辽东半岛滨海盐土脱盐过程中pH上升及碱化问题探讨

Studies on the increasing of pH value and alkalization of seashore saline soil during its desalting in Liaodong Peninsula

对鸭绿江口和辽河口滨海盐土脱盐过程的分析研究结果表明：不同母质的盐土脱盐，随着含盐量的下降，Ｎａ＋、Ｃｌ－、ＳＯ２－４、Ｍｇ２＋、Ｃａ２＋和Ｋ＋的绝对含量都逐渐减少，ＨＣＯ－３逐渐增加；Ｃｌ－和Ｎａ＋的相对含量逐渐下降，而ＳＯ２－４、Ｍｇ２＋、Ｋ＋特别是Ｃａ２＋、ＨＣＯ－３的相对含量逐渐增加。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－Ｃａ转化。钠吸附比（ＳＡＲ）和土壤碱化度（ＥＳＰ）在整个脱盐过程中始终下降，且ＥＳＰ渐近于０。ｐＨ值上升的真正原因是由于脱盐导致Ｃａ２＋淋失，相应提高了ＨＣＯ－３含量所致，而非交换性Ｎａ＋水解的结果。辽宁地区的滨海盐土脱盐过程盐渍性状和ｐＨ值的关系，与江苏沿海一致，滨海盐土脱盐同时脱碱，不会发生碱化现象。

Desalting process of seashore saline soil in the mouth of Yalu River and Liaohe River showed that the desalination of saline soils derived from different parent materials made the content of Na +, Cl -, SO 2- 4, Mg 2+ , Ca 2+ and K + decreased gradually and the content of HCO - 3 increased gradually. Moreover the relative contents of Cl - and Na + decreased slowly while those of SO 2- 4, Mg 2+ , and K + especially of Ca 2+ and HCO - 3 increased. Due to the different rates of ion migration, the chemical type of soil salts turned from ClNa to HCO 3Ca. SAR and ESP decreased all the time, and ESP reached zero approximately. The reason for pH increase might be caused by the leaching loss of Ca 2+ , not by hydrolysis of nonexchangeable sodium. The relationship between salt properties of seashore saline soil and its pH value during the process of desalting in Liaodong Peninsula was similar to that in Jiangsu Province, which was nothing to do with climate zone. Desalinization and dealkalization happened concurrently during the desalting process of seashore soil but no alkalization will happen at all.