Abstract:

This paper focused on the Fudong watershed of Taihu Lake Basin.Based on analyzing the element and isotopic geochemistry of sediments within the watershed and estuary,the quantitative relationship between soil erosion and the material fluxes from Fudong watershed to Taihu Lake were established.The results showed that the average material flux from the Fudong watershed to Taihu Lake was 6074 t/a in recent forty years,which was consistent with actual monitor data.The total amount of soil erosion within Fudong watershed was 25670 t/a,which meaned that only 237 percent of eroded soil transferred into Taihu Lake and the others were deposited in the channels and fields.Therefore,the mathematical relationship among the material flux from watershed to lake〖WTBX〗 (Q)〖WTBZ〗,the watershed erosion rate〖WTBX〗 (E)〖WTBZ〗 and watershed area 〖WTBX〗(A)〖WTBZ〗 was:〖WTBX〗E〖WTBZ〗=422〖WTBX〗Q/A〖WTBZ〗.According to the analysis of source of lake sediments by using multielement fingerprinting method,the soil erosion rate distribution of different land use types in Fudong watershed were calculated.The average soil erosion rates of forest lands,tea plantations and paddy fields were 1266，58355  and 17293 t/（km2·a） respectively,which was consistent with the results by using 137Cs tracer technique.Our study proved that the soil erosion of different land use types and the nutrient flux of catchment could be reconstructed by using lake sediment records.〖