Seasonal variation and source apportionment of the oxidative potential (OP) of PM2.5 in a metal-smelting city in China: Detection of the OP of PM2.5 from typical industrial sources by DTT assay

Abstract

The aggregate measure known as oxidative potential (OP) is used to assess the health risk associated with exposure to fine particulate matter (PM_2.5). Evaluation of the contributions of PM_2.5 sources to OP, especially typical industrial sources, is critical for human health. In this study, samples were collected from an industrial park, an urban site, and various pollution sources in a metal-smelting city (Baotou) across all four seasons in 2021, and the oxidative potential (OP) of PM_2.5 was investigated using the dithiothreitol (DTT) assay. CMB model were used to determine the connections between PM_2.5 and pollution sources.Moreover, a new method was proposed to quantify the contributions of various sources to the OP of ambient PM_2.5. The DTTm of ambient PM_2.5 during the sample period was 14.40 ± 6.73 pmol min⁻¹ μg⁻¹, with significant seasonal variations ranked as autumn > summer > winter > spring. Most detected constituents, such as secondary inorganic aerosol (SIA) species and some transition metals, exhibited positive correlations with DTTm (P < 0.05). According to the measurement of OP of different pollution sources, the sixteen sources ranked as follows: slag separation > electrolytic aluminum emissions > coal dust > vehicle exhaust > coking > fugitive dust from urban surfaces > tailings > steel slag > street dust > crushing plant emissions > soil > pulverized coal > dust from residual anode assembly > dust from roasted aluminum ash > sintered ash > sintering emissions. In general, the dominant sources of OP in ambient PM_2.5 are slag separation and electrolytic aluminum emissions.