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JOUR NAL O F E NVI R ONM E NT AL S C I E NC ES 87 (202 0) 1 – 9 3
Fig. 1 – Location of sampling site (https://map.baidu.com/).
plasma-mass spectrometry (ICP-MS, Agilent 7700X, USA) was crustal elements). The average concentrations of crustal
used for analysis of elements. Strict quality control was elements (Al, Fe, Ca, Mg, Na, Ti, Ba, and Sr) accounted for
performed throughout the experimental process, and a 23.8% of PM 10 mass. Crustal elements are mainly from fugitive
collision cell and shield torch were used to ensure the dust influenced by the overall level of urban sanitation,
accuracy of the measurement elements. Another part of filter greening cover, human earthmoving activities, and dust
was used for extraction with de-ionized water for an hour, control. The crustal elements had strong correlations (almost
then water-soluble inorganic ions were analyzed by ICS-90 ion more than 0.8). Considering the maturity of research at home
chromatography (Dean, USA). The carbon fractions were and abroad, eight heavy metal elements such as Zn, Pb, Mn,
measured by a thermo-optical carbon analyzer (DRI-2001A, Cu, As, V, Cr and Cd were selected to be discussed. During the
Atmoslytic, USA), following the IMPROVE protocol (Chow et experimental period, the average concentrations of the eight
al., 2007). heavy metals were 415.413, 183.587, 105.227, 82.368, 16.098,
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7.998, 49.795 and 4.529 ng/m . Zn and Pb were the most
1.3. Meteorological condition and PM concentration abundant heavy metals in PM 10 in Beijing.
PM 2.5 and PM 10 hourly mass concentrations were collected by
Quartz fiber on iron tower (next to the office building; 1 m above
ground) at IAP campus. Meteorological hourly data at Beijing
Olympic Sports Center (temperature (T), visibility (M) and
relative humidity (RH), etc.) were from the Beijing Meteorolog-
ical Bureau. The distance between two sites is 1.5 km.
1.4. Air mass back trajectories
Air mass backward trajectories were conducted by the Hybrid
Single Particle Lagrangian Integrated Trajectory (HYSPLIT) 4.0
Model to generate backward trajectories at three altitudes of
100, 500 and 1000 m above ground level (AGL).
2. Results and discussion
2.1. Metals in atmospheric particles
Fig. 2 – Mass distribution of non-crustal elements in
As shown in Fig. 2, Zn, Pb, Mo, Mn, and Cu are elements with particles.
high abundance among all tested elements (expected for