Development of a New Method for Monitoring Time-Integrated Water Fugacity by the Use of Elastic Recoil Detection Analysis

将各种玻璃表面的阳离子分别在HO和DO中浸出，并主要用弹性反冲检测分析和卢瑟福背散射研究了水化层中H-D交换和H(D)被阳离子取代的情况，以探索玻璃用于监测土壤水分和溶解阳离子的可能性。与水化速率类似，交换和置换的速率明显取决于玻璃的组成，特别是氧化铝的含量。对于一些低氧化铝含量的钠钙玻璃，这两个反应至少经历了两个阶段，并具有不同的温度依赖性。这些结果表明：(1)钠硅酸盐玻璃对土壤中水逸度的水化速率；(2)在特殊、干燥和炎热地区低铝玻璃对水蒸气的H-D交换速率，尽管这种交换能力在通常的环境中是不足的；以及(3)阳离子对土壤中阳离子的H置换速率和由此产生的深度剖面。我们第一个实际使用玻璃监视器的计划已经推迟，但我们已经准备好在(1)之前进行现场实验，并打算很快开始与位于乌鲁木齐的中央研究院中国研究所合作进行其他监测。我们现在可以获得所需成分的各种玻璃，并可以使用粒子加速器进行ERDA和RBS测量。然而，在完全实现实际监测之前，我们还需要进行大量的研究，在明确的条件下制备各种样品，以获得更多的重复性数据。

Cations in surfaces of various glasses were leached in H O or D O, and H-D exchange and H (D) -by-cation replacement in the hydrated layer were investigated mainly by elastic recoil detection analysis and Rutherford back-scattering, in search of possibilities for the use of the glasses in the monitoring of moisture and dissolved cations in the soil. Similarly with the hydration rate, the rates of the exchange and replacement were found to depend markedly on the composition of glass, especially on alumina content. For some soda-lime glasses of low alumina contents, the two reactions were shown to proceed by at least two stages and mechanisms of different temperature dependences. These results suggest the following potentialities in the utilization of glass for the monitoring : (1) the hydration rate of a sodium silicate glass for water fugacity in the soil, (2) the H-D exchange rate in low alumina-content glasses for water vapor in special, dry and hot area, though the exchange capacity is deficient for usual environments, and (3) rate and resultant depth profile of the H-by-cation replacement for cations in the soil. Our first plan for practical use of the glass monitors has delayed, but we are ready for field experiments by (1) and intend to begin soon other monitorings in collaboration with the institute of Academia Sinica in Ulumuqi, China. We can now obtain various glasses of desired compositions, and can use particle accelerators for the ERDA and RBS measurements. We have, however, still a lot of studies to carry out, preparing a variety of samples under well-defined conditions to obtain more reproducible data, before fully effectuating the practical monitoring.