Phosphorus-31 nuclear magnetic resonance assignments of biogenic phosphorus compounds in sediment of an artificial Fuyangxin River, China
2014
Zhang, Wenqiang | Shan, Baoqing | Zhang, Hong | Tang, Wenzhong
River eutrophication could drastically influence the phosphorus (P) in the water and sediment. To understand the biogenic-P species, distribution and bioconversion, five sediment samples were collected from an artificial river, and analyzed by phosphorus-31 nuclear magnetic resonance (³¹P-NMR). The P pollution in the water and sediment were both severe. The average concentrations of total P (TP) and solution reactive phosphorus in the water were 3.0 and 2.6 mg L⁻¹, respectively, which surpass grade V of the national quality standard (China) and should not be used for any purpose. The river sediments accumulated significant inorganic phosphorus (Pi) and organic phosphorus (Po); in the P fractionation, the rank order of the P fractions was as follows: Ca-P > NaOH-Pi > Res-P > KCl-P > NaOH-Po, with average relative proportions of 25.1:16.8:6.6:1.7:1:0. Six P compounds were detected in the NaOH-EDTA extract by³¹P-NMR. Mono-P (8.96–29.58 %) was the dominant forms of biogenic-P, and other smaller fractions of biogenic-P were also observed, including pyro-P (0.22–0.86 %), DNA-P (0.75–2.03 %), phon-P (0–1.57 %), and lipids-P (0–2.66 %). The TP and biogenic-P decreased along the direction of flows, with their average relative proportions 7.97:1.20:1.49:1.00:1.00 and 40.87:2.34:3.46:1.60:1 from the upstream to downstream, respectively. The concentration and species of Po in NaOH-Po were lower than found in³¹P-NMR analysis in this research. Thus, the use of 0.25 M NaOH and 50 mM EDTA extracts and solution³¹P-NMR analysis was a more accurate method for quantifying biogenic-P in the river sediments than P fractionation.
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