Microbial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils

TitleMicrobial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils
Publication TypeJournal Article
Year of Publication2018
AuthorsHemingway, JD, Hilton, RG, Hovius, N, Eglinton, TI, Haghipour, N, Wacker, L, Chen, M-C, Galy, VV
JournalScience
Volume360
Issue6385
Pagination209 - 212
Date PublishedJan-04-2019
ISSN0036-8075
Abstract

Lithospheric organic carbon (“petrogenic”; OCpetro) is oxidized during exhumation and subsequent erosion of mountain ranges. This process is a considerable source of carbon dioxide (CO2) to the atmosphere over geologic time scales, but the mechanisms that govern oxidation rates in mountain landscapes are poorly constrained. We demonstrate that, on average, 67 ± 11% of the OCpetro initially present in bedrock exhumed from the tropical, rapidly eroding Central Range of Taiwan is oxidized in soils, leading to CO2 emissions of 6.1 to 18.6 metric tons of carbon per square kilometer per year. The molecular and isotopic evolution of bulk OC and lipid biomarkers during soil formation reveals that OCpetro remineralization is microbially mediated. Rapid oxidation in mountain soils drives CO2 emission fluxes that increase with erosion rate, thereby counteracting CO2 drawdown by silicate weathering and biospheric OC burial.

URLhttps://www.sciencemag.org/lookup/doi/10.1126/science.aao6463
DOI10.1126/science.aao6463