近200年来湖北涨渡湖对江湖联通变化的环境响应  

Environmental changes in response to altered hydrological connectivities with the Yangtze River in Lake Zhangdu(Hubei Province)over the past 200 years

作　　者：张清慧[1,2] 董旭辉[2] 姚敏[1] 陈诗越[1] 羊向东[2] 

机构地区：[1]聊城大学环境与规划学院,聊城252059 [2]中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室,南京210008

出　　处：《湖泊科学》2013年第4期463-470,共8页Journal of Lake Sciences

基　　金：国家重点基础研究发展规划"973"项目(2012CB417000);国家自然科学基金重点项目(41072258)联合资助

摘　　要：江湖联通状况对湖泊生态系统有着重要影响,但是由于缺乏长期的生态水文监测数据,湖泊系统对其响应的过程与机理仍缺乏认识.本研究选择长江中下游地区典型湖泊———涨渡湖,结合该湖一沉积短柱的210Pb、137Cs年代测试,通过高分辨率的多指标分析(硅藻、元素地球化学和粒度),揭示近200年来湖泊生态系统对该湖与长江之间联通关系改变的响应过程.与历史文献记载一致,古湖沼学记录揭示出该湖与长江的联通状况经历了3个阶段.1)江湖联通期(1954年以前):该湖与长江自然相通,江湖水体交换频繁,丰富的贫营养浮游种Cyclotella bodanica表明该湖长期处于低营养及湖泊水位相对较高的状态.2)江湖隔绝期(1954 2005年):随着湖坝的兴建,江湖联通关系被隔绝,湖泊换水周期变长,透明度降低,喜好扰动环境的Aulacoseria granulata大量生长.相应地,富营养硅藻的增加、高TOC含量以及较高的沉积物TP、TN浓度表明,该湖营养水平逐渐升高.特别是近20年来,较高含量的富营养硅藻种———C.meneghinena、A.alpigena、Nitzschia palea、Surirella minuta和地球化学记录,包括TOC含量和沉积物TP、TN浓度,表明该湖富营养化程度加剧.3)江湖季节性联通期(2005年后):硅藻以附生种、底栖种为主,但仍有一定含量的富营养化属种,且TOC含量以及沉积物TP、TN浓度仍然保持较高水平,表明富营养程度有所缓解.古湖沼学和历史记录都揭示了自该湖与长江无连通后其生态状况的快速退化、重新联通后生态状况有所好转.因此,在长江中下游洪泛平原区,江湖关系的重新联通将是减轻湖泊生态压力的有效手段.Altered hydrological connectivity between lakes and rivers may impose significant effect on lake ecosystems. Due to lac- king of long-term data on lake environmental changes, the process and mechanism of limnological response to the changes in hydro- logical connectivity is still unknown. This work chose Lake Zhangdu from the Yangtze floodplain, to investigate the long-term （ about 200 years） environmental changes responding to altered connectivity with Yangtze River using a high-resolution multi-proxy analyse on 210 Pb/137 Cs dating, diatom, geochemistry and grain size. Palaeolimnological records revealed that the lake has experi- enced three changes of the hydrological connectivity with Yangtze River, which matches well with the documentary records. Prior to 1954（ stage I）, the lake connected naturally with the Yangtze River and a low-nutrient, relatively deep and disturbed lake condi- tion was inferred based on the high abundance Cyclotella bodanica. After 1954, with a dam construction（ stage II）, water resi- dence time of the lake became longer and hence decreased in clarity, which favors the growth of Aulacoseria granulata. Corre- spondingly, nutrient enriched gradually which indicated by the slightly increase of eutrophic diatoms, as well as significant higher concentration of TOC and sedimentary TP,TN. In recent 20 years, lake became more eutrophicated inferred from high percentages of eutrophic species C. meneghinena, A. alpigena, Nitzschia palea, Surirella minuta and geochemical records including TOC,sedimentary TP, TN. After 2005 （ stage III）, the lake condition improved slightly, indicated by diatom assemblage change with the increase of benthic species, although the concentration of TOC and sedimentary TP, TN were still high. Consequently, reconnection with Yangtze River may be an effective manner to relief the stressed floodplain lakes.

关 键 词：涨渡湖 湖泊沉积物 硅藻 江湖联通 环境响应 

分 类 号：X524[环境科学与工程—环境工程]