典型大气污染物在不同下垫面上干沉积速率的动态变化及空间分布

Temporal Variety and Spatial Distribution of Dry Deposition Velocities of Typical Air Pollutants Over Different Landuse Types

利用中国科学院红壤生态试验站微气象站实测的梯度资料和大叶阻力相似沉积模型 ,计算了农田和森林下垫面大气污染物的干沉积速率 ,并将此模型嵌套到区域酸性沉降模式系统 (RegADMS)中 ,模拟获得中国地区 1 1种大气污染物干沉积速率的空间分布。结果表明 :大气污染物干沉降速率 (Vd)有明显的时间变化 ,物种的干沉积速率一般白天大于晚上 ,冬春季大于夏秋季节。大气污染物Vd 也有明显的空间变化 ,中国地区SO2 、HNO3、NO、NO2 、NH3、O3、H2 O2 、TSP、PM1 0、SO2 -4 和NO-3 年平均Vd 分别为 0 35±0 0 0 4、 1 77± 0 0 1、 6 5× 1 0 - 5± 2 0× 1 0 - 7、 0 0 7± 0 0 0 0 7、 0 2 8± 0 0 0 3、 0 2 0± 0 0 0 1、0 5 4± 0 0 0 2、 7 2± 0 0 0 0 5、 0 44± 0 0 0 0 5、 0 2 5± 0 0 0 0 5、 0 2 7± 0 0 0 0 8cms- 1 。各种下垫面上粒子Vd 差别不大 ,气体污染物在各下垫面上的Vd 有所不同 ,表现为HNO3、NO2 、O3的Vd 在森林和草原上较大 ,而SO2 、NH3、H2 O2 的Vd 在水面上较大 ,NO的Vd 都很小 ,且在各种下垫面上差别不大。

The dry deposition velocities (V d), which were parameterized by use of a big leaf model, are calculated over farmland and forest with gradient meteorological data in red soil observation station of Chinese Academy of Science . Furthermore, the mesoscale meteorological model (MM5) and the regional acid deposition model system (RegADMS) coupled with the big leaf model were combined to simulate the distribution of dry deposition velocities of air pollutants over China. As the result, there are obvious temporal varieties in V d. Statistical daily and monthly-average dry deposition velocities values show that V d in daytime is higher than that in night, V d in spring and winter are more large than that in other seasons. There are also evident spatial varieties in V d, the estimated annual average dry deposition velocities over China are 0.35±0.004 cms -1 for SO 2, 1.77±0.01 cm s -1 for HNO 3 (g), 6.5×10 -5±2.0×10 -7cm s -1 for NO, 0.07±0.007 cm s -1 for NO 2 , 0.28±0.003 cm s -1 for NH 3, 0.20±0.001 cm s -1 for O 3, 0.54±0.002 cm s -1 for H 2O 2 , 7.2±0.0005 cm s -1 for TSP, 0.44±0.0005 cm s -1 for PM10, 0.25±0.0005 cm s -1 for sulfate aerosol, 0.27±0.0008 cm s -1 for nitrate aerosol, respectively. There is no evident difference in V d for particles. However, there is distinct difference in V d in different landuse types. For HNO 3、NO 2 and O 3, V d in forest and grassland are more large than those in the other landuse types. For SO 2、NH 3 and H 2O 2, V d in water are more large compared to those in other landuse types. For NO, there is no visible difference in V d because of small values.