The Gray Image Processes Techology Of Sediment Core And Its Application On The High Resolution Sediment Record In Inner Shelf Of The East China Sea

The exploration and application of proxy to environment changes is the essential problem in research of high resolution sedimentary records and their response to the global changes. It is also one of the research frontiers and focuses on current earth science. It is of important theoretical and practical significance. This study explores the technology of grey value X-ray image processing on sediment core, analyzes its influencing factors and its possible proxy to environment change. According to the core C0702 taken from Zhemin coastal mud area of inner shelf of the East China Sea, we study the sediment core using the technology of grey value X-ray image processing and traditional sediment core research method (grain-size analysis,X-ray diffraction,X-ray fluorescence spectrometer), combined with the 137Cs,210Pb radioactivity measurements which determine age of the core;then establish nearly 150a high resolution sedimentary record and illustrate its response to climate changes, sedimentary events and human activities. The study indicates that:The X-ray gray image of sediment core includes comprehensive information, we can quickly get high-resolution sedimentary record information from it. The X-ray image grey value of sediment core is a good proxy to comprehensive deposition records. Sediment grain-size is good related with X-ray image gray value. It is linear relationship between mean grain-size and gray value. Furthermore, we found a positive correlation between sand, silt and gray value and it is negative correlation between clay and gray value. The gray value is significantly correlated with dry density of sediment core. There is positive correlation between the gray value of gray image and Si,Ca. The vertical changing tendency of grey value is similar with ones of smectite and illite and it is oppositely related with vertical changing tendency of kaolinite and chlorite. The sediments of core C0702 taken from inner shelf of the East China Sea are mainly composed of silt and clay, with developments of silt laminae and horizontal beddings. There is no erosion trace or hiatus in it. In general, the composition of sediment over the core is stable, the sedimentary sequences are well conserved, indicating the sedimentary dynamic environment is nearly steady during the pormation of the sediment core. Its deposition rate is slow and there are differences among different times, the deposition rate was 1.82cm/a before 1986a and it is 0.87cm/a since 1986a.Both grain-size and gray value records show good cyclical fluctuations having the marked cycles of 10~12a, 7~8a, 3~5a and1a.Meanwhile, the high-resolution periodical records are also accompanied by non-periodic fluctuations. The elemental geochemical records also show similar fluctuation characteristics. The 3-5a cycle corresponds with the E1 Nino/Southern Oscillation (ENSO). The 11a cycle of sedimentary record is consistent well with the sunspot activity, demonstrating the impact on the deposition of solar activity.Non-periodic changes relate to East Asian monsoon fluctuations,sedimentary events and human activities. The sensitive grain-size component of <14.35μm is good responding to the East Asian winter monsoon. The stronger the East Asian winter monsoon results in the more of the sensitive grain-size of <14.35μm, and vice versa.In flood years, sediment grain-size has been reduced and it also has a very good reflection on the image gray of sediment core image. In storm years, the average grain-size and gray value increase suddenly because the fluctuations were mainly caused by by storm. The sedimentary records in the area are also reponsing to the discharges of water and sediment of the Yangtze River. The records show that the discharges of water and sediment are much more important before 1986. After that, enthropogenic impacts increase and become prominent, with the yearly increasing of heavy metals since 1986.