Characterization of biogenic phosphorus in sediments from the multi-polluted Haihe River, China, using phosphorus fractionation and 31P-NMR

• Seven P compounds were detected by the 31P-NMR analysis.
• Ortho-P (45.16–92.35%) and mono-P (6.57–45.70%) were the dominant forms.
• Biogenic-P accounted for 24% of P in the sediments.
• Po compounds would mineralize to Ortho-P and supporting growth of phytoplankton.

We studied the phosphorus (P) pollution, as described by concentrations, distribution and transformation potential, of sediments of the water scarce and heavily polluted Fuyang River, a tributary of the Haihe River, using P fractionation and phosphorus-31 nuclear magnetic resonance (31P-NMR). In terms of their contribution to total P, the rank order of the P fractions was as follows: H2SO4–P > NaOH–Pi > Res-P > NaOH–Po > KCl–P. Seven P compounds were detected by the 31P-NMR analysis. Orthophosphate (45.2–92.4%) and orthophosphate monoesters (6.6–45.7%) were the dominant forms. Smaller amounts of pyrophosphates (0.1–6.6%), deoxyribonucleic acid (0.3–3.9%), phosphonates (0–3.3%), phospholipids (0–2.7%) and polyphosphates (0–0.04%) were observed in the sediments. Results of P fractionation and 31P-NMR analysis showed that 35% of Pi was labile P, including KCl–P and NaOH–Pi (Fe–P and Al–P). Biogenic-P accounted for 24% of P in the sediments. Analysis of the relationships between P species and water quality indicated that the Po compounds would mineralize to form ortho-P and would be potentially bioavailable for recycling to surface water, supporting further growth of phytoplankton and leading to algal blooms.

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