湖泊沉积多指标记录的长寿湖近60年来营养化过程  

Trophication evolution recorded by multi-proxy evidences in Lake Changshou, Chongqing during the recent 60 years

作　　者：朱正杰[1,2] 肖军[3] 龚业超[1] 杨洪永[1] 张雄[1] 双燕[1] 毛玲玲[1] 

机构地区：[1]外生成矿与矿山环境重庆市重点实验室重庆地质矿产研究院,重庆400042 [2]煤炭资源与安全开采国家重点实验室重庆研究中心,重庆400042 [3]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710061

出　　处：《地球环境学报》2016年第3期292-300,共9页Journal of Earth Environment

基　　金：重庆市基础与前沿研究计划项目(cstc2013jcyj A20001)~~

摘　　要：长寿湖位于重庆市长寿区境内,是重庆市最大的湖泊旅游风景区和淡水鱼养殖基地之一。近年来,其营养化日趋严重。本文通过对有机质碳、氮含量、碳氮比值、有机质碳同位素等有机质指标的分析,结合^(137)Cs放射性核素定年,探讨了长寿湖近60年来有机质转化及营养演化过程。结果表明:长寿湖有机质主要来源于水生植物藻类,受陆源影响较小;湖泊环境演化分为两个截然不同的阶段:1980年以前,有机质碳、氮含量较低,C/N比值较小,有机质碳同位素值较大,暗示湖泊营养环境为贫营养化。1980年以后,有机质碳、氮含量较高,C/N比值较大,有机质碳同位素值偏负,说明湖泊已经处于营养化阶段,人为活动的增强及养殖业的发展是导致湖泊生产力增大的主要因素。长寿湖沉积物多指标忠实记录了湖泊环境的演化过程。Background,aim,and scope Lake Changshou,located in Changshou District,is one of the largest lake scenic spots and most important freshwater fish breeding bases in Chongqing.Recently,the eutrophication of this lake is increasing seriously.The aim of this study is to evaluate the process of eutrophication of Lake Changshou by using organic proxies,including carbon and nitrogen content of organic matter,C/N ratios,and carbon isotope composition of organic matter.Materials and methods Sediment core named CS1 and CS2 were retrieved from the central part of Lake Changshou in 2013 using a self-designed gravitational sediment sampler.Sediment samples were sectioned at 1 cm interval and put into plastic bags in the field.Sediment samples were dried using a vacuum freeze drier.Core CS1 samples were used for geochemical analysis,and CS2 samples were used for analyzing radionuclide^（137）Cs activities.Element analyses of total organic carbon（TOC） and nitrogen were measured by the element analyzer.Samples for organic carbon analysis were pretreated with HC1（1 mol·L^（-1））,then placed in water bath for two hours at 60℃ to remove carbonates,and rinsed repeatedly with distilled water for four times.After that,δ^（13）C values of organic matter were measured on the Finnigan Delta Plus isotope ratio mass spectrometer.A number of duplicate samples were also measured to monitor the measurement accuracy.The activity of^（137）Cs was measured at 661.6 k eV by γ-spectrometry using low-background germanium detector.Results Data of ^（137）Cs demonstrate that the average sedimentation rate of Lake Changshou is 0.85 cm·a^（-1）.Total organic carbon contents vary between 0.85%and 4.3%,with the mean value of 1.75%.Before 1980 AD,the average TOC is 1.25%,and after 1980 AD,the average TOC is 2.43%.Nitrogen contents and C/N ratios show similar variations with TOC.However,carbon isotope composition of organic matter shows contrast variations.The results indicate that the source of organic matter in Lake Changshou is

关 键 词：长寿湖 有机质碳同位素 营养化 人为活动 

分 类 号：X524[环境科学与工程—环境工程]