Linking the composition of dissolved organic matter and nutrient cycling in streams of temperate forested catchments

将温带森林流域溪流中溶解有机物的组成与养分循环联系起来

• 批准号: 452252890
• 负责人: Professor Dr. Karsten Kalbitz
• 金额: --
• 依托单位: Institut für Bodenkunde und Standortslehre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/452252890?language=en
• 关键词: Linking; composition; dissolved; organic; matter

Dissolved organic matter (DOM) is an important component of the carbon (C) and nutrient cycles in terrestrial and aquatic systems. Changing environmental conditions, such as decreasing acidic and nitrogen deposition and changing water regimes with more frequent and intense storm and drought events, strongly influence the dynamics of DOM with unknown effects on important ecological functions of DOM as its role in C and nutrient cycling. The stoichiometry of dissolved organic carbon (DOC), nitrogen (DON) and phosphorous (DOP) plays a crucial role in regulating ecosystem functioning. Soils determine the input of organic matter into the streams and depending on hydrological conditions surface organic horizons or subsoil mineral horizons will control amount and composition of stream DOM. However, changes in DOM composition because of changes on its source have not been linked to the role of DOM for nutrient cycling. Thus, the overall objective of the requested project is to shed light upon the complex interactions at the interface of terrestrial and aquatic ecosystems controlling amount, composition and functionality of DOM in streams. Our overarching hypothesis is that the composition of DOM determines its contribution to nutrient cycling in forested streams, i.e. serving as a C, N or P source for microorganisms. The selected forested catchments with differing bedrock and soil offer a suitable gradient in potential nutrient limitations to study the envisaged effects of DOM composition on its function. DOM composition will be analyzed along the soil-water-continuum (i.e. linking the composition of soil organic matter and DOM) in the selected catchments at different hydrological conditions. Differences in DOM composition will be used to determine the most important DOM sources in the catchment depending on the flow conditions. These studies on DOM composition will be linked to nutrient pulse addition experiments in the streams determining whether DOM serves mainly as a C, N or P source for microorganisms. This strong focus on field observations and experiments will be accompanied by incubation experiments in the laboratory to further elucidate the linkages between the composition of soil organic matter and DOM and the consequences for nutrient cycling along the terrestrial aquatic continuum. Methods of different complexity will be combined to determine the composition of organic matter in soils and water (Fluorescence Excitation-Emission Matrices, Fourier-Transform Infrared Spectrometry, Pyrolysis Gas Chromatography Mass Spectrometry, 31P-Nuclear Magnetic Resonance Spectroscopy). Only the combination of the unique expertise of the Czech and German partners with the well characterized long-term monitoring catchments of the Czech partner and the modern lab equipment of the German partner will ensure the success of the project, i.e. elucidating the role of DOM composition for its ecological function under the pressure of ongoing environmental changes.

溶解有机物 (DOM) 是陆地和水生系统碳 (C) 和养分循环的重要组成部分。不断变化的环境条件，例如酸性和氮沉降的减少以及随着更频繁和更强烈的风暴和干旱事件而改变的水情，强烈影响 DOM 的动态，但对 DOM 的重要生态功能（如其在 C 和养分循环中的作用）的影响尚不清楚。溶解有机碳（DOC）、氮（DON）和磷（DOP）的化学计量在调节生态系统功能中起着至关重要的作用。土壤决定了河流中有机物质的输入，并且根据水文条件，地表有机层或地下矿物层将控制河流 DOM 的数量和组成。然而，由于 DOM 来源的变化而导致的 DOM 组成的变化尚未与 DOM 在养分循环中的作用联系起来。因此，所请求项目的总体目标是阐明陆地和水生生态系统界面上复杂的相互作用，控制溪流中 DOM 的数量、组成和功能。我们的首要假设是，DOM 的组成决定了它对森林溪流中养分循环的贡献，即作为微生物的 C、N 或 P 源。选定的森林流域具有不同的基岩和土壤，为潜在养分限制提供了合适的梯度，以研究 DOM 组成对其功能的预期影响。将在不同水文条件下的选定流域中沿着土壤-水连续体（即连接土壤有机质和 DOM 的组成）对 DOM 组成进行分析。 DOM 组成的差异将用于根据流量条件确定流域中最重要的 DOM 源。这些关于 DOM 组成的研究将与溪流中的养分脉冲添加实验相关联，以确定 DOM 是否主要充当微生物的 C、N 或 P 源。这种对现场观察和实验的强烈关注将伴随着实验室的孵化实验，以进一步阐明土壤有机质和 DOM 的组成以及沿陆地水生连续体养分循环的后果之间的联系。将结合不同复杂性的方法来确定土壤和水中有机物的组成（荧光激发发射矩阵、傅里叶变换红外光谱法、热解气相色谱质谱法、31P-核磁共振光谱法）。只有将捷克和德国合作伙伴的独特专业知识与捷克合作伙伴特征明确的长期监测集水区以及德国合作伙伴的现代化实验室设备相结合，才能确保项目的成功，即阐明在持续环境变化的压力下DOM成分对其生态功能的作用。