Joint ANR-RGC Scheme

Impact of Air-Sea Exchanges on Air Quality in Coastal Megacities

Goals

---- To address production of organic gases and particles at sea surface impacted by urban pollution
---- To explore the atmospheric chemistry of halogen-NOx-VOC and impacts on the radical budget and formation of secondary compounds
---- To pursue the interplay between the sea-air exchange of chemicals, the sea-land breeze circulation and air quality (ozone and particulate matter) in coastal megacities.

Overall Strategy

This projects can be divided into 4 work packages (WP)

WP1: Sea-surface chemistry under polluted conditions ---- here the photochemical production of unsaturated carbonyls, possibly halogenated products, will be investigated in a multiphase simulation chamber. This family of reactive VOC has been recently identified under pristine conditions by the group at Lyon as arising from abiotic processes at the air/water interface. They act as sources of organic aerosols. WP1 will measure for the first time the boosting effect of air pollution on such emissions.

WP2: Gas-phase chemistry of functionalized/halogenated and reactive VOCs formed at the air-sea interface and of BVOCs ---- here the gas phase chemistry of the VOCs identified in WP1 will be investigated in a large outdoor chamber under various simulated environmental conditions and natural sunlight. This chemistry may lead to some HOx recycling, production of further reactive molecules, SOA precursors (such as glyoxal) and SOA. WP2 will aim at characterizing all of these secondary species.

WP3: Field study of atmospheric chemistry in coastal megacity and adjacent marine areas using Hong Kong as the case study ---- here the outcomes of the above WPs will be tested, identified and quantified in the field.

WP4: Model assessment of the impacts of sea-surface interactions on regional air quality under continental outflow and sea-land breeze circulations ---- here these data will be implemented into a model for impact assessments.

Collaborations