Rationale: Aerosols play an important role in depositing metals into forest ecosystems. Better understanding of forest aerosols with regard to their metal content and their possible sources is of great significance for air quality and forest health.
Methods: Particulate matter with an aerodynamic diameter less than 2.5 µm (PM(2.5)) in aerosols was collected every month for 20 months using moderate-volume samplers in the Dinghushan (DHS) nature reserve in southern China. The concentrations of metals (Al, Cd, Mn, Ni, Pb, and Zn) as well as the Pb isotopic ratios in the PM(2.5) samples were measured by inductively coupled plasma mass spectrometry (ICP-MS).
Results: Moderate pollution with aerosol PM(2.5) was detected at the DHS nature reserve with the air mass from mainland China being the predominant PM(2.5) source. The high enrichment factors (EFs) for the heavy metals Pb, Cd, and Zn, as well as the PM(2.5) mass concentrations, coupled with backward trajectory analysis, indicated the anthropogenic origins of the PM(2.5) and of the heavy metals in the PM(2.5). The Pb isotopic ratios revealed the contributions from various Pb sources, which varied between seasons.
Conclusions: Industrial emissions and automobile exhaust from the Pearl River Delta (PRD) primarily contributed to the anthropogenic Pb in PM(2.5), although there was occasionally a contribution from coal combustion during the wet season. Pb isotopic ratios analyses are helpful for air quality assessment and Pb source tracing.
Copyright © 2015 John Wiley & Sons, Ltd.