posted on 2023-08-30, 18:42authored byJunjie Wang, Lauriane Vilmin, José M. Mogollón, Arthur H. W. Beusen, Wim J. van Hoek, Xiaochen Liu, Philip A. Pika, Jack J. Middelburg, Alexander F. Bouwman
Nitrous oxide (N2O) is a long-lived greenhouse gas and
currently contributes ∼10% to global greenhouse warming. Studies
have suggested that inland waters are a large and growing global N2O source, but whether, how, where, when, and why inland-water
N2O emissions changed in the Anthropocene remains unclear.
Here, we quantify global N2O formation, transport, and
emission along the aquatic continuum and their changes using a spatially
explicit, mechanistic, coupled biogeochemistry–hydrology model.
The global inland-water N2O emission increased from 0.4
to 1.3 Tg N yr–1 during 1900–2010 due to
(1) growing N2O inputs mainly from groundwater and (2)
increased inland-water N2O production, largely in reservoirs.
Inland waters currently contribute 7 (5–10)% to global total
N2O emissions. The highest inland-water N2O
emissions are typically in and downstream of reservoirs and areas
with high population density and intensive agricultural activities
in eastern and southern Asia, southeastern North America, and Europe.
The expected continuing excessive use of nutrients, dam construction,
and development of suboxic conditions in aging reservoirs imply persisting
high inland-water N2O emissions.