Urban parks have multiple functions such as social culture, economy, and environmental services during urban development. The rapid development of cities and economy may lead to the accumulation of heavy metals in the soil of urban parks, which may threaten human health. A total of 140 soil samples were collected in 32 typical parks in Beijing. The accumulation characteristics of Pb in the soil of urban parks were analyzed using the single-factor pollution and geo-accumulation indices. The sources of Pb pollution in soils were quantitatively analyzed using the stable isotope of Pb, and the health risk was assessed using the probabilistic risk assessment method based on Monte Carlo simulation. The results showed that the geometric mean of Pb in soils of urban parks in Beijing was 38.63 mg·kg-1, which was 1.48 times the background value. However, it did not exceed the risk screening value(GB 36600-2018). The accumulation of soil Pb in urban parks increased with the increase in the proximity between the park and the central urban area and the increase in the establishment time. The soil Pb pollution index of 2 ring, 2-4 ring, and 4-6 ring parks were 0.16, 0.10, and 0.09, which did not reach the pollution level, and the geo-accumulation indices were 0.80, 0.07, and -0.31, respectively. Except for the no-moderate pollution level in ring 2 and ring 2 to ring 4, the other rings did not reach the pollution level. The sources of Pb pollution in urban parks were coal combustion, road dust, and paint, with the contributions of 45.4%, 19.6%, and 13.9%, respectively. The 95% quantiles of hazard index(HI) of soil Pb in the park for different age groups were 1.11E-01, 8.57E-02, 6.39E-02, 1.64E-02, 1.36E-02, 1.26E-02, 1.64E-02, and 1.78E-02, respectively, which indicated that there was no potential non-carcinogenic risk(HI<1). Exposure duration was the most sensitive to non-carcinogenic risks in people aged 0-18 years, and soil Pb concentration was the most sensitive to non-carcinogenic risks in people aged 18-80 years. The increase in body weight often reduced the non-carcinogenic risks. These results can provide theoretical basis for soil environmental risk control in urban parks.
Keywords: Beijing; Monte Carlo; health risk assessment; isotope tracing; lead(Pb); park soil.