一种大气污染物干沉积速率的计算方法及其应用

A Method Calculating Dry Deposition Velocity of Air Pollutants and Its Application

摘要:

介绍了一种计算大气污染物干沉积速率的方法。这种方法详细地考虑了植物生理特征和冠层内湍流结构对干沉积的影响,考虑了3层覆盖物对表面阻抗的影响,通过计算7个不同的阻抗因子获得干沉积速率。利用该方法计算了农田下垫面上7种不同大气污染物沉积的表面阻抗和江西(鹰潭)红壤典型地区农田下垫面上的二氧化硫(SO₂)和硫酸盐(SO₄^2-)的干沉积速率,估算了大气硫输入农田生态系统的干沉积通量,并与其他方法作了定量比较。结果表明:农田下垫面上SO₂与SO₄^2-的干沉积速率平均值分别为0.31cm/s,0.20cm/s;干沉积速率具有明显的日变化特征,一般白天大于夜间,中午时分出现最大值;月际变化也较明显,在冬季有大值;大气硫输入农田生态系统的全年干沉积通量为7.35g/m2。

Abstract:

This article introduces a way to calculate a dry deposition velocity(V_d) of air pollutants,which takes account of the effect of biological characteristics of vegetation and turbulence structure in canopy-on the dry deposition in detail and the effect of three-layer shrouds on surface resistance as well.A dry deposition velocity is obtained by adding up seven different resistance factors.The surface resistance of the dry deposition to farmland seven air pollutants and the dry deposition velocities of SO₂ and sulfate(SO₄^2-) are calculated based on the method.Their concentrations are measured on farmland at Yingtan,the typical red soil area of Jiangxi Province,and the dry deposition flux of sulphur from the atmosphere to the agrocosystem is estimated and compared quantitatively with other methods.The study shows that the average dry deposition velocities of SO₂ and SO₄^2- are 0.31cm/s and- 0.20-cm/s,respectively.These velocities have a significant temporal variation with higher value in daytime,lower at night and the highest at the noon.The monthly variation of the velocities is also evident with the maximum appearing in winter.The annual dry deposition flux of sulphur inputting into the farmland ecosystem is about 7.35g/m².