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Research Project: Increasing the Value of Cottonseed

Location: Commodity Utilization Research

Title: Forms and lability of phosphorus in algae and aquatic macrophytes characterized by solution 31P NMR coupled with enzymatic hydrolysis

Author
item FEIN, WEIYING - CHINESE RESEARCH ACADEMY OF ENVIRONMENTAL SCIENCES
item ZHU, YUANRONG - CHINESE RESEARCH ACADEMY OF ENVIRONMENTAL SCIENCES
item WU, FENGCHANG - CHINESE RESEARCH ACADEMY OF ENVIRONMENTAL SCIENCES
item He, Zhongqi
item ZHANG, CHEN - CHINESE RESEARCH ACADEMY OF ENVIRONMENTAL SCIENCES
item GEISY, JOHN - CHINESE RESEARCH ACADEMY OF ENVIRONMENTAL SCIENCES

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2016
Publication Date: 11/16/2016
Citation: Fein, W., Zhu, Y., Wu, F., He, Z., Zhang, C., Geisy, J.P. 2016. Forms and lability of phosphorus in algae and aquatic macrophytes characterized by solution 31P NMR coupled with enzymatic hydrolysis. Scientific Reports. 6:37164-37174. doi:10.1038/srep37164.

Interpretive Summary: Lake eutrophication is a serious environmental concern in China, especially in lakes from middle and lower reaches of Yangtze River watershed and the Southwest China Plateau. Increased information on forms and lability of phosphorus (P) in aquatic macrophytes and algae is crucial for better understanding of P biogeochemical cycling in eutrophic lakes. This work was a continuation of the efforts in increased understanding of the P forms and lability in aquatic macrophytes and algae. This study took aquatic macrophytes and algae samples for an indepth research by solution 31P NMR spectroscopy and enzymatic hydrolysis. Furthermore, we rigorously examined the accuracy of the two methods by comparison of the solution 31P NMR spectral changes of the NaOH-EDTA extracts of the six samples before and after enzymatic hydrolysis treatments. Based on these quantity and lability data, we proposed that biogeochemical cycling of Po in aquatic vegetative biomass residues is an important mechanism to self-regulate the nutrient status for eutrophic lakes and maintain their nutrient status for a long time.

Technical Abstract: Increased information on forms and lability of phosphorus (P) in aquatic macrophytes and algae is crucial for better understanding of P biogeochemical cycling in eutrophic lakes. In this work, solution 31P nuclear magnetic resonance (NMR) spectroscopy coupled with enzymatic hydrolysis (EH) was used to characterize P compounds in 0.5 M NaOH-25 mM EDTA extracts of the dominant aquatic macrophytes and alga in Tai Lake, China. NaOH-EDTA extractable Po ranged from 504 to 1643 mg kg-1 of aquatic macrophytes, from 2318 to 8395 mg kg-1 of algae, respectively. Using 31P NMR spectroscopy, 15 Po species in the mono- and diester region plus orthophosphate, pyrophosphate and phosphonates were detected. Using EH, phytate-like P was identified as the largest enzyme- labile Po class in most samples, followed by labile monoester P and diester P. Comparison of the two sets of data indicated that the distribution pattern of major P forms in the aquatic macrophytes and algae determined by two methods was similar. 31P NMR spectroscopic analysis of enzyme-treated extracts showed significant decreases in the monoester and pyrophosphate peaks with a corresponding increase in the orthophosphate signal, confirming the lability of the two types of NMR-identified Po. Based on these quantity and lability data, we proposed that biogeochemical cycling of Po in aquatic vegetative biomass residues is an important mechanism to self-regulate the nutrient status for eutrophic lakes and maintain their nutrient status for a long time.