TY - JOUR

T1 - Direct evidence for thickening nanoscale organic films at soil biogeochemical interfaces and its relevance to organic matter preservation

AU - Huang, Xizhi

AU - Li, Yiwei

AU - Guggenberger, Georg

AU - Kuzyakov, Yakov

AU - Liu, Bi Feng

AU - Wu, Jinshui

N1 - Funding information: The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (Grant number 41090283; Grant number 41430860; Grant number 41807051); Open funding from Key Laboratory of Agro-ecological Processes in subtropical region, Institute of Subtropical Agro-ecology, the Chinese Academy of Sciences (Grant number ISA2018301); China Postdoctoral Fund (Grant number 2019M662635). The publication was also supported by the Government Program of Competitive Growth of Kazan Federal University and the “RUDN University program 5-100”.

PY - 2020/7/31

Y1 - 2020/7/31

N2 - The emerging consensus on organic matter (OM) cycling in soil and sediment proposes that a continuum of biological and geochemical processes in the micro-environment controls the fate of OM. However, spatio-temporal observation of the biogeochemical nature and behaviour of OM at the soil-water interfaces (SWIs) is impeded by the heterogonous and opaque nature of their microenvironment. Herein, we used a novel SoilChip method (soil microarrays incubated with a predefined solution) to continuously mimic and trace the OM biogeochemistry at SWIs for 21 days. Combining X-ray photoelectron spectroscopy and ion sputtering on SoilChips, we provided the first direct evidence that a nanoscale organic film with a distinct composition and thickness gradually formed at the SWI within 21 days of cultivation. Although the OM coating on the SWI quickly reached equilibrium within 4 days, the formation of thicker mineral-organic association (MOA, 20-130 nm) and microbial biomass (>130 nm) continued, partially at the cost of the thin MOA (<20 nm). Consistent with the thickening SWI, the bioavailability of nutrients (dissolved organic C and ammonium) decreased gradually over 21 days, which restrained the microbial activities. Collectively, thickening SWIs act as a biogeochemical gate to regulate the bioavailability of specific organic compounds and determine their preservation or microbial mineralization. Further, thickening SWIs in thez-axis direction provide direct structural insight to increase carbon sequestration in soil and sediment.

AB - The emerging consensus on organic matter (OM) cycling in soil and sediment proposes that a continuum of biological and geochemical processes in the micro-environment controls the fate of OM. However, spatio-temporal observation of the biogeochemical nature and behaviour of OM at the soil-water interfaces (SWIs) is impeded by the heterogonous and opaque nature of their microenvironment. Herein, we used a novel SoilChip method (soil microarrays incubated with a predefined solution) to continuously mimic and trace the OM biogeochemistry at SWIs for 21 days. Combining X-ray photoelectron spectroscopy and ion sputtering on SoilChips, we provided the first direct evidence that a nanoscale organic film with a distinct composition and thickness gradually formed at the SWI within 21 days of cultivation. Although the OM coating on the SWI quickly reached equilibrium within 4 days, the formation of thicker mineral-organic association (MOA, 20-130 nm) and microbial biomass (>130 nm) continued, partially at the cost of the thin MOA (<20 nm). Consistent with the thickening SWI, the bioavailability of nutrients (dissolved organic C and ammonium) decreased gradually over 21 days, which restrained the microbial activities. Collectively, thickening SWIs act as a biogeochemical gate to regulate the bioavailability of specific organic compounds and determine their preservation or microbial mineralization. Further, thickening SWIs in thez-axis direction provide direct structural insight to increase carbon sequestration in soil and sediment.

UR - http://www.scopus.com/inward/record.url?scp=85091867626&partnerID=8YFLogxK

U2 - 10.1039/d0en00489h

DO - 10.1039/d0en00489h

M3 - Article

AN - SCOPUS:85091867626

VL - 7

SP - 2747

EP - 2758

JO - Environmental science: Nano

JF - Environmental science: Nano

SN - 2051-8153

IS - 9

ER -