The Research On Geochemistry Of Sulfur During Early Diagenesis In Sediments From Dashentang Coastal Zone And Liaohe Estuary

Coastal Zone, as the area of the intersection connection between land and sea, is the important area, where energy conversion and material circulation during early diagenesis occur. There are many complex and changing biogeochemical processes in coastal areas, such as deposition of organic matter, degradation, mineralization, etc. Therefore, we select two sediment cores from Liaohe Estuary and Dashentang Coast zone to study sulfur geochemistry during early diagenesis. The data results which include grain size,total organic carbon, Fe, Mn, SO42- and sulfides were obtained through experimental testing. Based on total organic carbon and grain size,the depositional environment is studied. And early diagenetic geochemistry of Fe, Mn and S was analyzed and the deference of early diagenetic from two study area are also discussed. In addition, diffusion flux of ion in pore water was calculated. Getting the following conclusions:1.The analysis of grain size shows that content of sand in sediment from Liaohe Estuary is higher than that from Dashentang Coast zone and storing of grain size from Dashentang Coast zone is better. And the content of total organic carbon in sediment from Liaohe Estuary is lower than that from Dashentang Coast zone. There is little correlation of average grain size and total organic carbon from Liaohe Estuary and which shows weak correlation from Dashentang Coast zone.It insinuates sediment grain size have no effect to preservation of organic matter.2.Multivariate Statistics and the results of sulfur isotope from Liaohe Estuary all suggest that:Fe2+ and Mn2+ which is produced redox reaction of Fe oxides and Mn oxides with organic matter release to pore water; S- which is produced through reduction reaction of sulfate and metal ion from sediment generate metal sulfides and then these metal sulfides become pyrite finally.There are different features of early diagenetic between sediment from Liaohe Estuary and that from Dashentang Coast zone.Fe oxides,Mn oxides and sulfate all come to pass the process of early diagenetic meanwhile. And it is obviously from Ocm to 8cm depth. However, the of Fe and Fe2+, Mn and Mn2+ suggest that early diagenetic reaction of them is not obvious. The stronger negative correlation of sulfate and total organic carbon shows that the reduction reaction of sulfate is obvious.3.The results of diffusion flux shows diffusion flux of SO42- is higher than that of Fe2+ and Mn2+.This indicates SO42" have the stronger ability of migration and activation. Comparison the two study area, the diffusion flux of SO42- in Dashentang Coast zone is larger than that in Liaohe Estuary, while the diffusion flux Fe2+ and Mn2+ in Dashentang Coast zone are all lower. This perhaps affect process of early diagenetic.