ATMOCHEM - Interaction of trace gases with mineral dust: Impact on atmospheric photochemical cycles and dust properties

该项目包括矿物粉尘对大气/环境科学若干方面的影响的实验(实验室)和理论(大气模拟)研究。实验室研究的目的是在与大气相关的条件下，研究几种重要的大气痕量气体与真实的(撒哈拉、中国、亚利桑那州)和合成的空中矿物气溶胶样品的相互作用。使用分散的、空气中的粉尘样品(而不是散装底物)将使描述这一过程的物理化学参数能够高度可信地转移到真实的大气中。得到的参数包括吸收系数/容量和反应机理，以及它们对大气变量的依赖，例如相对湿度、阳光照射强度和其他痕量气体的浓度。正在调查的痕量气体包括可能对大气NOY、NOx和Hox收支以及臭氧混合比率产生重大影响的大气物种。此外，实验数据将能够评估这种微量气体相互作用对矿物粉尘的光学和云形成特性的影响。实验室研究的过程的全球和区域影响将在大气模型中评估，这些大气模型具有现实的尘埃排放计划，并测试了包括上述大气变量影响在内的痕量气体气溶胶相互作用的表示。将在已知气相反应和其他气溶胶类型(硫酸盐和海盐)的现实框架内评估矿物粉尘在改变主要氮氧化物储存库浓度、HO2/OH收支以及对对流层臭氧的直接和间接影响方面的作用。此外，还将评估矿物粉尘在运输过程中的化学老化/吸湿性变化的影响，以及对光学性质和云/降水的修改以及辐射收支的相关影响。一旦用新的实验室数据加以改进，这些模型将能够对不同扬尘情况下未来污染物排放的影响提供更准确的预测。

This project includes experimental (laboratory based) and theoretical (atmospheric modelling) studies of the impact of mineral dust on several aspects of atmospheric / environmental science. The laboratory studies are designed to investigate the interactions of several important atmospheric trace-gases with authentic (Saharan, Chinese, Arizona) and synthetic, airborne mineral aerosol samples under conditions which are relevant for the atmosphere. The use of dispersed, airborne dust samples (rather than bulk substrates) will enable the physical-chemical parameters that describe the process to be transferred with a high level of confidence to the real atmosphere. The parameters obtained include uptake coefficients / capacities and reaction mechanisms and their dependence on atmospheric variables such as relative humidity, intensity of irradiation by sunlight and concentrations of other trace gases. The trace gases under investigation include atmospheric species that are likely to have significant impacts on the atmospheric NOy, NOx and HOx budgets and O3 mixing ratios. Furthermore, the experimental data will enable assessment of the impact of such trace-gas interactions on the optical and cloud forming properties of mineral dust. The global and regional impact of the processes studied in the laboratory will be assessed in atmospheric models which have realistic dust emission schemes, and tested representations of trace-gas aerosol interactions including the effect of the atmospheric variables mentioned above. The role of mineral dust in changing concentrations of e.g. key NOx reservoirs, the HO2 / OH budgets and both direct and indirect impacts on tropospheric ozone will be assessed within a realistic framework of known gas-phase reactions and other aerosol types (sulphate and sea-salt). In addition, the effects of chemical ageing / changing hygroscopic properties of mineral dust during transport and the associated impact on optical properties and modification of clouds / precipitation and the radiation budget will be assessed. Once improved with the new laboratory data, the models will be in a position to provide more accurate prognoses of the effects of e.g. future pollutant emissions under different dust loading scenarios.