Evidence for carbon cycling in a large freshwater lake in the Balkans over the last 0.5 million years using the isotopic composition of bulk organic matter
Evidence for carbon cycling in a large freshwater lake in the Balkans over the last 0.5 million years using the isotopic composition of bulk organic matter
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DOI：
10.1016/j.quascirev.2018.10.022
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发表时间：
2018-12
影响因子：
4
通讯作者：
G. Zanchetta;I. Baneschi;A. Francke;C. Boschi;E. Regattieri;B. Wagner;J. Lacey;M. Leng;H. Vogel;L. Sadori
中科院分区：
文献类型：
--
作者：
G. Zanchetta;I. Baneschi;A. Francke;C. Boschi;E. Regattieri;B. Wagner;J. Lacey;M. Leng;H. Vogel;L. Sadori
在奥赫里德湖ICDP钻探工程的DEEP岩心中，近516 ka以来的有机质碳同位素组成（δ 13 CTOC）与总有机碳（TOC）和总无机碳（TIC）呈负相关。这种关系的特点是δ 13 CTOC值较低的时期对应于较高的TIC和TOC。沿着TOC/TN，δ 13 CTOC和δ 13 CTIC的相关性表明，大部分有机质来自湖泊的水生初级生产力。TOC、TIC和δ 13 CTOC的组合能够解开长期的冰期/间冰期循环，并在较小程度上解开千年尺度的气候变率。从长期来看，δ 13 CTOC显示出适度的变化，表明溶解无机碳（DIC）库的δ 13 C受到岩溶泉水的供应的稳定，岩溶泉水的特征是δ 13 CDIC受基岩δ 13 C值的影响，湖水和混合良好的上层水柱的长停留时间促进了与大气CO2的平衡。然而，乔木花粉（AP%），TIC和TOC数据之间的比较表明，δ 13 CTOC信号调制土壤CO2通过径流和泉水排放，初级生产力的变化，以及有机质在湖泊内的再循环，都影响δ 13 CDIC。在某些间冰期（如MIS 7和MIS 9），异常低的δ 13 CTOC可能表明有机质循环的快速加强和/或分层的增加和甲烷生成的增强，即使后一过程没有得到沉积学数据的支持。
In the DEEP core from the Lake Ohrid ICDP drilling project, the carbon isotope composition of bulk organic matter (δ13CTOC) over the last 516 ka shows a negative correlation with total organic carbon (TOC) and total inorganic carbon (TIC). This relationship is marked by periods of lower δ13CTOCvalues corresponding to higher TIC and TOC. Along with TOC/TN, the correlation between δ13CTOCand δ13CTICsuggests that most of the organic matter in the core is from aquatic primary production within the lake. The combination of TOC, TIC, and δ13CTOCis able to disentangle long-term glacial/interglacial cycles and, to a lesser extent, millennial scale climate variability. Over the longer term, δ13CTOCshows modest variability, indicating that the δ13C of the dissolved inorganic carbon (DIC) pool is stabilised by the supply of karst spring water characterised by δ13CDICinfluenced by the bedrock δ13C value, and the long residence time of the lake water and well mixed upper water column promoting equilibration with atmospheric CO2. However, comparison between arboreal pollen (AP%), TIC and TOC data indicates that the δ13CTOCsignal is modulated by the leaching of soil CO2through runoff and spring discharge, changes in primary productivity, and recycling of organic matter within the lake, all affecting δ13CDIC. Exceptionally low δ13CTOCduring some interglacial periods (e.g. MIS7 and MIS9) possibly indicate rapid intensification of organic matter recycling and/or increasing stratification and enhanced methanogenesis, even if the latter process is not supported by the sedimentological data.