主要观点总结
中国科学院生态环境研究中心城市与区域生态国家重点实验室研究人员就腐殖酸对稻田土壤碳氮循环的影响展开研究。发现黄腐酸（FA）增强了土壤碳排放并促进了氮循环，为碳管理与减氮施肥策略提供了新视角。
关键观点总结
关键观点1: 黄腐酸对稻田土壤的影响
黄腐酸显著增强了土壤碳排放，通过调控微生物群落促进了稻田土壤氮循环。
关键观点2: 实验结果
添加黄腐酸后，二氧化碳和甲烷排放分别增加至94.08倍和5.06倍，氮固定能力提高1.2倍。
关键观点3: 宏基因组学分析
黄腐酸的应用显著提高了关键代谢基因的丰度，如木质素类化合物降解、甲烷生成、氮固定及尿素水解等。
关键观点4: 黄腐酸在碳氮循环中的作用
黄腐酸强化了碳氮代谢耦合作用，维持了碳氮平衡，为腐殖物质在减少氮肥使用和应对气候变化中的应用奠定了理论基础。
关键观点5: 研究意义
这一成果为提升稻田土壤碳氮管理效率及应对农业可持续发展挑战提供了重要启示。
正文
Fulvic Acid Enhances Nitrogen Fixation and Retention in Paddy Soils through Microbial-Coupled Carbon and Nitrogen Cycling
Fulvic Acid Enhances Nitrogen Fixation and Retention in Paddy Soils through Microbial-Coupled Carbon and Nitrogen Cycling.pdf
近日，中国科学院生态环境研究中心城市与区域生态国家重点实验室的研究人员围绕腐殖酸对稻田土壤碳氮循环的影响展开深入研究，为碳管理与减氮施肥策略提供了全新视角。研究发现，作为一种溶解性最强、活性最高的腐殖物质，黄腐酸（Fulvic Acid, FA）不仅显著增强了土壤碳排放，还通过调控微生物群落促进了稻田土壤氮循环。
实验结果表明，添加黄腐酸后，二氧化碳和甲烷排放分别增加至94.08倍和5.06倍。同时，通过15N标记实验发现，黄腐酸显著提升了氮固定能力（提高1.2倍），从而减缓了碳氮失衡。宏基因组学分析揭示，黄腐酸的应用显著提高了木质素类化合物降解、甲烷生成、氮固定及尿素水解等关键代谢基因的丰度，而抑制了氨氧化和厌氧氨氧化等过程。此外，代谢重建分析表明，在黄腐酸处理下，Azospirillaceae（固氮螺菌科）、Methanosarcinaceae（甲烷八叠球菌科）和Bathyarchaeota（深古菌门）等微生物发挥了重要作用，维持了碳氮平衡。
研究还构建了黄腐酸降解与氮固定及保留耦合的代谢路径，为腐殖物质在减少氮肥使用和应对气候变化中的应用奠定了理论基础。
这一成果为提升稻田土壤碳氮管理效率及应对农业可持续发展挑战提供了重要启示。
Figure 1. Emission rate curves for
CH
4
(A) and
CO
2
(B) during the incubation experiment; the N
2
O concentrations in the flask headspace after 8
h of stopping the air ventilation during the incubation experiment (C); variations of the total nitrogen content in the soil solution during the
incubation experiment (D); soil carbon and nitrogen contents in the soil at the end of the incubation period (day 42); the statistical significance of
the difference between treatments was determined using the t test (* p < 0.05 and *** p < 0.001) (E); the δ15N content in paddy soils in different
treatments was measured after incubation using synthesis gas (15N
2
:O
2
= 80:20). The significance of the difference between treatments was
determined using the Mann−Whitney U test (* p < 0.05) (F).
Figure 2. Functional profiles of the genes involved in carbon and nitrogen cycling; the complex organic matter degradation pathway (A) and
nitrogen metabolism pathway (C) in the present study; the red pentagrams represent the pathways enriched in the FA treatment, whereas the blue
pentagrams indicate the pathways enriched in the CK treatment. The abundance of genes involved in differential metabolic pathways for carbon
(B) and nitrogen cycles (D); the abundance values of genes in each treatment represent the averages of triplicate samples. The error bars indicate
the standard deviation (SD) of the mean. The significance of the difference between treatments was evaluated using the DESeq2 package (*p <
0.05 and **p < 0.01).
Figure 3. Differentially abundant MAGs between treatments; the taxonomic classification of MAGs was conducted against GTDB. The
phylogenetic tree was constructed based on the concatenated alignment of conserved
protein sequences from MAGs. Differential analysis was
performed using the Deseq2 package in R V4.3.1. The blue pentagrams represent the enrichment of MAGs in CK, while the red pentagrams
indicate that MAGs were enriched in the FA treatment (p < 0.05).
Figure 4. Metabolic properties of MAGs recovered from the fulvic acid-amended and control metagenomes in this study; solid circles indicate the
presence of genes. The red pentagrams represent the enriched MAGs in the FA treatment, while the blue pentagrams denote the enriched MAGs in
the CK treatment. The genes related to carbon metabolism and transport were searched against the KEGG database, whereas the genes related to
nitrogen metabolism were searched against NCycDB. Key microorganisms playing roles in carbon and nitrogen cycling in soils amended with fulvic
acid were highlighted in a blue box.
Figure 5. Overview of metabolic potentials in MAGs of Azospirillaceae (A), UBA233 (B), and Methanosarcinaceae (C); the genes involved in
glycolysis, methanogenesis, the reductive TCA (rTCA)/TCA cycles, nitrogen and sulfur metabolism, the urea cycle, fatty acid beta-oxidation,
fermentation, protein degradation, membrane transport, the pentose-phosphate pathway, and the Wood−Ljungdahl pathway are shown. The
dashed line represented the cross-feeding relationship between these microorganisms.
研究人员围绕黄腐酸对稻田土壤碳氮循环的影响展开深入研究，取得了重要进展。研究表明，黄腐酸不仅显著改变了土壤微生物群落结构，还通过强化碳氮代谢耦合作用，促进了土壤氮的固定和可利用性，同时引发了二氧化碳和甲烷排放的显著增加。
研究发现，黄腐酸作为碳源，促进了Azospirillaceae（固氮螺菌科）、Methanosarcinaceae（甲烷八叠球菌科）和Bathyarchaeota（深古菌门）在碳氮耦合代谢中的关键作用。这些微生物通过降解黄腐酸生成乙酸、甲基化化合物等代谢物，进一步驱动固氮和甲烷生成。此外，黄腐酸的应用显著抑制了氨氧化和厌氧氨氧化过程，有效减少了氮素损失，提升了稻田土壤的氮供应能力。
尽管研究揭示了黄腐酸在提高生物固氮效率和优化稻田土壤肥力方面的潜力，但其对温室气体排放的促进作用也引发了研究人员的关注。黄腐酸的应用需要在提升农业生产力与应对气候变化之间实现平衡。该研究为进一步理解稻田土壤的碳氮循环提供了新视角，同时为黄腐酸的合理使用和农业可持续发展提出了科学建议。
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https://www.springer.com/journal/44246
改性生物炭：合成及其去除环境中重金属的机制
Modified biochar: synthesis and mechanism for removal of environmental heavy metals
更好地理解土壤中铁循环对碳的稳定及降解的作用
Towards a better understanding of the role of Fe cycling in soil for carbon stabilization and degradation
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第二届Carbon Research青年学者论坛在宁波胜利召开
