三江平原典型湿地系统湿沉降中氮浓度及沉降量初步研究

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的氮浓度及沉降量进行了初步研究。结果表明,各形态氮的月均浓度差别较大且动态变化明显,原因主要与人类活动、降水强度及频次、风向和地理位置有关;各形态氮浓度均存在明显的季节变化,春季最高,秋、冬季次之,夏季最低。春、秋季降水中各形态氮浓度的离散程度较大,原因与降水气团来源复杂性、沙尘和高空污染物输送等因素有关;降水量与各形态氮浓度呈较弱的负相关(p>0.05),NH4 -N与NO3--N、TON呈显著正相关(p<0.05),它们可能具有同源性。NH4 -N与NO3--N的良好相关性与其在液相中的反应有关;生长季降水pH的变化主要与氨挥发有关,非生长季主要与氨挥发减弱、秸秆和化石燃料燃烧以及沙尘输送等因素有关;各形态氮的沉降量具有明显的季节性,春季所占比例最高(4.57kg N/hm2),占60.41%,夏、秋季相近,冬季最低(8.29%);全年TN沉降量为7.57 kgN/hm2,TIN为沉降主体,占84.54%;NH4 -N和NO3--N为TIN沉降主体,分别占TN沉降量的52.58和29.99%。图4,表2,参16。

Study on Nitrogen Concentration and Deposition Amount in Wet Deposition in Typical Wetland Ecosystem of Sanjiang Plain

The nitrogen(N) concentration and deposition amount in wet deposition in typical wetland ecosystem of Sanjiang Plain were studied from July 2004 to June 2005.The results showed that there were significant differences among monthly average N concentrations,and the reasons were mainly correlated with human activities,precipitation intensity and frequency,wind direction and geographical location.The concentrations of different N forms all had significant seasonality.The values in spring were the highest,while the lowest values were achieved in summer.The separation degree of the concentrations of different N forms were the highest in spring and autumn due to the complex source of precipitation airmass,atmospheric dust and the transportation of pollutant in high altitude,etc.The precipitation had faintly negative correlations with N concentrations(p>0.05),but NH 4-N had significantly positive correlations with NO3-N and TON (p<0.05),and they might have homologue.The better correlation between NH 4-N and NO-3-N was correlated with their reactions in liquidoid;The pH of precipitation in growing season was mainly correlated with ammonia(NH3) volatilization,but it was controlled by many factors,such as the lower NH3 volatilization,the burning of straw and fossil fuel and the dust transportation in high altitude,in non-growing season.The N deposition amount in spring was the highest(4.57kg N/hm2),and its proportion was 60.41%,while the lowest value was achieved in winter.In conclusion,the TN deposition amount in a year was 7.57 kg N/hm2, TIN was the main deposition body and its proportion was 84.54%;NH 4-N and NO-3-N were the main body of TIN,and their proportions were 52.58 and 29.99%,respectively.