Project

soils; carbon cycle; radiocarbon; rivers; erosion; weathering; land-ocean interactions

Lead
Eine elementarer Bestandteil des globalen Kohlenstoffkreislaufs ist der Transport organischer Kohlenstoffverbindungen, die in terrestrischen Ökosystemen produziert werden, über Flüsse in die Meere, wo sie im Sediment begraben werden. Dieser Prozess reguliert CO2 und O2 Konzentrationen in der Atmosphäre über verschiedenste Zeitspannen. Darüber hinaus dient terrestrischer Kohlenstoff in ozeanischen Sedimentabfolgen der Rekonstruktion von Veränderungen von Umwelt und Klima in der Vergangenheit. Trotz der Relevanz des Kohlenstofftransports in Flüssen sind die zugrundeliegenden Prozesse noch nicht vollständig verstanden, dementsprechend lassen sich zukünftige Veränderungen nicht zuverlässig vorhersagen und auch die Interpretation terrestrischen Kohlenstoffs in Ozeansedimenten ist nur eingeschränkt möglich.
Lay summary
Ziele Die Ziele dieses Projekts umfassen a) das Verhältnis zwischen Kohlenstoff und Mineralpartikeln in durch Erosion geprägten Landschaften zu verstehen, b) die Entwicklung von Bindungen zwischen organischem Kohlenstoff und Mineralpartikeln im Laufe des Transports von Land zu Ozean nachzuverfolgen und c) die Verknüpfungen von Prozessen des terrestrischen und marinem Kohlenstoffkreislauf im globalen Kontext zu betrachten. Unser Fokus liegt im Besonderen auf dem Zusammenspiel von organischem Material und Mineralien, da vermutet wird, dass Letztere die Reaktivität von Kohlenstoffverbindungen sowohl in terrestrischen als auch in aquatischen Systemen stark beeinflussen. Die Resultate dieses Projekts werden in neue Datenbanken inkorporiert, die eine umfassende Analyse von Kohlenstoff in Flüssen und Küstensedimenten aus globaler Perspektive ermöglichen. Einordnung des Projekts im wissenschaftlichen und sozialen Kontext Flüsse waren in der gesamten Zivilisationsgeschichte von existenzieller Bedeutung, sei es als Wasserlieferanten, zur Erhaltung der Bodenfruchtbarkeit oder als Transportwege. Auch im globalen Kohlenstoffkreislauf nehmen Flüsse eine Schlüsselposition ein, da sie terrestrische und marine Kohlenstoffvorräte verknüpfen und Prozesse innerhalb ihres Einzugsgebiets widerspiegeln. Dementsprechend ist es wichtig, die unterschiedlichen Vorgänge, die den Transport von Kohlenstoff in Flüssen steuern, zu untersuchen, um den Kohlenstoffkreislauf auf der Erde besser zu verstehen und damit die Folgen von natürlichen wie menschengemachten Einflüssen auf diesen einschätzen zu können.

Direct link to Lay Summary

Last update: 13.09.2019

Lead
Export of carbon produced by the terrestrial biosphere by rivers and its subsequent burial in ocean sediments represents a key component of the global carbon cycle, and regulates atmospheric CO2 and O2 concentrations over a range of timescales. Terrestrial organic carbon buried in marine sedimentary sequences also provides a window into past variations in terrestrial ecosystems and their response to natural (e.g., climate) and human-induced environmental variations. While there have been considerable advances in our understanding of carbon transport within river basins, major gaps in our understanding of underlying processes persist which limit our ability to predict future responses to natural and anthropogenically-driven change, and to accurately interpret sedimentary records.
Lay summary
Objectives The objectives of this project are to (a) explore links between carbon and mineral particle dynamics in eroding terrestrial landscapes, (b) assess the evolution of organic matter-mineral associations along the land-to-ocean continuum, and (c) derive global-scale perspectives on coupled terrestrial-marine carbon cycle processes. We place particular emphasis on interactions between organic matter and minerals as this is hypothesized to strongly influence of organic matter reactivity and stability in terrestrial and aquatic systems, its transport in rivers and its dispersal in the ocean. Information obtained from this study will be incorporated into new databases in order to place information on carbon signatures in rivers and adjacent continental margins in a global context. Scientific and Social Context of the Research Project River have been focal points of human civilization for millennia due to their importance as sources of water, fertile soils and transportation. River systems also form a key component the global carbon cycle, linking terrestrial and marine carbon pools, and integrating processes occurring within their watersheds.  Studies of the processes that influence carbon processing and transport in rivers are therefore essential to understand carbon cycling on large portions of the earth surface.  Equipped with this understanding, we are in a better position to assess the influence of natural processes and human activity on this aspect of carbon cycle, as well as on land-ocean interactions.

Direct link to Lay Summary

Last update: 13.09.2019

Natural persons

Number	Title	Start	Funding scheme

Fluvial export of carbon produced by the terrestrial biosphere and its subsequent burial in ocean sedimentary sinks forms an integral component of the global carbon cycle, influencing atmospheric CO2 and O2 concentrations over a range of timescales. This process of transfer and sequestration of terrestrial organic carbon (OC) in marine sedimentary sequences also provide a crucial window into past variations in terrestrial ecosystems and their response to natural (e.g., climate) and anthropogenic forcing. Considerable effort has been expended over past decades to determine the nature of organic matter (OM) transported and exported by rivers from terrestrial drainage basins, constrain associated fluxes, and elucidate driving processes, yet major gaps in our understanding of underlying processes persist. These include: (i) The extent to which the mobilization and transport of organic matter (OM) and mineral phases is (de)coupled; (ii) The timescales of transfer of OM and its links to intermediate storage processes and transport pathways; (iii) The degree to which biospheric organic carbon discharged from rivers reflects drainage basin-wide processes. Consequently, we have limited ability to predict future responses of this component of the carbon cycle to natural and anthropogenically-driven change, and to accurately interpret sedimentary records. These problems are exacerbated by the dramatic transformations that landscapes and fluvial networks have experienced, particularly during the 20th and the start of the 21st centuries, as a consequence of human activities, rendering it challenging to deconvolute natural versus anthropogenic controls on terrestrial OC cycling.The main focus of the CAPS-LOCK project since its inception has been to understand the role of climate and anthropogenic activity on timescales of biospheric carbon storage in terrestrial drainage basins. We have approached this problem through investigation of a broad range of modern river systems and via reconstruction of past dynamics of fluvial OC export from river-proximal sediment records, focusing on the deglacial and Holocene. New insights gleaned from these investigations have shaped follow-up studies in order to address emerging questions and paradoxes. In this third phase of the CAPS-LOCK project, we seek to answers the following new questions: (1) To what extent, and under which conditions, is soil and carbon mobilization coupled or de-coupled? (2) How does the partnership between organic matter and mineral phases evolve along the land-ocean aquatic continuum? (3) How do characteristics of different drainage basins manifest themselves in terms of the characteristics of terrestrially-derived OC carried by rivers and accumulating in continental margin sediments? We plan to address these questions through execution of work packages that will explore links between carbon and sediment dynamics in eroding landscapes, assess the evolution of organic matter-mineral associations along the land-ocean aquatic continuum, and derive global-scale perspectives on coupled terrestrial-marine carbon cycle processes. We focus particular attention on the interplay between organic matter and minerals as our prior investigations highlight the pervasive influence of mineral interactions on carbon cycling - both in the context of OM reactivity/stability in terrestrial and aquatic systems and its transport and dispersal. These activities will also involve merging of innovative approaches that will allow assessment of dynamics of mineral and carbon mobilization in landscapes and across the land-ocean aquatic continuum. This and other information will be fed into nascent databases in order to place findings into a global context.