A better understanding of hydroxyl radical photochemical sources in cloud waters collected at the puy de Dôme station – experimental versus modelled formation rates

• DOI: 10.5194/acp-15-9191-2015
• Publication Date: 2015-08-19T13:06:07Z
• Authors: A. Bianco; M. Passananti; H. Perroux; G. Voyard; C. Mouchel-Vallon; N. Chaumerliac; G. Mailhot; L. Deguillaume; M. Brigante
• Keywords: Hydroxyl radical

Abstract. The oxidative capacity of the cloud aqueous phase is investigated during three field campaigns from 2013 to 2014 at top puy de Dôme station (PUY) in France. A total 41 samples are collected and corresponding air masses classified as highly marine, marine continental. Hydroxyl radical (HO•) formation rates (RHO•f) determined using a photochemical setup (xenon lamp that can reproduce solar spectrum) chemical probe coupled with spectroscopic analysis trap all generated radicals for each sample. Using this method, obtained values correspond HO• without its sinks. These correlated concentrations naturally occurring sources HO•, including hydrogen peroxide, nitrite, nitrate iron. hydroxyl measured ranging approximately 2 × 10−11 4 10−10 M s−1, quantum yield (ΦHO•) estimated between 10−4 10−2. Experimental compared modelled calculated by model multiphase chemistry (M2C2), considering only radicals. comparison experimental results suggests photoreactivity iron species source overestimated model, H2O2 photolysis represents most important (between 70 99 %) water sampled PUY (primarily continental).