Source Apportionment of Atmospheric NMHCs over the Chinese Marginal Seas

Non-methane hydrocarbons (NMHCs) in the marine atmosphere have been studied extensively due to their important roles in regulating atmospheric chemistry and climate. However, very little is known about the distribution and sources of NMHCs in the lower atmosphere over the marginal seas. Herein, we characterised the atmospheric NMHCs (C2-C5) in both the coastal cities and the marginal seas of China, with a focus on identifying the sources of NMHCs in the coastal atmosphere. The terrestrial NMHCs, especially alkanes, may be an important source/reservoir in the marine atmosphere, with 3 factors constraining its input: distance from the ocean sites to the nearest land, retention of air mass over land, and air mass transport time. The positive matrix factorisation extracted 4 isolated sources of atmospheric NMHCs, showing that terrestrial sources (industrial activities, vehicular exhaust, and vegetation emission) primarily constitute (~80%) the NMHCs in the nearshore atmospheres, and they partially influence atmospheric secondary organic aerosol and ozone levels. This indicates the potential importance of terrestrial outflow in shaping the air quality and regulating climate dynamics in the marginal seas.
Reference: Wang, J., Xue, L., Ma, Q.Y., et al. (2024). The role of oceanic ventilation and terrestrial outflow in atmospheric non-methane hydrocarbons over the Chinese marginal seas. Atmos. Chem. Phys., 24, 8721–8736. https://doi.org/10.5194/acp-24-8721-2024