陈光杰,,
刘术,
黄林培,
陈小林,
王教元,
刘园园,
孔令阳
云南师范大学旅游与地理科学学院, 高原地理过程与环境变化云南省重点实验室, 云南 昆明 650500
基金项目: 国家重点研究发展计划项目（批准号：2017YFA0605202）、国家自然科学基金项目（批准号：41771239、41171048和41302151）和教育部科学技术研究项目（批准号：213034A）共同资助
详细信息
作者简介: 邓颖, 男, 25岁, 硕士研究生, 湖泊沉积与环境研究, E-mail:1047622803@qq.com
通讯作者: 陈光杰, E-mail:guangjiechen@gmail.com
中图分类号: Q949.27+1;P941.78收稿日期:2018-03-27
修回日期:2018-05-17
刊出日期:2018-07-30
Sediment and historical records of hydrological fluctuation, recent environmental and ecological changes in Cibi Lake of northwest Yunnan
Deng Ying,Chen Guangjie,,
Liu Shu,
Huang Linpei,
Chen Xiaolin,
Wang Jiaoyuan,
Liu Yuanyuan,
Kong Lingyang
Yunnan Provincial Key Laboratory of Plateau Geographical Processes and Environmental Change, School of Tourism and Geography, Yunnan Normal University, Kunming 650500, Yunnan
More Information
Corresponding author: Chen Guangjie,E-mail:guangjiechen@gmail.com
MSC: Q949.27+1;P941.78--> Received Date: 27 March 2018
Revised Date: 17 May 2018
Publish Date: 30 July 2018
摘要
摘要:云南高山湖泊对区域气候变化和流域人类活动十分敏感，部分水体同时面临着污染物增加、生物群落快速演替、生态系统功能降低等问题。位于滇西北高山地区的茈碧湖历史资料表明，该湖近现代以来经历了明显的水文波动与人类活动影响。本研究通过对茈碧湖沉积物进行年代序列测定、元素和粒度等多指标分析，重建了近300年来（对应于钻孔顶部18 cm深度样品）茈碧湖环境变化历史，并结合对硅藻的分析，识别了气候变化和人类活动对生物群落变化的驱动影响。结果表明，沉积物粒度记录了茈碧湖水文变化的长期波动，水库修建与水文调控的增强使得湖泊水位波动明显，与文献记录的水文事件基本一致。硅藻群落结构以浮游种为主，1860年前硅藻组合以对水体扰动力有较强耐受性的Cyclostephanos dubius为主要优势种；1860年以来小型硅藻Cyclotella ocellata占据主要优势，同时Cyclotella comta成为次优势种；1990年开始，底栖硅藻Fragilaria spp.属相对丰度增加并出现明显波动，喜营养盐的Fragilaria crotonensis出现。多变量数理分析显示，气候变暖以及湖泊营养水平变化的共同作用是驱动茈碧湖硅藻组合长期演替的重要因素，分别独立解释了群落变化的27.5%和21.3%；其中湖库改造工程导致的外源物质输入增多，使得营养水平总体上升，是导致20世纪90年代以来硅藻组合出现明显变化的诱因。因此，在气候变暖的背景下，对云南高山湖泊的保护需要进行流域开发和水文调控的综合评价。
关键词: 茈碧湖/
气候变暖/
湖泊沉积物/
硅藻组合/
水文调控
Abstract:Mountain lakes in Southwest China are sensitive to regional climate change and catchment development, and an increasing number of surface water bodies have experienced water pollution, rapid community succession and the degradation of ecosystem functioning. The documentary records for Cibi Lake, an alpine lake from northwest Yunnan, showed that this lake has experienced pronounced hydrological fluctuations and human activities for the last three centuries. In this study, a 36-cm long sediment core(26°10.6'N, 99°56.4'E) was collected from the deep basin of Cibi Lake(26°06'~26°14'N, 99°51'~99°58'E) and the core was extruded at 0.5 cm intervals for the depth above 5 cm with the core depth below 5 cm sectioned at 1 cm intervals. In the laboratory, we conducted the multi-proxy analyses(including sediment dating, element content and grain size components), to reconstruct the history of lake environmental changes for the last three centuries, meanwhile, together with the diatom analysis for revealing the long-term impact of climate change and human activity on community shift. The chronological profile for the sediment core was constructed through measuring 210Pb and 137Cs radio-activities using a Canberra gamma spectrometer with the constant rate of supply model(CRS). According to the CRS results and the earliest documented time points of Cibi Lake, based on the core depth of 18 cm represents 300 years to analyze the sediments. The grain size composition of the sediments revealed the long-term history of hydrological fluctuation, corresponding well to the documented events of hydrologic regulation and reservoir construction. The diatom community was dominated by planktonic taxa prior to ca. 1860, when Cyclostephanos dubius, known for tolerating strong hydrological fluctuation, was predominant. After ca. 1860, this species was slowly replaced by small-sized planktonic species such as Cyclotella ocellata, with Cyclotella comta being sub-dominant from ca. 1990, the benthic taxa(i.e. Fragilaria spp.) generally increased with obvious fluctuations, with the occurence of eutrophic and planktonic species such as Fragilaria crotonensis. Multivariable analyses further showed that both climate warming and nutrient levels were among the key factors in causing the long-term succession of diatom assemblages, independently explaining 27.5%and 21.3%of community variation, respectively. In addition, the increased input of allochthonous materials and a longer water rendition due to damming may have enhanced nutrient level, leading to a significant shift in diatom assemblage since the 1990s. These results show that Cibi Lake has remained a deep-water and oligotrophic lake over the last three centuries and was characterized by stable thermal stratification, which may have modulated the long-term pattern of biological community response to hydrological and climatic changes. Therefore, the sensitivity of biological indicators to hydrological fluctuation and their differences in response to multiple environmental gradients should be evaluated in paleoenvironmental and paleoecological studies for deep lakes. In the context of climate warming, it is also necessary to highlight the important role of catchment development and hydrological regulation in the sustainable management of alpine lakes in Yunnan.
Key words:Cibi Lake/
climate warming/
lake sediment/
diatom assemblage/
hydrological regulation
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