Risk and sources of heavy metals and metalloids in dust from university campuses: A case study of Xi'an, China

Abstract

College students study and live at university for several years; however, the pollution levels, ecological health risks, and sources of heavy metals and metalloids (HMMs) in the dust found at university campuses are still unknown. In this study, dust samples from university campuses in Xi'an were collected and the Zn, Mn, As, Pb, V, Cr, Co, Cu, Ba, and Ni contents were measured using X-ray fluorescence spectrometry. The pollution levels and ecological health risks of these HMMs were evaluated using the geo-accumulation, pollution load, and potential ecological risk indices and a health risk assessment model while their sources were apportioned using positive matrix factorization. The mean HMM concentrations in the dust were higher than the corresponding background values in the topsoil of Shaanxi Province. The Mn, V, Co, As, and Ni concentrations in the dust samples analyzed were within the levels categorized as no pollution by the geo-accumulation index standard, whereas other HMMs caused pollution to different degrees. Assessment of the pollution load index indicated that the dust samples analyzed were moderate contamination with HMMs. Pb and Cu in the dust presented considerable and moderate ecological risks, respectively; the other HMMs presented low ecological risks. The combined ecological risk of the HMMs measured in the dust samples was considerable. The non-carcinogenic and carcinogenic risks to male and female college students were within the safe levels. This study found three main sources of the HMMs measured in the dust: traffic, natural, and mixed sources (the latter including automobile repair industry waste and paints and pigments), which accounted for 47.5%, 29.3%, and 23.2% of the total HMM concentration, respectively.