DEVELOPMENT OF AN ELECTRON MICROPROBE METHOD FOR THE DETERMINATION OF PHOSPHORUS AND ASSOCIATED ELEMENTS IN SEDIMENTS

Abstract

In order to further improve understanding of the behavior of phosphorus in sediments and in the global exogenic cycle, a standardized technique for the determination of phosphorus and associated elements in sediments is developed in this study that is independent of the problems inherent in selective extraction methods. The method consists of electron probe microanalysis of solid powders (e.g., sediment samples) with an energy-dispersive spectrometer (EDS) and four wavelength-dispersive spectrometers (WDS). The concentrations of phosphorus and associated elements are analyzed simultaneously at a large number of randomly selected points on each sample and the results are processed statistically.The experimental procedure of this study provides a reasonable approach for evaluating and optimizing the microanalysis technique. The results show that the method has good precision and accuracy not only for phosphorus but also for associated elements such as Al, Si, Ca, Ti, Mn and Fe. The detection limits for these elements are completely acceptable for the purpose of studying the geochemical composition of sediments.The major applications of the microanalysis method so far have been to check the selective extraction techniques on sediments and to reveal correlative relationships among associated elements. The method may also be applied to many additional problems, such as the examination of intrasample variability and the possibility for the determination of the bulk composition of soils or sediments.