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Distribution characteristics and source analysis of metal elements in indoor PM2.5 in high-rise buildings during heating season in Northeast China

This study aims to investigate whether sources of metal elements in fine particulate matter and their distribution in high-rise buildings vary with floor levels. Inductively coupled plasma emission spectrometry (ICP-AES) was used to determine the contents of 11 common heavy metals in PM2.5 samples collected from different floors of a high-rise residential building in Northeast China during the heating season. The sources of metal elements in PM2.5 samples on different floors were analysed by the enrichment factor method and the principal component analysis method. The concentration of metal elements is higher in lower floors (<7th floor) and lower in higher floors (>7th floor). The enrichment factor method shows that the enrichment factors of As, Cd, Cu and Pb may be seriously affected by human sources, while the enrichment factors of the other seven metals are less than 10, indicating that their sources may be natural sources. The principal component analysis shows that the main sources of indoor metal elements in high-rise residential buildings are divided into four main components, including coal combustion (31.44%), automobile emissions and transportation (21.60%), soil dust, particulate matter discharged from agricultural production and atmospheric dust (13.43%), metallurgical, chemical and ore mining (12.61%).