Volume 16, No. 9, September 2016, Pages 2085-2095 PDF(562 KB)
Supplementary MaterialPDF (177 KB)
Atmospheric Signature and Potential Sources of Rare Earth Elements in Size-Resolved Particulate Matter in a Megacity of China
Qili Dai1, Liwei Li1, Tingkun Li1, Xiaohui Bi1, Yufen Zhang1, Jianhui Wu1, Baoshuang Liu1, Jixin Gao1, Wancong Gu1, Lin Yao2, Yinchang Feng1
1 State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
2 Hangzhou Environmental Monitoring Center Station, Hangzhou, Zhejiang 310007, China
- Concentrations and fractionation of REEs in TSP, PM10 and PM2.5 were analyzed.
- Total concentration of REE in Hangzhou is higher than those of most other cites.
- La, Ce and Sm are obviously enriched in Hangzhou.
- REEs pollution events were identified by the sharp variation of REE ratios.
The atmospheric signature and potential sources of rare earth elements (REEs) in ambient particulate matter (PM) collected at urban (ZH) and background sites (ZWY) between February 2011 and January 2012 in the Yangtze River Delta region were investigated in this study. The average total concentrations of REEs for TSP, PM10 and PM2.5 were measured to be 11.98, 9.37, 2.24 ng m–3 in ZH, which were 1.9, 1.8, 1.3 times higher than those measured in ZWY. The size distribution pattern of the REEs shows that they are significantly fractionated into coarse particles (e.g., approximately 50% in PM2.5–10). However, La, Ce and Sm are even more enriched in PM with respect to each other and other REEs. It is also shown that Ce contamination is prevalent throughout the study area, which is particularly exemplified in the finer particulate matter fraction; this significant Ce contamination could be primarily attributed to vehicle emissions. Additionally, the REEs’ pollution events during the sampling campaign were identified by the time series of the REE ratios. And the contaminations of La, Sm and Ce show clearly wind-induced variations. The enrichment factors for REEs indicate that La, Ce, Nd and Sm originated from a mix of anthropogenic and natural emission sources with small EF values.
Aerosol chemistry; Particulate matter; REEs; Source.