关键词: 硝态氮, 水平运移, 小叶章湿地, 土壤, 三江平原

Abstract: Two typical soils（meadow marsh soil and humus marsh soil）,located in zones different in moisture regime in Calamagrostis angustifolia wetland of the Sanjiang Plain were selected for study of horizontal movement of nitrate nitrogen（NO^-₃-N） with KNO₃ as tracer.Results show that NO^-₃-N concentration and the movement rate were significantly and negatively related to the distance of NO^-₃-N horizontal movement in the two typical soils（P<0.01）,showing a first-order exponential decay curve.NO^-₃-N horizontal movement was mainly controlled by concentration gradient,soil water potential gradient and soil matric potential;But the rate of the movement was significantly and positively related to soil moisture content（P<0.05）,showing an exponential growth curve,and so was the concentration of NO^-₃-N in horizontal movement with the diffusion rate of soil water（P<0.01）,showing a Boltzmann curve in the 0-20 cm soil layers and exponential growth curves in other soil layers.In conclusion,meadow marsh soil is more propitious to horizontal movement of NO^-₃-N than humus marsh soil,which is attributed to the significant differences in physical properties（grain composition and porosity,etc.） between the two typical soils,and hydraulic conditions might be important factors leading to formation of the two soils different in physical properties.

Key words: nitrate nitrogen, horizontal movement, Calamagrostis angustifolia wetland, soil, Sanjiang Plain