Dr. Tom Bianchi is an organic geochemist at the Ocean Processes Analysis Lab in the Institute for the Study of Earth, Oceans, and Space at the University of New Hampshire. Dr. Bianchi studies the biogeochemical dynamics of aquatic systems, with particular emphasis in estuarine and coastal ecosystems, applications of chemical biomarkers in paleooceanography, sea-level rise effects on carbon storage in coastal system, and chemical biomarkers of colloidal, particulate, dissolved and sedimentary organic carbon.

Dr. Tom Bianchi
University of New Hamshire
Institute for the Study of Earth, Oceans, and Space
Ocean Processes Analysis Lab

Earth's Carbon Cycle: A Tale of Molecules, Mud, and Global Change

Roughly 90% of the organic carbon (OC) buried in the global ocean is stored in muddy sediments along continental margins. Estuarine "hotspots" are especially important, with deltas accounting for about 40% of this burial and fjords for around 12%. To understand the sources and fate of OC in aquatic systems, researchers have widely applied molecular biomarkers and bulk geochemical proxies. In my work, I will explore the application of both bulk analytical techniques and molecular biomarkers to investigate how environmental changes across the land–ocean aquatic continuum (LOAC) are influencing OC burial and long-term carbon sequestration.  These muds produced by rock weathering play a critical role in the global carbon cycle by binding and shielding OC from degradation. The quantity and characteristics of OC stored in these muds influence the extent, duration, and mechanisms of carbon sequestration. Human activities—such as dam construction, levee building, and climate change—have significantly altered patterns of mud accumulation and OC content across different environments. I show that climate warming has generally increased mud–OC fluxes (e.g., due to glacier melt, enhanced erosion, and dam-induced burial), although the effects vary regionally. However, it remains uncertain whether these changes lead to greater or lesser long-term OC sequestration, given the complexity and variability of involved timescales.