Prof Tim Eglinton, Geological Institute at ETH Zurich, will be giving this special Cabot lunchtime seminar on the dynamics of organic carbon movement through river basins.

Abstract

How much of the organic carbon produced by the terrestrial biosphere is discharged by rivers to the oceans? From where within a river basin does this carbon originate? How long does it take for organic matter produced by land plants to travel through river systems to the oceans?  These fundamental questions are of central importance for understanding this key component of the global carbon cycle – yet at present we do not have satisfactory answers to these and numerous other questions relating to carbon cycling in river drainage basins.

In an effort to bridge this information gap, we are undertaking studies designed to constrain the source and age of terrestrial organic carbon transported through, and exported from river drainage basins. This presentation will illustrate a range of sampling and analytical approaches that we are employing to examine carbon provenance and dynamics. Observations from studies of a broad range of modern fluvial systems will be synthesized in order to explore the factors that influence the source and age characteristics of specific components of terrestrial biospheric carbon carried by rivers to the ocean.  Particular emphasis will be placed on molecular-level radiocarbon (¹⁴C) measurements that provide a window on the dynamics of terrestrial carbon delivery to the oceans.  When coupled with isotopic signals of carbon source (d¹³C, dD), novel insights can be gleaned concerning the processes involved in carbon storage and transport within fluvial systems.  Implications for our understanding of continental organic carbon cycling and for interpretation of paleoclimate records will be discussed.