Impacts of Sandstorms on Chemistries of Ambient PAHs in a Small City in North China

Abstract

Sandstorm events frequently perplex northern China, addressing the people's concern due to subsequent increases in the toxicity and carcinogenicity of PM2.5-bound PAHs (PB-PAHs) in receptor area of sand dust. Here, we enacted a field campaign in a small city between Beijing and Baoding in spring of 2021 covering the sandstorm period (SSP) and non-sandstorm period (NSSP) to examine the sandstorm impacts on chemistries of PB-PAHs. SSP exhibited a slightly high average PAH concentrations of 10.3 ng m–3 than 9.16 ng m–3 in the NSSP. At the same time, the average PM2.5 concentrations obviously increased from 60.7 μg m–3 to 75.2 μg m–3. Positive matrix factorization (PMF) analysis manifested that sandstorm largely enhanced the oil leakage and combustion (OLC) fractions from 18.0% in the NSSP to 34.4% in the SSP. Potential source contribution function (PSCF) indicated that OLC partly came from sandstorm origin area–Inner Mongolia. Low diagnostic ratios of FA / (FA + PY) in the SSP also indicated OLC was more important. Accordingly, the largest contributor of incremental lifetime cancer risks (ILCRs) changed from vehicle exhaust (VE) (36.2%) in the NSSP to OLC (34.4%) in the SSP. VE and industrial emission (IE) contributions decreased obviously due to emission control and traffic limitation in the SSP. Coal burning (CB) still held a high contribution to PAHs regardless of the implementation of “coal to gas” law in the sampling area. In addition, sandstorms increased the levels of high molecular weight PAHs (HMW-PAHs) with high toxicity by 4.07%. ILCRs for adults and children increased from 3.90 × 10–7 to 4.74 × 10–7 and from 2.41 × 10–7 to 2.93 × 10–7, respectively, in the SSP, which should be more concerned.