作 者：
张芳;塔西甫拉提·特依拜;梁辰;依力亚斯江·努尔麦麦提
关键词：
天山北麓;苏打盐碱化土壤;pH测定;水土比;静置时间
摘 要：
【目的】pH值是碱土诊断及分类的重要依据。测定天山北麓苏打盐碱化土壤pH值,并分析其影响因素,为盐碱化土壤pH值测定的适应方法提供依据。【方法】采用电位法,对新疆天山北麓典型的碳酸盐含量高、碱性强、盐分类型复杂的苏打盐碱化土壤样本,分别设置不同水土比(1∶1、2.5∶1、5∶1)和不同静置时间(1、5、10、30和60min)进行pH值测定。【结果】1水土比对pH值测定影响较大,但碱性强弱并不是稀释效应的决定性因素,含有较多CaCO_3的氯化物盐样本稀释效应最强,最大pH值增加量达0.57个单位,这种稀释效应主要来自CaCO_3与中性钠盐反应生成的苏打水解。2水土比2.5∶1时,难溶盐类的溶解基本达到稳定;而1∶1水土比不适用于研究区盐碱化土壤的pH值测定。3静置时间对奇台碱土pH值测定的影响小于艾比湖盐土,静置过程中大气CO_2溶解不影响pH值测定结果。【结论】对于天山北麓盐碱土,可设定为5∶1水土比,悬液充分搅拌后即进行pH值测定,其测定精度与实验效率均较高。
译 名：
The Affecting Factors in pH Measurement of Sodic Soil in the Northern Piedmont of Tianshan Mountains
作 者：
ZHANG Fang;Tashpolat Tiyip;LIANG Chen;Ilyas Nurmuhammat;College of Resources & Environment Science,Xinjiang University;Postdoctoral Station of Ecology,Xinjiang University;Key Laboratory of Oasis Ecology ( Xinjiang University) Ministry of Education;
关键词：
the northern piedmont of Tianshan Mountains;;sodic soil;;pH measurement;;water/soil ratio;;standing time
摘 要：
【Objective】pH is one of the most important criteria in alkaline soil identification and classification. This study aims to provide an appropriate method to measure the pH of sodic soil in the northern piedmont of Tianshan Mountains and analyze the factors that may affect the measurement.【Method】The sodic soil widely distributed in the northern piedmont of Tianshan Mountains in Xinjiang contains a high concentration of salt and alkalinity. The pH measurement experiments using different water/soil ratios( 1∶ 1,2. 5∶ 1,5∶ 1) and standing times( 1 min,5 min,10 min,30 min,60 min) have been performed on soil samples that are typical in the area.【Result】The results show that water/soil ratio had significant impact on the determination of the sodic soil pH value,and evidently there was a dilutive effect. However,the soil alkalization degree was not a dominant factor of dilution effect. Chloride salt soil samples with a higher proportion of Ca CO3 had the strongest dilution effect,and the maximum pH increment was 0. 57 units. The dilution effect was mainly related to the hydrolysis effect of soda which was produced from the chemical reaction of Ca CO3 with neutral sodium salt.The dissolution of insoluble carbonates was stabilized when water/soil ratio was 2. 5∶ 1. The 1∶ 1 water/soil ratio was not suitable for the pH measurement for sodic soil because of the incomplete dissolution of salt and desorption of the acidic ionic and alkaline ion from soil colloids. Standing time of soil suspension showed weaker impact on pH value determination than that of water/soil ratio. In addition,standing time had weaker impact on the high alkaline degree soil samples from Qitai area than the saline soil samples from Ebinur Lake area.No evident pH decline phenomena occurred in the standing process because of the dissolution of CO2 from the air during the soil suspension. After standing time reaching 60 minutes,the pH value fluctuated between + 0.04 and-0. 07 without affecting the judgment on the soil alkaline degree. The in situ alkaline soil pH measurement had great uncertainties caused by the testing environmental change and artificial factors. 【Conclusion】Therefore,the pH measurement in laboratory is still an appropriate method in the study to monitor the soda salt-sodic soil widely distributed in the northern piedmont of Tianshan Mountains in Xinjiang. The water/soil ratio should be set to 5∶ 1,and then the pH value can be measured directly after the soil suspension is fully completed. By doing so,the measurement can not only reach a high accuracy,but it can significantly increase the experiment efficiency.
