The Formation And Release Of Phosphine In The Intertidal Marshes Of The Yangtze Estuary: Environmental Factors And Regulation

Phosphine, a volatile constituent of the global biogeochemical phosphorus cycle, has been proved to be widespread in the environment. Now the study of phosphine is mainly focused on researches of phosphine in air, land, marsh and lake. Phosphine exists in two different forms:free gaseous phosphine and matrix-bound phosphine. The discovery of phosphine is an important complement to the biogeochemical cycle of phosphorus, however, its function and status in the biogeochemical recycle has not been identified so far. 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. The intertidal sediment of the Yangtze estuary is the source of the phosphate cycle and the accumulation of phosphine, so it is great significance for the research of phosphine in the phosphate biogeochemical cycle in the Yangtze estuary.The study area is situated on the Yangtze Estuary and adjacent coastal tidal flat areas. They are XP, LHK, WSK, BLG, LC, DXG and YY. Both field and laboratory experiments were carried out to study the distribution characteristics, emission flux, transformation mechanism of phosphine in marine sediments. The main results are as follows:1. The content of matrix-bound phosphine is obviously different in temporal change and spatial distribution in the intertidal sediment of the Yangtze estuary. The contents of matrix-bound phosphine are 2.4～15.78 ng/kg, and 4.08～12.06 ng/kg (2009.09),2.40～7.74 ng/kg (2010.01),3.07～7.34 ng/kg (2010.05),4.60～15.78 ng/kg (2010.08), and it was lower than other matrix-bound phosphine contents of aquatic environment. The trend of temporal change is very obvious.2. The flux of phosphine is obviously different in temporal change and spatial distribution in the intertidal sediment of the Yangtze estuary. The flux of phosphine is 0.21-36.52ng m-2·h-1, the highest in WSK(2009.09), the lowest in YY(2010.01). The flux of phosphine in different seasons are 4.20-36.52 ng·m-2·h-1 (2009.09),0.21-0.90 ng·m-2·h-1 (2010.01).1.23-6.33 ng·m-2·h-1 (2010.05),3.85-32.40 ng·m-2·h-1 (2010.08), and it has a clear seasonal trend.3. The research proved that there are significant correlations of matrix-bound phosphine with the flux of phosphine in intertidal surface sediments of the Yangtze Estuary.. The major environmental control factors of matrix-bound phosphine are the phosphate-solubilizing bacteria and the alkaline phosphatase activity (APA). The phosphorus form also is one of the factors because the pronounced correlations of the phosphate-solubilizing bacteria with the phosphorus form.4. There is significantly correlation among the content and the flux of matrix-bound phosphine, the organic matter(OC,ON), salinity,temperature. But it is not obvious between the particle size and the matrix-bound phosphine content relevance.