Modeling the effect of silicon and calcium availability on the future sustainability of Arctic permafrost carbon pools based on laboratory and field experiments

基于实验室和现场实验，模拟硅和钙的可用性对北极永久冻土碳库未来可持续性的影响

• 批准号: 404594332
• 负责人: Dr. Mathias Göckede
• 金额: --
• 依托单位: Max-Planck-Institut für Biogeochemie (MPI-BGC)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/404594332?language=en
• 关键词: Modeling; effect; silicon; calcium; availability

Globally averaged temperature observations have increased since the onset of industrialization, and increase rates have been particularly high at the northern high latitudes. Warmer conditions threaten to degrade the vast pool of organic carbon currently stored in the in northern permafrost soils (estimated at 1330-1580 petagram), with potentially drastic consequences for global climate. The carbon cycle within Arctic permafrost ecosystems, as well as the sustainability of carbon pools, is not only controlled by temperature conditions. The amount of carbon emitted to the atmosphere in form of CO2 or CH4, depend strongly on other environmental boundary conditions such as moisture content, temperature, or pH of the soil. Also the quality of the organic matter (e.g. content of nutrients, nutrient stoichiometry and carbon compounds) plays a dominant role, with phosphorus (P) being of high importance. The potential influence of other, minor chemical elements have been largely neglected in this context. More specifically, two elements have been shown to be highly important for carbon fixation and turnover in marine systems, i.e. silicon (Si, important for C-fixation by diatoms) and calcium (Ca, important for C-fixation by coccolithophores). For terrestrial and semiaquatic systems, however, only few studies have analyzed links between Si and Ca content and carbon turnover rates, and even fewer results have yet been published for permafrost soils despite the potential importance for current and future carbon cycle processes. Silicon was shown to mobilize P from soil binding sites, therefore increasing P availability, whereas Ca is known to decrease P availability by forming insoluble Ca-P phases. The aim of this project is to constrain the net effect of competing processes linked to the availability of Si and Ca, and their effect on P availability, on the mineralization of organic matter in degrading permafrost soils, and quantify potential feedbacks with climate change. We will execute manipulation experiments both in-situ and in the laboratory, which will link enhanced Si and/or Ca contents (mimicking mobilization during permafrost thaw) to changes in decomposition/mineralization rates in the soil, and related shifts in CO2/CH4 emissions from permafrost ecosystems. These results will subsequently be used to test if the consideration of Si and Ca availability can improve the performance of a process-based model when compared against pan-Arctic carbon flux observations. Combining prognostic simulations of thaw depth with data on the vertical distribution of Si and Ca pools, we will furthermore estimate how Si and Ca availability may be affected through increases in thaw depth under future climate change. Taken together, these results will allow assessing the impact of Si and Ca availability on carbon fluxes in permafrost soils, and their contribution to the feedbacks between permafrost carbon cycle processes and future climate change.

自工业化开始以来，全球平均气温观测值有所增加，北部高纬度地区的增长率尤其高。更温暖的条件有可能使目前储存在北方永冻土中的大量有机碳库退化(估计为1330-1580毫克)，可能对全球气候造成严重后果。北极永久冻土生态系统内的碳循环以及碳库的可持续性不仅受温度条件的控制。以二氧化碳或甲烷的形式排放到大气中的碳量在很大程度上取决于其他环境边界条件，如土壤的水分含量、温度或pH值。此外，有机质的质量(如养分含量、营养化学计量比和碳化合物)起主导作用，磷(P)的重要性很高。在这种情况下，其他次要化学元素的潜在影响在很大程度上被忽视了。更具体地说，有两种元素已被证明对海洋系统中的碳固定和周转非常重要，即硅(硅，对硅藻固定碳很重要)和钙(钙，对球藻生物固定碳很重要)。然而，对于陆地和半水生系统，很少有研究分析硅和钙含量与碳周转速率之间的联系，对于永久冻土，尽管对当前和未来的碳循环过程具有潜在的重要性，但发表的结果更少。研究表明，硅可以从土壤结合部位激活磷，从而增加磷的有效性，而钙通过形成不溶的钙-磷相来降低磷的有效性。该项目的目的是限制与硅和钙有效性相关的竞争过程的净影响，以及它们对磷有效性的影响，并量化与气候变化相关的潜在反馈。我们将在现场和实验室进行操纵实验，将增加的硅和/或钙含量(模拟多年冻土融化期间的动员)与土壤分解/矿化速率的变化以及永久冻土生态系统二氧化碳/甲烷排放的相关变化联系起来。这些结果随后将被用来测试与泛北极碳通量观测相比，考虑硅和钙的有效性是否可以改善基于过程的模型的性能。结合融化深度的预测性模拟和硅库和钙库的垂直分布数据，我们将进一步估计在未来气候变化下，融化深度的增加可能如何影响硅和钙的有效性。综上所述，这些结果将有助于评估硅和钙的有效性对多年冻土中碳通量的影响，以及它们对多年冻土碳循环过程和未来气候变化之间的反馈的贡献。