农田生态系统大气氮、硫湿沉降通量的观测研究

2007年10月至2008年9月,借助自动降雨收集器(APS-2A)及自动气象观测站(VSALA-M52),在中国科学院红壤生态实验站(江西鹰潭)农田区内定位采集雨水样本,探讨了大气氮、硫湿沉降特征,估算了大气氮、硫的湿沉降向农田生态系统的输入通量.结果表明,雨水中氮、硫素的月质量浓度变异较大,全氮(T-N)、铵态氮(NH_4~+-N)、硝态氮(NO_3~--N)和硫(SO_4~(2-)-S)的月质量浓度,即ρ(T-N)、ρ(NH_4~+-N)、ρ(NO_3~-N)和ρ(SO_4~(2-)S)分别为1.09～7.84、0.64~6.25、0.34～1.83和0.95～7.64mg·L~(-1),均与降水呈负相关,其中ρ(T-N)、ρ(NH_4~+-N)、ρ(SO_4~(2-)-S)与降水的相关性达到比较显著水平(n=11,p<0.10).湿沉降月通量F(T-N)、F(NI_4~+N)、F(NO_3~--N)和F(SO_4~(2-)-S)分别为1.0～7.84、0.64～6.25、0.17～1.54和1.22～9.15 kg·hm~(-2),均与降水呈正相关,其中F(T-N)、F(NH_4~+-N)和F(SO_4~(2-)-S)与降水的相关性均达到显著水平(n=11,p<0.05).季节上,雨水氮、硫浓度及湿沉降氮、硫通量均呈冬春>夏秋的特性.湿沉降向农田生态系统输入N 35.94 kg·hm~(-2)·a~(-1)和S45.93 kg·hm~(-2)·a~(-1),其中NH4~+-N的年沉降通量为22.92 kg·hm~(-2),占湿沉降氮总量的63.75%.

Observations of the input for atmospheric wet-deposition of nitrogen and sulfur into Agro-ecosystem

Atmospheric nitrogen and sulfur deposition, especially for atmospheric wet deposition has led to changes in agro-ecosystems from nitrogen/sulfur limited to nitrogen/sulfur saturated. Rainwater samples were collected by ASP-2 automatic sampler and rainfall was recorded by automatic weather station on an event basis in an agro-ecosystem at Red Soil Ecological Experiment Station, Chinese Academy of Sciences, in the suburb of Yingtan city, Jiangxi Province during Oct. 2007-Sep. 2008 period. Based on these data, characteristics of atmospheric wet-deposition nitrogen and sulfur were studied and its input to the agro-ecosystem were estimated. The results were showed that monthly mass concentration for total nitrogen(T-N), NH_4~+-N, NO_3~--N, SO_4~(2-)-S in rainwater, ρ(T-N), ρ(NH_4~+-N),/>(NO_3~--N) and P(SO_4~(2-)-S) ranged from 1.09～7.84, 0.58～6.25, 0.26～1.83 and 0.95～7.64 mg·L~(-1), respectively. The monthly mass concentration for nitrogen and sulfur all had negative correlations with corresponding rainfall. Moreover, the correlative level of ρ(T-N), ρ(NH_4~+-N) and ρ(SO_4~(2-)-S) reached significance(n=ll, p<0.10). Monthly wet-deposition fluxes for(T-N), NH_4~+-N, NO_3~-N and SO_4~(2-)-S, F(T-N),F(NH_4~+-N), F(NO_3~--N) and F(SO_4~(2-)-S) were the respective ranges of 1.06～7.84, 0.64～6.25, 0.17～1.54 and 1.22～9.15 kg·hm~(-2), which all had positive correlations with corresponding rainfall. Because of these, the correlative level of F(T-N),F(NH_4~+-N) and F(SO_4~(2-)-S) reached marked significance(n=ll, p<0.05). For seasonal characteristic, there were higher in autumn and winter than spring and summer for mass concentration of nitrogen and sulfur in rainwater and higher in winter and spring than summer and autumn. Inputs of wet-deposition nitrogen and sulfur to the agro-ecosystem were 35.9 and 45.93 kg·hm~(-2)·a~(-1), respectively. NH_4~+-N input was 22.92 kg·hm~(-2), accounting for 63.75%.