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Observations of gas phase hydrochloric acid in the polluted marine boundary layer
Author(s) -
Crisp Timia A.,
Lerner Brian M.,
Williams Eric J.,
Quinn Patricia K.,
Bates Timothy S.,
Bertram Timothy H.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd020992
Subject(s) - aerosol , chlorine , hydrochloric acid , environmental chemistry , particulates , environmental science , halogen , interquartile range , population , chemistry , inorganic chemistry , organic chemistry , medicine , alkyl , demography , surgery , sociology
Ship‐based measurements of gas phase hydrochloric acid (HCl), particulate chloride (pCl − ), and reactive nitrogen oxides (NO y ) were made in the polluted marine boundary layer along the California coastline during spring 2010. These observations are used to assess both the rate of Cl atom production from HCl and the role of direct HCl emissions and subsequent partitioning as a source for pCl − . Observations of HCl made in coastal Southern California are broadly correlated with NO z (NO z ≡ NO y – NO x ), peaking at 11 A.M. The observed median HCl mixing ratio in Southern California is 1.3 ppb (interquartile range: 0.53–2.7 ppb), as compared to 0.19 ppb (interquartile range: 0.10–0.38 ppb) measured along the Sacramento River between San Francisco and Sacramento. Concurrent measurements of aerosol ion chemistry indicate that aerosol particles sampled in Northern California are heavily depleted in Cl − , corresponding to a mean pCl − deficit of 0.05 ± 0.03 (1σ) ppb for sub‐10 µm aerosol particles. In comparison, aerosols measured in Southern California indicate that over 25% of particles showed an addition of Cl − to the particle population. Observations presented here suggest that primary sources of HCl, or gas phase chlorine precursors to HCl, are likely underestimated in the California Air Resource Board emissions inventory. These results highlight the need for future field observations designed to better constrain direct reactive halogen emissions.