Total nitrogen and total phosphorous in urban soils used for different purposes in Beijing, China

The concentration and spatial distribution of total nitrogen (TN) and total phosphorus (TP), as well as variations in their levels, in land used for various activities were investigated, and the Kriging interpolation method was applied to describe the spatial distribution of TN and TP in urban soils in Beijing, China. The concentration of soil TP was higher in the middle of the city and lower in the outsides of the city. However, the levels of soil TN had no definite spatial distribution pattern. The contents of TN and TP were compared in land used for different purposes, and the spatial distribution of TN and TP, as well as the impact of human activities on TN and TP contents, in urban soils were also analyzed. Our results demonstrated that the TN levels depend on the coverage of natural vegetation at each type of site, and the TP content is affected by the usage and disposal of phosphorus-containing materials at each type of site.