| Phosphine (PH3), as a kind of reduced phosphorus compounds in the natural enviroment, exists in two different forms, i.e. free phosphine (Gaseous PH3) and matrix bound phosphine (MBP). The former has been detected in the atmosphere and biogas in urban and suburban areas. The latter was shown to be ubiquitously present in soils, sediments, sewage slurry etc. PH3 has been proven to participate in the global phosphorus biogeochemical cycle, but most previous studies were mainly focused on terrestrial ecosystems. Therefore studies on the biogeochemistry of PH3 in marine environments will be helpful to the understanding of the phosphorus biogeochemical cycles, and its potential effect on the environment especially the seas.In the present dissertation, the diurnal and seasonal variations of gaseous PH3 in the inshore atmosphere are studied and MBP was detected in Qingdao atmosphere for the first time. Environmental and meteorologic factors are found to influence the occurring and distribution of PH3 in Qingdao atmosphere and the contribution of atmospheric PH3 to the sea is estimated on a local scale. The distributions of MBP in sediments and the influence of environmental factors are investigated in the coastal areas of China, i.e. the Yellow Sea and the East China Sea shelf, Changjiang Estuary, northeastern Hainan Island, and some typical rivers around these areas. These studies contribute to understand not only phosphorus biogeochemical cycle, but also the possible impact of PH3 on marine ecosystem. The main research work is as follows:1. A chromatographic method using capillary column as a trap has been developed in lab to determine PH3 in atmosphere and sediments. The detection limits are 0.01 ng·m-3 and 0.02 ng·kg-1, and the precisions are <3% and <20% for air and sediments, respectively. The influence of cryogenic trap and chromatographic operation conditions were studied to obtain optimum results. The method avoids the interference of nitrous oxide and water vapor by using PLOT Q capillary as enrichment column. MBP in the marine sediments was digested by using sulfuric acid. Sediment sample storage experiments have been done to test reliability of the storage procedure used in this study, and the results showed that the effects of storage appear negligible in two months.2. Gaseous PH3 in the inshore atmosphere was observed from October 2005 to August 2006 at a coastal site of the Yellow Sea in China. The concentration of gaseous PH3 ranged from 0.01 to 14.86 ng m-3 with an average of 1.14 ng m-3. The concentration showed a diurnal variation in gaseous PH3 with the peak occurring at morning and the lowest point at noon. An obvious seasonal variation of atmospheric gaseous PH3 was found, with the gaseous PH3 levels in the summer higher than those in the winter. The gaseous PH3 levels in the atmosphere were apparently affected by temperature, radiation, sources and other meteorological factors. The data indicate that gaseous PH3 can be transported between the terrestrial and inshore atmosphere of Qingdao and the Yellow Sea or the East China Sea in both directions. The study increases evidence that gaseous PH3 participates within the global biogeochemical phosphorus cycle in phosphorus transport from land and inshore waters to the sea where commonly phosphorus is scarce and where gaseous PH3 inflow could be of important.3. MBP in the inshore atmosphere was observed from March 2004 to December 2005 at a coastal site of the Yellow Sea in China. The MBP was first detected in atmosphere and its concentration ranged from 0.01 to 22.63 pg·m-3 with an average of 1.02 pg·m-3. An obvious seasonal variation of atmospheric MBP was found with autumn>winter>summer, spring. The MBP levels in the atmosphere were apparently affected by aerosol source, aerosol mineral composition, humidity or rainfall and MBP physicochemical properties. MBP in terrestrial atmosphere is six times higher than those in marine atmosphere. MBP deposition flux is about 0.0189μmol·m-y-1 in the Yellow Sea,that is 7.57×105 mol MBP-phosphorus is deposited to the Yellow Sea via atmosphere each year which is half of free phosphine deposition flux. Atmospheric MBP V deposition plays an important role as gaseous PH3 in determining the biogeochemistry of phosphorus especially reduction state phosphorus in coastal and shelf regions.4. MBP in the coastal sediments of China were investigated from 2004 to 2008. MBP occurs from temperate zone to tropical zone. For example, MBP in surface sediments of the Yellow Sea, Changjiang Estuary, the East China Sea, the coast of northeast Hainan, Jiaozhou Bay, Sanggou Bay are 0.19～38.24 ng·kg-1, 0.1～169.4 ng·kg-1, 0.51～23.1 ng·kg-1, 0.21～5.45 ng·kg-1, 0.34～17.15 ng·kg-1, 2.11～71.79 ng·kg-1, respectively, while MBP in river sediments around Jiaozhou Bay and northeast of Hainan are 0.28～319 ng·kg-1 and nd～82.1 ng·kg-1, respectively. MBP in soils, lagoon and mangrove surface sediments are nd～4.88 ng·kg-1, 1.34～12.74 ng·kg-1 and 0.76～42.21 ng·kg-1, respectively.5. The concentration of MBP in the sediments showed seasonal variation, with the MBP levels in the summer higher than those in the autumn and winter in the Changjiang estuary, Sanggou Bay, Wenchang River and Wenjiao Rive, and Mangrove. The distribution of MBP in surface sediments showed certain spatial variation with MBP concentrations decreasing from the coast to the shelf in Changjiang Estuary and the East China Sea. Higher MBP was found in the central and northern of the Yellow Sea adjacent Sanggou Bay. The vertical distribution of MBP in Jiaozhou Bay, Changjiang Estuary and Mangrove sediments showed that higher MBP generally occurred in the bottom or subsurface layer with strong reducing conditions.6. Environmental factors such as types of sediments, temperature, organic matter, redox conditions, pH were found to affect levels and distribution of MBP in sediments. Clay sediments are favorable for MBP accumulation due to large surface area and adsorption pots, and reducing condition, anoxia water, and neutral condition is also favor to the exsistence of MBP. Strong correlations between temperature, organic matter and MBP not only proved their effect on MBP in the sediments, but also showed that biological activity may control MBP production. However, MBP was found in some land sediments with lower pH or acid soils imply that MBP production and elimination are complicated, and more studies should be done.7. The studies on PH3 in the coastal areas of China improved our understanding of global biogeochemical phosphorus cycle Global PH3 cycles and global phosphorus biogeochemical cycles including PH3 are drawing based on the reference and this work. Early diagenesis schematic diagram of PH3 in the sediments was established. PH3, as a phosphorus species, is unstable and easily converted to other phosphorus compound. Although PH3 content in natural environment is low, it is an potential link in phosphorus biogeochemical cycle.
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