A review of carbon cycling and sequestration in urban soils Heavy metal concentration in Nanjing urban soils and their affecting factors Spatial distribution of soil carbon and nitrogen in urban greenspace of Beijing A study on heavy metal pollution in different greenbelts types of Shanghai Distribution and risk assessment of polycyclic aromatic hydrocarbons in urban soils: A review. Quality changes of soils in urban and suburban areas and its eco-envir onmental impacts——A review The effects of different land-use types on quality of urban soils