Collaborative Research: Heterogeneous Chlorine Activation from Saline Playas

干旱调动了盐沼中的自然灰尘，这些灰尘可以与燃烧源排放的氮氧化物发生反应。这种反应释放出氯原子，氯原子是强有力的大气氧化剂，但由于缺乏测量，在用于评估区域空气质量的模型中被忽略了。该提案将测量现实世界中的干盐湖尘埃颗粒与氮氧化物的基本速率常数，以便对德克萨斯州等盐干盐湖地区的区域空气质量影响进行可靠的评估。活性氯（Cl）原子在被激活时可以作为有效的大气氧化剂，影响甲烷等温室气体的寿命和对流层臭氧丰度。该提案假设，风吹含氯化物的灰尘从干燥的盐湖床（干盐湖）可以转化为硝酰氯（ClNO2）的非均相反应与气态五氧化二氮（N2O5）。ClNO2光解产生Cl原子，Cl原子可以显著改变臭氧产生的光化学和甲烷的寿命。本研究将测量微量气溶胶流动反应器中盐与N2O5反应生成ClNO2的动力学。将使用化学电离质谱法监测反应堆中的ClNO2，并使用单粒子质谱法、离子色谱法和X射线衍射法分析干盐湖粉尘。 深入分析化学和大气条件下，氯可以从盐水盐湖释放将提供一个机制框架，可以在化学气候和空气质量模型，使更强大的预测和评估。

Droughts mobilize natural dust from salt playas that can react with nitrogen oxides, criteria pollutants that are emitted by combustion sources. This reaction releases chlorine atoms that are potent atmospheric oxidants but are neglected in models used to assess regional air quality because of lack of measurements. The proposal will measure the fundamental rate constants of real-world playa dust particles with nitrogen oxides to enable robust assessments of regional air quality impacts in salt playas regions such as Texas.Reactive chlorine (Cl) atoms when activated can serve as potent atmospheric oxidants that would effect lifetimes of greenhouse gases like methane and also tropospheric ozone abundance. The proposal hypothesizes that wind blown chloride-containing dust from dried saline lake beds (playas) can be converted to nitryl-chloride (ClNO2) by heterogeneous reactions with gaseous dinitrogen pentoxide (N2O5). The ClNO2 photolysis produces Cl atoms that could alter the ozone production photochemistry and the methane lifetime significantly. The research will measure the kinetics of ClNO2 production from reactions of salt with N2O5 in a trace gas-aerosol flow reactor. Chemical ionization mass spectrometry will be used to monitor ClNO2 in the reactor and the playa dusts will be analyzed using single-particle mass spectrometry, ion chromatography and X ray diffraction. The in depth analysis of the chemical and atmospheric conditions under which chlorine can be released from the saline playas will provide a mechanistic framework that could be implemented in chemistry-climate and air-quality models to make more robust predictions and assessments.