HYDROGEOCHEMICAL STUDY ON THE CHEMICAL COMPONENTS OF ACID SNOW AND THOSE ACCUMULATION AND MIGRATION PROCESS IN THE SNOWPACK

研究结果总结如下：1)北ku地区积雪中主要阳离子和阴离子为H^+、Na^+、K+、Ca^<2+>、Mg^<2+>、NH_4^+和Cl^-、SO_4^2、NO_3^-。2)新雪的平均pH值为4.6,nss-SO_4^<2->和NO_3^-是积雪酸化的主要离子。(3)融雪期早期发生融雪消融时，由于雪中的大部分离子在雪颗粒表面附近出口，导致离子浓度高于整个雪堆平均浓度2 ~ 4倍的融水从雪堆流出。4)建立了一种新的积雪模型，该模型考虑了积雪季节发生的四个主要物理过程，并且只需要常规可用的数据。通过对鹤山山脚Siramine积雪的模拟，验证了模型的性能。5)利用融水的指数函数估算了离子析出量。利用积雪模型，结合融水量与洗脱离子量的指数关系，较好地模拟了包内离子浓度剖面的时间变化。6)在温暖的雪区，如日本北陆地区，不会发生强酸冲击，因为降雪和消融在雪季是重复的。

Research results are summarized as follows ;1) The major cations and anions in the snow in Hokuriku region are H^+, Na^+, K+, Ca^<2+>, Mg^<2+>, NH_4^+, and Cl^-, SO_4^2, NO_3^-.2) Mean pH value of the new snow is 4.6, and nss-SO_4^<2-> and NO_3^- are major two ions contribute to snow acidification.3) When snow ablation occurs in the early melt season, the melt water whose ion concentration is 2 to 4 times higher than the mean concentration of the whole pack flows out from the pack because most of ions in the snow exit near the surfaces of snow particles.4) A novel snow cover model is developed that considers the four main physical processes that occur during snow season and only requires the data routinely available. The model performance is tested through simulating the snow cover at Siramine, the foot of Mt. Haku.5) The amount of ion elution is estimated by the exponential function of melt water. The time variation of ion concentration profile in the pack is well simulated by using the snow cver model combined with the exponential relation between the melt water and the amount of eluted ion.6) Strong acid shock does not occur in the warm snow region like Hokuriku region, Japan because snowfall and its ablation are repeated in snow season.