中文摘要：

通过水平土柱室内模拟试验,研究了硝态氮在5种淹水频率洪泛区湿地土壤中的水平运移过程及土壤理化性质对硝态氮水平运移的影响。结果表明,5种淹水频率洪泛区湿地土壤硝态氮运移通量与运移距离呈负相关的关系,并随运移距离的增加呈指数衰减变化;与土壤水分扩散率呈一定的正相关关系,并随土壤水分扩散率的增加呈指数增长。5个不同淹水频率洪泛区湿地各层土壤硝态氮水平运移规律在一定程度上存在差异,表层土壤硝态氮通量明显低于亚表层土壤硝态氮通量。通过建立硝态氮通量与土壤基本理化性质关系的数学模型发现,硝态氮的运移通量随着土壤容重和含水率的增加而减小,并在一定程度上受土壤结构的影响。

英文摘要：

Nitrate nitrogen migration can greatly affect water quality of rivers and lakes. It is for this need that the primary objective of this paper is to present our simulation results of the nitrate nitrogen migration in the horizontal soil columns so as to better identify the discrepancies in transport flux of nitrate in the different floodplain wetlands with different flood frequencies. In proceeding with our research, we have simulated the horizontal migration of nitrate nitrogen in five flood wetlands with different flooding frequencies, that is, the permanent flood, one-year flood, five-year flood, ten-year flood, one-hundred-year flood in Erbaifangzi wetland in a lab-simulation scale, with the effects of soil properties on nitrate nitrogen migration discussed. Our simulation results indicate that similar changing tendency of the horizontal migration of nitrate nitrogen in the above said wetlands, may have noticeable inverse relationship with the migration distance, and vary exponentially in one-order exponent decay with the increase of the distance. However, the migration flux of the nitrate nitrogen in the five flood wetlands with different flooding frequencies can be found proportionally correlated with the water diffusion coefficients and exponentially increased with the increase of the water diffusion coefficients. At the same time, the changing curves of the horizontal migration of nitrate nitrogen prove to be somewhat different at the different soil strata of the above said five flooding frequencies. Such difference may have resulted from the different soil properties influenced by the flooding frequencies. And in this case, the migration flux of the nitrate nitrogen in the surface soil tends to be obviously lower than those in subsurface soils. We have developed a numerical model for the relation between the migration fluxes of nitrate nitrogen and the corresponding soil properties and proved that the migration fluxes of the nitrate nitrogen can not only be influenced by the water potential gradient and t