Organic phosphorus speciation in environmental samples Method development and applications

Abstract: This thesis investigates the development of new methodology for the identification and quantification of organic phosphorus compounds in environmental samples.Phosphorus is a vital element for primary production and one of the factors contributing to eutrophication. Eutrophication of aquatic systems leads to algal blooms, changes in ecological balance and deteriorating water quality. Difficulties in studying organic phosphorus stem from the fact that organic phosphorus is present in the environment in a variety of forms and each form may have different degradation and turnover time, having very different effects on eutrophication.New methods for the quantification of phosphorus derived from three groups of organic phosphorus compounds were developed. For the determination of phosphorus derived from DNA and phospholipids selective extraction was combined with digestion and colorimetric determination of the extracted phosphate. For quantification of inositol phosphates high performance liquid chromatography was coupled with tandem mass spectrometry using electrospray ionization.  The methods were applied to studying the distribution of these compounds in a small catchment and in the case of DNA-P and phospholipid-P, the degradation of the fractions in lake sediments. The studies showed that phosphorus bound to DNA, phospholipids and inositol phosphates constitute a sizeable part of the total phosphorus in different environmental samples. The phospholipid-P fraction was the smallest one, accounting for, on average, only a few percent of the total phosphorus in the sample. Inositol phosphates were most prevalent in the soils, with inositol hexakisphosphate accounting for over 10% of the total phosphorus content. The highest content of DNA-P was found in sediments and it was shown that DNA-P degrades more rapidly than phospholipid-P and therefore plays a more critical role in internal loading.