Large-scale distribution of hydrogen peroxide from aircraft measurements during the TROPOZ II experiment

Aircraft measurements of hydrogen peroxide (H₂O₂) were performed during the TROPOZ II meridional campaign. A specially designed automatic H₂O₂ analyser on board the airplane allowed us to obtain more than 43,000 H₂O₂ measurements. The data set covers a latitude range from 60°N to 60°S and altitudes up to 11 km. Concentration of H₂O₂ ranged from 0.42 ppb (percentile 5) to 6.31 ppb (percentile 95) and exhibited a variability factor of as much as 15. Hydrogen peroxide concentration was typically low (<2 ppb) in the boundary layer of both hemispheres except for the inter-tropical belt, even in America, as well as Africa where the mean mixing ratio reached 5 ppb. In the northern uppermost troposphere a significant increase in H₂O₂ (>3 ppb) could be noticed. Some episodes of high hydrogen peroxide mixing ratio were encountered in the vicinity of cloud systems probably by exchange of H₂O₂ from the liquid phase to the gas phase.     

北京市大气光化学氧化剂污染研究

根据在北京市开展的光化学氧化剂系列研究,讨论北京市主要光化学氧化剂O₃,H₂O₂和有机过氧化物的污染浓度水平及其污染特征,探讨光化学氧化剂的形成机制及其主要影响因素。结果表明,北京市存在严重的光化学氧化剂污染,中关村大气臭氧(0₃)最大浓度不仅逐年递增,而O₃最大值的出现时间也提前,说明大气光化学活性逐年增强。光化学烟雾的重要产物过氧化氢(H₂O₂)和甲基过氧化氢(MHP)的浓度水平较高,最大浓度分别为3.69和3.26ug/m3。日益严重的大气NO_x污染为光化学氧化剂的生成提供了充足的前体物,北京市的大气污染己逐渐转为机动车尾气污染型,控制北京市光化学氧化剂污染的有效途径是降低NO_x排放。      

广州市大气中过氧化物的研究

采用高效液相色谱(HPLC)荧光法于1998年7月和10月测定了广州市大气中的5种过氧化 物:过氧化氢(H₂O₂)、羟甲基过氧化氢(HMHP)、甲基过氧化氢(MHP)、1-羟乙基过氧化氢(1-H EHP)及乙基过氧化氢(EHP).其中主要过氧化物是H₂O₂、HMHP和MHP,其最高浓度分别为1.6(10 ^-9、0.67(10^-9和0.54(10^-9(V/V).在光照强,相对湿度低的情况下,H₂O₂和MHP呈现明显的日 变化规律,早晚浓度低,最大值多出现在14:00～16:00.同时测定了大气温度,湿度和紫外辐射U VB及大气中O₃, NO_X和SO₂,发现H₂O₂和MHP与O₃、温度和UVB具有一定的正相关关系,而与NO_X, SO₂ 和相对湿度具有一定的负相关关系.     

Atmospheric chemistry of peroxides: a review

Inorganic and organic peroxides have become the focus of increased attention by atmospheric chemists during the last decade. Hydrogen peroxide serves as an important link between gas phase radicals and aqueous phase chemistry in the atmosphere. As an important aqueous phase oxidant of S(IV), H₂O₂ plays a major role in the acidification of clouds, fogs, dew and rain. Several studies have indicated that peroxides and their precursor radicals cause damage to a variety of plant tissue.In this article we review analytical techniques, discuss and review the various sources of peroxides in the gas and aqueous phases and examine their reactions with S(IV) and N(III).     

Comparison of H2O2 and O3 content in atmospheric samples in the San Bernardino mountains,Southern California

Concentrations of atmospheric H₂O₂ were measured in air, rain, cloud and dew samples in forested areas of the San Bernardino Mountains, southern California, from spring through fall of 1987–1990 O₃ measurements in air were also conducted for comparison. Typical ranges of H₂O₂ concentrations measured were 1–3 ppb in air, 10–90 μM in rain and cloud water, and < μM in dew. The results show that gas-phase H₂O₂ concentrations were slightly higher at nighttime than at daytime or nearly constant throughout a 24-hr period, whereas O₃ concentrations were highest during the afternoon, when polluted air masses from Los Angeles carried by daily sea breezes reached the mountain region. Afternoon concentrations of gaseous H₂O₂ and O₃ in the mountain region were compared with those measured in Los Angeles urban sites to elucidate the regional variation of these oxidants. The results show that ambient concentrations of H₂O₂ and O₃ were about 50–100% higher at the mountains sites than at the Los Angeles sites.     

碳同位素比技术定量估算城市大气CO2的来源

要有效地减少城市碳排放和正确地判断城市现有减排措施的有效性就必须准确地确定城市大气CO2的来源.由于碳同位素比从污染源到受体的传输过程中同位素分馏现象不明显,本研究建立了一套基于碳同位素比技术定量估算城市大气CO2来源的方法,并用该方法初步定量分析了上海市嘉定区大气CO2中来自燃煤、机动车尾气和生物质贡献的时空分布.上海市嘉定区大气CO2的上述3种来源中,生物质的贡献最大.燃煤的贡献在夜间(00:00、04:00和20:00)多于白天(08:00、12:00和16:00),且随高度的升高而增大;机动车尾气的贡献则随高度的升高而降低.大气CO2浓度时空分布特征体现了上海市郊嘉定区大气CO2的排放特征和各来源的传输特性.     

Sulfur dioxide,hydrogen sulfide,total reduced sulfur,chlorinated hydrocarbons and photochemical oxidants in southern California museums

Indoor and outdoor concentrations of the air pollutants ozone, NO₂, SO₂, H₂S, total reduced sulfur (TRS), peroxyacetyl nitrate (PAN), methyl chloroform and tetrachloroethylene, have been measured at three southern California museums. Indoor maxima were 175 ppb for NO₂, 77 ppb for O₃, 0.7 ppb for PAN, 1.2 ppb for C₂Cl₄, >6.3 ppb for CH₃CCl₃, 2.5 ppb for SO₂, 1.4 ppb for TRS, and 46 ppt for H₂S. Indoor levels and indoor/outdoor (I/O) ratios for the chlorinated hydrocarbons pointed out to indoor sources. Outdoor and indoor levels of SO₂ and TRS were low at all three museums, but I/O ratios for SO₂ were high and averaged 0.89. H₂S concentrations were low, 16–46 ppt at one museum and less than 6 ppt at the other two museums. I/O ratios for the air pollutants with outdoor sources (ozone, PAN and NO₂) showed substantial variations, from low values of 0.02–0.33 at locations without influx of outdoor air to high values of 0.85–0.88 at locations experiencing high influx of outdoor air. Of the 10 institutions we have surveyed in southern California to date, eight exhibit high I/O ratios, e.g. 0.60–1.00 for PAN. Of the four museums surveyed that were equipped with HVAC and chemical filtration, only two yielded the expected low I/O ratios.     

气相过氧化氢的生成及大气中浓度的测定

研究了ＨＣ－ＮＯ２－空气体系中Ｈ２Ｏ２和有机氢过氧化物的生成。模拟实验结果表明：Ｈ２Ｏ２生成浓度的最大值与碳氢化合物的初始浓度成正比;生成规律与Ｏ３生成规律类似,比值［Ｏ３］ｍａｘ／［Ｈ２Ｏ２］ｍａｘ随［ＨＣ］０增大而减小。在乙烯、戊烷体系中,Ｈ２Ｏ２在总过氧氢化物的比例为０．６左右;而丙烯体系中,随光照时间的延长,有较多的有机氢过氧化物产生。大气监测结果显示：Ｈ２Ｏ２的生成受污染物排放、日照及温度的影响,早晚浓度低,午后形成峰值,日变化规律与Ｏ３浓度变化相似,监测到的最大浓度值在春季为１．３×１０－９,在秋节为０．６４×１０－９。     

Seasonal,diurnal and nocturnal variations of carbonyl compounds in the semi-urban environment of Orléans,France

Atmospheric carbonyls were measured at a semi-urban site in Orléans, France, from October 2010to July2011. Formaldehyde, acetaldehyde and acetone were found to be the most abundant carbonyls, with average concentrations of 3.1, 1.0, 2.0 ppb, respectively in summer, 2.3, 0.7, 2.2 ppb, respectively in autumn, 2.2, 1.0, 2.1 ppb, respectively in spring,and 1.5, 0.7, 1.1 ppb, respectively in winter. Photo-oxidation of volatile organic compounds(VOCs) was found to make a remarkable contribution to atmospheric carbonyls in the semi-urban site based on the distinct seasonal and diurnal variations of the carbonyls, as well as the significantly positive correlations between the carbonyls and ozone. The significantly negative correlations between NO x and O_3 as well as the carbonyls and the positive correlations between wind speed and O_3 as well as the carbonyls implied that the carbonyls and O_3 at the semi-urban site were probably formed during air mass transport from neighboring cities.     

Measurements of H2O2, aldehydes and organic acids in Los Angeles rainwater: Their sources and deposition rates

Rainwater samples were collected in Los Angeles, during 1985–1991 to determine concentration levels, sources and deposition rates of atmospheric H₂O₂, aldehydes and organic acids, in addition to major cations, anions and pH. Volume-weighted mean concentrations of H₂O₂, aldehydes (formaldehyde + acetaldehyde + glyoxal + methylglyoxal) and organic acids (formic acid + acetic acid) in rain collected at Westwood were 4.4., 3.9 and 16.5 μM, respectively, during the 6-year study period. Monocarboxylic organic acids were estimated to account for 27% (2–80%) of total free acidity (as on overall average) in rain collected at Westwood, whereas sulfuric acid and nitric acid accounted for 39% and 34% of the total acidity, respectively. Concentrations of aldehydes were strongly dependent on precipitation volume and decreased with increasing precipitation volume, whereas H₂O₂ and organic acids were only weakly dependent on precipitation volume. These results indicate that concentrations of aldehydes in rain are mainly controlled by dilution, whereas H₂O₂ and organic acid concentrations are controlled by other factors, such as decomposition of H₂O₂ by reacting with S(IV) and continuous aqueous formation/decomposition of organic acids by reactions involving aldehydes, dissolved OH radicals and H₂O₂. Principal component analyses indicate that aldehydes in rainwater mainly originate from gases and aerosols derived from anthropogenic sources, whereas the sources of H₂O₂ and organic acids in rain do not correlate with anthropogenic sources or marine and continental sources. There is good agreement between reported gas-phase concentrations of H₂O₂, aldehydes and organic acids in Los Angeles and calculated equilibrium concentrations of these chemical species from their rainwater concentrations and Henry's law constants. Temporal variations of concentrations of chemical species indicate that H₂O₂, aldehydes and organic acids were highest in the early afternoon. Summer rains contained the highest concentration of these chemical species, suggesting the photochemical activities during rain storms significantly affect their concentration levels. Estimation of annual rate of wet and dry depositions of H₂O₂, aldehydes and organic acids for the period studied, indicates that 84% of H₂O₂, 97% of aldehydes and 94% of organic acids, respectively, are annually scavenged from the atmosphere, by dry deposition, which is the dominant process for removal of these atmospheric pollutants in Los Angeles.     

Kinetics of microwave-enhanced oxidation of phenol by hydrogen peroxide

Aqueous solutions of phenol were oxidized by hydrogen peroxide assisted by microwave (MW) irradiation. A simple kinetic model for the overall degradation of phenol in the presence of excess H₂O₂ is proposed in which the degradation rate of phenol is expressed as a linear function of the concentrations of phenol and H₂O₂. A detailed parametric study showed that the degradation rate of phenol increased with increasing [H₂O₂] until saturation was observed. Phenol degradation followed apparent zero-order kinetics under MW radiation or H₂O₂ oxidation. However, after 90 min of irradiation, the observed kinetics shifted to pseudo first order. The overall reaction rates were significantly enhanced in the combined MW/H₂O₂ system, mainly because microwave could accelerate H₂O₂ to generate hydroxyl radical (·OH) and other reactive oxygen intermediates. The observed synergetic effects of the MW/H₂O₂ process resulted in an increased in the net reaction rate by a factor of 5.75. When hydrogen peroxide is present in a large stoichiometric excess, the time required to achieve complete mineralization is reduced significantly.     

Ozone concentrations at a remote mountain site and at two regional locations in southwestern Alberta

Ozone concentrations at a remote site in the Rocky Mountains of southwestern Alberta averaged 43.4 ppb over a 2 year period and the Canadian air quality objective of an 80 ppb hourly average was exceeded 1.5% of the time. The diurnal variation in O₃ concentrations was small, 2.9 ppb, indicative of a remote location, above the nocturnal inversion and not greatly influenced by local emissions. During the period when O₃ concentrations were highest, winds were generally from the southwest, suggestive of the long range transport of anthropogenic pollutants from distant sources rather than the generation of O₃ from local emissions. In contrast, hourly O₃ concentrations at two regional air quality monitoring sites showed an average diurnal variation of 14 ppb. Only two hourly averages exceeded 80 ppb during the 2 years, and the mean O₃ concentration was 26 ppb. When these regional sites were within the urban plume from Calgary, the O₃ concentrations were depressed to a mean of 18 ppb. Ozone concentrations in downtown Calgary averaged 13 ppb. Under Alberta climatological and meteorological conditions, hourly O₃ objectives are most likely to be exceeded in remote areas, rather than in cities or in areas under the direct influence of urban emissions.     

福建茫荡山地区春季大气O3、HONO、HCHO、H2O2对 ·OH的贡献率研究

2009年春季在福建南平市茫荡山地区进行观测,测量了.OH源O3、HONO、HCHO和H2O2的浓度.结果表明O3、HCHO、HONO、H2O2浓度分别为4.96×10-8、3.97×10-10、2.53×10-10、1.18×10-10,低于华北农村的浓度.利用CMAQ计算O3、HCHO、HONO、H2O2对.OH的贡献率,分别为57.0%、7.7%、34.9%、0.4%.O3光解是该地区最重要的.OH来源.O3、HCHO、H2O2对.OH的贡献呈现单峰变化,在12:00～13:00达到峰值.HONO对.OH的贡献曲线呈波动状,和人类居住环境清晨出现峰值的情况不同.     

Perturbations to tropospheric oxidants, 1985–2035: 2. Calculations of hydrogen peroxide in chemically coherent regions

Increasing global emissions of trace gases NO, CH₄, and CO, along with perturbations initiated by changes in stratospheric O₃ and H₂O, may cause tropospheric hydrogen peroxide (H₂O₂) levels to change. Specific scenarios of CH₄CONO emissions and global climate changes are used to predict HO₂ and H₂O₂ changes from 1985 to 2035 in a one-dimensional model that simulates different chemically coherent regions (e.g. urban, non-urban continental and marine mid-latitudes; marine and continental low latitudes).If CH₄ and CO emissions continue to increase throughout the troposphere at current rates (1% yr⁻), there will be large increases in H₂O₂, for example, more than 100% in the urban boundary layer from 1985 to 2035. Globally, H₂O₂ will increase 22% with HO₂ increasing 8% and O₃ increasing 13%. When CH₄, CO and NO emissions are specified on a regionally varying basis and are parameterized for high and low potential growth rates, globally averaged increases in surface concentrations are 12% for H₂O₂ and 18% for O₃. A global warming (with increased H₂O vapor) or stratospheric O₃ depletion superimposed on CH₄, CO and NO emissions changes will cut O₃ increases but add to peroxide, increasing levels as much as 150% above present day in some regions.Both globally uniform and region-specific scenarios predict a 10–15% loss in global OH from 1985 to 2035. Thus, conversion of OH to HO₂ and H₂O₂ in the atmosphere may signify a loss of gaseous oxidizing capacity in the atmosphere and an increase in aqueous-phase oxidizing capacity.     

化学预氧化对苏氨酸生成三氯乙醛的影响

以具有最大比三氯乙醛生成潜能(SCHFP)的苏氨酸为研究对象,分析了次氯酸钠(NaClO)、二氧化氯(ClO_2)、高锰酸钾(KMnO_4)、过氧化氢(H_2O_2)、臭氧(O_3)和臭氧过氧化氢(O_3/H_2O_2)等预氧化剂对三氯乙醛(CH)生成的影响,以确定合适的预氧化剂及其适宜投加量,为CH的控制提供指导.结果表明,能够有效去除一天CH生成量(CH1d)的预氧化方式依次为H_2O_2、ClO_2、KMnO_4和NaClO,适宜投加量分别为3、0.5、0.6和0.5mg·L-1,对CH1d相应的去除率分别为61.54%、47.63%、29.77%和10.94%;能够有效去除CH生成潜能(CHFP)的预氧化方式依次为KMnO_4、NaClO、H_2O_2和ClO_2,适宜投加量分别为0.6、0.5、3和0.5mg·L~(-1),对CHFP相应的去除率分别为41.01%、33.38%、8.36%和2.40%;O_3和O_3/H_2O_2预氧化能够使CH1d和CHFP增加,不适用于对CH的控制.     

Hydrogen peroxide levels in Los Angeles: A screening-level evaluation

The major factors affecting the diurnal variation of gaseous hydrogen peroxide were studied using a one-dimensional vertical gas-phase chemistry/transport screening model. The model which included diurnal variations of the inversion layer, surface emissions, dry deposition of air pollutants, and meteorological conditions such as solar radiation, temperature, relative humidity and wind speed, was used to evaluate the influence of the ratio of NMHC/NO_x, the emission rates of NO_x and NMHC, the deposition velocity of H₂O₂, and the height of inversion layer on the ground level gaseous H₂O₂ concentrations. The model was found to yield reasonable agreement with field data from the Carbonaceous Species Methods Comparison Study at Glendora, California, in 11–21 August 1986. Specifically, model predictions and field results all indicated that during clear skies, ambient H₂O₂ concentration was highest at about early afternoon when O₃ concentration was highest and NO_x was lowest. It was concluded that the predicted gaseous H₂O₂ concentration is most sensitive to the emission rate of NO_x and the ratio of NHMC/NO_x, but it is less sensitive to the deposition velocity, height of inversion layer, and the emission rate of NMHC.     

O3/H2O2法灭活水中剑水蚤类浮游动物

为解决水源水中孳生的水蚤类浮游动物难以被常规的水处理工艺有效地去除,困扰水厂正常生产运行的问题,进行了O₃氧化、H₂O₂氧化和O₃/H₂O₂高级氧化对水体中剑水蚤类浮游动物灭活效果的试验研究.发现3种方法中,O₃/H₂O₂联合时除蚤效果最佳,在蒸馏水中投量为O31.0mg/L、H₂O₂4mg/L时,接触30min达到100%的灭蚤率;单独O₃氧化效果也较好,投加1.0mg/L的灭蚤率为80%;H₂O₂氧化效果不理想,投加4mg/L几乎无灭蚤效果.进而考察确定了O₃/H₂O₂灭活剑水蚤的最佳工艺条件为:先加O₃后加H₂O₂,投加间隔时间30～60s为宜;并探讨了H₂O₂投量、水体pH值以及有机物含量对O₃/H₂O₂系统灭活剑水蚤效果的影响.试验中发现H₂O₂投量在4～10mg/L之间效果无较大变化,有机物含量对灭蚤影响较大,pH值的影响则较小.最后对O₃/H₂O₂预氧化与水处理混凝沉淀工艺的协同除蚤效能进行了考察.结果表明,O₃/H₂O₂预氧化与水处理混凝沉淀工艺的协同作用将会进一步提高除蚤的效果.     

A clean production process of sodium chlorite from sodium chlorate

This paper presents a novel cleaner production process for producing sodium chlorite by reducing sodium chlorate with hydrogen peroxide. In the new process, chlorine dioxide is generated by reducing chlorate ions with hydrogen peroxide in the presence of sulfuric acid: it then reacts with aqueous sodium hydroxide solution and hydrogen peroxide to produce sodium chlorite. The reaction conditions that were experimentally investigated included: reaction temperatures, concentrations of sodium chlorate solution, molar ratio of NaClO₃:H₂SO₄:H₂O₂, and acidity. Waste acid in the chlorine dioxide generator is dramatically reduced with recycling in the new process. The by-produced sodium sulfate in sulfuric acid is minimized and reclaimed.     

Evaluation of a number of chemical mechanisms for their application in models describing the formation of photochemical ozone in Europe

A series of 24 chemical mechanisms from the literature are compared against each other using harmonized emissions, photolysis rate coefficients for simple inorganic chemistry and life cycle data for ozone, PAN and H₂O₂. The evaluation sought to understand the impact of parameterizing hydrocarbon oxidation on the peak concentrations of photochemically-generated secondary pollutants. Only seven of the 24 chemical mechanisms gave peak concentrations of ozone, PAN and H₂O₂ simultaneously in their respective central ranges. PAN and H₂O₂ were generally calculated with a much lower precision compared to ozone. Only 11 mechanisms out of 24 gave responses to both 50% hydrocarbons and NO_x emissions controls in their respective central bands. The lack of coordinated ozone, PAN and hydrogen peroxide measurements across Europe currently limits the adequacy of model comparisons and hence the confidence which may be placed in assessments of likely impacts of future control strategies.     

基于腔衰减相移光谱法的二氧化氮分析仪的设计与应用

基于腔衰减相移光谱法设计了一套二氧化氮在线分析仪,通过优化测量参数,该仪器可长期稳定运行,其时间分辨率为60 s,检出限为0.191 ppb,在0~300 ppb范围内,NO₂气体浓度与相位正切信号值具有较好的二次拟合关系,R²为0.9995.另外,该仪器在泰安站进行了长期外场观测,并与改装后的进口商品化仪器PKU-Thermo 42i-TL进行比对实验,结果表明,两者的测量结果一致性较好,R²=0.9811,表明其具有良好的运行稳定性和测定结果准确性,适用于环境大气二氧化氮浓度的在线监测.外场观测结果表明,春季泰安站二氧化氮浓度均值为12.39 ppb,有明显日变化规律.