Affecting factors and health risks of organophosphate esters in urban soil and surface dust in a typical river valley city based on local bivariate Moran's I and Monte-Carlo simulation

A total of 102 urban soil and surface dust samples were collected from Lanzhou of China to clarify the occurrences, sources, affecting factors, and health risks of 13 organophosphate esters (OPEs). The total concentration of 13 OPEs (Ʃ₁₃OPEs) in urban soil and surface dust ranged from 80.1 to 749 and 244 to 4905 ng/g, dominated by chlorinated OPEs (39.9% and 65.1%). The Ʃ₁₃OPEs in the two media was higher in the central and eastern of Lanzhou due to local topography and wind direction. OPEs in the two media originated from industrial, traffic and commercial activities (37%–53.4%), atmospheric depositions (24.3%–31.3%), and OPEs-containing material emissions (14.5%–31.7%). Transport station number, residential/commercial area distribution, and road length were positively correlated with Ʃ₁₃OPEs in the two media, suggesting that traffic activities are the main factors influencing the distribution of OPEs. Probabilistic non-cancer (< 1) and cancer (< 1×10^-6) risks of human exposed to OPEs were low, mainly attributed to OPEs-containing material emissions (47.5%–62.0%) in urban soil and industrial/traffic activities (57.8%–92.2%) in surface dust. Reducing the frequency of human exposed to the two media and controlling the release of OPEs from pollution sources may mitigate population exposure risks.