PM2.5-bound heavy metals measured in indoor–outdoor new campus in Tianjin, China: characterization and sources

To investigate PM2.5-bound heavy metals in indoor–outdoor new campus in Tianjin, PM2.5 sampling was conducted on university campus on December 3–21, 2015. One sample was obtained per day at each site. The sources of heavy metal were analyzed using enrichment factor analysis, the geoaccumulation index, and principal component analysis. The results showed that the heavy metals of Zn, Pb, Cr, and Cu in PM2.5 were the major elements in indoor and outdoor, accounting for approximately 80% of the eight investigated elements. Regarding the indoor elements, approximately 40–43% of Pb, 26–29% of Cu, 34–39% of Zn, 52% of Cd, and 40–42% of Mn originated from the outdoor environment. Cd indicated extreme contamination, and Zn and Pb indicated heavy contamination, both indoors and outdoors. Among the elements, Cd exhibited the highest enrichment degree. Because of its low background value and high toxicity coefficient, Cd represented a severe ecological hazard. V, Cu, Zn, Cd, Cr, Ni, and Pb originated primarily from anthropogenic pollution. By contrast, Mn originated primarily from lithophile pollution. Results revealed that heavy metal elements in Tianjin during winter originated primarily from industrial emissions, soil and road dust, fossil and other fuel combustion, and ship emissions. Ambient environment emissions were the dominant sources of heavy metals in winter in university campus of Tianjin.