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Lookup NU author(s): Dr Evangelos Petropoulos
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© 2024 Elsevier Ltd. Despite that the heavy metals in urban soils pose a threat to public health, the critical factors that influence their concentrations in urban soils are not well understood. In this study, we conducted a survey of surface soil samples from urban green spaces in Shanghai, to analyze the concentrations of the key heavy metals. The results showed that Zn was the most abundant metal with an average concentration of 122.99 mg kg−1, followed by Pb (32.72 mg kg−1) and Cd (0.23 mg kg−1). All concentrations were found to be below the risk screening values defined by the National Environmental Quality Standards for soils of development land in China (GB36600-2018), indicating no current risk in Shanghai. However, there was a clear accumulation of heavy metals, as the mean concentrations were significantly higher than the background values. Furthermore, we explored the relationships between key heavy metals with population density, GDP and green space area. Both Spearman correlation and Random Forest analysis indicated that per capita green space area (pGSA) and population density were the most crucial factors influencing the status of heavy metals in urban soils, unlike edaphic factors e.g. SOM content in farmland soils. Specifically, there was a significantly positive linear correlation between heavy metal concentrations and population density, with correlation coefficients ranging from 0.3 to 0.4. However, the correlation with pGSA was found to be non-linear. The nonlinear regression analysis revealed threshold values between heavy metals concentrations and pGSA (e.g Zn 22.22 m2, Pb 24.92 m2, and Cd 25.92 m2), with a sharp reduction in heavy metal concentrations below the threshold and a slow reduction above the threshold. It suggests that an increase in per capita green space area can mitigate the accumulation of heavy metals caused by growing population density, but the effect is limited after the threshold. Our findings not only provide insights into the distribution patterns of heavy metals in the urban soils at the local scale, but also contribute to the urban greening at the global scale and offer guidance for city planning in the face of increasing population densities over the coming decades.
Author(s): Luo S, Chen R, Han J, Zhang W, Petropoulos E, Liu Y, Feng Y
Publication type: Article
Publication status: Published
Journal: Chemosphere
Year: 2024
Volume: 352
Print publication date: 01/03/2024
Online publication date: 03/02/2024
Acceptance date: 18/01/2024
ISSN (print): 0045-6535
ISSN (electronic): 1879-1298
Publisher: Elsevier Ltd
URL: https://doi.org/10.1016/j.chemosphere.2024.141266
DOI: 10.1016/j.chemosphere.2024.141266
PubMed id: 38316278
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