摘要
对滨海重盐土室内淋洗模拟脱盐过程的分析研究结果表明：随着含盐量的下降，Ｎａ＋、Ｃｌ－、ＳＯ４－２、Ｍｇ２＋、Ｃａ２＋和Ｋ＋的绝对含量都逐渐减少，ＨＣＯ３－逐渐增加；Ｃｌ－和Ｎａ＋的相对含量逐渐下降，而ＳＯ４－２、Ｍｇ２＋、Ｋ＋特别是Ｃａ２＋、ＨＣＯ３－；的相对含量逐渐增加，当含盐量降至 １ｇ／ ｋｇ以下时结果更加明显。由于各离子的迁移能力不同，导致土壤的盐分化学类型由Ｃｌ－Ｎａ向ＨＣＯ３一Ｃａ转化。淋洗试验中淋洗液的盐分化学类型变化滞后于土样。ｐＨ值在整个脱盐过程中先上升后下降，ｐＨ值下降时的土壤含盐量在小于１ｇ／ ｋｇ范围。在 ｐＨ值先上升后下降的变化过程中，Ｃａ２＋含量是先下降后上升，而ＨＣＯ３－；含量是先上升后下降，残余碳酸钠（ＲＳＣ）的变化趋势也与ＨＣＯ３＝一样，土壤ｐＨ值与可溶性Ｃａ２＋含量呈互为增减的关系。钠吸附比（ＳＡＲ）和土壤碱化度（ＥＳＰ）在整个脱盐过程中始终下降。 ｐＨ值上升的真正原因是由于脱盐导致Ｃａ２＋淋失，相应提高了ＨＣＯ３－含量所致，而非交换性Ｎａ＋水解的结果。滨海盐土脱盐同时脱碱，不会发生碱化现象。淋洗试验盐渍性状变化过程基本反映了实际条件下滨海盐土脱盐过程盐渍性状的变化规律。
The experiments on indoor imitating process of soil column leaching for desalting were conducted on heavily saline soil in seabeach. The results showed that the absolute amounts of Na+, C1-, SO4-2, Mg2+, Ca2+ and K+ decreased gradually with the decreasing of salt content while that of HCO3-, increased. Furthermore, the relative contents of Cl- and Na+ decrease slowly but those of SO2-4, Mg2+, K+, especially of Ca2+ and HCO3-, increased significantly. Due to the different transfer rates of ions, the soil chemical type took a shift from Cl-Na to HCO3-Ca. The changes of salt chemical type in leaching solution happened more slowly than in the column soil. During the whole leaching process in the experiments, the pH value, HCO3-, content and RSC went up, then went down with the shifting point of soil salt content being < 1g/ kg, it is quite the contrary for Ca2+ content in soil. Both the SAR and ESP decreased all the time and ESP almost reached zero. The real reason for pH increase during the process of desalting was not the hydralization of nonexchangeable Na+ but the leaching loss of Ca2+ and a small increase of HCO3-. Therefore the desalting process happened in seabeach soil would not cause alkalization.
出处
《土壤学报》
CAS
CSCD
北大核心
2000年第4期521-528,共8页
Acta Pedologica Sinica
