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1.
北京市大气光化学氧化剂污染研究   总被引:21,自引:3,他引:21  
根据在北京市开展的光化学氧化剂系列研究。讨论了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,探讨光化学氧化的形成机制及其影响因素。  相似文献   

2.
广州市大气中过氧化物的研究   总被引:2,自引:0,他引:2  
 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, NOX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NOX, SO2 和相对湿度具有一定的负相关关系.  相似文献   

3.
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.  相似文献   

4.
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。  相似文献   

5.
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.  相似文献   

6.
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.  相似文献   

7.
刘昊  王会祥 《环境科学》2013,34(9):3352-3357
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.  相似文献   

8.
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.  相似文献   

9.
崔福义  吴雅琴  刘冬梅  张敏 《环境科学》2005,26(5):89-89-94
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.  相似文献   

10.
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.  相似文献   

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