[Nitrogen forms and its distribution character in immerged and water-level-fluctuating zone soils of the backwater reach from input river of Three Gorges Reservoir].

This study measures the contents of different nitrogen forms in the immerged soils and the soils of water-level-fluctuating zone of the backwater area from input river of Three Gorges Reservoir, and analyzes the relationship between nitrogen forms and environmental parameters. The results indicates that: (1) Content of TN in the surface immerged soils ranged from 436.0 to 921.6 mg/kg, and that in the soils of water-level-fluctuating zone ranged from 1253.5 to 2439.8 mg/kg. Compared with the TN content in surface immerged soils from the shallow lakes in the middle and lower reaches of Yangtze River, content of TN in the surface immerged soils is in the mid-lower level and the TN content in the soils of water-level-fluctuating zone is higher than that in the surface immerged soils. (2) Content of transferable nitrogen in the surface immerged soils ranged from 289.7 to 511.3 mg/kg, and that in the soils of water-level-fluctuating zone ranged from 271.6 to 595.1 mg/kg. Organic matter-sulfide form nitrogen (OSF-N) is the predominant form of the transferable nitrogen, whereas ion-exchangeable form nitrogen (IEF-N) is predominant in the transferable inorganic nitrogen. (3) Correlation coefficients between nitrogen forms and environmental parameters show that OSF-N is the main impact factor to increase the concentrations of total nitrogen and transferable nitrogen in the surface immerged soils and the soils of water-level-fluctuating zone. The increasing of the concentration of the transferable nitrogen is mainly from OSF-N.