干旱区地理2011，Vol.34Issue(4)：621-628,8.
不同预处理方法对尕海沉积物粒度测试的影响
Influence of test results of Gahai Lake sediment particle size under different pretreatment methods
摘要
Abstract
The particle size character of lake sediments is an important substitution indicator to study the evolution of ancient environments around the lakes, and the particle size measurement results are closely related to the pre-treatment methods. In this study, 48 samples were chosen from Gahai Lake core drilled in the center of the Qaidam Basin, and each sample was pretreated in five methods, including the pretreating with distilled water - method A, pretreating with (NaPO3) 6 - method B, pretreating with H2O2 - method C, pretreating with HC1 - method D, and the comprehensively pretreating with H2O2, HC1, (NaPO3)6 - method E, Pretreated samples are dispersed by ultrasonic for 10 minutes before examining by Malvem Mastersizer 2000. The results show that average particle size of the 48 samples after different pretreatments displays different degrees of thinning. The changes of average particle size are most apparent after pretreatment of method C, with the thinning of 10%. The other three methods are proved to be ineffective. The average content of coarse sediment is reduced by about 8% after the pretreatment of methods B and C, while there is almost no change for other three pretreatment methods. Overall, Gahai Lake sediments can achieve perfect dispersion effect in ultrasonic fragmentation and high-speed stirring with the laser grain-size equipment. The pretreatment only has the remarkable effects on minority of samples. Comparatively, method C is the most effective way. So we speculate that the pretreatment with H2O2 is the best method to conduct similar salt lake sediment tests. HC1 can react easily with the particles due to its nature as a strong acid and engender unpredictable results to the testing samples. Therefore we believe hydrochloric acid should be used with caution in other particle size measurements. Using a weaker acid, such as acetic acid, may be more preferable. The sensitivities of sediments with different nature to the pretreatment methods are very different, which were well verified in this experiment. The sediments from gray and dark gray silt layer( depth of 11 -21 m) , whose deposition type is stable deep lake sediments from Gahai DG02 drilling, are proved insensitive to pretreatment methods, while aeolian sand and alluvial phase, powder sand are relatively sensitive to the pretreatment methods. The conclusions of this study only apply to the Qaidam Gahai Lake or similar salt lake basin sediments. The pretreatment methods need to be adjusted according to the actual situation in order to achieve the optimal effects when doing the particle size measurements of other types of sediments. This experiment is the first one to employ relatively complete salt lake basin drilling samples, to explore effects of various pretreatment methods on salt lake basin sediment particle, while identifying the reaction of sediments on different types of pretreatment. There is an instructional meaning for the experiment conclusion to study the salt lake sediments in future.关键词
粒度测试/预处理方法/分散效果/尕海沉积物/敏感度Key words
particle size measurement/ pretreatment methods/ dispersion effect/ sediment in gahai Lake/ sensitivity分类
天文与地球科学引用本文复制引用
李华勇,潘安定,明庆忠..不同预处理方法对尕海沉积物粒度测试的影响[J].干旱区地理,2011,34(4):621-628,8.基金项目
国家自然科学基金项目(批准号40671187/U0933604/40872118及2009CC007)资助 （批准号40671187/U0933604/40872118及2009CC007）
