Atmospheric Research》2005,73(1-2):45-67
Aerosol particles were collected during the period from 23 to 28 April 1991 at Hohhot in the Inner Mongolia Autonomous Region of China, which is in an urban area located near one of the source areas of atmospheric mineral particles. The four samples were examined by a transmission electron microscope equipped with an energy-dispersive X-ray (EDX) analyzer to obtain the size and elemental composition of individual mineral particles.On the basis of EDX analyses for 385 particles, mineral particles were present in an extremely high number (98%) of particles in the radius range of 0.1–3 μm. Particles mainly composed of silicates comprised 70% of mineral particles. “Ca-rich” particles were detected in 18% of all the particles. Most of Ca would be present as CaCO3, although the internal mixture of CaCO3 and CaSO4 was also found. Particles mainly composed of halite (NaCl) were present in low percentages of about 2% of mineral particles, and most of the particles were modified. The sample collected in the situation of weak wind contained spherical fly ash particles with about 13% of the particles analyzed. For the samples other than this sample, the grand abundance of mineral particles other than fly ash particles was larger than 98%.The hygroscopic properties of mineral particles were examined by the dialysis (extraction) of water-soluble material with distilled water. The sample collected in the situation of anthropogenic influence showed the presence of water-soluble material in mineral particles. On the basis of the EDX analysis and the water dialysis, it is suggested that the formation of CaSO4 has occurred through chemical reactions of CaCO3 in mineral particles with sulfuric acid in the atmosphere of Hohhot.  相似文献   

16.
The amounts of SOA and reactive oxygen species (ROS) formed by the reaction of α-pinene with ozone (O3) in the presence of nitric oxide (NO) were studied by varying the ratio of O3 to NO in a chamber under conditions that simulate the indoor environment. The particle mass was measured using a tapered element oscillating microbalance (TEOM) and a scanning mobility particle sizer (SMPS) was used to obtain particle volume distributions. The concentrations of particle-bound reactive species (ROS) were quantitatively determined from collected filters by the measuring the oxidation of dichlorofluorescin (DCFH) to a fluorescent product. The measured fluorescent intensities were converted to equivalent H2O2 concentrations. Three sets of experiments using different concentration ratios of NO/O3 were conducted. Measured steady-state, particle-bound ROS concentrations ranged from 0.58 to 6.78 nmol/m3 of H2O2. The SOA yields were examined using Odum’s SOA yield model that relates the mass of SOA formed to the mass of hydrocarbon consumed. For the condition where NO and O3 were in a concentration ratio of 0.5, the SOA yield was the highest with 22 % of α-pinene converted to SOA. Under these experimental conditions, the highest concentration of nitrate radical in these experiments would have been produced.  相似文献   

17.
Abstract

Aqueous‐phase H2O2 production in a rainband and its possible effect on sulphate production are studied by means of a two‐dimensional numerical model. In‐cloud peroxide production is incorporated into this chemistry model and its simulation results are compared with those in which aqueous‐phase H2O2 came only from the dissolution of gaseous H2O2 from the cloud interstitial air.

Results are presented for two different polluted situations ‐ Case 1 having initial SO2 and sulphate aerosol profiles representative of a moderately polluted air mass, and Case 2 having chemical profiles expected to increase the relative importance of oxidation to nucleation as a means of contributing sulphate to cloud and rain. Sulphate production increased in both cases, although in Case 1 the effect of this increase on the concentration of sulphate in rain is negligible because nucleation and scavenging of aerosol are the major processes by which sulphate enters cloud and rain. In Case 2, sulphate concentrations in rain increase by 5–10%. Under environmental conditions of low sulphate aerosol, where oxidation reactions are the dominant means for sulphate to enter cloud and rain, the neglect of sulphate produced by the additional H2O2 may lead to error. The usual uncertainties in the initial SO2 and sulphate aerosol vertical profiles, however, could be a more significant source of error in simulations of the chemistry of cloud and precipitation than the neglect of aqueous‐phase peroxide production during the lifetime of even a long‐lived system.  相似文献   

18.
Measurements of hydroperoxides (H2O2 and MHP) at ground level were made from 2012 to 2015 in Imizu City, Toyama Prefecture in central Japan. H2O2 and MHP concentrations ranged from 0.01 to 3.5 ppb and from below the level of detection (< 0.01 ppb) to 1.4 ppb, respectively. The concentrations of H2O2 and MHP were high in the summer and low in the winter. The H2O2 concentration was at its maximum in July and August, whereas the concentration of O3 in the daytime was highest in May and June. The ratio of [H2O2]/[SO2] presented clear seasonal variations. Many cases showed the condition of [H2O2] < [SO2], called oxidant limitation especially in the cold months. Hydroperoxide concentrations in the rainwater were also high in the summer. The concentrations of MHP were much lower than those of H2O2 in the rain water. High concentrations of H2O2 (> 2.5 ppb) were detected in the summer during the inflow of air pollution. The concentrations of H2O2 were significantly high in July and August of 2013. The H2O2 was well correlated with the O3 in July and August whereas there was no correlation between O3 and H2O2 in May and June. There was a negative correlation between NOX and H2O2.  相似文献   

19.
Factors influencing the18O content of stratospheric H2O are reviewed in order to provide a theoretical framework for the interpretation of measurements of this quantity, which are now becoming available. Depletions in18O of 5–10% in stratospheric H2O are expected based on the known correlation between that of D and18O in tropospheric H2O and observed measurements of large (typically 50%) depletions of D in stratospheric H2O. H2O formed in the stratosphere as a result of oxidation of CH4 can be expected to reflect primarily the18O content of stratospheric O2, which is the same as that of tropospheric O2 (slightly enhanced with respect to standard mean ocean water). Thus, a reduction in the18O depletion is expected with increasing altitude, but not a large enhancement in18O in upper stratospheric H2O as found in recent far infrared measurements. The observed large enhancement of18O in stratospheric O3 is not expected to be reflected in stratospheric H2O. Necessary laboratory data for the improved quantification of these effects are reviewed.  相似文献   

20.
The influence of sunlight and dissolved organic carbon (DOC) on the photochemically mediated cycling of hydrogen peroxide (H2O2) was investigated in rainwater samples collected in Wilmington, North Carolina USA. Upon exposure to simulated sunlight 14 of 19 authentic rainwater samples exhibited significant decreases in H2O2. The concentration of hydrogen peroxide did not change significantly in organic-free synthetic rainwater spiked with H2O2 in the light or in dark controls suggesting that the loss was not due to direct photolysis or dark mediated reactions. There was a significant correlation between pseudo-first order rate constants of H2O2 decay and initial H2O2 concentrations. There was also a significant correlation between the rate constant and the abundance of DOC suggesting that rainwater organic carbon plays an important role during photolytic decay either via direct reaction or indirectly through production of peroxide reactive species or scavenging of peroxide generating radicals. Several rain samples exhibited an initial increase in H2O2 during the first 2 h of irradiation. These increases were generally small and most likely do not represent a significant input of peroxide in precipitation. The photo-induced destruction of H2O2 is important because it may partly explain the late afternoon decrease of peroxide concentrations observed in earlier field studies and the substantial under saturation (<10%) of this oxidant in rainwater compared with gas phase concentrations.  相似文献   

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