Open AccessSea‐salt aerosol chemistry in coastal areas: A model study
Author(s) -
Moldanová Jana,
Ljungström Evert
Publication year - 2001
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd900462
Subject(s) - bromine , sea salt , chlorine , deposition (geology) , halogen , salt (chemistry) , seawater , environmental chemistry , sea salt aerosol , chemistry , aerosol , scavenging , acid deposition , environmental science , oceanography , geology , organic chemistry , soil water , antioxidant , soil science , paleontology , alkyl , sediment
A trajectory model of Coastal Chemistry and Deposition of Sea‐Salt Particles (CCDSSP) has been developed. Release of reactive Cl and Br species takes place under a variety of conditions. The expulsion of HCl by strong acids was found to be the most important mechanism of Cl release. In a clean marine environment, Br is released mainly through a catalytic mechanism involving HOBr, BrCl, and Br 2 , as described in earlier model studies. This pathway is ineffective for chlorine release, and formation of HOCl and Cl 2 leads to further activation of Br 2 . In environments rich in oxides of nitrogen, reactive uptake of N 2 O 5 , ClONO 2 , and BrONO 2 leads to release of chlorine and bromine from the sea‐salt particles. The importance of these processes is enhanced in the winter half year, when reactive uptake of N 2 O 5 causes approximately 40% of the total Cl release and BrONO 2 becomes the dominant pathway of bromine release. Simulated peak winter concentrations of reactive halogen species were similar to those in summer simulations, leading to an increasing relative importance of halogens in VOC oxidation in wintertime, when Cl can account for 9% of the VOC oxidation. The model simulated sea‐salt deposition along the trajectory quite satisfactorily when compared to measurements. With increasing time of transport from the coast, the sea‐salt deposition becomes less important, while deposition of HCl keeps almost constant. The Cl − deficiency in the deposited, aged sea salt is thus fully compensated for, and an excess of Cl − is found because of HCl deposition. The excess Cl − is coupled with acidity which is not accounted for in deposition measurements.