高空臭氧保护我们，为什么近地面的臭氧却是污染物？
If high-altitude ozone protects us, why is ground-level ozone a pollutant?
地面臭氧是汽车尾气中的氮氧化物和挥发性有机物在阳光下降合成的，会刺激呼吸道、伤害植物。
Ground-level ozone forms photochemically from NOx and VOCs in sunlight and irritates lungs and damages plants.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#臭氧 #光化学 #污染
氟利昂怎样破坏臭氧层？
How do CFCs destroy the ozone layer?
CFC 在平流层受紫外光分解释放 Cl·，催化循环破坏 O₃（O₃→O₂）；一个氯原子可毁掉成千上万个臭氧分子。
UV splits CFCs in the stratosphere, releasing Cl· that catalytically destroys O₃ (O₃→O₂); one Cl atom can wreck thousands of ozone molecules.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#氟利昂 #臭氧层 #自由基
为什么羟基自由基（·OH）被称为大气的“清洁剂”？它与甲烷反应速率很慢这一点为何反而重要？
Why is the hydroxyl radical (·OH) called the “detergent of the atmosphere”, and why does its very slow reaction with methane actually matter?
·OH主要来自臭氧光解产生的O(¹D)与水汽反应及HO₂+NO途径，带未配对电子，几乎能氧化一切还原性痕量气体。CH₄+·OH氢摘取一步活化能高，室温速率常数仅约6×10⁻¹⁵ cm³ s⁻¹，正是这最慢的一步决定了甲烷约十年的大气寿命，也是多数VOCs降解链的起始与速控步。OH平均浓度仅约10⁶个/cm³，却决定大气总体氧化容量，故称“清洁剂”。
In the sunlit troposphere ·OH arises when O(¹D) atoms from ozone photolysis react with water vapour, and via HO₂ + NO. With its unpaired electron it attacks nearly every reduced trace gas. Methane oxidation starts with H-abstraction, CH₄ + ·OH → ·CH₃ + H₂O, whose high barrier leaves a room-temperature rate constant of only ≈6×10⁻¹⁵ cm³ s⁻¹; this single slow step sets methane's roughly decade-long atmospheric lifetime and initiates degradation chains for most VOCs. Although mean ·OH levels are barely 10⁶ molecules cm⁻³, they define the atmosphere's total oxidizing capacity — hence “detergent”.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Finlayson-Pitts B.J. & Pitts J.N. Jr.《Chemistry of the Upper and Lower Atmosphere》, Academic Press, 2000
B.J. Finlayson-Pitts & J.N. Pitts Jr., Chemistry of the Upper and Lower Atmosphere, Academic Press, 2000
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780122570605 (2000)
#羟基自由基 #大气氧化 #甲烷寿命
一氧化二氮（N₂O）为什么也是重要温室气体？
Why is N₂O an important greenhouse gas?
它的温室效应约为 CO₂ 的 300 倍，还会破坏臭氧，主要来自化肥与燃烧，且大气寿命长。
Its warming power is about 300× CO₂ and it also harms ozone; sources are fertilizers and combustion, and it persists long in air.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#氧化亚氮 #温室 #农业
酸雨为什么能一点一点腐蚀大理石雕像？
Why does acid rain slowly erode marble statues?
大理石主要成分是碳酸钙，酸和它反应生成可溶的钙盐，表面被逐渐溶蚀、变得粗糙。
Marble is mostly calcium carbonate; acid converts it to soluble calcium salts, gradually dissolving and roughening the surface.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#酸雨 #大理石 #碳酸钙
PM2.5 里的“二次”颗粒物从哪来？
Where do secondary PM2.5 particles come from?
由 SO₂、NOₓ、VOCs 在大气中经气相与颗粒相反应生成硫酸盐、硝酸盐和二次有机气溶胶。
They form from SO₂, NOₓ and VOCs through gas- and particle-phase reactions into sulfates, nitrates and secondary organic aerosol.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#PM2.5 #二次气溶胶 #大气