曾令晗1,2,
卞昊昆3,
陈旭1
1. 中国地质大学(武汉)地球科学学院地理系, 湖北 武汉 430074
2. School of Geography, University of Nottingham, Nottingham, NG7 2RD
3. 北京化工大学生命科学与技术学院, 北京 100029
基金项目: 国家自然科学基金项目（批准号：41202248和41572343）和中央高校基本科研业务费专项项目（批准号：G1323511656）共同资助
详细信息
作者简介: 季婧, 女, 23岁, 硕士研究生, 湖泊沉积与环境演化研究, E-mail:jing-ji@cug.edu.cn
中图分类号: P593;P941.78 收稿日期:2018-03-02
修回日期:2018-05-16
刊出日期:2018-07-30
Variations in sedimentary nitrogen, phosphorus and silicon and regional environmental changes in East Dongting Lake in recent 50 years
Ji Jing1,,Zeng Linghan1,2,
Bian Haokun3,
Chen Xu1
1. Department of Geography, School of Earth Sciences, China University of Geosciences(Wuhan), Wuhan 430074, Hubei
2. School of Geography, University of Nottingham, Nottingham, NG7 2RD
3. College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029
MSC: P593;P941.78
--> Received Date: 02 March 2018
Revised Date: 16 May 2018
Publish Date: 30 July 2018
摘要
摘要:氮磷硅是水生生物生长所需的生源要素，但过量营养物质输入会导致水体富营养化。长江中下游地区湖泊富营养化已成为区域最严重的生态环境问题之一，已有的研究大多聚焦于氮磷输入对富营养化的影响，而对硅元素的关注较少。文章基于东洞庭湖湖心和湖滨两处浅孔岩芯年代学、总氮（TN）、总磷（TP）、总有机碳（TOC）和生物硅（BSi）分析，并结合流域历史资料数据，揭示东洞庭湖近50年以来的氮、磷、硅元素变化过程，为深入认识人类活动影响下湖泊演化机制提供新线索。研究结果表明，20世纪80年代以来TN、TP和TOC含量均明显增长，主要是由于人为输入氮磷的增加和湖泊内源生产力的提高；生物硅含量呈波动变化。同时，BSi：TN和BSi：TP大幅下降，反映了湖泊中氮磷硅元素非平衡增长过程，硅缺乏现象凸显。BSi：TOC降低反映初级生产力中非硅质藻类（蓝绿藻等）相对增加。氮磷输入增加和大坝对硅的拦截效应会加重水体硅缺乏，进而加剧非硅质藻类增殖风险。
关键词: 生物硅/
湖泊沉积物/
洞庭湖/
富营养化
Abstract:Dongting Lake(28°30'~30°20'N, 110°40'~113°10'E), the second largest freshwater lake in China, has suffered from eutrophication during recent years. Presently, lake eutrophication has become one of the most serious environmental issues in the middle and lower reaches of the Yangtze River. Nitrogen, phosphorus and silicon are bioelements for the growth of aquatic organisms. However, excessive nutrient inputs cause eutrophication of inland waters. The impacts of nitrogen and phosphorus influxes on eutrophication have been extensively investigated in previous studies, while little knowledge is available about the linkage between silicon budget and eutrophication. In this study, a 71-cm-long sediment core was collected in the central part of Dongting Lake(DTC:29°19.767'N, 112°57.610'E) and a 46-cm-long sediment core was collected in the littoral part of Dongting Lake(DTW:29°16.865'N, 112°53.568'E). Sediment cores were sectioned at an interval of 1 cm in the field. Total nitrogen(TN), total phosphorus(TP), total organic carbon(TOC) and biogenic silica(BSi) were analyzed in the two 210Pb-dated sediment cores. Sub-samples were analyzed at 2 cm intervals. In total, 36 samples were analyzed in the central core and 23 samples were analyzed in the littoral core. Based on the sedimentary records and historical documents from the catchment, this study aims to reveal changes in nitrogen, phosphorus and silicon, and to provide new clues for tracking the responses of lake ecosystem to human activities in recent 50 years. The results revealed that the contents of TN and TP increased clearly after the 1980s, probably resulting from a rising influx of anthropogenic nitrogen and phosphorus. The upward trend of TOC reflected the increasing autochthonous production. BSi showed fluctuant trends in the two sediment cores. Meanwhile, both the ratio of BSi to TN and the ratio of BSi to TP dropped markedly, indicative of silicon depletion due to the unbalanced increase of nitrogen, phosphorus relative to silicon in the lake. Declining BSi:TOC ratio indicated an increasing contribution of non-siliceous algae(e.g. blue-green algae). Increasing inputs of anthropogenic nitrogen and phosphorus and the retention of silicon by dams would accelerate silicon depletion, subsequently aggravating the proliferation of non-siliceous algae.
Key words:biogenic silicon/
lake sediments/
Dongting Lake/
eutrophication
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