Deposition Rate, Grain-Size Change Characteristics And Their Environment Evolution Of Sediment Cores In Wu-Liangsu Lake

In this paper, the characteristics of grain size composition, grain size parameters, grain size frequency curves and deposition rate change were analysised. In order to investigate the history sediment deposition process and environmental evolution characteristics of Wu-liangsu lake. The main conclusions of the paper are as follows:1The average deposition rate was0.49cm/、0.79cm/a、0.86cm/a、 and0.95cm/a of WLSH-1、WLSH-4、WLSH-2and WLSH-3in Wu-liangsu lake. The deposition rate may reflect the pace of paludification process of the lake. In the past80year, the changes of deposition rate showed:there was a growing trend about deposition rate. Especially after the21st century, the deposition rate increased significantly. It indicates the accelerating trend that wetland evolves to swamps.2Wetland sediment mainly consists of terrigenous material. Also there are a lot of Silt, less sand and clay in the middle in the Wu-liangsu lake. Frequency curve shows that the area affected mainly by the role of hydrodynamic and supplemented by aeolian role.3Combined with210Pb and137Cs dating, the sediment dating age can be calculated. According to the age, it is known that sediment shows staged sedimentary change characteristics in vertical.In addition to WLSH-4km back gate features two stages, the rest three cylindrical sample features three stages in general. Vertical granularity change characteristics reveals that average particle size of WLSH-1, WLSH-2and WLSH-4sediment cylindrical sample are fine to coarse to fine from the bottom up while WLSH-3cylindrica sample is coarse to fine.The research achievements of this paper can provide theory support and scientific basis for the prevention and control of paludification process and the recovery of wetland ecosystem of Wu-liangsu lake.