WEI Zong-Qiang;WU Shao-Hua;ZHOU Sheng-Lu;LI Jing-Tao;ZHAO Qi-Guo

Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China);School of Geographic and Oceanographic Science, Nanjing University, Nanjing 210093 (China)

carbon mineralization;microbial activity;soil fertility;soil sealing;water-soluble organic carbon

Installation of impervious surface in urban area prevents the exchange of material and energy between soil and other environmental counterparts, thereby resulting in negative effects on soil function and urban environment. Soil samples were collectedat 0—20 cm depth in Nanjing City, China, in which seven sites were selected for urban open soils, and fourteen sites with similar parent material were selected for the impervious-covered soils, to examine the effect of impervious surface on soil properties and microbial activities, and to determine the most important soil properties associated with soil organic carbon (SOC) transformation in the urban soils covered by impervious surfaces. Soil organic carbon and water-soluble organic carbon (WSOC) concentrations, potential carbon (C) and nitrogen (N) mineralization rates, basal respiration, and physicochemical properties with respect to C transformation were measured. Installation of impervious surface severely affected soil physicochemical propertiesand microbial activities, e.g., it significantly decreased total N contents, potential C mineralization and basal respiration rate (P < 0.01), while increased pH, clay and Olsen-P concentrations. Soil organic carbon in the sealed soils at 0-20 cm was 2.35 kg m~(-2), which was significantly lower than the value of 4.52 kg m~(-2) in the open soils (P < 0.05). Canonical correlation analysis showed WSOC played a major role in determining SOC transformation in the impervious-covered soil, and it was highlycorrelated with total N content and potential C mineralization rate. These findings demonstrate that installation of impervious surface in urban area, which will result in decreases of SOC and total N concentrations and soil microbial activities, has certain negative consequences for soil fertility and long-term storage of SOC.