Source Apportionment of Topsoil Heavy Metals and Associated Health and Ecological Risk Assessments in a Typical Hazy City of the North China Plain

The North China Plain (NCP) is the most populous plain in China and forms the core of the Beijing-Tianjin-Hebei economic circle. With urbanization, anthropogenic heavy metals have increasingly dispersed and accumulated in urban topsoil, especially in hazy cities. To investigate the major sources of haze and their relation to topsoil heavy metals concentrations in cities of the NCP, 220 topsoil samples (0-10 cm) were collected from Shijiazhuang city (capital of Hebei Province). The concentrations of eight selected metals were determined. Statistical and spatial distribution analyses suggest that coal combustion and industrial processes (Ni, Cr, Cd and Hg) were the dominant anthropogenic sources of haze in Shijiazhuang city, followed by vehicle exhausts (Pb, Zn Cu and Hg). Contrastingly, As was derived from parent materials of the NCP. A health risk assessment showed that Pb, Cr and As pose significant non-carcinogenic risks to children (hazard index > 1) via oral ingestion. A potential carcinogenic risk to children (CRs > 10(-4)) is also posed by As. While Cd and Hg do not pose health risks in Shijiazhuang city, they may pose important ecological risks as ecological risk factors > 40 were observed, resulting in ecological risk indexes of 150-600 (moderate to considerable ecological risks).

Automated summary

The study revealed that haze in Shijiazhuang city mainly originates from coal combustion, industrial processes, and vehicle exhausts, while heavy metal concentrations in soil pose varying risks to children's health and the ecological environment.