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A clear understanding of the impacts of urban land expansion on ecosystem services is crucial for sustainable urban planning. Although various studies have shown that urban land expansion caused a degradation of ecosystem services, the relationship between the spatial variation of urban land expansion and ecosystem services still remains unclear. This study quantified the ecosystem services and urban land expansion indicators of Wuhan for 1990-2015 and analyzed the spatial and temporal variation characteristics of ecosystem service values (ESVs) and urban land expansion indicators. Using spatial autocorrelation analysis and linear regression, the quantitative and qualitative correlations between ecosystem services and urban land expansion indicators were explored. The total ESV of Wuhan decreased by 16.47%, representing a loss of 1636.19 million yuan. Areas with extremely low ESVs continuously expanded outward from the urban center. During 2010-2015, the urban land expansion area, intensity, damage weight, and distance peaked, which caused an enormous decrease of the total ESV. Negative correlations were found between urban land expansion and all ecosystem services; the correlation with food production was most significant, indicating that urban land expansion had the strongest impact on food production. The expansion area is the main factor causing the decline of each ecosystem service among urban land expansion indicators. This study presents the impact characteristics of urban land expansion on ecosystem services, and the results provide a reference for reasonable decision making in urban planning., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Oral ingestion is the main exposure pathway through which humans ingest trace metals in the soil, particularly for children. Metals in different soil particle size fractions may vary in terms of concentration and properties. Urban school/kindergarten soil samples were collected from three cities: Lanzhou in northwest China, Wuhan in central China, and Shenzhen in southeast China. Soil samples were classified according to particle size (<63 μm, 63-150 μm, 150-250 μm, and 250-2000 μm) to estimate the effects of soil particle size on the total content and bioaccessibility of metals (Cd, Cr, Cu, Ni, Pb, and Zn). Based on the results, we assessed whether the standard size <150 μm (containing < 63 μm and 63-150 μm), recommended by the Technical Review Workgroup (TRW) of the Environmental Protection Agency (EPA), and <250 μm (containing < 63 μm, 63-150 μm, and 150-250) recommended by the Bioaccessibility Research Group of Europe (BARGE), are suitable where the largest proportion adhering to hands is the finest soil (<63 μm). The results showed that different metals exhibited different relationships between soil particle size and content and between soil particle size and bioaccessibility. Pb and Zn generally exhibited the greatest bioaccessibility in the coarsest particle sizes (250-2000 μm); whereas the highest Ni bioaccessibility occurred in the finest sizes (<63 μm); the bioaccessibility of other metals did not exhibit any obvious relationships with particle size. When assessing health risks using bioaccessible metal content in the recommended soil particle size ranges (<150 μm and <250 μm) and in finer particles (<63 μm), the results for noncarcinogenic risks to children exhibited no obvious difference, while the actual carcinogenic risks may be underestimated with the use of soil particle size ranges < 150 μm and <250 μm. Therefore, when choosing an optimal particle size fraction to evaluate the health risk of oral soil ingestion, we recommend the use of the bioaccessible metal content in <63 μm soil fraction., (Copyright © 2019 Elsevier Inc. All rights reserved.)