Characteristics, sources, and health risk assessment of trace elements in PM10at an urban site in Chengdu, Southwest China

Abstract

To investigate trace element pollution of PM10in urban Chengdu, a Southwest megacity of China, as well as to assess the human health risks caused by exposure to PM10, we analyzed ambient PM10samples collected at an urban site in Chengdu from November, 2014 to October, 2015. The annual mean concentration of PM10in the sampling period was 173.6 ± 77.9 µg m–3, which is 2.5 times higher than the national recommended standard of 70 µg m–3The mean metals content in PM10was in the following order: iron (Fe) > zinc (Zn) > titanium (Ti) > copper (Cu) > manganese (Mn) > lead (Pb) > barium (Ba) > chromium (Cr) > strontium (Si) > nickel (Ni) > arsenic (As) > vanadium (V) > antimony (Sb) > cobalt (Co) > cadmium (Cd) > bismuth (Bi). The concentration of As in PM10was observed to be 2.9 times higher than the secondary level recommended by the China National Ambient Air Quality Standard (GB3095-2012), whereas the concentrations of other metals were within the limit. Enrichment factor analysis indicated that As, Pb, Zn, Cu, Cd, and Sb mainly originated from anthropogenic sources. Five factors were identified by positive matric factorization (PMF) model. The sources identified were soil dust (48.4%), road dust (19.4%), fossil fuel combustion (14.9%), electroplating industry (13.8%), and metallurgy industry (3.5%). Particle morphology and chemical composition analysis revealed six major particle types, namely aluminosilicate, sulfur-containing, carbon-containing, chlorine-containing, biomass burning, and metal particles. The results of the health risk assessment indicated that Cr can be carcinogenic to both children and adults, and other trace elements were determined to be below the legislation threshold (Environmental Protection Agency limit values), except for As, which was observed to be above the threshold.