Fields Surveys in the Forests Affected by Acid Snow and Rain

从新泻县降雪的pH值测量和成分分析来看，降雪的特征与岛根至秋田县日本海沿岸的降雪几乎相同。运用多元回归分析方法，发现新雪pH值偏低的主要原因是雪中的硫酸盐离子。从新泻县森林的一些实地调查中，几乎没有发现因酸雪和降雨而枯萎的树木，尽管应该存在这种损害的可能性。雪松是一种常绿树，由于雪松的树干和常绿叶子比较粗糙，它比阔叶树有能力包括更多的酸性沉淀物。而阔叶树树干上融化的雪水则被树干释放出的碱性物质中和或松弛，酸雨和积雪对土壤的影响目前还不是很严重。然而，从土壤pH值和土壤淋溶量的结果来看，在新泻县主要采集的113个土壤样品中，估计有35%已经酸化，早春融雪水中的氢离子浓度有明显高于晚春的趋势。地面上的新鲜降雪被反复溶解和结晶压缩，形成冰冷的颗粒雪。这种重复导致硫酸盐、硝酸盐和氯离子集中在冰雪颗粒的表面附近。一些实验室实验通过球状冰的形成来检验这种集中现象。

From the measurement of the pH levels and the analysis of components of the fallen snow in Niigata Prefecture, the characteristics of the snow were almost the same as those observed in the snow along the coast of the Sea of Japan from Shimane to Akita Prefecture. Using the multiple regression analysis method, the cause for the lower value of pH in the fresh snow has become evident as a result of mainly the sulfate ions contained in the snow.From some field surveys in the forests at Niigata Prefecture, few withered trees due to acid snow and rain have been found, although the possibility such damaged trees should exist. Cedar, a kind of evergreen tree, has the capability to include more amounts of acidic deposits than the broadleaf trees because of the cedar's rougher trunk and evergreen leaves. While, the flow-down water of melted snow along the trunks of broadleaf trees was neutralized or relaxd with the basic substances released from the trees.The influence of acid rain and snow on soil is not such a serious problem at the present time. However, from the results of the pH measurement of soil and the amounts of leached-elements from the soil, 35% of 113 soil samples mostly gathered in the Niigata Prefecture was estimated to be already acidified.There is a remarkable tendency for the hydrogen ion concentration in snowmelt water in the early spring to be higher than that in the late spring. The fresh fallen snow on the ground is compressed by repeated dissolution and crystallization and forms icy granular snow. The repetition causes sulfate, nitrate and chloride ions to be concentrated near the surface of the icy granular snow. Some laboratory experiments were performed to examine this concentration phenomenon by the formation of spherical ice.