Characterization of phosphorus forms in lake macrophytes and algae by solution 31P nuclear magnetic resonance spectroscopy

Authors: FENG, WEIYING - Chinese Research Academy Of Environmental Sciences; ZHU, YUANRONG - Chinese Research Academy Of Environmental Sciences; WU, FENGCHANG - Chinese Research Academy Of Environmental Sciences; MENG, WEI - Chinese Research Academy Of Environmental Sciences; GIESY, JOHN - University Of Saskatchewan; He, Zhongqi; SONG, L - Chinese Academy Of Sciences; FAN, M - Procter & Gamble

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2015
Publication Date: 4/1/2016
Citation: Feng, W., Zhu, Y., Wu, F., Meng, W., Giesy, J.P., He, Z., Song, L., Fan, M. 2016. Characterization of phosphorus forms in lake macrophytes and algae by solution 31P nuclear magnetic resonance spectroscopy. Environmental Science and Pollution Research. 23:7288-7297.

Interpretive Summary: Lake eutrophication is a threat to water quality and ecosystem heath worldwide. In most sceneries, phosphorus (P) is the limiting factor that contributes to lake eutriphication. However, the composition, sources, bioavailability and biogeochemical cycling of organic P (Po) in lakes are not well understood. There is even less information on the chemical composition and characteristics of Po of aquatic macrophytes and algae. Therefore, in this work, we investigated the characteristics of Po of aquatic macrophytes and algae taken from the eutrophic Tai Lake (China) by solution 31P NMR analysis. Our data indicated that orthophosphate monoesters were the major component of Po from both aquatic macrophytes and algae. The bioavailable Po was an important internal source of P to support growth of algae to form blooms when external sources of P have been controlled. In other words, the biogeochemical cycle of Po of aquatic macrophytes and algae in lakes might be an important process to self-regulate the nutrient status for eutrophic lakes and maintain their eutrophic status in a long time scale. Our findings derived from this study would be helpful in better understanding nutrient cycling, relevant eutrophication processes and pollution control for freshwater lakes.

Technical Abstract: Aquatic macrophytes and algae are important sources of phosphorus (P) in the lake environment that cause blooms of algae under certain biogeochemical conditions. However, the knowledge of forms of P in these plants and algae and their contribution to internal loads of lake P is very limited. Without such knowledge, it is difficult to develop appropriate strategies to remediate aquatic ecosystems that have undergone adverse eutrophication. Therefore, in this work, P was extracted from six aquatic macrophytes and algae samples collected from Tai Lake of China, and characterized by solution 31P- nuclear magnetic resonance (NMR) spectroscopy. Extraction data indicated that 0.5 M NaOH-25 mM EDTA was the most optimal agent with extraction recovery of total phosphorus (TP) and organic P (Po). Concentrations of Po in algae and aquatic macrophytes were 5552 mg•kg-1 and 1005 mg•kg-1, and accounted for 56% and 47.2% of TP, respectively. Solution 31P-NMR data showed that, in these samples, 79.8% was orthophosphate monoesters (Mono), 18.2% was pyrophosphate (Pyo) and approximately 2.1% was orthophosphate diesters (Dies). Mono in algae included ß-glycerophosphate (44.1%), '-glycerophosphate (13.5%), glucose 6-phosphate (13.5%) and other Mono (34.5%). Mono P of aquatic macrophytes were ß-glycerophosphate (27.9%),'-glycerophosphate (24.6%), adenosine 5’ monophosphate (8.2%) and others Mono (39.4%). Results and knowledge derived from this study would be helpful in better understanding nutrient cycling, relevant eutrophication processes and pollution control for freshwater lakes.