posted on 2023-11-10, 15:40authored byXueqin Zhang, Mengying Xie, Chen Cai, Hesamoddin Rabiee, Zhiyao Wang, Bernardino Virdis, Gene W. Tyson, Simon J. McIlroy, Zhiguo Yuan, Shihu Hu
Pyrogenic carbon (PC) can mediate
electron transfer and thus catalyze
biogeochemical processes to impact greenhouse gas (GHG) emissions.
Here, we demonstrate that PC can contribute to mitigating GHG emissions
by promoting the Fe(III)-dependent anaerobic oxidation of methane
(AOM). It was found that the amendment PCs in microcosms dominated
by Methanoperedenaceae performing Fe(III)-dependent
AOM simultaneously promoted the rate of AOM and Fe(III) reduction
with a consistent ratio close to the theoretical stoichiometry of
1:8. Further correlation analysis showed that the AOM rate was linearly
correlated with the electron exchange capacity, but not the conductivity,
of added PC materials, indicating the redox-cycling electron transfer
mechanism to promote the Fe(III)-dependent AOM. The mass content of
the CO moiety from differentially treated PCs was well correlated
with the AOM rate, suggesting that surface redox-active quinone groups
on PCs contribute to facilitating Fe(III)-dependent AOM. Further microbial
analyses indicate that PC likely shuttles direct electron transfer
from Methanoperedenaceae to Fe(III) reduction. This
study provides new insight into the climate-cooling impact of PCs,
and our evaluation indicates that the PC-facilitated Fe(III)-dependent
AOM could have a significant contribution to suppressing methane emissions
from the world’s reservoirs.