节点文献
典型红壤农田区大气氮沉降通量研究
【作者】 崔键；
【作者基本信息】 南京师范大学 ， 自然地理， 2011， 博士
【摘要】 大气氮沉降作为营养源和酸源,沉降数量的急速增加,将严重影响生态系统的生产力和稳定性,对农田生态系统的影响日益显现。本文以典型红壤农田区大气氮化物为研究对象,通过5年连续定位监测,借助大叶阻力相似模型和自动气象观测场,计算不同形态含氮化合物的干沉降速率,进而估算大气氮沉降通量,探讨大气氮沉降的特征。主要研究结果如下：1.大气氮化物干沉降速率(Vd)呈现明显的日变化和月季变化,日峰值出现在11：00-13：00,昼>夜；Vd(NH3)、Vd(NO2)和Vd(NH4+/NO3-)以冬春季及花生季/早稻季较高而Vd(HNO3)则表现为春夏季高于秋冬季和早稻季>中稻季>花生季>晚稻季。Vd(NH3)、Vd(NO2)、Vd(HNO3)和Vd(NH4+/NO3-)年均值分别为0.25±0.01、0.12±0.01、0.78±0.04和0.15±0.01cm/s,年内波动较大,尤以NH3和NO2最明显；年际上,Vd(NH3)和Vd(HNO3)呈逐年递减,Vd(NO2)相对较稳定,Vd(NH4+/NO3-)则呈先降后增趋势。2.NH3、NO2、粒子NH4+-N、粒子NO3--N的浓度分别为164.64±93.16、67.67±44.66、1.9±1.26和3.21±2.17μgN/m3,降水NH4+-N、NO3--N、DON、TNI的浓度分别为1.05-1.49、0.54-0.72、0.56-3.71、2.63-5.72 mgN/L,而HNO3(g)的浓度较低,几乎为0。NH3的浓度以冬春季较高,降水DON浓度以夏秋季较高,而NO2、粒子态氮及降水NH4+-N、NO3--N和TN均表现为秋冬季高于春夏季。大气氮化物浓度以非生长季较高。作物生长季内,NH3以花生/早稻季较高,NO2、粒子态氮及降水NH4+-N浓度均以中/晚稻季较高,而降水NO3--N、DON和TN浓度则表现为早/晚稻季>花生/中稻季。3.大气氮湿沉降通量为59.18±29.93kgN/(ha-yr),其中DIN和DON沉降量基本相当。大气氮干沉降通量为73.09±12.87 kgN/(ha-yr),其与湿沉降(仅DIN)的比值为2.4。干沉降以气态氮为主,其占干沉降通量的98.09%。季节上,大气氮湿沉降表现为春夏季>秋冬季而干沉降表现为冬春季>夏秋季。作物生长季内,大气氮干、湿沉降通量分别为34.38±9.87和36.57±25.13 kgN/(ha-yr),均以花生季最高、晚稻季最低。4.研究区大气氮总沉降通量为94.50-185.99 kgN/(ha-yr),其中DIN总沉降通量为104.20±15.29 kgN/(ha-yr),沉降途径上以干沉降为主,沉降组分上以还原态氮沉降尤其是NH3为主。大气氮总沉降通量有冬春季>夏秋季的特征,作物生长季内总沉降通量为70.95±30.88 kgN/ha,略高于非生长季。
【Abstract】 An important source of plant nutrient and soil acidification, increased N deposition from the atmosphere will greatly impact production and stability of global terrestrial and aquatic ecosystems. With the spread of air pollution and acid rain from city to suburb and country, special attention is paid to the atmospheric environment in vast rural areas and the effect of atmospheric nitrogen deposition on agricultural ecosystems is increasingly obvious. In this study, the characteristics of atmospheric nitrogen were discussed by rainfall, nitrogen concentration observation and nitrogen deposition velocity of atmospheric nitrogen compounds (Vd) with a big-leaf resistance analogy model and the Auto-Meteorological Experiment Station in a typical red soil agro-ecosystem in Southeastern China for five years (2005-2009). The detailed results were as follows:1. During 2005-2009, the Vd was much higher in the daytime than in the nighttime and had a peak value around noon (11:00-13:00). All of Vd(NH3), Vd(NO2) and Vd(NH4+/NO3-) were higher in winter and spring while Vd(HNO3) in spring and summer. There were also obvious characteristics which Vd(NH3), Vd(NO2) and Vd(NH4+/NO3-) higher during peanut and early-rice growing stage while Vd(HNO3) during early-rice and middle-rice growing stage. The Vd was fluctuations, especially for Vd(NH3) and Vd(NO2) inner one year. The annual Vd were O.25±0.01,0.12±0.01,0.78±0.04 and 0.15±0.01 cm/s for NH3, NO2, gaseous HNO3 and aerosol particles (aerosol NH4+or NO3-), respectively. What’s more, both Vd(NH3) and Vd(HNO3) were on the decrease each year. Vd(NO2) remained steady while Vd(NH4+/NO3-) declined in 2005-2007 and then increased in 2007-2009.2. The atmospheric nitrogen concentrations of dry deposition (Ca) were respecially 164.64±93.16, 67.67±44.66,1.9±1.26 and 3.21±2.17μgN/m3 for Ca(NH3), Ca(NO2), Ca(NH4+) and Ca(NO3-) while the atmospheric nitrogen concentrations of wet deposition (Cw) were in the range of 0.05-1.49,0.54-0.72, 0.56-3.71,2.63-5.72 mgN/L for annual means of CW(NH4+-N), Cw(NO3--N), Cw(DON) and CW(TN) in rainwater, respectively. As for gaseous HNO3, its monthly and annual means all went to zero. Seasonally, there had higher vales for Ca(NH3) in spring and winter, for CW(DON) in summer and autumn, and for Ca(NO2), Ca(NH4+), Ca(NO3-), Cw(NH4+-N), Cw(NO3--N) and Cw(TN) in autumn and winter. Both Ca and Cw was higher in non-crop growing stage than that in crop growing stage. During the crop growing stage, there were higher for Ca(NH3) in peanut stage and early-rice stage, and for Ca(NO2), Ca(NH4+), Ca(NO3-) and Cw(NH4+-N) higher in middle-rice stage and late-rice stage, and for Cw(NO3--N), CW(DON) and Cw(TN) higher in early-rice stage and late-rice stage in 2005-2009.3. The nitrogen fluxes of dry deposition (Fd) and wet deposition (Fw) were 73.09±12.87 and 59.18±29.93 kgN/(ha-yr) in 2005-2009, separately. And the ratio of Fw(DIN) and Fw(DIN) was 2.4. In dry deposition, Fd(N, NH3+NO2) was the predominantly Fd, which accounted for 98.09% of Fd. And in wet deposition, Fw(DON) and Fw(DIN) had a similar size. Seasonally, there were higher for Fd in spring and winter, and for Fw in spring and autumn. During the crop growing stage, the Fd and Fw were respectively 34.38±9.87 and 36.57±25.13 kgN/(ha-yr), which highest in peanut stage and lowest in late-rice stage.4. Over the agricultural ecosystem, annual bulk deposition flux of atmospheric nitrogen (Ft) ranged from 94.50-185.99 kgN/(ha-yr), including Ft(DIN) which was 104.20±15.29 kgN/(ha-yr). Ft(DIN) was inputed maily by dry deposition, and Ft(NHx) was the major protein, especially for Ft(NH3). What’s more, the Ft had higher value in spring and winter. And the Ft was 70.95±30.88 kgN/ha during the crop growing stage, litter higher than that during non crop growing stage. Inorganic nitrogen was the maily deposition method, which was in the range of 84.24-119.27 kgN/(ha-yr) and averaged 104.20 kgN/(ha-yr).