Level and Contamination Assessment of Environmentally Sensitive Elements in Smaller than 100 μm Street Dust Particles from Xining, China

Concentrations of the environmentally sensitive elements (ESEs) As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining were measured using X-ray fluorescence spectrometry and their contamination levels were assessed based on enrichment factor (EF), geoaccumulation index (I(geo)) and pollution load index (PLI). The concentrations of As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining are 0.1–0.8, 2.7–10.9, 0.7–5.2, 0.3–1.1, 0.6–2.5, 1.2–11.1, 0.7–1.3 and 0.4–2.9 times the background values of Qinghai soil, respectively. The calculated EF and I(geo) values reveal the order Co > Pb > Cu > Zn > V > Ni > Mn > As. The EF and I(geo) values of Co, Cu, Pb and Zn are higher indicating that there is considerable pollution by these elements in smaller than 100 μm street dust particles, especially for Co. The EF and I(geo) of Mn, Ni and V are lower and the assessment results indicate an absence of distinct Mn, Ni and V pollution in the studied samples. The mean value of PLI(site) is 1.14, indicating a slightly pollution in the whole city of Xining. The order of PLI(area) for the five tested districts is Center District (CD) > East District (ED) > West District (WD) > North District (ND) > South District (SD), showing that ESEs pollution in the South District is the lightest while it is the highest in the Central District.