Determination of streaming potential coefficients in various physical and chemical conditions to quantitatively estimate interstitial fluid's flow from tempral and spatial self-potential variations on Miyakejima island

我们通过室内实验测定了不同物理和化学条件下的Zeta电位，以定量评估与Miyakejima 2000峰顶喷发相关的组织间流体流动的时间和空间自然电位变化。在第一年，我们设计和准备了必要的仪器，并在宫岛岛和小岛岛收集了岩石样本。由于我们发现小岛岛的地形效应约为10 mV/m(海拔变化1m前降低10 mV)，是宫岛岛(1 mV/m)的10倍，因此测量和比较这两个岛的岩石样品的zeta电位成为本研究的另一个目标。Mikyakejima和Kozushima岛分别由玄武岩和流纹岩组成，主要结果如下：(1)用HCl-KCl-KOH组成的间隙流体测定了Miyakejima岩石的zeta电位与p的关系。Zeta-电位值在-10~-20 mV范围内变化，其绝对值比石户和水谷(1981)S的Zeta-电位值小10倍，在较高的pH条件下，Zeta-电位值变大，并与他们的结果相似。(2)对于两岛岩石，pH&Gt；3范围内Zeta-电位值的pH依赖性基本相同。在较小的pH范围内，宫岛岩石的Zeta-电位绝对值逐渐变小，在pH 2左右变为零，在进一步的酸性条件下变为正值，而小岛岩石的Zeta-电位绝对值没有明显变化，仍为负值。(3)对于较细的岩石样品，Zeta-电位绝对值越大。

We determined zeta-potential in various physical and chemical conditions by room experiment to quantitatively evaluate interstitial fluid's flow from temporal and spatial self-potential variations in association with Miyakejima 2000 summit eruption. In the first year, we designed and prepared necessary apparatus and collected rock samples on Miyakejima and Kozushima islands. Since we found that the topographic effect on Kozushima island is about 10mV/m (10mV decrease pre 1m altitude change), which is 10 times larger than that on Miyakejima island (1mV/m), measurement and comparison of zeta-potentials for the rock samples in both islands become another target of this study. Mikyakejima and Kozushima islands are composed of basalts and rhyolites, respectively.Main results are as follows:(1)p dependence of zeta-potential for Miyakejima rocks was determined by using interstitial fluids of HCl-KCl-KOH composition. Zeta-potential values in pH 3-10 range from -10 to -20 mV, whose absolute value is 10 times smaller than Ishido & Mizutani (1981)'s results, which were regarded as representative zeta-potential values. In the higher pH conditions, zeta-potential absolute value gets larger and becomes similar to their results.(2)For both islands' rocks, pH dependence of zeta-potential in pH>3 range is almost the same. In the smaller pH range, zeta-potential absolute value of Miyakejima rocks is getting smaler, becomes zero at about pH 2 and changed to be positive in further acid condition, whereas that of Kozushima rocks shows no such significant variation and remains negative.(3)For results with the finer rock samples, the larger zeta-potential absolute value is obtained.