Reactive chlorine in the marine boundary layer in the outflow of polluted continental air: A model study

Abstract

[1] Results from a numerical one-dimensional model show that continental pollution that is advected over the ocean leads to substantial acid displacement from newly emitted sea salt aerosol. Oxidation of HCl by OH and cycling between the gas and aerosol phase lead to a build-up of nighttime Cl 2 mixing ratios of up to 90 pmol mol À1 in our base scenario and 125 pmol mol À1 in a sensitivity study with high wind speeds. Therefore the recirculation of continental airmasses over the ocean and back to the coast might explain previous measurements of high nighttime Cl 2 in onshore winds. Furthermore, the model runs suggest a substantial contribution of daytime Cl-radical chemistry to the oxidation of volatile organic compounds under these conditions. Citation: Pechtl, S., and R. von , Reactive chlorine in the marine boundary layer in the outflow of polluted continental air: A model study, Geophys. Res. Lett., 34, L11813,

Chlorine activation by N<sub>2</sub>O<sub>5</sub>: simultaneous, in situ detection of ClNO<sub>2</sub> and N<sub>2</sub>O<sub>5</sub> by chemical ionization mass spectrometry

“…During this period, the prevailing wind direction was westerly to northwesterly at 5-10 m/s, suggesting these data represent sampling of aged continental airmasses. Our observations show concentration maxima were 10-100 pptv during this period, which on the one hand are significant, relative to previously predicted values of ClNO 2 (Pechtl and von Glasow, 2007), but also illustrate the low detection limits of this method. Most nights while within the Long Island Sound (data not shown), N 2 O 5 reached 100-250 pptv on average during night, with average nighttime ClNO 2 being generally equal to or higher at mixing ratios of 150-200 pptv.…”

“…A recent theoretical study predicted ClNO 2 mixing ratios of up to 50 parts per trillion by volume (pptv) in polluted regions (e.g. the Long Island Sound) (Pechtl and von Glasow, 2007).…”

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

“…By or after sorption and reactions such as photolysis, oxidation and reduction, any kind of these chlorine species can induce chloride condensation at the ISA particle surface. Acid tropospheric aerosols and gases such as H 2 SO 4 , HNO 3 , oxalic acid and weaker organic acids further induce the formation of gaseous HCl from sea-salt aerosol (Drozd et al, 2014;Kim and Park, 2012;Pechtl and von Glasow, 2007). Since 2004, evidence and proposals for possible catalyst-like sunshineinduced cooperative heterogeneous reaction between Fe(II), Fe(III), Cl − , q Cl and HCl fixed on mineral dust particles and in the gaseous phase on the CH 4 oxidation have been known (Oeste, 2004;.…”

Evolving research directions in Surface Ocean - Lower Atmosphere (SOLAS) science

“…Furthermore, ship emissions may induce release of reactive chlorine from sea salt, [80] which has a lifetime of several days due to multi-phase cycling. [119] As the increase in chlorine atoms is maintained for a longer period than the lifetime of the ship plume this will further reduce the atmospheric lifetime of methane. Elevated levels of formaldehyde (HCHO) in ship plumes detected by satellite [104] are probably attributable to enhanced oxidation of methane caused by elevated OH concentrations.…”