Title | Evidence for organic phosphorus activation and transformation at the sediment-water interface during plant debris decomposition. |
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Authors | Zhang, W.; Zhu, X.; Jin, X.; Meng, X.; Tang, W.; Shan, B. |
Journal | Sci Total Environ |
DOI | 10.1016/j.scitotenv.2017.01.103 |
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. (31)P 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. |
Evidence for organic phosphorus activation and transformation at the sediment-water interface during plant debris decomposition.