Spatial variation of organic carbon sequestration in large lakes and implications for carbon stock quantification
Spatial variation of organic carbon sequestration in large lakes and implications for carbon stock quantification
复制标题
DOI：
10.1016/j.catena.2021.105768
复制
发表时间：
2022-01
期刊：
影响因子：
6.2
通讯作者：
Q. Lin;E. Liu;E. Zhang;R. Bindler;B. Nath;Ke Zhang;Ji Shen
中科院分区：
文献类型：
--
作者：
Q. Lin;E. Liu;E. Zhang;R. Bindler;B. Nath;Ke Zhang;Ji Shen
湖泊被认为是碳转化和储存的关键地带，湖泊沉积物封存了大量的有机碳。了解沉积过程和OC埋藏模式对于澄清湖泊在全球碳循环中的作用至关重要。然而，由于OC的产生和来源、水动力条件和水下地形的差异，在一个水生系统中，OC的沉积可能具有很大的空间异质性。估计世界各大湖泊的有机碳封存的不确定性仍然缺乏约束。本研究以两个不同水深和营养状态的大型湖泊（50和249 km2）为例，采用多核古湖泊学技术，对近百年来OC积累的空间变化特征及其主要影响因素进行了研究。多核对比结果显示，各湖主要有机和营养参数的时间变化趋势相似，表明各湖全湖沉积环境变化过程具有一致性。沉积物中保存的OC主要为原生OC。然而，常绿储量在空间上存在着~ 3倍的差异，平均OC积累速率分别在9.5 ~ 27.4 g m−2yr−1（1963年以后在低中营养化深湖泸沽湖）和17.4 ~ 43.5 g m−2yr−1（1980年以后在富营养化洱海浅湖）之间。这些变化主要归因于与人为土地利用变化和磷负荷有关的水生初级生产和陆源碎屑供应的空间差异，而不是与湖内沉积物集中相关的运输和再分配。泸沽湖单一中心-核心方法对全湖OC储量高估了32%，低估了48%，表明空间变异性是类似大型和/或形态复杂水体OC储量量化的重要不确定性来源。因此，内陆水域有机碳积累的空间异质性需要大量的研究，以提供对碳固存模式和机制的更深入的了解。
Lakes are recognized as critical zones for carbon transformation and storage, and lacustrine sediments sequestrate considerable amounts of organic carbon (OC). Understanding sedimentation processes and OC burial patterns is crucial to clarifying lakes’ role in global carbon cycling. However, OC sedimentation may be quite spatially heterogeneous within an aquatic system, owing to the differences in OC production and sources, hydrodynamic conditions and underwater topography. The uncertainties in estimating OC sequestration in the world’s large lakes remain poorly constrained. This study takes the test case of two large lakes (50 and 249 km2) with different water depth and trophic status, using a multi-core paleolimnological technique, to identify the spatial variation in OC accumulation and its main influencing factors over the past century. Results of multi-core comparisons revealed similar temporal trends in major organic and nutrient parameters, suggesting coherent processes of whole-lake sedimentary environment changes for each lake. The OC preserved in sediments was primarily of autochthonous origin. However, OC standing stocks varied ∼3-fold spatially, and average OC accumulation rates ranged between 9.5–27.4 g m−2yr−1(post–1963 in oligo-mesotrophic deep-lake Lugu) and between 17.4–43.5 g m−2yr−1(post–1980 in eutrophic shallow-lake Erhai), respectively. These variations were primarily attributable to the spatial differences in aquatic primary production and terrestrial detritus supply relating to anthropogenic land-use change and phosphorus loading, rather than intra-lake sediment focusing-related transport and redistribution. The single central-core approach from Lugu Lake would overestimate whole-lake OC stock by 32% or underestimate the value by 48%, indicating spatial variability is an important source of uncertainty for OC stock quantification in similar large and/or morphometrically complex waterbodies. Therefore, spatial heterogeneity of OC accumulation in inland waters requires considerable research with well-placed multi-cores to provide a deeper understanding of carbon sequestration patterns and mechanisms.