title: [Distribution and Content of Transferable Nitrogen in the Soil of Water Level Fluctuating Zones of Mainstream and Its Tributary of Three Gorges Reservoir Areas During the Dry Period].
abstract: In order to find the intrinsic correlation between water eutrophication and transformation of nitrogen in soil of water level fluctuating zone (WLFZ) of Three Gorges Reservoir Areas (TGRA), the method of sequential extraction process was applied to analyze the content and distribution characteristics of total transferable nitrogen (TF-N) in the mainstream of Yangtze River (Wanzhou section) and its tributaries of Mixi and Zhuxi River. The results showed that, compared with the main stream, the contents of soil organic matter (SOM) and total nitrogen (TN) were higher, while cation exchange capacity( CEC) and pH value were lower in the tributaries during the dry period. The main species of TF-N in soil was organic matter-sulfide form of nitrogen (OSF-N) in the WLFZ and the content of different TF-N species was in the order of OSF-N > iron-manganese oxide form of nitrogen (IMOF-N) > ion extractable form of nitrogen (IEF-N) > carbonate form of nitrogen (CF-N). The spatial distribution pattern of total TF-N was in the order of Zhuxi River > Mixi Valley > the main stem of Yangtze River. There were no significant differences between IEF-N and OSF-N contents both in the main and tributaries of Yangtze River. The distribution of CF-N and IMOF-N had similar patterns, whereas the TF-N showed a reverse pattern in comparison with the former two species in the main and tributary of Yangtze River, which was a main factor of TF-N differences between the main steam and tributaries of the Yangtze River.
mesh_terms: D002681:China; D005068:Eutrophication; D009584:Nitrogen / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012987:Soil; D014874:Water Pollutants, Chemical; D009584:Nitrogen