|ZHANG Fengju,XUE Bin,YAO Shuchun.Spatiotemporal pattern of inorganic carbon sequestration in Lake Hulun since 1850. J. Lake Sci.2019,31(6):1770-1782. DOI:10.18307/2019.0617
|湖泊沉积物碳埋藏及其驱动机制是陆地生态系统碳循环及全球变化研究的热点问题之一，但以往湖泊碳循环的研究大多局限于有机碳，较少考虑无机碳的地位和作用.我国干旱-半干旱地区湖泊众多、无机碳储量丰富，在区域碳循环过程中的作用日益突出，因此探讨这些地区湖泊沉积物无机碳埋藏变化对深入理解区域碳循环具有重要意义.本研究通过对内蒙古高原呼伦湖15个沉积岩芯样品无机碳含量（TIC）的测定，结合沉积岩芯210Pb、137Cs年代标尺，分析了1850年以来呼伦湖无机碳埋藏速率时空变化，并揭示了影响呼伦湖无机碳埋藏的主要因素.结果表明，1980s之前，呼伦湖无机碳含量总体维持在相对稳定的低值，1980s之后开始快速增加，且近百年来呼伦湖平均无机碳含量在不同湖区差异不显著.1850年以来呼伦湖无机碳埋藏速率变化范围约为7.10~74.29 g/（m2·a），平均值约为36.15 g/（m2·a），且大体上可分为3个阶段，即1900s以前相对稳定的低值阶段、1900s-1950s期间的快速增加阶段以及1950s以来的波动增加阶段，各阶段无机碳埋藏速率平均值分别约为10.40、26.29和41.00 g/（m2·a）.空间上，呼伦湖无机碳埋藏速率整体表现为中部高、南北两端低的分布格局，这可能与湖心水动力条件相对稳定，有利于碳酸盐沉积有关.此外，呼伦湖无机碳埋藏速率与湖区温度变化呈显著正相关，而与周边人类活动影响关系不明显，表明在未来全球变暖背景下，呼伦湖无机碳埋藏速率将进一步增加，湖泊在区域碳循环中的作用将更加显著.
|关键词: 无机碳埋藏速率 时空变化 影响因素 呼伦湖
|Spatiotemporal pattern of inorganic carbon sequestration in Lake Hulun since 1850
ZHANG Fengju1, XUE Bin2, YAO Shuchun2
1.School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou 221116, P. R. China;2.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China
|Carbon sequestration and its driving mechanism in lake sediments is one of the hot issues in research of terrestrial ecosystem carbon cycling and global change. However, previous studies on lake carbon burial were often limited to organic carbon, and less work have taken inorganic carbon into account. A large number of lakes are distributed in arid and semi-arid regions of China, and these lakes have a huge potential to sequester inorganic carbon. Therefore, exploring the changes of inorganic carbon burial in lake sediments is of great significance for understanding the regional carbon cycle. In this study, fifteen sediment cores were collected in the Lake Hulun of northeastern Inner Mongolia using a gravity core sampler. The total inorganic carbon (TIC) contents as well as the sediment ages were analyzed to investigate the spatiotemporal changes of inorganic carbon burial and its driving factors over the past century. The results indicated that TIC content of Lake Hulun was remained stable and relatively low before 1980s, and then demonstrated an increasing trend. No significant variation was observed in the average TIC content among all the sediment cores. The inorganic carbon burial rate (ICBR) varied from 7.10 g/(m2·a) to 74.29 g/(m2·a) among the studied sediment cores and the average value was 36.15 g/(m2·a). In general, the changes of ICBR can be divided into three stages. The ICBR was very low before 1900s, followed by an obvious increase between 1900s and 1950s, and exhibited an overall fluctuating upward tendency after 1950s. The average ICBR for the three time periods were 10.40 g/(m2·a), 26.29 g/(m2·a) and 41.00 g/(m2·a), respectively. Spatially, the ICBR showed much higher values in the central lake area than in the northern and southern area. This was probably because the central part of the lake was characterized by relatively stable hydrodynamic conditions, leading to more deposition of carbonate minerals. In addition, the ICBR was positively linked to temperature rather than human activities in Lake Hulun, implying that ICBR will continue to increase and lakes will be an increasingly important carbon pool in the future as global warming proceeds.
|Key words: Inorganic carbon burial rate spatiotemporal variation influence factor Lake Hulun