title: Evidence for organic phosphorus activation and transformation at the sediment-water interface during plant debris decomposition.
abstract: The processes and mechanisms through which phosphorus (P) is released from sediment and organic P is transformed, induced by the decomposition of plant (duckweed (Lemma minor L.)) debris, were studied experimentally. In the simulation experiments, the dissolved oxygen concentration, pH, and oxidation-reduction potential at the water-sediment interface first decreased rapidly. The lowest oxidation-reduction potential reached was 225.4mV, and the solution became weakly acidic (pH5.14) and anoxic (dissolved oxygen concentration 0.17mg·L-1). The dissolved oxygen concentration, pH, and oxidation-reduction potential then became stable. The soluble reactive P, total dissolved P, and total P concentrations in the overlying water all increased rapidly because of the particulate P and dissolved organic P released as the plant debris decomposed.31P NMR analysis of the solution showed that orthophosphate monoesters were the main organic P compounds in the sediment. The orthophosphate monoester and orthophosphate diester concentrations were higher during the first 7d of the experiment (at 71.2 and 15.3mg·kg-1, respectively) than later (60.8 and 14.6mg·kg-1, respectively). The decomposition of the duckweed could have mineralized the orthophosphate monoesters and orthophosphate diesters to give orthophosphate. The results indicated that the decomposition of aquatic plant debris is a key factor in the release of P from sediment even when external P is excluded. It is therefore necessary to remove plant debris from freshwater ecosystems to control the release of P from plant debris and sediment.
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, P. O. Box 2871, Beijing 100085, PR China.
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, P. O. Box 2871, Beijing 100085, PR China; University of Chinese Academy of Science, Beijing 100049, PR China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Zhu
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, P. O. Box 2871, Beijing 100085, PR China; University of Chinese Academy of Science, Beijing 100049, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Jin
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, P. O. Box 2871, Beijing 100085, PR China; University of Chinese Academy of Science, Beijing 100049, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Meng
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, P. O. Box 2871, Beijing 100085, PR China. Electronic address: wztang@rcees.ac.cn.
authors.forename: Wenzhong
authors.initials: W
authors.lastname: Tang
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, P. O. Box 2871, Beijing 100085, PR China. Electronic address: bqshan@rcees.ac.cn.
authors.forename: Baoqing
authors.initials: B
authors.lastname: Shan
mesh_terms: D004784:Environmental Monitoring; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus
keywords: Decomposition; Organic phosphorus; Plant debris; Sediment; Solution (31)P NMR