To discover the characteristics of nitrogen pollution

the authors collected and studied water samples from the upstream of Hanjiang River for six times in 2011. A careful examination of the samples revealed that the average nitrogen concentration in the forms of ammonia nitrogen(NH3-N)

nitrate nitrogen(NO3-N) and nitrite nitrogen(NO2-N) was 1.037 mg/L

1.751 mg/L

and 0.044 mg/L

respectively. The annual distribution curve of NH3-N concentration fell into the double-peak pattern with the highest concentration in flood season

relatively low concentration in dry season

and the lowest in normal water period. The annual distribution of NO3-N concentration fell into the single-peak pattern curve with the highest concentration in flood season

relatively low concentration in dry season

and the lowest in normal water period. The annual distribution of NO2-N also fell into the single-peak pattern curve with the highest concentration in flood season

relatively low concentration in the dry season and common water period with little difference. The spatial distribution of nitrogen pollution demonstrated increasing in concentration of NH3-N and NO3-N at first

and then decreasing in these two types of pollutants all the way from the source to the downstream part of Hanjiang River. The source of the NH3-N pollution mainly comes from rural domestic waste water

and livestock and poultry breeding. NO3-N pollution is mainly due to soil erosion.