Study on the measurement of deposition of small-sized droplets in the atmosphere

众所周知，由于人类活动，雾比雨污染更严重，酸性更强，影响森林环境等生态系统。然而，与雾滴沉积有关的向林木输送的污染物的数量是通过测量雾滴沉积引起的“穿透落差”和“树干落差”间接估计的，没有对这一数量进行直接测量。本研究通过在稳定雾的Kamaishi矿大型长立井中进行基础实验，建立了聚合物吸水剂测定雾水沉积通量FW的方法。组分的沉积通量Fi可以通过Fi=Fwci来计算，其中Ci是组分在液滴相中的浓度。基于这一思想，我们在马鞍山进行了实地观测。2002年夏季在日本中部赤城测量FW和确定收集的雾…中离子物种的浓度再来点水。在这些实验中，模拟针叶和落叶的人造叶子是通过切割一张高吸水性聚合物制成的，并通过悬挂在现场周围的树木和一棵模仿圣诞树的塑料针叶树上暴露在雾中。结果表明，模拟叶片的FW值在迎风侧大于背风侧。挂在树荫下的针叶和落叶也有相似的FW值。这表明沉积通量与叶片的形状无关。另一方面，收集的雾水的酸度很高，达到pH=2.7。优势离子形态为H+、NH4+、SO42-和NO3-。当pH>4时，H+不再是一个重要组分。9月5日是水体污染物浓度最高的月份，雾造成的总沉降量分别为0.22、0.07、0.06和0.04meq/m2，其中H+、NH4+、SO42-和NO3-的日沉降量最大。为了评估雾在总沉降量中的作用，需要进行长期观测，其中不仅包括与雾有关的酸性组分沉降量的测量，还包括与降雨有关的酸性组分沉降量的测量。较少

It is known that fogs are more polluted and acidic than rain due to human activities, affecting ecosystems such as forest environments. However the amount of pollutants transported to forest trees associated with the deposition of fog droplets has been indirectly estimated through the measurement of 'through fall' and 'stem fall', caused by deposition of fog droplets, and there has been no direct measurement on this amount. In this study, we developed a method for the measurement of the deposition flux of fog water, Fw, with a polymeric water absorbent, by conducting basic experiments in a large-scale long vertical shaft in Kamaishi Mine, which afforded a steady fog. The deposition flux of a component, Fi, can be calculated through Fi=FwCi, where Ci is the concentration of the component in the droplet-phase. Based on this idea, we made field observations at Mt. Akagi in central Japan in the summer of 2002, to measure Fw and determine the concentrations of ionic species in collected fog … More water. In these experiments, artificial leaves imitating coniferous and deciduous leaves were prepared by cutting a sheet of a super absorbent polymer and exposed to fogs by hanging to trees around the site and a plastic coniferous tree imitating a Christmas tree. As a result, Fw values of the imitation leaves found to be larger at the windward side than the leeward side. Similar Fw values were obtained from the coniferous and deciduous leaves, hung to the shades of the trees. This suggests that the deposition flux is independent of the shape of leaves. On the other hand, the acidity of collected fog water was high, attaining pH=2.7. Dominant ionic species were H+, NH4+, SO42- and NO3-. However, H+ was not an important component when pH exceeded 4. The amounts of total deposition due to fog were 0.22, 0.07, 0.06 and 0.04 meq/m2 in a day, for H+, NH4+, SO42- and NO3- in September 5, when the concentrations of the aqueous species were highest. To evaluate the role of fogs in total deposition, long term observations are needed, in which the measurement of the deposition amount of acidic components associated with not only fogs but also rain is included. Less