| 摘要: |
| 选择我国东部季风区湖泊升金湖86cm沉积岩芯为研究对象,在可靠深度-年代模型基础上,通过沉积物干湿重及总有机碳(Total Organic Carbon,TOC)含量指标分析,重建升金湖过去千年有机碳埋藏速率变化。结果表明:升金湖过去千年碳埋藏速率呈总体增加趋势,平均碳埋藏速率约为12.61g/(m2?a),总碳储量约为1.68Tg C(1Tg=1012g)。根据碳埋藏变化特征,并结合流域内碳来源、气温降水、人类活动情况；可将过去千年升金湖有机碳埋藏划分为三个不同阶段:阶段Ⅰ:1000~1600 A.D.,自然沉积阶段,升金湖有机碳埋藏速率处于近千年最低水平,主要受沉积速率控制。此时段可分为两个亚期:(A)1000~1350 A.D.,有机碳埋藏速率在该阶段较快,主要是由于该时期流域干湿交替剧烈,湖泊沉积环境不稳定,推测流域水土侵蚀严重,使得湖泊沉积速率较高所致。(B)1350~1600 A.D.,该时期受低沉积速率与低TOC含量影响,湖泊有机碳埋藏速率缓慢下降,推测主要因为流域降水增多,湖泊水位上升,水动力变弱导致沉积速率变慢,而人类活动微弱,外源输入依旧较低使得湖泊TOC含量仍处于较低水平。阶段Ⅱ:1600~1850 A.D.,自然环境与人类活动共同影响阶段,升金湖有机碳埋藏速率显著增加,主要受快速上升的TOC含量控制。自然环境方面,此阶段流域水文干旱化有利于外源的输入,此外气温较低,有机质矿化较慢；人为环境方面,此阶段地区人口迅速上升,人类活动影响显著增强。阶段Ⅲ:1850~2000 A.D.,该阶段多指标指示自然环境已经不再是控制升金湖流域碳埋藏速率的主导因素,随着近现代生产生活方式的转变,TOC含量与沉积速率都在持续增加,导致该阶段有机碳埋藏速率达到了近千年来的峰值。 |
| 关键词: 碳埋藏 升金湖 湖泊沉积物 千年 碳循环 |
| DOI： |
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| 基金项目:国家自然科学(41771228)、安徽师范大学校博士启动金项目(2017XJJ36)。 |
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| Changes in organic carbon accumulation and its influencing factors over the past millennium in Lake Shengjin, lower reaches of the Yangtze River |
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hanruichao, wangyong
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anhui normal university
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| Abstract: |
| The 86 cm sedimentary core of Shengjin Lake in the eastern monsoon region of China was selected as the research object. Based on the reliable depth-age model, the change of organic carbon Accumulation rate in Shengjin Lake over the past millennium was reconstructed by analyzing the dry and wet weight of sediments and the total organic carbon (TOC) content index. The results showed that the carbon Accumulation rate of Shengjin Lake in the past millennium showed an overall increasing trend. The average carbon Accumulation rate was about 12.61g/(m2?a), and the total carbon storage was about 1.68 Tg C (1Tg=1012g). According to the characteristics of carbon Accumulation change, combined with the carbon source, temperature and precipitation, and human activities in the basin, the organic carbon Accumulation of Shengjin Lake in the past thousand years can be divided into three different stages: Stage I: 1000~1600 A.D., natural deposition stage, Shengjin Lake with organic carbon Accumulation rate at the lowest level, mainly controlled by deposition rate. This period can be divided into two sub-periods: (A) 1000 A.D.~1350 A.D. The Accumulation rate of organic carbon is faster at this stage, mainly due to the higher temperature, the faster mineralization rate of organic matter and the lower exogenous input, resulting in low TOC content. At the same time, the dry-wet alternation is severe during this period, and the sedimentary environment of the lake is unstable. (B) 1350~1600 A.D., which was affected by low deposition rate and low TOC content, and the Accumulation rate of organic carbon in the lake decreased slowly. It is speculated that the increase of precipitation in the basin, the high water level of the lake, and the weak hydrodynamic force lead to the slow deposition rate, while the external input is still low, so that the TOC is still at a low level.Stage II: about 1600~1850 A.D., the Accumulation rate of organic carbon in Shengjin Lake increased significantly under the influence of natural environment and human activities. It is mainly controlled by a large amount of input TOC content. In terms of natural environment, the exogenous input increased rapidly and the temperature was low, and the mineralization of organic matter was slow. In terms of human environment, the population in this stage increased rapidly, and the impact of human activities increased significantly. Stage III: The age is about 1850~2000 A.D.At this stage, multiple indicators indicate that the natural environment is no longer the dominant factor controlling the carbon Accumulation rate in the Shengjin Lake Basin.With the transformation of modern production and lifestyle, TOC content and deposition rate continue to increase, resulting in the peak of organic carbon Accumulation rate in this stage for nearly a thousand years. |
| Key words: Carbon Accumulation shengjin lake lake sediments millennium carbon cycle |
