Measurement of aquatic humus content by spectroscopic analyses

To develop a specified method to estimate humus contents in natural fresh waters, the colour of humic water samples was measured for fractionated and original water samples by spectrophotometry. The results were compared to those of the comparator method and they support the use of 400 or 465 nm. The combination of absorbance and fluorescence measurements proved to be the more reliable method to measure the aquatic humus content. The humic matter which fluoresces most, fulvic acid (FA), and which absorbs most, humic acid (HA), have opposite trends in molecular weight and both of them differ from other humic-solute fragments which enables a compositional inspection of the dissolved humic solutes on the basis of combined fluorometric and spectrophotometric measurements.