Dynamics in Phosphorus Pools in Soils and Sediments along the Land-Freshwater Continuum of Agricultural Catchments

农业流域陆地-淡水连续体土壤和沉积物中磷库的动态

• 批准号: 412678780
• 负责人: Dr. Harald Neidhardt
• 金额: --
• 依托单位: Forschungsbereich Geographie
• 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 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/412678780?language=en
• 关键词: Dynamics; Phosphorus; Pools; Soils; Sediments

Pronounced amounts of the precious nutrient phosphorus (P) are mobilized from arable soil due to erosion and surface run-off and are transferred into the receiving waters. Along its transport path, retention and interim storage of P occurs in soils and sediments of interconnected vegetated buffer strips, drainage channels and stream beds. Retention and storage of P constitutes an important ecosystem function; however, P can be re-released from respective storage pools due to biogeochemical processes, thereby continuously increasing P fluxes to downstream water bodies for years and decades. This does not only increase the risk of eutrophication, it also counteracts contemporary conservation measures aiming to reduce P inputs into the surface waters.If we are to mitigate P transfer from arable soil to surface waters, we must understand P pool dynamics not only in arable soil itself, but also within the interlinked P transfer continuum. Here, dynamic changes in the hydrological regime and redox conditions occur, which have in turn a pronounced influence on the storage of P within the different storage pools (e.g., P sorbed to Fe-minerals is partially released under reducing conditions). However, due to methodological limitations, changes of P pools in soils and sediments and transformation pathways involved still remain barely understood. The objectives of this study are therefore (i) to unravel the mechanisms underlying the retention and dynamic transfer of P between the different storage pools in drainage channels, vegetated buffer strips, and eroded arable soil; (ii) and to elucidate the significance of biotic and abiotic processes underlying the changes in P pools. Laboratory incubation experiments will be conducted based on an innovative isotopic labelling approach that uses the analysis of stable oxygen isotope ratios in inorganic phosphate (δ18OPi) in order to trace changes in P pools of soil and sediments under dynamic redox conditions. In summary, crucial information will be obtained regarding the cycling of P in agricultural catchments, which will allow predicting the stability of respective storage pools in the long-term in dependence on their position within the P transfer continuum and the prevailing environmental conditions therein.

由于侵蚀和地表径流，大量宝贵的营养磷(P)从耕地土壤中被动员起来，并转移到接收水中。在磷的运输路径上，磷在相互连接的植被缓冲带、排水沟和河床的土壤和沉积物中发生滞留和临时储存。磷的滞留和储存是一项重要的生态系统功能；然而，由于生物地球化学过程，磷可以从各自的储存池重新释放，从而在数年乃至数十年内不断增加向下游水体的磷通量。这不仅增加了富营养化的风险，还抵消了当代旨在减少向地表水输入磷的保护措施。如果我们要减少从耕地土壤到地表水的磷转移，我们必须了解不仅在耕地土壤本身，而且在相互关联的磷转移连续体内的磷库动态。在这里，水文状况和氧化还原条件发生了动态变化，这反过来又对不同储存池中磷的储存产生了显著影响(例如，在还原条件下，吸附在铁矿物上的磷被部分释放)。然而，由于方法的局限性，土壤和沉积物中磷库的变化及其转化途径仍鲜为人知。因此，本研究的目的是(I)揭示排水沟、植被覆盖的缓冲带和侵蚀耕地土壤中不同储存池之间磷的保留和动态转移的机制；(Ii)并阐明磷库变化背后的生物和非生物过程的重要性。实验室培养实验将基于一种创新的同位素标记方法进行，该方法使用无机磷酸盐中稳定的氧同位素比率(δ18OPi)的分析，以跟踪土壤和沉积物中磷库在动态氧化还原条件下的变化。总而言之，将获得关于农业集水区磷循环的关键信息，这将使人们能够根据它们在磷转移连续体中的位置和其中的主要环境条件来预测各个储存池在长期内的稳定性。