Soil denitrification in Shanghai urban riparian zone

From April 2011 to February 2012, soil samples were bi-monthly collected from 6 different type riparian zone locations in Shanghai city, Pudong (PD), Jinshan (JS), Jiading (JD), Qingpu (QP), Chongming (CM), and Minhang (MH). The denitrification rate in soil was measured by the acetylene inhibition method. The results show that the denitrification rate in riparian soil varies from 1.00 μmol·m^-2·h^-1 to 82.92 μmol·m^-2·h^-1 with a significant spatiotemporal deviation. Denitrification rates in riparian soil near the farmland (PD and JD) are higher than those in grassland (QP and MH) and the bushland (JS and CM). Denitrification rate decreases from the soil surface to the deeper layer and is higher in the top 2~5 cm. There is distinctive seasonal variation of soil denitrification rate with higher in summer and autumn and lower in spring and winter. Denitrification rate is the highest in summer. Temperature, pH, soil organic carbon (SOC), and soil total nitrogen (STN) content are the important factors influencing soil denitrification rate, with the denitrification rate positively correlated with temperature, STN and SOC and negatively with pH.