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《Journal of Lake Science》 1997-01
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PALEOLIMNOLOGY OF RECENT SEDIMENTS IN YANGCHENG LAKE

Ji Lei; Zhu Yuxin ;Wu Ruijin; Xiang Liang; Qian Junlong; Pan Hongxi (Lake Sedimentation and Environment Lab, Nanjing Inst. of Geography and Limnology, CAS, Nanjing 210008)  
Seven cores of recent sediments were obtained in Yangcheng Lake, among which 102cm-core YC1 and 55cm-core YC3 in the western part of the lake kept undisturbed. The core profile is divided into 3 lithological beds which are separated by 2 long-term sedimentation hiatus, name-ly upper bed A of sapropel, middle bed B of silty clay, and lower bed C of sticky silty clay (so called "hard earth bed").14C, 210Pb, water content, grainsize, magnetic susceptibility, nutrient elements, metal ele-ments (both total and liable facies), stable isotope of organic carbon and fossil pigments were analysed. Chronic stratigraphic study demonstrates that beds A, B and C belong respectively to the deposits of Late Pleistocene, Holocene and about recent 100 years. The environmental char-acteristics of every bed are described as follows.Bed C: Reworked fluvial sediments, in which lower values of TOC, TN, pigment content,CD/TC and heavy metals and higher values of C/N, 13C, allogenic metals (Al, Na, Mg, Ca and Ti) manifest more intense erosion of catchment land, lower primary productivity and eu-trophic state. Bed B: Lacustrine sediments, of which every environmental proxy sits between beds A and C. Bed A: Lacustrine sediments, of which higher valucs of TOC, TN, pigment con-tent, CD/TC and heary metals and lower values of C/N, 13C and allogcnic metals show en-hanced primary productivity and eutrophication of the lake.Detailed ana1ysis of the beds demonstrates slightly higher pollution coefficient of Cu, Co,Zn, Cr, Ni in 0-2cm on surficial sediments. In the accumulation rate profile, the accumulation of many heavy metals is increased gradually upwards, extensively since the 1970s. The accumu-lation rate of nutrient elements and pigmcnts also indicate more intense lake eutrophication since the 1970s-1980s.
【Fund】: 江苏省自然科学基金!BK93162201
【CateGory Index】: P343.3
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