Validating HONO as an Intermediate Tracer of the External Cycling of Reactive Nitrogen in the Background Atmosphere.

In the urban atmosphere, nitrogen oxide (NO═NO + NO)-related reactions dominate the formation of nitrous acid (HONO). Here, we validated an external cycling route of HONO and NO, i.e.

The association of chemical composition particularly the heavy metals with the oxidative potential of ambient PM in a megacity (Guangzhou) of southern China.

Atmospheric fine particulate matters (PM) can cause adverse health effects through the generation of reactive oxygen species (ROS), which is normally characterized by the oxidative potential (OP). However, the particulate components that are mainly responsible for the ROS-induced OP remain controversial and warrant further investigation, especially in megacities where high exposure exists and particulate composition is complex. In this study, we measured the OP of PM using the dithiothreitol (DTT) assay with and without chelation of metals in a megacity in southern China, Guangzhou, in January and April.