Stable hydrogen isotope composition of n-alkanes in urban atmospheric aerosols in Taiyuan, China

Abstract The hydrogen isotope compositions ( δ D) of n -alkanes associated with particulate matter with a diameter of ≤10 μm from Taiyuan, China, during heating and non-heating periods were measured via gas chromatography–isotope ratio mass spectrometry to reveal the spatial and temporal characteristics of five functional zones and to provide another constraint on atmospheric pollutants. The δ D values of n -C 16 to n -C 31 during the heating and non-heating periods ranged from −235.9‰ to −119.8‰ and from −231.3‰ to −129.2‰, respectively, but these similar spans had different distribution features. During the heating period, the δ D distributions between non–central heating and commercial districts were consistent, as were those between residential and industrial districts; the n -alkanes came from two or more types of emission sources. Coal soot might be the primary local emission source, but not the only source. During the non-heating period, the n -alkanes of n -C 16 to n -C 20 were more depleted in D with the increasing carbon number in all functional zones, but there was no rule for n -C 21 to n -C 31 . Specifically, coal soot and vehicle exhaust might be the primary sources of n -alkanes for non–central heating districts in the heating and non-heating periods, respectively, according to the δ D distribution of n -C 18 to n -C 22 ; gasoline vehicle exhaust might be an n -alkane source, and the hydrogen isotope fractionation effect during the condensation process should be a pollution mechanism for the commercial district during the heating period; the δ D distribution difference of n -C 16 to n -C 18 between the two periods in the residential and industrial districts was consistent, which indicates a similar source of fossil fuel combustion and a similar isotope fractionation effect during the non-heating period.