Concentration and Ecological Risk Assessment of Heavy Metals in PM2.5 Collected in Urban and Suburban Areas of Beijing

Abstract

Atmospheric PM2.5 pollution and ambient air quality were investigated in Beijing, and the ecological risks of the trace heavy metals in PM2.5 were analyzed. PM2.5 samples were collected from Dongzhimen and Huairou by a middle volume sampler, and 16 kinds of trace metals were determined by inductively couple plasma-mass spectrometry (ICP-MS). The results showed that the average concentration of PM2.5 in the urban area was 92.35 μg·m-3, and the number of days higher than the Ambient Air Quality Standards (GB 3095-2012) accounted for 41.7% of the total number of days. The average concentration of PM2.5 in the suburban area was 70.90 μg·m-3, and the standard exceedance rate was 31.7%. In general, the spatial and temporal distributions of heavy metals were as follows:nighttime > daytime; urban area > suburban area; winter > autumn > spring > summer. The enrichment factors for Pb, As, Zn, Ni, and Cu in the urban area and Pb, As, Zn, Cr, Ni, and Cu in the suburban area indicated that most came from anthropogenic sources. The result for the geoaccumulation index indicated that Ni is affected by anthropogenic sources and natural resources, while Cu, Zn, As, Cd, and Pb might have been derived from human activities. The potential ecological risk of Cu, Zn, Pb, and Cd was high, while the degree of ecological harm posed by Cd was extremely strong.