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Enrichment of lignin-derived carbon in mineral-associated soil organic matterAuthor(s): Wenjuan Huang; Kenneth E. Hammel; Jialong Hao; Aaron Thompson; Vitaliy I Timokhin; Steven J. Hall
Source: Environmental Science & Technology. 53(13): 7522-7531. https://doi.org/10.1021/acs.est.9b01834.
Publication Series: Scientific Journal (JRNL)
Station: Forest Products Laboratory
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DescriptionA modern paradigm of soil organic matter proposes that persistent carbon (C) derives primarily from microbial residues interacting with minerals, challenging older ideas that lignin moieties contribute to soil C because of inherent recalcitrance. We proposed that aspects of these old and new paradigms can be partially reconciled by considering interactions between lignin decomposition products and redox-sensitive iron (Fe) minerals. An Fe-rich tropical soil (with C4 litter and either 13C-labeled or unlabeled lignin) was pretreated with different durations of anaerobiosis (0−12 days) and incubated aerobically for 317 days. Only 5.7 ± 0.2% of lignin 13C was mineralized to CO2 versus 51.2 ± 0.4% of litter C. More added lignin-derived C (48.2 ± 0.9%) than bulk litter-derived C (30.6 ± 0.7%) was retained in mineral-associated organic matter (MAOM; density >1.8 g cm−3), and 12.2 ± 0.3% of lignin-derived C vs 6.4 ± 0.1% of litter C accrued in clay-sized (<2 μm) MAOM. Longer anaerobic pretreatments increased added lignin-derived C associated with Fe, according to extractions and nanoscale secondary ion mass spectrometry (NanoSIMS). Microbial residues are important, but lignin-derived C may also contribute disproportionately to MAOM relative to bulk litter-derived C, especially following redox-sensitive biogeochemical interactions.
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CitationHuang, Wenjuan; Hammel, Kenneth E.; Hao, Jialong; Thompson, Aaron; Timokhin, Vitaliy I.; Hall, Steven J. 2019. Enrichment of lignin-derived carbon in mineral-associated soil organic matter. Environmental Science & Technology. 53(13): 7522-7531. https://doi.org/10.1021/acs.est.9b01834.
KeywordsLignin, carbon, soil organic matter, iron, microbial residues
- Lignin decomposition is sustained under fluctuating redox conditions in humid tropical forest soils
- Iron addition to soil specifically stabilized lignin
- Organo-mineral interactions and soil carbon mineralizability with variable saturation cycle frequency
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