Toxic metals in size-fractionated road dust from typical industrial district: Seasonal distribution, bioaccessibility and stochastic-fuzzy health risk management

Abstract

To explore the spatio-temporal pollution characteristics and induced heath risk of toxic elements (Cu, Cr, Cd, Zn, and Pb) in road dust from different land use patterns of a typical industrial district (the Qingshan District), the seasonal contents and bioaccessibility fraction of toxic metals in the diverse particle sizes (diameters < 63 μm, 63–100​ μm and 100–150 μm) were investigated. The stochastic simulation of triangular fuzzy number (SS-TFN) was introduced to conduct the improved health risk assessment. The mean contents of the studied metals exceeded their corresponding values of soil background, while below the screening value of metals for construction land. Both the pollution level and bioaccessibility of dust metals generally increased with the decrease of particle size. Seasonally, the heavy metal contamination in winter dust was generally more serious than that in summer, with the summer pollution levels of dust metals decreasing in the order of Zn > Pb > Cd > Cu > Cr, while the winter in Cd > Zn > Pb > Cu > Cr. Further, there were no non-carcinogenic risks for the public to expose to dust metals, but the risk levels of dust metals at some points in industrial area and sensitive area had a deteriorating trend. Meanwhile, there were no carcinogenic risks, with Cr dominated. The dust metal contamination and corresponding health risk in sensitive area and industrial area were obviously higher than that in residential area and traffic area. Stochastic-fuzzy health risk assessment provides more scientific and accurate risk management advice for both decision makers and potential receptors.