The determination and distribution of various trace elements in natural waters by x-ray fluorescence spectroscopy

Abstract

A method was developed for the analysis, consecutively, of six trace metals uranium, copper, nickel, cobalt, iron, and manganese in a sample of fresh water and sea water through a combination of solvent extraction with an 8-hydroxy quinoline-chloroform mixture and X-ray fluorescence spectrometry. The primary concentration step which may be carried out on board ship requires only three reagents and minimal equipment, thus reducing the risk of contamination and chemical changes due to storage. In addition, the method is nondestructive and extracted samples evaporated on filter paper may be stored for future reference. A precision of 10% or better was obtained for the six elements with a sample volume of 500 ml. The analysis was applied to sea water and fresh water samples obtained from various sources. Coastal sea water trace element content was found to be lower than that from mid-ocean. What appears to be significant differences in the trace element levels were found in the water masses studied but little variation with latitude was detected. Several of the elements, notably uranium, displayed an increase in concentration with depth. Examination of fresh water samples indicated that biological activity is related to the extractable trace metal content in that increased activity was accompanied by higher content or trace metals. This view has as yet not been substantiated by biological studies. Other samples showed evidence of differences which may be associated with the water source and pollution.