科研之友
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摘要
Formaldehyde (HCHO), as well as correlative pollutants was measured from 1 to 31 July in 2007 at Mazhuang, a rural site located in the east of China. Gaseous HCHO was scrubbed from the air with an acidic 2,4-dinitrophenylhydrazine (DNPH) solution, which leaded to the reaction of HCHO with DNPH and produced a stable product, 2,4-dinitrophenylhydrazone, followed by online analysis by high-performance liquid chromatography (HPLC) coupled with Ultraviolet detector. During the observation period, mixing ratios of HCHO ranged from 0.2 ppbv to 6.2 ppbv, with an average of 1.5 +/- 0.67 ppbv. HCHO shows an evident diurnal variation, the maximum appeared during 12:00-14:00. The average concentration diurnal variations of measured HCHO, ozone (O(3)), Methylhydroperoxides (MHP, CH(3)OOH), hydrogen peroxide (H(2)O(2)), nitrogen oxides (NO(x)) and meteorological parameters were compared. The similar variations of HCHO, O(3) and radiation imply that photo-oxidation of hydrocarbons might be the major source for HCHO. Based on the maximum incremental reactivity (MIR) coefficient of HCHO, the calculation shows that HCHO contributes about 20% to total observed O(3) during the study period. In order to compare the contributions of O(3), HCHO and HONO to OH radical, photolysis rate parameters (J-values) of the three compounds were calculated by the Tropospheric Ultraviolet and Visible (TIN) Radiation Model (4.4 version). Based on the comparison, this study reaches the conclusion that O(3) is the dominant source of OH radical at Mazhuang. This study also uses P(HCHO)/P(O(3)) which represents the ratio of contrbutions of HCHO and O(3) to OH radical, to discuss the action of HCHO in OH radical soucers. The result shows that P(HCHO)/P(O(3)) is 12.5% on average, with the maximum of 21.0% at 13:00(P.M). and minimum of 7.5% before 9:00(A.M). and after 17:00(P.M.).Therefore HCHO is also an important source of OH radical and cannot be ignored.
- 出版日期2010-6
- 单位北京大学
