CHARACTERIZATION OF SOLUBLE UNREACTIVE PHOSPHORUS USING P-31 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

P-31-NMR spectra of soluble unreactive phosphorus (SUP) were obtained over a year from a small mid-western lake (Crystal Lake). Lake water s amples were concentrated with ultrafiltration (UF) and reverse osmosis membranes (RO). These membranes were also used to fractionate the SUP according to molecular weight. A sample from the Mississippi River wa s also analyzed with P-31-NMR. Diester and monoester phosphates, phosp honates, tri- and/or tetrapolyphosphates, and orthophosphate were dete cted in these samples. Use of the lanthanide shift reagent (LSR) prase odymium ethlylenediamine tetraacetate, alkaline bromination degradatio n procedures, and adjustment of sample pH in conjunction with P-31-NMR spectroscopy provided additional information regarding the SUP. It wa s found that the SUP pool exists as a variety of organic phosphorus co mpounds which vary with respect to their apparent molecular size. Seco ndly, P-31-NMR data from Crystal Lake demonstrate that the SUP composi tion varies as a function of season and/or general lake conditions. Th irdly, comparison of Crystal Lake and Mississippi River spectral data shows that the SUP composition differs between distinct hydrological s ites. P-31-NMR spectral data, in conjunction with other information su ch as LSR data, pH adjustment data, and alkaline bromination data, als o illustrate that a portion of the SUP may become incorporated into an aggregate that forms during UF/RO concentration procedures. (C) 1997 Elsevier Science B.V.