Gas-particle interactions above a Dutch heathland: II. Concentrations and surface exchange fluxes of atmospheric particles
Gas-particle interactions above a Dutch heathland: II. Concentrations and surface exchange fluxes of atmospheric particles
复制标题
荷兰荒原上空的气体-粒子相互作用：II。
DOI：
10.5194/acp-4-1007-2004
复制
发表时间：
2004
影响因子：
6.3
通讯作者：
Martin Gallagher
中科院分区：
文献类型：
--
作者：
E. Nemitz;Mark A. Sutton;G. Wyers;R. Otjes;M. Mennen;E. Putten;Martin Gallagher
抽象的。大小相关的颗粒数通量测量涡协方差（EC）和连续通量的铵（NH 4+）测量的空气动力学梯度法（AGM）的报告为荷兰石楠。白天沉积速度（Vd）的峰值为5至10 mm s-1的EC与颗粒直径（dp）增加0.1-0.5 µm的范围内，比目前的模型预测的更快。平均Vd为2.0 mm s-1（白天：2.7;夜间0.8 mm s-1）NH 4+通量AGM总体上与以前的测量和NH 4 +-N干沉降量的20%的NH3-N在测量期间的干输入的协议。这些表面交换通量一起分析，同时气相通量测量的气体-颗粒相互作用的迹象。在温暖的下午，酸和气溶胶的表观通量在石南荒原上显示出几个一致的异常，所有这些都与沉积过程中的NH 4+蒸发相一致：（i）HNO 3和HCl的冠层阻力高达100 s m-1，（ii）小颗粒的同时颗粒排放（Dp 0.18 µm），（iii）NH 4+的沉积速度比来自尺寸分布和尺寸隔离的EC颗粒通量。这些观测结果与以下观测结果一致：（i）NH 3和HNO 3的表面浓度产物远低于热力学平衡值;（ii）Damkohler数，表明化学转化足够快以修改交换通量。测量结果表明，在1 km的边界层上，挥发性NH 4+的平均去除率为3−30×10-6 s-1，而NH3的沉积被低估了20 ng m-2 s-1（28%），可能会发生通量逆转。
Abstract. Size-dependent particle number fluxes measured by eddy-covariance (EC) and continuous fluxes of ammonium (NH4+) measured with the aerodynamic gradient method (AGM) are reported for a Dutch heathland. Daytime deposition velocities (Vd) by EC with peak values of 5 to 10 mm s-1 increased with particle diameter (dp) over the range 0.1–0.5 µm, and are faster than predicted by current models. With a mean Vd of 2.0 mm s-1 (daytime: 2.7; night-time 0.8 mm s-1) NH4+ fluxes by AGM are overall in agreement with former measurements and NH4+-N dry deposition amounts to 20% of the dry input of NH3-N over the measurement period. These surface exchange fluxes are analyzed together with simultaneous gas-phase flux measurements for indications of gas-particle interactions. On warm afternoons the apparent fluxes of acids and aerosol above the heathland showed several coinciding anomalies, all of which are consistent with NH4+ evaporation during deposition: (i) canopy resistances for HNO3 and HCl of up to 100 s m-1, (ii) simultaneous particle emission of small particles (Dp 0.18 µm), (iii) NH4+ deposition faster than derived from size-distributions and size-segregated EC particle fluxes. These observations coincide with the observations of (i) surface concentration products of NH3 and HNO3 well below the thermodynamic equilibrium value and (ii) Damkohler numbers that indicate chemical conversion to be sufficiently fast to modify exchange fluxes. The measurements imply a removal rate of volatile NH4+ of 3−30×10-6 s-1 averaged over the 1 km boundary-layer, while NH3 deposition is underestimated by typically 20 ng m-2 s-1 (28%) and flux reversal may occur.