Pollution-Derived Br Boosts Oxidation Power of the Coastal Atmosphere.

The bromine atom (Br) has been known to destroy ozone (O) and accelerate the deposition of toxic mercury (Hg). However, its abundance and sources outside the polar regions are not well-known. Here, we report significant levels of molecular bromine (Br)─a producer of Br─observed at a coastal site in Hong Kong, with an average noontime mixing ratio of 5 ppt.

Photodissociation of particulate nitrate as a source of daytime tropospheric Cl.

Chlorine atoms (Cl) are highly reactive and can strongly influence the abundances of climate and air quality-relevant trace gases. Despite extensive research on molecular chlorine (Cl), a Cl precursor, in the polar atmosphere, its sources in other regions are still poorly understood. Here we report the daytime Cl concentrations of up to 1 ppbv observed in a coastal area of Hong Kong, revealing a large daytime source of Cl (2.