Distribution Of Matrix-bound Phosphine In Intertidal Sediments Of The Yangtze Estuary

Phosphine,a volatile constituent of the global biogeochemical phosphorus cycle,has been proved to be widespread in the environment;however,its function and statusin the biogeochemical recycle has not been identified so far.It exists in two different forms:free gaseous phosphine and matrix-bound phosphine(matrix-bound phosphine).Now people have focused mainly on researches of phosphine in air,land,marsh and lake.Nevertheless, little information is available on the function of phosphine in marine environment.Therefore,it is of great significance to study the distribution, emission, transfer, transformation of phosphine in marine environment and its possible link to phosphorus cycle. Both field and laboratory experiments were carried out to study the distribution characteristics,emission flux,transformation mechanism of phosphine in marine sediments. Phosphine was analyzed by an improved GC-NPD method,coupled with cryo-trapping enrichment technology.The distributions of matrix-bound phosphine and environmental factors in marine sediments under different environments,such as the coast of China,the Changjiang River Estuary was investigated.The estuarine and coastal tidal flat, as a typical transitional zone between land and ocean, is a multifunctional and complex ecosystem with special ecological values and potential resources. Due to the intertraction of land and ocean, the estuarine and coastal tidal flat is characterized by intense hydrodynamic conditions, frequent sediment transport and material exchange, steep physiochemical gradients and high biodiversity, especially the periodical change process of "exposure-immersion" in the tidal flat that is raised by tidal and flood.The study area is situated on the Yangtze Estuary and adjacent coastal tidal flat areas. They are LHK, WSK, BLG, DH, LC, FX and JS. The main results are given as follows:1. Extract organic phosphorus in the sediment samples of Yangtze Estuary seven typical ample sections. The result was LOP was 2.02 to21.37μg/g, MOP was 19.55 to 99.12μg/g, NOP was 3.32 to 46.82μg/g respectively. MOP was the highest content component, the next was MOP, and the last one was NOP. 2. There were obviously temporal change and spatial distribution of matrix-bound phosphine in the tidal flat surface sediments of the Yangtze Estuary. The contents of matrix-bound phosphine in different seasons were respectively 1.17～3.25 ng/kg,0.65～2.4 ng/kg,0.92～3 ng/kg and 0.5～1.4 ng/kg, and it was lower than other matrix-bound phosphine contents of aquatic environment.3. Undering the periodical change of exposure-immersion condition, The spatial and temporal distributions of matrixa recontrolled Probably by salinity and sediment temperature.OC,ON,Eh, Ph and grain size can also affect the content of matrix-bound phosphine in intertidal surface sediments of the Yangtze Estuary.4. The pronounced correlations of matrix-bound phosphine with apatite-bound phosphate and organic components of sediments implied that matrix-bound phosphine may derive from the mechanochemical reduction of apatite-bound phosphate and the microbial degradation of organic phosphorus.5. Combined with the contents of this paper, the author gained the marine ecosystem model of phosphorus cycling figure, adding the marine ecosystem biogeochemical cycling of phosphorus in theory.