Source-specific ecological risk analysis and critical source identification of heavy metals in road dust in Beijing, China

• Published in: Journal of hazardous materials Vol. 388; p. 121763
• Main Authors: Men, Cong, Liu, Ruimin, Xu, Libing, Wang, Qingrui, Guo, Lijia, Miao, Yuexi, Shen, Zhenyao
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.04.2020
• Subjects: China; Critical source; dust; environmental assessment; fertilizers; fuel combustion; Heavy metals; Integrated ecological risk; pesticides; risk assessment; Road dust; Source-specific risk apportionment; spring; toxicity; traffic; China; Integrated ecological risk; Critical source; Road dust; Source-specific risk apportionment; Heavy metals
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.121763

[Display omitted] •A new method amended existing widely used risk assessment methods was developed.•Critical sources and critical source area for road dust were introduced and identified.•Fuel combustion contributed the largest to heavy metal but less to ecological risks.•Pesticide and fertilizers contributed half of risks, posing no less than moderate risks.•Traffic exhaust was critical in all seasons, with higher impact within smaller ring roads. To explore the spatial variation of source-specific ecological risks and identify critical sources of heavy metals in road dust, 36 road dust samples collected in Beijing in March 2017 were analyzed for heavy metals. A new method that takes into consideration the heavy-metal toxic response and is flexible to changes in the number of calculated heavy metals, called the Nemerow integrated risk index (NIRI), was developed for ecological risk assessment. The NIRI indicated that heavy metals posed considerable to high risks at the majority of sites, and 22 % of the sites suffered extreme risk in spring (NIRI > 320). Four main sources were identified based on positive matrix factorization (PMF): traffic exhaust, fuel combustion, construction, and use of pesticides and fertilizers. Owing to the lower toxic response factors of representative heavy metals of fuel combustion than those of other sources, although fuel combustion had the highest contribution (34.21 %) to heavy metals in spring, it only contributed 5.57 % to ecological risks. Critical sources and critical source areas were determined by considering the contributions to both heavy metals and ecological risks. The use of pesticide and fertilizer and traffic-related exhaust were identified as critical sources of heavy metals in spring. Source-specific ecological risks and critical sources of heavy metals changed with the changing seasons, which suggests that different strategies should be adopted in different seasons.