3月21日的《科学》（Science）杂志报道说，新的实验显示，带有电子负荷的二氧化氮与水的反应是地球较低大气层中羟基基团（OH）的一个关键性的来源。正如Shuping Li及其同事所发现的，即使在相对较低浓度的情况下，羟基基团仍然是大气中的重要成分，因为它们充当的是“净化剂”的角色，即它们控制着大气清除污染物的能力。到现在为止，对流层OH被认为主要是由于日光将位于大气层中的臭氧分子进行分解之后产生的。但是Li及其同事经过计算后发现，在某些情形下，处于激发态的二氧化氮和水的反应可以产生多达50%的大气层较低部位的OH。正如Paul Wennberg 及 Donald Dabdub在一则相关的Perspective中所讨论的，这一发现对城市空气质量模型的制作可能有意义，因为OH与二氧化氮基团之间的反应对决定臭氧产生的速率是很重要的。（来源：EurekAlert!中文版）
生物谷推荐原始出处：
（Science），Vol. 319. no. 5870, pp. 1657 - 1660，Shuping Li，Amitabha Sinha
Atmospheric Hydroxyl Radical Production from Electronically Excited NO2 and H2O
Shuping Li, Jamie Matthews, Amitabha Sinha*
Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(1D) + H2O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation.
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0314, USA.
