Abstract
The concentration of total phosphorus in sandy and muddy bottom sediment were studied by using two kinds of procedures, the H2SO4-HNO3 digestion and the HF-HNO3 digestion. The recovery ratio of the H2SO4-HNO3 digestion procedure to the HF-HNO3 digestion procedure was between 90% and 101% and the mean value was 97%. The analitic accuracy of the H2SO4-HNO3 digestion procedure based up on the coefficient of variation was between 0.3% and 1.4%.
There were no recongnizable differences of values between ground and unground samples in the H2SO4-HNO3 digestion procedure. It was necessary to use a watch glass to prevent a loss of phosphorus during the evaporation of sulfric acid due to heating.
These procedures were also used for other kinds of rock samples such as basalt, andesite, rhyo-dacite welded tuff, sandstone etc. The recovery ratio of the H2SO4-HNO3 digestion procedure to the HF-HNO3 digestion procedure was between 79% and 104% (mean : 94%). These results suggested that the H2SO4-HNO3 digestion procedure was useful as an extraction procedure for measuring total phosphorus of bottom sediment and was applicable to rock samples.
