Collaborative Research: Heterogeneous Chlorine Activation from Saline Playas

干旱调动了盐场中的天然粉尘，这些粉尘可以与氮氧化物反应，氮氧化物是燃烧源排放的污染物。这个反应释放出氯原子，氯原子是强有力的大气氧化剂，但由于缺乏测量，用于评估区域空气质量的模型忽略了氯原子。该提案将测量真实世界中的Placa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碱地地区的区域空气质量影响进行强有力的评估。当被激活时，活性氯(Cl)原子可以作为强有力的大气氧化剂，影响甲烷等温室气体的寿命，也会影响对流层臭氧的丰度。该提议假设，风吹来的来自干燥盐湖床(Playas)的含氯粉尘可以通过与气态五氧化二氮(N2O5)的异相反应转化为氯硝酸盐(ClNO2)。ClNO2光解产生的氯原子可以显着改变臭氧的产生、光化学和甲烷的寿命。这项研究将在微量气体-气溶胶流动反应器中测量盐与N2O5反应生成ClNO2的动力学。将使用化学电离质谱仪监测反应堆中的ClNO2，并将使用单粒子质谱仪、离子色谱和X射线衍射法对Playa粉尘进行分析。对盐湖释放氯的化学和大气条件的深入分析将提供一个机制框架，可在化学-气候和空气质量模型中实施，以作出更有力的预测和评估。

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.