Spatial distribution of organic carbon fractions and δ13C in urban soils, Shanghai, China

Urban areas are characterized by diverse land-use patterns and are strongly influenced by anthropogenic activities. However, few studies have examined the effects of urbanization on concentrations of soil organic carbon (SOC) and its various components or δ13C in urban soils. The aim of this study was to assess the spatial distribution of SOC fractions and δ13C signatures of urban soils in Shanghai, China. The results showed that SOC fractions and δ13C compositions differ over a range of spatial scales. The concentrations of SOC, readily oxidizable organic carbon (C), black carbon (BC) and δ13C in surface soils (0–20 cm) were 10.5, 3.5, 6.9 g kg−1 and −24.9‰, respectively, and the corresponding concentrations in deep soils (20–100 cm) were 8.4, 2.8, 6.0 g kg−1 and −23.9‰. In urban soils, BC accounted for a higher proportion of the SOC pools. Concentrations of SOC, readily oxidizable organic C and BC were higher, whereas the 13C ratio was much lower in the city centre. The effects of carbon isotope fractio...