Отправлено: 18.09.19 12:42. Заголовок: Critical Evaluation of the Use of Laser Diffraction for Particle-Size Distribution Analysis

Critical Evaluation of the Use of Laser Diffraction for Particle-Size Distribution Analysis
G. Eshel,* G. J. Levy, U. Mingelgrin, and M. J. Singer
Soil Sci. Soc. Am. J. 68:736–743 (2004)


Работа интересна тем, что в ней приведены корреляционные уравнения для связи лазерного и ситового метода и оценки коэффициента корреляции
Коэффициент корреляции порядка 0.7
Расчеты проводились по 42 образцам


ABSTRACT
Determination of soil particle-size distribution (PSD) by sieving, hydrometer, and pipette methods as Hell as by laser diffraction (LD) suffers from inherent flans, mainl) due to the difficulty in defining the size of irregularly shaped particles. Therefore these methods > ield only estimates of PSD. The objective of this study was to determine whether a functional relationship exists between the PSDs obtained by the combined sieve-pipette method and those obtained by LD. Samples from 42 California soils were analyzed. For the LD measure* ments a Beckman-Coulter LS-230 apparatus with a 750-nm laser beam that measures particles in the range of 0.04 to 2000 |xm was used, employing the Mie theory for the PSD calculations. Values of 1.5 and 0.2 for the real part and the imaginary term of the refractive index (Kl), respectively, gave satisfactory results for the optical model calculations. Volume percentage of the day-size fraction obtained by LD was generally lower than mass percentage of the day fraction derived by the pipette method. The opposite trend was noted for the silt-size fraction. Coeffirients of determination for the regression equations for the day, silt, and sand fractions determined by the two methods were 0.702, 0.6X9, and 0.X21, respectively. (>ood agreement between measured and calculated LD values for one size dass was accompanied by poor agreement between measured and calculated values for the other. The 1.1) method provides a continuous PSD curve, which enables a detailed data analysis and a flexible application of different partide-si/e dependent dassiflcation systems.