SGER: Measurements of Nitrous Acid and Nitric Acid during BEARPEX 2009

这一探索性项目涉及开发和初步实地测试一种采用长光程吸收光度法测量空气中亚硝酸和硝酸的新仪器。这两种酸都是氮氧化物的氧化产物。亚硝酸被认为在某些条件下是羟基自由基的重要来源，羟基自由基是最重要的大气氧化剂。硝酸的沉积是对流层中无机氮氧化物去除的主要原因。2009年夏季在加州的Blodgett Forest进行的一项多研究者研究（BEARPEX-09）中的现场测试侧重于生物源排放及其对大气化学的影响，将包括通过与基于不同原理的方法进行并排比较来调查测量中的潜在干扰。以前在高海拔和极地环境中的亚硝酸测量方法的现场相互比较产生了不同的结果，这表明存在测量伪影，它们可能是站点依赖性的。在BEARPEX期间获得的其他痕量气体和气溶胶成分的大量数据将允许详细检查可能的HONO测量伪像及其在非常不同的森林环境中的原因。更广泛的影响将包括更好地了解这两种酸的化学性质，进而更好地了解大气氧化化学和自由基预算。一名研究生和两名本科生将通过参与该项目接受培训。该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。

This exploratory project involves development and initial field testing of a new instrument employing the LOng Path Absorption Photometry (LOPAP) method to measure nitrous and nitric acids in air. Both acids are oxidation products of nitrogen oxides. Nitrous acid is thought to be, under some conditions, a significant source of hydroxyl radical, the most important atmospheric oxidant. Deposition of nitric acid is responsible for much of the removal of oxidized inorganic nitrogen from the troposphere. Field testing during a multi-investigator study focusing on biogenic emissions and their effects on atmospheric chemistry in Blodgett Forest, California in summer 2009 (BEARPEX-09) will include investigation of potential interferences in the measurements via side-by-side comparison with a method based on a different principle. Previous field intercomparisons of nitrous acid measurement methods in high-altitude and polar environments yielded differing results, suggesting that measurement artifacts exist and that they may be site dependent. The large array of data for other trace gases and aerosol composition to be obtained during BEARPEX will allow detailed examination of possible HONO measurement artifacts and their causes in the very different forest environment. Broader impacts will include better understanding of the chemistry of these two acids and, in turn, better understanding of atmospheric oxidation chemistry and radical budgets. One graduate and two undergraduate students will be trained through participation in the project. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).