Natural rubber

Quantum mechanics

Composite number

Isotopes of carbon

Materials science

Carbon fibers

Earth science

Geology

Oceanography

Physics

Organic chemistry

Total organic carbon

Environmental chemistry

Environmental science

Composite material

Chemistry

Stable isotope ratio

Charcoal

Carbon black

CMOS

Optoelectronics

Isotopic signature

Nature Communications

A portion of the charcoal and soot produced during combustion processes on land (e.g., wildfire, burning of fossil fuels) enters aquatic systems as dissolved black carbon (DBC). In terms of mass flux, rivers are the main identified source of DBC to the oceans. Since DBC is believed to be representative of the refractory carbon pool, constraining sources of marine DBC is key to understanding the long-term persistence of carbon in our global oceans. Here, we use compound-specific stable carbon isotopes (δ 13 C) to reveal that DBC in the oceans is ~6‰ enriched in 13 C compared to DBC exported by major rivers. This isotopic discrepancy indicates most riverine DBC is sequestered and/or rapidly degraded before it reaches the open ocean. Thus, we suggest that oceanic DBC does not predominantly originate from rivers and instead may be derived from another source with an isotopic signature similar to that of marine phytoplankton.

Isotopic composition of oceanic dissolved black carbon reveals non-riverine source