A Comparative Study On The Characteristics Of Modern Sediments From The Huanghe And Changjiang Estuaries

Modern sediments on the Yellow Sea and East China Sea Shelves are mainly from the Huanghe and Changjiang Rivers. To identify the sediment sources from the two rivers on the Yellow Sea and East China Sea Shelves accurately is significant for understanding modern sediment dynamics, shelf development and evolution, and the effect of rivers on the seas. A comparative study on the characteristics and identification signatures of the surface and suspended sediments taken in the Huanghe and Changjiang estuary areas will offer a basic, yet essential information of the two major end members of sediment sources, which is a presupposition for identifying sediment sources on the shelves.By using scaning electron microscope (SEM), cathode luminescence microscope, X-Ray diffractometor and ICP-AES, mineralogical and geochemical characteristics of the sediments of the Huanghe and Changjiang were studied and some identification signatures of sediments were found.Study on surface sediments indicates:(l) Cathode Luminescence(CL) of the quartz from the Huanghe are mainly brown, brown-purple, while from the Changjiang are mainly blue, purple -blue and purple. This distinct difference is a new identification signature for sediments from the Huanghe and Changjiang. (2) Quartzs from the two rivers have the general characteristics of fluvial quartz. X-Ray diffraction analyse of the Huanghe and Changjiang suspended sediments indicates:(l) The Huanghe and Changjiang suspended sediments part between 2μ m and 16μm is compose of quartz, plagioclase, K-feldspar, mica, chlorite, kaolinite and a small quantity of illite, calcite , dolomite; the quantity of plagioclase and calcite in the Huanghe sediments are higher than them in the Changjiang; the quantity of mica and chlorite in Changjiang is much than them in Huanghe.(2) The clay mineral combination of the Huanghe and Changjiang in the part of < 2 u m are illite, chlorite, kaolinite, semctite; the quantity of semctite and chlorite is much than them inChangjiang; the quantity of illite and kaolinite in Changjiang is much than them in Huanghe; the sequence of clay mineral content in Huanghe is illite> chlorite> kaolinite> semctite, it is illite> kaolinite =chlorite > semctite. Major elements(Fe> Mg,Ca. Na, Al, K, Ti, Mn) and trace elements(BaN Sn Pb, Cu, Zn, V, Ni)of the Huanghe and Changjiang suspended sediments are analysed with ICP-AES. The contents of Ca, Na, Sr are higher in Huanghe suspended sediments than in Changjiang suspended sediments, The contents of Fe, Mg, Al, K, TK Mn, Ba, Pb, Cu, Zn, V, Ni are lower than Changjiang . The sorts of the Huanghe and Changjiang suspended sediments are all poor.The comparative study on mineralogical and geochemical characteristics of the common minerals(quartz, feldspar, calcite, clay) of sediments taken in the Huanghe and Changjiang indicates that the CL difference of quartz, the three composition end-members of Illite- chlorite+kaolinite- semctite, the composition of major elements and trace elements of suspended sediments from the two rivers can be used to identify the sediment from the Huanghe and Changjiang.