Lipid biomarker estimates of seasonal variations of aerosol organic carbon sources in coastal Qingdao, China

Abstract Aerosols represent a significant source of organic carbon (OC) to China’s marginal seas, but their provenance and chemical composition remain understudied. At the boundary of the East Asian continent and China’s marginal seas, the coastal city of Qingdao is well-situated to study the sources and seasonal variations of organic aerosols and their contribution to marginal seas. Twenty-nine aerosol samples collected in 2015–2016 were analyzed for total OC (TOC), n-alkanes (C17–C33), n-alkanols (C20–C32) and n-fatty acids (n-FAs, C14–C32). Concentrations of TOC (5.7–18 μg/m3), n-alkanes (17.5–143 ng/m3), n-alkanols (18–41 ng/m3) and n-FAs (99.3–160 ng/m3) were highest in winter when total aerosol concentrations were highest. Organic carbon-normalized (OC-normalized) biomarker concentrations were used to apportion different sources of aerosol OC: short- and mid-chain n-alkanes (