基于质量法的土壤水溶性盐总量测定方法改进

Improvement of the Determination Method for Total Amount of Soil Water-soluble Salts Based on Gravimetric Method

【目的】利用现有常规测定方法批量测定土壤水溶性盐总量时存在浸提液用水质量不统一、浸提液获取慢、浸提液吸液量大、蒸干时间长导致测试效率低等突出问题。因此,探究基于质量法对土壤水溶性盐总量的测定方法进行改进。【方法】试验利用不同盐分水平的土壤对现有常规土壤盐分含量测定方法中的浸提方式、浸提液用量及试验用水质量进行改进研究。【结果】在中度及以下盐化土壤条件下,将浸提方式由抽滤改为离心,并将离心参数设置为转速4000r min^(-1),离心8 min即可保证测试结果准确度,提高测试效率;无论浸提液盐分含量高低,当浸提液的吸液量由50 ml或100 ml降为20 ml时均可保证盐分测定结果的精密度和准确度,有效缩短蒸干时间;蒸馏水可以替代去CO_(2)的蒸馏水或超纯水作为土壤水溶性盐测定用水,既避免了进一步制水的时间消耗,又可以进一步降低测试成本。【结论】试验所得中度盐化及以下土壤含盐量测定方法可在保证改良方法合理性及应用效果条件下,从试验准确度、效率和成本等方面对现有方法进行了有效改进。

[Objective]The conventional method of determining the total amount of soil water-soluble salts in batches has some obvious disadvantages including inconsistent water quality and low testing efficiency,which was caused by slow acquisition of the extraction solution,high liquid absorption and long evaporation time.[Method]The different soil samples with different levels of salt content from different regions were selected to study the optimal extracting method,the optimal absorbed amount of extraction solution,and the quality of testing water based on gravimetric method.[Result]The results showed that the determination accuracy and efficiency could both be improved under moderate and lower saline soil conditions though changing the extraction method from suction filtration to centrifugation when 4000 r and 8 min were chosen as the centrifugal parameters.Independent of the salt content level of the extraction solution,reducing absorbed amount of extraction solution from 50 or 100 ml to 20 ml could both ensure the precision and accuracy of the salt determination results,and meanwhile reduce the evaporation time.Replacing CO_(2)-removed distilled water or ultrapure water with distilled water as extraction water could not only reduce the time cost of further water preparation,but also further reduce the monetary cost of the determination.[Conclusion]The existing method can be effectively improved from the aspects of test accuracy,efficiency and cost under the suitable conditions for the improved determination method.