title: Characteristics and degradation of carbon and phosphorus from aquatic macrophytes in lakes: Insights from solid-state (13)C NMR and solution (31)P NMR spectroscopy.
abstract: Water extractable organic matter (WEOM) derived from macrophytes plays an important role in biogeochemical cycling of nutrients, including carbon (C), nitrogen (N) and phosphorus (P) in lakes. However, reports of their composition and degradation in natural waters are scarce. Therefore, compositions and degradation of WEOM derived from six aquatic macrophytes species of Tai Lake, China, were investigated by use of solid-state (13)C NMR and solution (31)P NMR spectroscopy. Carbohydrates were the predominant constituents of WEOM fractions, followed by carboxylic acid. Orthophosphate (ortho-P) was the dominant form of P (78.7% of total dissolved P) in the water extracts, followed by monoester P (mono-P) (20.6%) and little diester P (0.65%). The proportion of mono-P in total P species increased with the percentage of O-alkyl and O-C-O increasing in the WEOM, which is likely due to degradation and dissolution of biological membranes and RNA from aquatic plants. Whereas the proportion of mono-P decreased with alkyl-C, NCH/OCH3 and COO/N-C=O increasing, which may be owing to the insoluble compounds including C functional groups of alkyl-C, NCH/OCH3 and COO/N-C=O, such as aliphatic biopolymers, lignin and peptides. Based on the results of this study and information in the literature about water column and sediment, we propose that WEOM, dominated by polysaccharides, are the most labile and bioavailable component in debris of macrophytes. Additionally, these WEOMs would also be a potential source for bioavailable organic P (e.g., RNA, DNA and phytate) for lakes.
authors.affiliation: College of Water Sciences, Beijing Normal University, Beijing 100875, China; State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: Shasha
authors.initials: S
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: zhuyuanrong07@mails.ucas.ac.cn.
authors.forename: Yuanrong
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: mengwei@craes.org.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Meng
authors.affiliation: USDA-ARS Southern Regional Research Center, 1100 Robert E Lee Blvd, New Orleans, LA 70124, USA.
authors.forename: Zhongqi
authors.initials: Z
authors.lastname: He
authors.affiliation: College of Water Sciences, Beijing Normal University, Beijing 100875, China; State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: Weiying
authors.initials: W
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Department of Biomedical and Veterinary Biosciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
mesh_terms: D001673:Biodegradation, Environmental; D002244:Carbon / Q000378:metabolism*; D002681:China; D004784:Environmental Monitoring; D005068:Eutrophication; D060106:Lakes; D010758:Phosphorus / Q000378:metabolism*; D010944:Plants; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon
keywords: Eutrophication; Nuclear magnetic resonance spectroscopy; Phosphorus; Plant-derived water extractable organic matter; Sediment