中文摘要：

2004年7月至2005年6月对三江平原典型湿地系统大气湿沉降中的氮素动态进行了研究，并探讨了其生态效应。结果表明，各形态氮月均浓度之间差别较大，具有明显的季节性，原因主要与人类活动、降水强度及频次、风向、地理位置以及氮氧化物自然排放有关；湿沉降的TN组成以TIN为主（51．38％-98．96％），TIN又以NH^＋ 4-N和NO^- 3-N特别是NH^＋ 4-N为主，降水天气系统的路径在很大程度上影响着降水中各形态氮的组成；降水量与各形态氮浓度均呈较弱的负相关（P〉0．05），而NH^＋ 4-N与NO^- 3-N、TON均呈显著正相关（P〈0．05），它们可能具有同源性。NH^＋ 4-N与NO^- 3-N的良好相关性与其在液相中的反应有关；生长季是全年氮沉降的重要时期。其TN沉降量为非生长季的1．84倍，二者所占比例分别为64．78％和35．22％。除NO^- 2-N外，其它各形态氮的沉降量均以生长季为主体；全年TN沉降量为7．57kg／hm^2，TIN／TON之比为5．47，TIN为沉降主体，占84．56％。NH^＋ 4-N和NO^- 3-N是TIN沉降的主体，其所占全年的比例分别为52．55％和30．03％；氮是该区植物生长的限制因素，生长季的氮沉降对于促进植物生长直接生态意义重大，而非生长季的氮沉降对于大量补充次年植物生长初期所需养分的间接生态意义明显，其生态作用不容忽视；近年来湿地系统氮沉降量的降低可能是导致其退化的重要原因，其生态影响也不容忽视。

英文摘要：

The dynamics of nitrogen （N） in the atmospheric wet deposition in typical wetland ecosystem of Sanjiang plain was studied from July 2004 to June 2005, and its ecological effects were also analyzed. The results show that there are significant differences among monthly average N concentrations, and the seasonality is evident. The reasons are mainly correlated with human activities, precipitation intensity and frequency, wind direction, geographical location and NOx natural emission. The total inorganic nitrogen （TIN） is the main body of the total nitrogen （TIN） in wet deposition （51.38% - 98.96%）, and the ammonium nitrogen （NH^＋ 4-N）, nitrate nitrogen （NO^- 3-N）, especially NH^＋ 4-N, are the main body of TIN. The path of precipitation synoptic system, to a great extent, affects the composition of N in wet deposition. The precipitation only has faintish negative correlations with N concentrations （p 〉 0.05）, but the NH^＋ 4-N has significant positive correlations with NO^- 3-N and TON （p 〈 0.05）, and they might have homologue. The better correlation between NH^＋ 4-N and NO^- 3-N is mainly related with their reactions in liquidoid. The growing season is the important phase of N deposition in a year, its deposition amount is 1.84 folds of that in nongrowing season, and their proportions are 64.78% and 35.22%, respectively. The deposition amounts of N in growing season are much higher than those in non-growing season except nitrite nitrogen （NO^- 2-N）. The total N deposition amount in a year is 7.57 kg/hm^2, and TIN/TON ratio is 5.47. These show that TIN is the main deposition body and its proportion is 84.56%. Moreover, NH^＋ 4-N and NO^- 3-N are the main body of TIN, and their proportions are 52.55% and 30.03%, respectively. Further analysis indicates that N is the limited factor that affects the growth of plant. The N deposition in growing season has direct ecological signification which might stimulate the growth of plant, but in non-growing season, the N deposition