| Autor: |
Yu, Zengshou, Warner, Jeffrey A., Dahlgren, Randy A., Casey, William H. |
| Zdroj: |
Geochimica et Cosmochimica Acta; December 1996, Vol. 60 Issue: 24 p4945-4956, 12p |
| Abstrakt: |
Reaction of iodide [I−(aq)] with a series of volcanic-ash soils was compared with reaction onto noncrystalline materials that constitute much of the inorganic fraction of these soils, Our hypothesis is that these high-surface-area materials account for iodide retention by providing sites for anion exchange. Iodide sorption onto imogolite and ferrihydrite is rapid (<30 min) but not particularly extensive; imogolite has a threefold to fourfold greater affinity for iodide compared to ferrihydrite on a mass basis. In contrast, rates of iodide retention by volcanic-ash soils were slow and did not attain a steady-state after 300 h. The extent of this largely irreversible reaction can be attenuated by sterilization, but it cannot be suppressed. The iodide retained by the soils can only be completely recovered by treatment with boiling 2 Msodium hydroxide. The amount of iodide retention by soils was inversely correlated with pH, but showed no relationship with organic matter concentration, surface area, or imogolite and ferrihydrite concentrations. |
| Databáze: |
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