摘要
Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.
Hydroxyl release of red soil and latosol surfaces was quantitatively measured using a self-made constantpH automated titration instrument, to study the changes of hydroxyl release with different added seleniteamounts and pH levels, and to study the effects of electrolytes on hydroxyl release. Hydroxyl release increasedwith the selenite concentration, with a rapid increase at a low selenite concentration while slowing down ata high concentration. The pH where maximum of hydroxyl release appeared was not constant, shifting toa lower valus with increasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a high electrolyteconcentration. For NaC1O4, NaC1 and Na2SO4, hydroxyl release was in the order of NaClO4 ＞ NaCl >Na2SO4, and the difference was very significant. But for NaCl, KCl and CaCl2, the order of hydroxyl releasewas NaCl ＞ KCl ＞ CaCl2, and the difference was smaller. The amount of hydroxyl release from Xuwenlatosol was greater than that from Jinxian red soil. Hydroxyl release existed in a wider range of pH withXuwen latosol than with Jinxian red soil, due to their difference in soil properties. However, both soils hadsimilar curves of hydroxyl release, indicating the common characteristics of variable charge soils.
基金
Project supported by the National Natural Science Foundation of China(Nos.49971046 and 49831005).
