Using solid 13C NMR coupled with solution 31P NMR spectroscopy to investigate molecular species and lability of organic carbon and phosphorus from aquatic plants in Tai Lake, China

Authors: LIU, SHASHA - Beijing Normal University; ZHU, YUANRONG - Chinese Research Academy Of Environmental Sciences; WU, FENGCHANG - Chinese Research Academy Of Environmental Sciences; MENG, WEI - Chinese Research Academy Of Environmental Sciences; WANG, HAO - Beijing Normal University; He, Zhongqi; GUO, WENJING - Beijing Normal University; SONG, FANHAO - Chinese Research Academy Of Environmental Sciences; GIESY, JOHN - University Of Saskatchewan

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2016
Publication Date: 2/22/2017
Citation: Liu, S., Zhu, Y., Wu, F., Meng, W., Wang, H., He, Z., Guo, W., Song, F., Geisy, J.P. 2017. Using solid 13C NMR coupled with solution 31P NMR spectroscopy to investigate molecular species and lability of organic carbon and phosphorus from aquatic plants in Tai Lake, China. Environmental Science and Pollution Research. 24:1880-1889.

Interpretive Summary: Aquatic plants are involved in the storage and release capacity for organic matter and nutrients. In a previous work, we characterized the water extractable organic matter (WEOM) derived from six aquatic macrophytes species of Tai Lake, China, using both solid-state 13C NMR and solution 31P NMR spectroscopy. As a continuation of this project, in this study, we investigated the solid 13C NMR and solution 31P NMR spectral features of the whole biomass of the six macrophyte species. Furthermore, different parts (i.e., stem, leaf, and root) of one plant were also analyzed by solid 13C NMR and solution 31P NMR spectroscopy. Detailed chemical composition and functional groups of the biomass of these whole aquatic plants would provide better understanding of dynamics of their storage and release for nutrients in lakes through WEOM or other mechanisms. The storage nutrient ability and degradation degree of aquatic plants are mainly dependent on the compositional characteristics of biomass of the aquatic plants.

Technical Abstract: Aquatic plants are involved in the storage and release capacity for organic matter and nutrients. In this study, solid 13C and solution 31P nuclear magnetic resonance (NMR) spectroscopy were used to characterize the biomass samples of six aquatic plants. Solid 13C NMR spectroscopy revealed the dominant presence of carbohydrates and lignins/tannins in the biomass of the six aquatic plants. Examination of the 13C NMR peaks around 30 ppm revealed that the relative abundance of the waxy biopolymers cutan and alike decreased from emergent, to floating, and to submerged aquatic plants. Thus, using the waxy biopolymers as biomarkers, the relative 13C NMR peak intensity in this region could be used to distinguish the origins of the lake organic matter coming from different types of plant litter. Solution 31P NMR analysis of the NaOH-EDTA extracts of the six aquatic plants showed the presence of more organic P forms than their water extracts reported previously. However, similar to water extracts, phytate, the major organic P form in the many environmental samples, was detected only in one of the five plant tested (floating plant water poppy). These observations implied that not all P species in these plant biomasses were easily released to the aquatic environment, and the P species and its bioavailability also differed among the aqauitic plants. Data in this work increased the knowledge of chemical composition of the aquatic plant biomasses, and would improve our ability to predict the identity and fate of plant-derived organic matters and P in lake ecosystems.