Heterogeneous Chemistry of Surface Exchange

采用湿壁流管和气泡柱方法，以及一种新型光化学和非均相流管模拟化合物和实际样品，研究了由穿透物、茎流和土壤的可溶性和不可溶性成分催化的非均相过程，导致NO2的吸收和HONO的释放。摄取速率对pH的依赖性可以阐明芳香族（即酚类）、烯烃、脂肪族和羧基结构对摄取过程的贡献。大气相关性可以通过在高湿条件下选择的气溶胶室实验来证明，通过涂覆由熔融二氧化硅制成的亲水纳米颗粒，通过穿透及其典型成分来增强气溶胶表面。采用鲁米诺仪器对实际NO2水平进行监测。亚硝酸（HONO）痕量的形成可以通过OH自由基的光诱导光化学间接检测，并将通过一种新型的长路径吸收光度计技术（LOPAP）直接检测。通过离子色谱、GC-MS、HPLC-UV和FTIR对气溶胶样品进行分析，可以发现植物毒性和硝化产物的形成。与子项目P2至P4密切合作，将相关非均相反应的速率常数纳入FLAME-SVAT-CN模型簇的微量气体模块的大气化学。

The heterogeneous processes, catalysed by soluble and insoluble constituents of throughfall, stemflow and soil, leading to an uptake of NO2 and release of HONO, are investigated by employing the wetted-wall flowtube and bubble column methods and a novel photochemical and heterogeneous flowtube to model compounds and to real samples. The dependence of uptake rates on pH can clarify the contributions of aromatic (i.e. phenolic), olefinic, aliphatic and carboxylic structures to the uptake process. The atmospheric relevance can then be demonstrated by selected aerosol chamber experiments at high humidities, enhancing the aerosol surface by coating hydrophilic nanoparticles, made of fused silica, with throughfall and its typical constituents. Realistic NO2 levels are employed and monitored by a Luminol instrument. Formation of nitrous acid (HONO) traces can be detected indirectly by light-induced photochemistry of OH radicals and it will be detected directly by a novel long-path absorption photometer technique (LOPAP). The formation of phytotoxic, nitrated products can be shown by analysis of aerosol samples employing ion chromatography, GC-MS, HPLC-UV and FTIR. In close cooperation with the sub-projects P2 to P4, the rate constants of the relevant heterogeneous reactions are incorporated into the atmospheric chemistry of the trace gas module of the FLAME-SVAT-CN modelling cluster.