江西红壤地区农田生态系统大气氮沉降通量的研究

ATMOSPHERIC NITROGEN DEPOSITION IN AGRECOSYSTEM IN RED SOIL REGION OF JIANGXI PROVINCE

2004年12月至2005年11月在江西鹰潭中国科学院红壤生态实验站进行了为期1a的大气氮沉降的外场观测试验。本文对观测得到的数据资料进行分析,定量给出了农田生态系统大气氮化物浓度和氮沉降通量。结果表明,鹰潭地区农田下垫面大气中NH3、NOx和ON(有机氮)的平均浓度分别为24.6、3.54、7.2μgm-3。气溶胶中铵盐、硝酸盐、ON的平均浓度分别为4.16、4.64、0.92μgm-3。降水中NH4+离子、NO3-离子、ON的平均浓度分别为0.89、0.73、0.26mgL-1。全年大气氮沉降总量为N6.26gm-2,其中干沉降为N3.19gm-2,占总沉降量的51%;湿沉降为N3.07gm-2,占总沉降量的49%。无机氮沉降为N5.47gm-2,占总沉降量的87.4%;有机氮沉降为N0.79gm-2,占总沉降量的12.6%。与草地、森林、湖泊等其他下垫面相比,江西红壤地区农田下垫面大气氮沉降量相对较大,对农田生态系统氮素平衡将产生重要影响。

During the period from December 2004 to November 2005, atmospheric deposition was monitored at the Yingtan Red Soil Ecological Station, Chinese Academy of Sciences, in Jiangxi Province. Observation data were analyzed with focus on concentrations of nitrogen oxidants and nitrogen deposition flux. Over the farmland, the concentrations of NH3, NOx, organic nitrogen （ON） were 24.6, 3.54, and 7.2 μg m^-3, respectively,in the atmosphere, 4.16, 4.64 and 0.92 μg m^-3, respectively, in aerosols, and 0.89, 0,73 and 0.26 mg L^-1, respectively, in precipitation. The total nitrogen deposition is N 6.26 g m^-2, of which 3.19 g m^-2 or 51% was dry deposition, and 3.07 g m^-2 or 49 % wet deposition, and 5,47 g m^- 2 or 87.4 %, inorganic nitrogen and 0.79 g m^-2 or 12.6% organic nitrogen. Compared with other types of landuse, such as grassland, forest and lake, farmland receive more atmospheric nitrogen deposition in Jiangxi Province, which will have significant impact on nitrogen balance within the farmland ecosystem.