To investigate the distribution and dynamics of phosphorus (P) in soils for environmental protection and agronomical usage, 31 P nuclear magnetic resonance spectroscopy ( 31 P NMR) was used to characterize the contents and chemical properties of P in sewage sludge from 13 wastewater treatment plants in Shanghai. The samples were extracted with 0.25 M sodium hydroxide (NaOH) / 0.05 M sodium ethylenediamietetraacetic acid (Na 2 EDTA) in ratio of 1:20 (w/v). Total P recovery in the extract ranged from 91 to 116% when compared to traditional chemical methods. The dominant forms of P in all samples were inorganic orthophosphates and orthophosphates monoesters. Orthophosphate diesters and pyrophosphates were present in only two and four samples, respectively. This study provides detailed information on the distribution, contents, and chemical properties of P in sewage sludge that may be of value in the utilization of sewage sludge for agronomic purposes.

Twenty-seven surface soil samples were collected from four landscape sites in Shanghai, and seven soil profile samples were gathered from the two older sites for evaluation of horizontal and vertical distribution of soil properties to reveal their relationship with plant roots. Results indicated that urban soil had significant heterogeneities. Soil total nitrogen was significantly correlated with organic matter and total potassium was more abundant than total phosphorus. The available contents of iron, manganese, zinc and copper were higher than the standards for plant growth established by Soltanpour. pH and electrical conductivity increased with increasing soil vertical depth, possibly due to leaching, while the nutrients limiting plant growth such as nitrogen, phosphorus, potassium, iron, copper and zinc had more shallow distributions due to absorption by plant roots. However, with the increasing of soil depth, contents of magnesium, sodium, sulfur and chloride increased due to leaching and bio-cycling, which was further shown by the correlation analysis.