Serious haze-fog problems in Beijing have aroused considerable concern. The objectives of this study are to determine elemental concentrations in PM2.5, assess their enrichment in PM2.5, and identify their sources during winter in Beijing. Daily PM2.5 samples were collected at the Beijing Normal University campus from January 28 to February 27, 2014. Twenty-three metal elements were determined following digestion by using inductively coupled-plasma mass spectrometry (ICP-MS). The daily PM2.5 concentration ranged from 21.8 to 474.3 mu g m(-3), with a mean of 172 mu g m(-3). The daily PM2.5 concentration exceeded 75 mg m(-3) (China ambient air quality standards: grade II) for 23 days of the month; therefore, ambient air pollution was severe. The median of daily elemental concentrations in the air decreased in the order of K, Na, and Al (> 10(3) ng m(-3)); Ca, Fe, Mn, Mg, Zn, Pb, and Cu (> 10(2) ng m(-3)); Ba, P, Ti, and Sr (> 10 ng m(-3)); and Rb, Sb, Ga, V, Ce, Cd, Tl, Li, La, and Co (> 1 ng m(-3)). Average and median values of enrichment factors were > 100 for Cd, Sb, Pb, Cu, Zn, and Tl but < 10 for Sr, V, K, Co, Na, Li, Rb, La, Mg, Ce, Ca, Fe, and Al. Enrichment factor, correlation, and principal component analyses demonstrated that Cd, Sb, Pb, Cu, Zn, and Tl in PM2.5 mainly originated from anthropogenic sources, whereas V, Co, Na, Li, Rb, La, Ce, Fe, and Al mainly originated from lithogenic sources. However, the ignition of fireworks during Spring Festival resulted in three pronounced peaks of Ba, K, Mg, Sr, and Cu concentrations. Therefore, national and local governments should continue controlling atmospheric emissions of toxic heavy metals and prohibit firework displays in megacities during Spring Festival.