carbon cycle; climate; continental margins; radiocarbon; rivers; proxies; drainage basin; terrestrial biosphere; biological markers; land use; soils; Anthropocene
Galy Valier, Peucker-Ehrenbrink Bernhard, Eglinton Timothy (2015), Global carbon export from the terrestrial biosphere controlled by erosion, in Nature
, 521, 204-207.
Feng Xiaojuan, Gustafsson Orjan, Holmes R. Max, Vonk Jorien, van Dongen Bart, Semiletov Igor, Dudarev Oleg, Yunker Mark, Macdonald Robie, Wacker Lukas, Montlucon Daniel, Eglinton Timothy (2015), Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic: 14C characteristics of sedimentary carbon components and their environmental controls, in Global Biogeochemical Cycles
, 29, 1855-1873.
Feng Xiaojuan, Gustafsson Orjan, Holmes R. Max, Vonk Jorien, van Dongen Bart, Semiletov Igor, Dudarev O., Yunker Mark, Macdonald Robie, Montlucon Daniel, Eglinton Timothy (2015), Multi-molecular tracers of terrestrial carbon transfer across the pan-Arctic: comparison of hydrolyzable components with plant wax lipids and lignin phenols, in Biogeosciences
, 12, 4841-4860.
Tao Shuqin, Eglinton Timothy, Montlucon Daniel, McIntyre Cameron, Zhao Meixun (2015), Pre-aged soil organic carbon as a major component of the Yellow River suspended load: Regional significance and global relevance, in Earth and Planetary Science Letters
, 414, 77-86.
The abundances, distributions, and isotopic signatures of source-specific ‘biomarker’ compounds preserved in aquatic sediments are increasingly being used to derive a diverse array of paleoenvironmental and paleoclimatic information. With analytical advances and development of streamlined methodological approaches, there is growing emphasis on biomarker-based reconstructions of past climate at high temporal resolution, and as part of multi-proxy investigations. Many of these investigations are focused on continental margin settings characterized by strong terrestrial and aquatic inputs and enhanced sediment accumulation rates. On a global basis, continental margin sediments are locations of extensive burial of both marine and terrestrial carbon. The pace and efficacy of biospheric carbon sequestration within these systems represents a major factor in regulating atmospheric CO2.Crucial to the accurate interpretation of molecular proxy records embedded in continental margin sediments is a robust understanding of the provenance of the signals, as well as the timescales associated with their transfer from biological source to sedimentary sink. There is often an implicit assumption that the delivery of these signals to the sedimentary archive is virtually instantaneous, however there is growing evidence from biomarker 14C measurements that transport may take several hundred to several thousand years. Storage in soils and at other locations within terrestrial drainage basins may induce significant temporal lags, potentially aliasing marine and terrestrial proxy signals in down-core records. We hypothesize that the magnitude of such temporal lags may vary as a function of climate and other (e.g., anthropogenic) controls on biospheric carbon storage in terrestrial drainage basins, potentially yielding complex age relationships among proxy records through time, and influencing the dynamic of carbon exchange between atmospheric and marine sedimentary reservoirs. In this study, we propose a detailed examination of the temporal relationships between three different terrestrial biomarker proxies in well-dated continental margin sediment cores for which climate-driven changes have already been documented. We focus primarily on tropical regions where past changes in the hydrologic cycle appear to have influenced continental vegetation and, we suspect, carbon storage and transport within continental drainage basins. The approach involves measurement of the radiocarbon contents and other isotopic characteristics of specific molecular species (plant waxes, lignin-derived phenols, and soil bacteria-derived ether lipids) that both serve as tracers of terrestrial carbon and are employed extensively as proxies of continental vegetation and climate. There are two elements to the proposed project: (1) application of established and novel molecular isotopic methods to existing sediment cores that record past climate variability, and (2) examination of relationships between drainage basin characteristics of terrestrial carbon transport within a modern river system.In addition to consequences for interpretation of sediment records, changes in the delivery of carbon produced by the terrestrial biosphere to continental margin sediments may have significant implications for climate and anthropogenically-driven carbon redistribution between the atmospheric and long-term storage pools.