Atmospheric characteristics and population exposure assessment of black carbon at a regional representative site in the Yangtze River Delta region, China based on the five-year monitoring

Highlights: • BC concentration in YRD was at low to medium level compared with other regions. • Annual BC level was decreased by 45.4% from 2014 to 2018. • Traffic was identified as the dominant source for ambient BC in YRD region. • Male generally taken the higher inhalation exposure level of BC compared to female. • Infants generally suffered the relative higher estimated daily intakes of BC. To investigate the multi-year atmospheric characteristic and population exposure level of black carbon (BC) in the Yangtze River Delta (YRD) region, China, about five years of ambient BC measurement was performed at Dianshan Lake (DSL) regional Supersite from February 2014 to February 2019. BC concentration at DSL was 1.39 ± 1.15 μg m⁻³, which was at low to medium level compared to other areas in the world, and annual BC level was decreased by an average of 45.4% from 2014 to 2018. The absorption Ångström exponent (AAE) value was 1.30 ± 0.173, indicating the predominant contribution of liquid fuel sources such as traffic exhaust to BC. Meanwhile, AAE and BC values both showed the winter-high and summer-low temporal patterns, which highlighted the increasing contribution from solid fuels to BC in winter. Moreover, diurnal characteristics of BC, AAE, carbon monoxide and nitrogen oxide demonstrated the dominance of traffic sources for BC. The average estimated daily intakes (EDIs) of BC through inhalation for 17 population age subgroups were 0.0177–0.0811 μg kg⁻¹ day⁻¹, which the highest EDIs for male and female were both observed in infants (9 months ~ < 1 year). Male generally taken higher exposure level of BC compared to female. This work could improve the insights for atmospheric characteristic and population exposure level of BC, and potentially facilitate the development of abatement policies of BC in YRD region, China.