Abstract: Characteristics of nitrogen loss with surface runoff from farmlands in hilly areas around the Tai Lake were studied.The results indicate that the concentration of TN varied with surface runoff and its peak lagged behind that of the latter in time.At the prior period of runoff,NH₃-N and NO₃^--N were similar in concentration,but later on NO₃^--N rose while NH₃-N declined slowly.The concentrations of NO₃^--N were relatively low and fell down quickly with the time.As for TN and NO₃^--N,contents of the dissolved were higher than those of the suspended,whereas in the case of NH₃-N concentration,the dissolved was equivalent to that of the suspended.The average content of inorganic nitrogen weighted by runoff was higher than organic nitrogen.Organic nitrogen,especially the suspended form,showed the characteristic of varying with the flux of runoff.

Key words: overland runoff, non-point source pollution, inorganic nitrogen, organic nitrogen