Distinct black carbon at two roadside sites in Yantai: Temporal variations and influencing factors

Abstract

Continuous BC measurements were performed at two roadside sites-Donghai hotel (DH, background roadside) and Huangwu office (HW, hot traffic) in Yantai for the first time. The campaign average BC concentrations for DH and HW were 1.4 ± 0.9 and 3.2 ± 2.2 μg m−3, respectively. Biomass burning contributed to 24.6 ± 12.2% of the total BC at DH, while that for HW was 19.4 ± 12.7%. HW showed a distinct “mixed pattern” with four peaks during a day due to the interaction between traffic control regulations and rush hours while DH exhibited a “rush hour-related pattern” with two peaks appearing in morning and evening rush hours. Higher BC level was found during weekdays compared to weekends. Lower reduction rates during nighttime compared to daytime indicates high contributions of heavy-duty vehicles. Temperature of 0–10 °C, RH of 40–60% and slow wind conditions are beneficial to the BC loading. Potential source contribution function (PCSF) models indicates that air masses originating from the middle and west Shandong were the potential areas responsible for the black carbon at DH and HW. We find that the exposure to BC at DH and HW might cause health risk equivalent to 6 and 14 passive-smoking cigarettes per day, respectively.