Reaction with the hydroxyl radical (OH) is often the first step in the removal of many atmospheric pollutants. The nitrogen oxides (NO_x) generated by lightning can increase the amount of HO_x (HO_x = OH + HO₂) present in the atmosphere, but direct HO_x production from lightning has never been quantitatively investigated in the laboratory. In this laboratory study, prodigious amounts of HO_x were generated by both visible and subvisible electrical discharges over ranges of pressure and water vapor mixing ratios relevant to the troposphere. Also measured were NO, total nitrogen oxides (NO_x), ozone (O₃), and OH exposure, which is the integral of the hydroxyl radical concentration over time since the discharge. HO_x and OH exposure were approximately independent of pressure from 360 to 970 hPa and increased only slightly as water vapor increased from 1,000 to 8,000 parts per million volume (ppmv), while NO_x was approximately independent of both pressure and water vapor over the same ranges. These laboratory measurements of excessive HO_x and OH exposure are similar to measurements of electrically generated HO_x discovered in electrified anvil clouds during a 2012 airborne study, thus demonstrating the relevance of these laboratory results to the atmosphere and the importance of understanding the electrically generated HO_x contribution to atmospheric oxidation.

中文翻译：

---

放电产生大量的羟基和氢过氧自由基

与羟基自由基（OH）的反应通常是去除许多大气污染物的第一步。闪电产生的氮氧化物（NO _x）可以增加大气中存在的HO _x（HO _x  = OH + HO ₂）的量，但是从未在实验室中对闪电产生的直接HO _x进行定量研究。在该实验室研究中，在与对流层有关的压力和水蒸气混合比范围内，可见光和亚可见光放电均产生大量的HO _x。还测量了NO，总氮氧化物（NO _x），臭氧（O ₃）和OH暴露，这是自放电以来随时间变化的羟自由基浓度的积分。HO _x和OH的暴露量与360 hPa至970 hPa的压力无关，并且仅随着水蒸气从百万分之1,000（ppmv）到8,000 8,000的增加而略有增加，而在同一时间内，NO _x几乎不受压力和水蒸气的影响范围。这些实验室过高的HO _x和OH暴露测量类似于在2012年的一次机载研究中在电化铁砧云中发现的电生成的HO _x的测量，因此证明了这些实验室结果与大气的相关性以及理解电生成的HO的重要性_X 对大气氧化的贡献。