Origin and fate of dissolved organic matter in the subsoil driven by dynamic exchange and remobilization processes

动态交换和再动员过程驱动的底土中溶解有机物的起源和归宿

• 批准号: 233437591
• 负责人: Professor Dr. Georg Guggenberger
• 金额: --
• 依托单位: Professur für Bodenkunde und Bodenschutz
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/233437591?language=en
• 关键词: Origin; fate; dissolved; organic; matter

Results obtained so far from the subsoil observatories and sequential column experiments indicate a cascade of sorption-desorption processes of dissolved organic matter (DOM) on soil minerals while travelling to the subsoil. Further, results suggest that the sorption capacity of the subsoil is limited, possibly due to high C loading of the reactive minerals in the sandy soil. We assume that the microbial activity might depend on the C loading of the minerals controlling remobilization processes, in addition to the composition of organic matter (OM) on mineral surfaces. Consequently, in the second phase we will address the complex interplay of continuous sorption processes combined with microbial processes and subsequent remobilization depending on source and composition of OM and surface characteristics of the mineral phase. We hypothesize that (i) the composition of DOM entering the mineral soil affects exchange/remobilization processes stronger in the upper part of the soil than deeper subsoil due to an increased microbial processing with increasing soil depth, (ii) the exchange/remobilization of sorbed OM increases with increasing C loading of the minerals, and (iii) microbial transformation of mineral-associated OM is an important source of DOM in larger soil depths. We will approach these hypotheses by a set of experiments starting from complex field conditions to controlled laboratory approaches. The field approaches include a DO13C switch-off pulse in the Grinderwald observatories and a DO13C injection experiment at Grinderwald and two regional sites to study the fate of DOM of different source and composition in the subsoil depending on mineralogical properties and microbial activity. In a comparative way, sorption capacity, C loading, spatial C distribution, C exchange, and OM composition and decomposability (the latter determined by P6) on mineral surfaces will be related to source, composition, C exchange, and microbial stability of DOM. A similar analytical approach will be performed in flow cell experiments, where under defined boundary conditions transport, sorption, and mineralization of the applied DO13C will be assessed. Finally, in a laboratory column experiment with 13C-labeled DOM the effects of microbial activity, manipulated by different incubation temperatures, on the translocation of DOM by sorption and exchange/remobilization processes depending on the mineral surface properties will be studied. With that P5 focuses on the central hypothesis 3 of the frame proposal but also addresses hypotheses 2. P5 will deliver crucial data for the integrative modeling of OC in subsoils such as DOC and DO13C concentration and fluxes, DOM stability against microbial decay, sorption capacity and C loading of the soils and, therefore, for testing the central hypothesis 5.

到目前为止，从底土观测站和连续柱实验获得的结果表明，一个级联的吸附-解吸过程的溶解有机质（DOM）对土壤矿物，而旅行到底土。此外，结果表明，底土的吸附能力是有限的，可能是由于高C负载的活性矿物在桑迪土壤。我们认为，微生物的活动可能取决于C负载的矿物控制再动员过程中，除了矿物表面的有机质（OM）的组成。因此，在第二阶段，我们将解决的复杂的相互作用的连续吸附过程相结合的微生物过程和随后的再动员取决于源和组成的OM和矿物相的表面特性。我们假设：（i）进入矿质土壤的DOM组成对土壤上部交换/再活化过程的影响比深层土壤更强，这是由于随着土壤深度的增加，微生物处理增加，（ii）吸附OM的交换/再活化随着矿物C负载的增加而增加，微生物对矿物伴生有机质的转化是较大土壤深度DOM的重要来源。我们将通过从复杂的现场条件到受控的实验室方法的一系列实验来接近这些假设。实地方法包括在Grinderwald观测站的DO 13 C关闭脉冲和在Grinderwald和两个区域站点的DO 13 C注入实验，以研究取决于矿物学特性和微生物活性的底土中不同来源和成分的DOM的命运。在比较的方式，吸附能力，C负载，空间C分布，C交换，和OM组成和分解（后者由P6决定）在矿物表面将有关的DOM的来源，组成，C交换，和微生物的稳定性。将在流动池实验中进行类似的分析方法，其中将在定义的边界条件下评估所应用的DO 13 C的运输、吸附和矿化。最后，在实验室柱实验与13 C标记的DOM的微生物活性的影响，通过不同的培养温度，对DOM的迁移的吸附和交换/再活化过程取决于矿物的表面性质进行了研究。因此，P5侧重于框架提案的中心假设3，但也涉及假设2。P5将提供关键数据，用于对底土中的OC进行综合建模，例如DOC和DO 13 C浓度和通量，DOM对微生物腐烂的稳定性，土壤的吸附能力和C负荷，因此，用于测试中心假设5。