Particle-associated organic phosphorus

Little is known about the relationship between organic phosphorus fractions determined by different quantification methods. From the few experiments where sequential phosphorus fractionation and NMR have been applied together (in bulk soil and in particle size fractions) in the tropics, it appears that phosphate diesters extracted by sodium bicarbonate are labile compounds from microbial biomass and easily decomposable organic matter associated with the sand fraction, while those in sodium hydroxide extracts are microbial... 

Transport of contaminants by surface runoff is illustrated in the experimental results of Turner et al. (2004), which deal with the colloid-mediated transfer of phosphorus (P) from a calcareous agricultural land to watercourses. Colloidal molybdate-reactive phosphorus (MRP) was identified by ultrafiltration associated with particles between l am and Inm in diameter. Colloidal P compounds can constitute a substantial component of the filterable MRP in soil solution and include primary and secondary P minerals, P occluded or adsorbed on or within mineral or organic particles, and biocolloids (Kretzschmar et al. 1999). 

Phosphorus in its simplest form, dissolved orthophosphate, is taken up by photosynthetic organisms at the base of the marine food web. When phosphate is exhausted, organisms may utilize more complex forms by converting them to orthophosphate via enzymatic and microbiological reactions. In the open ocean most phosphorus associated with biogenic particles is recycled within the upper water column. 

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