民勤盆地土壤盐分含量、盐渍化程度及类型研究

Study on soil salinity content,degree and type of salinization in Minqin Basin

摘要:

【目的】明确区域土壤盐渍化现状是土壤盐渍化修复和改善的前提，对提高土地生产力和生态系统稳定性具有重要意义。【方法】以干旱、半干旱区民勤盆地为研究区，对 0~10、10~20 和 20~30 cm 土层土壤的盐分含量、盐基离子分布及相关性进行定量分析并定性判断土壤盐渍化程度和类型。 【结果】1）不同土层土壤盐分含量均值在 4. 35~6. 37 g/kg，且为中等变异程度，盐分离子中 SO₄ ^2-、Ca²⁺ 和 Cl^- 的含量较高 ，而 CO₃ ^2- 含量最少 ；2）阴离子以 SO₄ ^2- 和 Cl^- 为主 ，二者之和超过总盐含量的 50. 00%；阳离子以 Ca²⁺和 Na⁺为主，分别占阳离子总量的 48. 65% 和 31. 04%；3）总盐与 SO₄ ^2-、Ca²⁺和 Mg²⁺均呈极显著（P＜0. 01）正相关，与 HCO₃ ^-呈极显著负相关；4）非盐化土、轻度、中度、重度和盐渍土 5 种土壤类型在研究区均有分布，其中中度盐渍土分布最广（32. 42%），重度盐渍土次之（25. 92%）； 5）盐渍化类型包括氯化物-硫酸盐型、硫酸盐型、氯化物型、硫酸盐-氯化物型和苏打型 5 种，以氯化物-硫酸盐型为主（56. 03%），硫酸盐型为辅（33. 57%）。【结论】研究区的土壤盐渍化依旧威胁着土壤安全，其程度与类型以中度盐渍土和氯化物-硫酸盐为主，盐分化合物表现为硫酸钙、硫酸镁、氯化钾和碳酸氢钠。

Abstract:

【Objective】 To clarify the current status of regional soil salinization is the premise of soil salinization restoration and improvement，which is of great significance to improve land productivity and ecosystem stability. 【Method】 Taking the Minqin Basin arid and semiarid areas as the study area，quantitative analysis was conducted on soil salinity in different soil layers （0~10 cm，10~20 cm and 20~30 cm），including content，distribution and correlation of salt base ions. The degree and type of salinization were qualitatively determined in order to provide a theoretical basis for the improvement and ecological restoration of saline soil in the Minqin basin，as well as the sustainable development of regional resources and environment.【Result】1） Average soil salt content in different soil layers ranged from 4. 35 to 6. 37 g/kg，with a moderate degree of variability. The content of SO₄ ^2- ，Ca²⁺ and Cl^- was higher，while the content of CO₃ ^2- was the least. 2） The anions were mainly SO₄ ^2- and Cl^- ，with the sum of the two exceeding 50. 00% of the total salt content. The cations were mainly Ca²⁺ and Na⁺ ，accounting for 48. 65% and 31. 04% of the total cations，respectively. 3） Total salt was extremely significant positively correlated with SO₄ ^2- ，Ca²⁺ and Mg²⁺（P ≤0. 01），and extremely significant negatively correlated with HCO₃ ^- ；4） Five types of nonsalinized soil，mild，moderate，intense and salinized soil were all distributed in the study area，among which the moderate salinized soil was the most widely distributed （32. 42%），followed by severe salinized soil （25. 92%）；5） The types of salinization include chloride-sulfate type，sulfate type，chloride type，sulfate‐chloride type and soda type，with chloridesulfate type being the main type （56. 03%），and sulfate type being the secondary type （33. 57%）.【Conclusion】 Salinization in the study area still poses a threat to soil security，with the degree and type mainly being moderate saline soil and chlorinesulfate. Salt compounds are CaSO₄，MgSO₄，KCl and NaHCO₃.