State Key Laboratory of Organic Geochemistry , Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510 640 , China.
University of Chinese Academy of Sciences , Beijing 10069 , China.
Environ Sci Technol. 2018 Nov 6;52(21):12306-12315. doi: 10.1021/acs.est.8b03196. Epub 2018 Oct 17.
A vertical wetted-wall flow-tube technique was used to explore the ionic strength effects at the air-water interface in mediating the sea-surface reaction between ozone (O) and pyruvic acid (PA). The uptake coefficients of ozone on aqueous PA increase substantially with the concentrations of bromide (Br) ions, clearly indicating that the dry deposition of ozone could be significantly enhanced due to the presence of carbonyl compounds such as PA at the bromide-rich sea surface. Based on the observed uptake coefficients, the estimated deposition velocity of ozone (100 ppb) for a nanomolar range of PA concentrations is ∼1 × 10 m s, which represents a significant contribution to the known deposition velocity of ozone at the sea surface. The analysis of reaction products by ultra-high-resolution Fourier transform-ion cyclotron resonance mass spectrometry suggests the formation of oligomers during both the dark and light-induced heterogeneous reactions between gaseous O and PA occurring at the surface of a dilute aqueous phase (representative of cloud droplets). The detected high-molecular-weight compounds are much more complex than the oligomeric species identified during the photolytic degradation of bulk aqueous PA alone.
采用垂直浸润壁流管技术研究了离子强度在调节臭氧（O）与丙酮酸（PA）在海-气界面反应中的作用。臭氧在水溶液中的吸收系数随着溴化物（Br）离子浓度的增加而显著增加，这清楚地表明，由于羰基化合物（如 PA）在富含溴化物的海表面的存在，臭氧的干沉降可能会显著增强。基于观察到的吸收系数，估算的臭氧（100ppb）在纳摩尔范围 PA 浓度下的沉积速度约为 1×10 m s，这代表对已知的臭氧在海表面的沉积速度的重要贡献。通过超高效分辨率傅里叶变换离子回旋共振质谱分析反应产物表明，在气态 O 和 PA 在稀水溶液（代表云滴）表面的非均相光诱导和暗反应中形成低聚物。所检测到的高分子量化合物比单独光解降解大量水溶液 PA 时鉴定的低聚物物种复杂得多。
