阳澄湖近代沉积物的古湖泊学研究  

PALEOLIMNOLOGY OF RECENT SEDIMENTS IN YANGCHENG LAKE

作　　者：吉磊[1] 朱育新[1] 吴瑞金[1] 项亮[1] 钱君龙[1] 潘红玺[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所湖泊沉积与环境开放研究实验室,南京210008

出　　处：《湖泊科学》1997年第1期22-28,共7页Journal of Lake Sciences

基　　金：江苏省自然科学基金!BK93162201

摘　　要：对阳澄湖两个短柱状样进行了地层年代以及各种环境指标分析．结果表明，湖底沉积物由校长期沉积间断所分割的3个岩性层组成：下部层C属再沉积的更新世晚期硬土层；中部层B为全新世沉积；上部层A为近100年以来的表层沉积．对层A的详细分析显示，本世纪以来，特别是70－80年代以来，金属元素、营养元素和色素的沉积通量明显提高，说明湖泊重金属污染和富营养化程度的不断加重．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.

关 键 词：古湖泊学 阳澄湖 沉积物 环境演化 重金属污染 

分 类 号：P512.3[天文地球—地质学]