Abstract: We studied the dynamic changes of atmospheric nitrogen deposition concentration and amount in precipitation collected by a standard rain gage, in Maoershan area. The total amount of atmospheric nitrogen deposition from precipitation was 19.16 kg·hm^-2, and the proportions of NH⁺₄-N, NO^-₃-N and DON to total nitrogen deposition in precipitation were 52%, 26% and 22%, respectively. The ratio of NH⁺₄-N to NO^-₃-N was nearly 2.0. On a seasonal basis, the average content of NH⁺₄-N deposition in precipitation was 1.59 mg·L^-1 with the greatest contribution to atmospheric nitrogen wet deposition. There was an obvious seasonal change in the contents of total atmospheric nitrogen wet deposition, being the highest value in May and September and lowest in July. Moreover, the monthly amounts of NH⁺₄-N, NO^-₃-N and total nitrogen input from wet deposition were all positively related with the time of rainfall (P<0.01) with the correlation coefficients of 0.65, 0.63 and 0.76, respectively. However, the monthly amount of DON nitrogen input from wet deposition was not significantly correlated with the time of rainfall (P>0.05) with the correlation coefficient of 0.24. The high annual NH⁺₄/NO^-₃ ratio compared with the more developed region suggested that N deposition in this region was mostly affected by agricultural activities rather than industrial activities.

Key words: Maoershan region, atmospheric nitrogen wet deposition, precipitation, seasonal dynamics